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Sample records for randomly oriented zno

  1. Performance of inverted polymer solar cells with randomly oriented ZnO nanorods coupled with atomic layer deposited ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Zafar, Muhammad [School of Chemical Engineering, Chonnam National University, 300 Youngbong-dong, Gwangju 500-757 (Korea, Republic of); Yun, Ju-Young [Center for Vacuum, Korea Research Institute of Standards and Science, 267 Gajeong-ro, Daejeon 305-600 (Korea, Republic of); Kim, Do-Heyoung, E-mail: kdhh@chonnam.ac.kr [School of Chemical Engineering, Chonnam National University, 300 Youngbong-dong, Gwangju 500-757 (Korea, Republic of)

    2017-03-15

    Highlights: • Hydrothermally grown, randomly oriented, and low areal density ZnO nanorods have been successfully adopted as the electron transport layer in inverted organic solar cells. • The addition of atomic layer deposited ZnO on the ZnO nanorods effectively enhance the photovoltaic performances of inverted organic solar cells. • The inverted organic solar cells with 5 nm thick-ALD ZnO showed the highest power conversion efficiency of 3.08%, which is an enhancement of approximately 80% compared to the cells without the ALD ZnO layer (PCE = 1.67%). - Abstract: Nanostructuring of the electron transport layer (ETL) in organic photovoltaic cells (OPV) is of great interest because it increases the surface area of the cell and electron transport. In this work, hydrothermally grown, randomly oriented, and low areal density ZnO nanorods (NRs) have been adopted as the ETL, and the effect of adding atomic layer deposited (ALD) ZnO on the ZnO NRs on the inverted organic solar cell performance has been investigated. The fabricated inverted organic solar cell with 5-nm-thick ALD-ZnO grown on the ZnO NRs showed the highest power conversion efficiency (PCE) of 3.08%, which is an enhancement of 85% from that of the cell without ALD-ZnO (PCE = 1.67%). The ultrathin ALD-ZnO was found to act as a curing layer of the surface defects on the hydrothermally grown ZnO NRs, resulting in an improvement in photovoltaic performance.

  2. Performance of inverted polymer solar cells with randomly oriented ZnO nanorods coupled with atomic layer deposited ZnO

    Science.gov (United States)

    Zafar, Muhammad; Yun, Ju-Young; Kim, Do-Heyoung

    2017-03-01

    Nanostructuring of the electron transport layer (ETL) in organic photovoltaic cells (OPV) is of great interest because it increases the surface area of the cell and electron transport. In this work, hydrothermally grown, randomly oriented, and low areal density ZnO nanorods (NRs) have been adopted as the ETL, and the effect of adding atomic layer deposited (ALD) ZnO on the ZnO NRs on the inverted organic solar cell performance has been investigated. The fabricated inverted organic solar cell with 5-nm-thick ALD-ZnO grown on the ZnO NRs showed the highest power conversion efficiency (PCE) of 3.08%, which is an enhancement of 85% from that of the cell without ALD-ZnO (PCE = 1.67%). The ultrathin ALD-ZnO was found to act as a curing layer of the surface defects on the hydrothermally grown ZnO NRs, resulting in an improvement in photovoltaic performance.

  3. RF sputtering enhanced the morphology and photoluminescence of multi-oriented ZnO nanostructure produced by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Al-Salman, Husam S., E-mail: husam.shakir@yahoo.com [School of Physics, University Sains Malaysia, Penang 11800 (Malaysia); Dept. of Physics, College of Science, University of Basrah, Basrah (Iraq); Abdullah, M.J. [School of Physics, University Sains Malaysia, Penang 11800 (Malaysia)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer A ZnO nanostructure was synthesized using the CVD and RF techniques. Black-Right-Pointing-Pointer High-quality ZnO nanorods were obtained. Black-Right-Pointing-Pointer The nanorods grow at a random angle on the substrate surface. Black-Right-Pointing-Pointer The RF sputter-coating step enhanced the structural quality of the ZnO film. - Abstract: Pure hexagonal wurtzite ZnO nanostructure was successfully synthesized by chemical vapor deposition (CVD) and RF-magnetron sputtering without using any catalysts. In the two-step process, high-quality multi-oriented ZnO nanorods were obtained. Multi-oriented spear-like ZnO rods were pre-deposited on the SiO{sub 2}/Si(1 0 0) substrate by CVD at 700 Degree-Sign C followed by RF sputtering of the ZnO nanostructure. The synthesized ZnO nanostructures were characterized by X-ray diffraction, field emission scanning electron microscopy, and photoluminescence (PL). The results show that the RF sputtering of the ZnO nanostructure, which was coated with a ZnO film produced by CVD, might have promoted the uniformity and crystalline quality of the multi-oriented spear-like ZnO film. The PL spectra revealed a sharp and dominant peak located at approximately 382 nm with a UV-to-visible PL intensity ratio (I{sub UV}/I{sub VS}) of 42 for the sample that was produced by the two-step process. The growth mechanism of the multi-oriented spear-like ZnO nanorods was investigated.

  4. Preferred oriented ZnO films growth on nonoriented substrates by CVD

    Science.gov (United States)

    Abduev, A.; Akhmedov, A.; Asvarov, A.; Omaev, A.

    2012-02-01

    The processes of CVD synthesis of ZnO layers with different preferred orientation on non-crystalline substrates where studied. Synthesis was carried out in a hydrogen atmosphere on substrates with ZnO buffer layers with various preferred orientation, namely in the plane perpendicular as well as parallel to plane of the substrate. ZnO buffer layers were synthesized by magnetron sputtering of ZnO ceramic targets. Conditions for the ZnO layers formation by CVD with (002), (100), (110) preferred orientations and mixed (100) - (110) orientations were determined.

  5. C-Axis-Oriented Hydroxyapatite Film Grown Using ZnO Buffer Layer

    Science.gov (United States)

    Sakoishi, Yasuhiro; Iguchi, Ryo; Nishikawa, Hiroaki; Hontsu, Shigeki; Hayami, Takashi; Kusunoki, Masanobu

    2013-11-01

    A method of fabricating c-axis-oriented hydroxyapatite film on a quartz crystal microbalance (QCM) sensor was investigated. ZnO was used as a template to obtain a hexagonal hydroxyapatite crystal of uniaxial orientation. The ZnO was grown as a c-axis film on a Au/quartz with the surface structure of a QCM sensor. Under optimized conditions, hydroxyapatite was deposited by pulsed laser deposition. X-ray diffraction showed the hydroxyapatite film to be oriented along the c-axis. Because Au and ZnO are applied to many devices, the anisotropic properties of hydroxyapatite may be incorporated into these devices as well as QCM sensors.

  6. Atomic structure and orientation relations of interfaces between Ag and ZnO

    NARCIS (Netherlands)

    Vellinga, W.P; de Hosson, J.T.M.

    This paper presents the results of investigations of Ag-ZnO interfaces, produced by internal oxidation of an Ag-Zn alloy. ZnO precipitates with the wurtzite structure were found exhibiting mainly one orientation relation with the Ag matrix. However, closely related ORs were found, rotated by small

  7. From Bloch to random lasing in ZnO self-assembled nanostructures

    DEFF Research Database (Denmark)

    Garcia-Fernandez, Pedro David; Cefe, López

    2013-01-01

    In this paper, we present measurements on UV lasing in ZnO ordered and disordered nanostructures. Bloch lasing is achieved in the ordered structures by exploiting very low group-velocity Bloch modes in ZnO photonic crystals. In the second case, random lasing is observed in ZnO photonic glasses. We...... study the lasing threshold in both cases and its dependence on the structural parameters. Finally, we present the transition from Bloch to random lasing by deliberately doping a ZnO inverse photonic crystal with a controlled amount of lattice vacancies effectively converting it into a translationally...

  8. Photocatalytic degradation of methyl orange over single crystalline ZnO: orientation dependence of photoactivity and photostability of ZnO.

    Science.gov (United States)

    Kislov, Nikolai; Lahiri, Jayeeta; Verma, Himanshu; Goswami, D Yogi; Stefanakos, Elias; Batzill, Matthias

    2009-03-03

    The photocatalytic destruction of methyl orange in aqueous solution has been studied over single crystal ZnO surfaces under UV irradiation. Differences in the apparent reaction rates between the polar surfaces (first order) and the nonpolar ZnO(10-10) surface (zero order) were observed. Reaction rates for different crystallographic orientations showed the highest activity for ZnO(10-10) followed by ZnO(0001)-Zn and the lowest activity for ZnO(000-1)-O surfaces. In addition, the etching of surfaces by photolysis has been studied. For this process, strongly face-dependent behavior was also observed. Possible reasons for the face dependencies are discussed.

  9. Orientation Control of ZnO Films Deposited Using Nonequilibrium Atmospheric Pressure N2/O2 Plasma

    Science.gov (United States)

    Nose, Yukinori; Nakamura, Tatsuru; Yoshimura, Takeshi; Ashida, Atsushi; Uehara, Tsuyoshi; Fujimura, Norifumi

    2013-01-01

    Nonequilibrium atmospheric pressure N2/O2 plasma was applied to the chemical vapor deposition (CVD) of zinc oxide (ZnO) films on glass substrates at the substrate temperature of 200 °C. Although the deposition temperature is very low, the ZnO films showed (0001) preferred orientation including a small amount of diffraction from the (1011) plane. We attempted to improve the (0001) preferred orientation for ZnO films without increasing the substrate temperature. After systematic experiments, we found that adjusting the ratio of the oxygen flow rate in the total gas flow rate [O2/(O2+ N2) ratio] was effective for orientation control of the ZnO films. This result indicates the potential of nonequilibrium atmospheric pressure N2/O2 plasma for the low-temperature CVD process of ZnO films used in piezoelectric devices and transparent thin-film transistors on a flexible substrate.

  10. (0 0 2-oriented growth and morphologies of ZnO thin films prepared by sol-gel method

    Directory of Open Access Journals (Sweden)

    Guo Dongyun

    2016-09-01

    Full Text Available Zinc acetate was used as a starting material to prepare Zn-solutions from solvents and ligands with different boiling temperature. The ZnO thin films were prepared on Si(1 0 0 substrates by spin-coating method. The effect of baking temperature and boiling temperature of the solvents and ligands on their morphologies and orientation was investigated. The solvents and ligands with high boiling temperature were favorable for relaxation of mechanical stress to form the smooth ZnO thin films. As the solvents and ligands with low boiling temperature were used to prepare Zn-solutions, the prepared ZnO thin films showed (0 0 2 preferred orientation. As n-propanol, 2-methoxyethanol, 2-(methylaminoethanol and monoethanolamine were used to prepare Zn-solutions, highly (0 0 2-oriented ZnO thin films were formed by adjusting the baking temperature.

  11. Optimization of processing parameters on the controlled growth of c-axis oriented ZnO nanorod arrays

    Energy Technology Data Exchange (ETDEWEB)

    Malek, M. F., E-mail: mfmalek07@gmail.com; Rusop, M., E-mail: rusop@salam.uitm.my [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre (NST), Institute of Science (IOS), Universiti Teknologi MARA - UiTM, 40450 Shah Alam, Selangor (Malaysia); Mamat, M. H., E-mail: hafiz-030@yahoo.com [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Musa, M. Z., E-mail: musa948@gmail.com [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM) Pulau Pinang, Jalan Permatang Pauh, 13500 Permatang Pauh, Pulau Pinang (Malaysia); Saurdi, I., E-mail: saurdy788@gmail.com; Ishak, A., E-mail: ishak@sarawak.uitm.edu.my [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM) Sarawak, Kampus Kota Samarahan, Jalan Meranek, 94300 Kota Samarahan, Sarawak (Malaysia); Alrokayan, Salman A. H., E-mail: dr.salman@alrokayan.com; Khan, Haseeb A., E-mail: khan-haseeb@yahoo.com [Chair of Targeting and Treatment of Cancer Using Nanoparticles, Deanship of Scientific Research, King Saud University (KSU), Riyadh 11451 (Saudi Arabia)

    2016-07-06

    Optimization of the growth time parameter was conducted to synthesize high-quality c-axis ZnO nanorod arrays. The effects of the parameter on the crystal growth and properties were systematically investigated. Our studies confirmed that the growth time influence the properties of ZnO nanorods where the crystallite size of the structures was increased at higher deposition time. Field emission scanning electron microsope analysis confirmed the morphologies structure of the ZnO nanorods. The ZnO nanostructures prepared under the optimized growth conditions showed an intense XRD peak which reveal a higher c-axis oriented ZnO nanorod arrays thus demonstrating the formation of defect free structure.

  12. Electrochemical Synthesis of Highly Oriented, Transparent, and Pinhole-Free ZnO and Al-Doped ZnO Films and Their Use in Heterojunction Solar Cells.

    Science.gov (United States)

    Kang, Donghyeon; Lee, Dongho; Choi, Kyoung-Shin

    2016-10-04

    Electrochemical synthesis conditions using nonaqueous solutions were developed to prepare highly transparent (T > 90%) and crystalline ZnO and Al-doped ZnO (AZO) films for use in solar energy conversion devices. A focused effort was made to produce pinhole-free films in a reproducible manner by identifying a key condition to prevent the formation of cracks during deposition. The polycrystalline domains in the resulting films had a uniform orientation (i.e., the c-axis perpendicular to the substrate), which enhanced the electron transport properties of the films. Furthermore, electrochemical Al doping of ZnO using nonaqueous media, which was demonstrated for the first time in this study, effectively increased the carrier density and raised the Fermi level of ZnO. These films were coupled with an electrodeposited p-type Cu2O to construct p-n heterojunction solar cells to demonstrate the utilization of these films for solar energy conversion. The resulting n-ZnO/p-Cu2O and n-AZO/p-Cu2O cells showed excellent performance compared with previously reported n-ZnO/p-Cu2O cells prepared by electrodeposition. In particular, replacing ZnO with AZO resulted in simultaneous enhancements in short circuit current and open circuit potential, and the n-AZO/p-Cu2O cell achieved an average power conversion efficiency (η) of 0.92 ± 0.09%. The electrodeposition condition reported here will offer a practical and versatile way to produce ZnO or AZO films, which play key roles in various solar energy conversion devices, with qualities comparable to those prepared by vacuum-based techniques.

  13. Controlled growth of vertically aligned ZnO nanowires with different crystal orientation of the ZnO seed layer

    Science.gov (United States)

    Cha, S. N.; Song, B. G.; Jang, J. E.; Jung, J. E.; Han, I. T.; Ha, J. H.; Hong, J. P.; Kang, D. J.; Kim, J. M.

    2008-06-01

    A novel synthesis and growth method achieving vertically aligned zinc oxide (ZnO) nanowires on a silicon dioxide (SiO2) coated silicon (Si) substrate is demonstrated. The growth direction of the ZnO nanowires is determined by the crystal structure of the ZnO seed layer, which is formed by the oxidation of a DC-sputtered Zn film. The [002] crystal direction of the seed layer is dominant under optimized thickness of the Zn film and thermal treatment. Vertically aligned ZnO nanowires on SiO2 coated Si substrate are realized from the appropriately thick oxidized Zn seed layer by a vapor-solid growth mechanism by catalyst-free thermal chemical vapor deposition (CVD). These experimental results raise the possibility of using the nanowires as functional blocks for high-density integration systems and/or photonic applications.

  14. Low temperature growth of highly transparent c-axis oriented ZnO thin films by pulsed laser deposition

    NARCIS (Netherlands)

    Amirhaghi, S.; Craciun, V.; Craciun, D.; Elders, J.; Boyd, I.W.

    1994-01-01

    The effects of the oxygen partial pressure, substrate temperature and laser wavelength on the structural and optical properties of thin films of ZnO grown on silicon and glass substrates by pulsed laser deposition have been studied. Regardless of thickness, all the grown layers are c-axis oriented

  15. Fabrication and Characterization of Highly Oriented N-Doped ZnO Nanorods by Selective Area Epitaxy

    Directory of Open Access Journals (Sweden)

    Yang Zhang

    2015-01-01

    Full Text Available High-quality nitrogen-doped ZnO nanorods have been selectively grown on patterned and bare ZnO templates by the combination of nanoimprint lithography and chemical vapor transport methods. The grown nanorods exhibited uniformity in size and orientation as well as controllable density and surface-to-volume ratio. The structural and optical properties of ZnO nanorods and the behaviour of N dopants have been investigated by means of the scanning electron microscope, photoluminescence (PL spectra, and Raman scattering spectra. The additional vibration modes observed in Raman spectra of N-doped ZnO nanorods provided solid evidence of N incorporation in ZnO nanorods. The difference of excitonic emissions from ZnO nanorods with varied density and surface-to-volume ratio suggested the different spatial distribution of intrinsic defects. It was found that the defects giving rise to acceptor-bound exciton (A0X emission were most likely to distribute in the sidewall surface with nonpolar characteristics, while the donor bound exciton (D0X emission related defects distributed uniformly in the near top polar surface.

  16. Optically driven random lasing in ZnO nanorods prepared by chemical bath deposition

    Science.gov (United States)

    Maryam, W.; Fazrina, N.; Hashim, M. R.; Hsu, H. C.; Halim, M. M.

    2017-09-01

    In this paper, we report on room temperature UV lasing emission observed in a mirror-less ZnO sample prepared by two-step chemical bath deposition technique; a popular low cost method for making ZnO nanorods. We attribute the mechanism of the laser emission to coherent multiple light scattering between the nanorods within the illuminated area of excitation. Reduced threshold condition was observed for the nanorods having smallest crystallite size. Furthermore, the ability to maintain the number of modes at different excitation areas of the sample as well as at different pump powers suggests this method of growing the ZnO nanorods as a promising growth method for industry in developing high efficiency low cost random lasers for future integrated photonic devices.

  17. ZnO nanorods as scatterers for random lasing emission from dye doped polymer films.

    Science.gov (United States)

    Zhang, Dingke; Wang, Yanping; Ma, Dongge

    2009-05-01

    A random lasing emission from 4-(dicy-anomethylene)-2-t-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) doped polystyrene (PS) thin films was realized by the scattering role of ZnO nanorods. The device was fabricated by spin-coating DCJTB doped PS on ZnO nanorods. The ZnO nanorods were grown on indium-tin-oxide (ITO) glass substrate by hydrothermal synthesis method. It can be seen that the device emits a resonance multimode peak at center wavelength of 630 nm with a mode line-width of less than 0.23 nm and exhibits threshold excitation intensity as low as 0.375 mJ pulse(-1) cm(-2). The agreement of the dependence of threshold pumped intensity on the excitation area with the random laser theory indicates that the lasing emission realized here is random laser. Our results demonstrate that the nanostructured ZnO nanorods are promising candidate as alternative sources of coherent light emission to realize organic lasers.

  18. Nonvolatile Resistance Random Access Memory Devices Based on ZnO Nanorod Arrays

    Directory of Open Access Journals (Sweden)

    Liang-Wen Ji

    2015-02-01

    Full Text Available In this paper, a nonvolatile resistance random access memory (RRAM device based on ZnO nanorod arrays has been fabricated and characterized. Vertically aligned ZnO nanorod layers (NRLs were deposited on indium tin oxide (ITO electrodes using a hydrothermal process/ chemical bath deposition (CBD. It can be found the Ag/ZnO NRL/ITO capacitor exhibits bipolar resistive switching behavior. The resistive switching behavior may be related to the oxygen vacancies and/or zinc interstitials confined on the surface of the ZnO NRs, giving rise to the formation of straight and extensible conducting path along each ZnO NR. Furthermore, superior stability in resistive switching characteristics was also observed. Both growing times and annealing times were investigated and annealing was done in oxygen for 3, 6 and 9 minutes at different temperatures. For ZnO nanorods that had been annealed for 6 minutes the forming voltage was about 6.06V, the Set voltage was about 3.25V and the Reset voltage was -2.78V. The original resistance was 7×106Ω. The resistance in the low-resistance state was 108Ω and in the high-resistance state was 2016Ω, the resistance ratio was 18.7.

  19. Enhanced Light Scattering by Preferred Orientation Control of Ga Doped ZnO Films Prepared through MOCVD

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    Long Giang Bach

    2016-01-01

    Full Text Available We have explored the effective approach to fabricate GZO/ZnO films that can make the pyramidal surface structures of GZO films for effective light scattering by employing a low temperature ZnO buffer layer prior to high temperature GZO film growth. The GZO thin films exhibit the typical preferred growth orientations along the (002 crystallographic direction at deposition temperature of 400°C and SEM showed that column-like granule structure with planar surface was formed. In contrast, GZO films with a pyramidal texture surface were successfully developed by the control of (110 preferred orientation. We found that the light diffuse transmittance of the film with a GZO (800 nm/ZnO (766 nm exhibited 13% increase at 420 nm wavelength due to the formed large grain size of the pyramidal texture surface. Thus, the obtained GZO films deposited over ZnO buffer layer have high potential for use as front TCO layers in Si-based thin film solar cells. These results could develop the potential way to fabricate TCO based ZnO thin film using MOCVD or sputtering techniques by depositing a low temperature ZnO layer to serve as a template for high temperature GZO film growth. The GZO films exhibited satisfactory optoelectric properties.

  20. Structural and optical properties of highly (110)-oriented non-polar ZnO evaporated films on Si substrates

    Science.gov (United States)

    Yang, Shang-Dong; Zheng, Yu-Xiang; Yang, Liao; Liu, Zhun-Hua; Zhou, Wen-Jie; Wang, Song-You; Zhang, Rong-Jun; Chen, Liang-Yao

    2017-11-01

    Zinc oxide (ZnO) films with thicknesses from (9.1 ± 0.7) to (145 ± 7) nm were deposited on silicon substrates by ion-assisted electron beam evaporation (EBE), and transformed to a highly (110)-oriented non-polar phase through thermal treatment at temperatures of 300, 500, and 700 °C. The structural, morphological and optical properties of the ZnO thin films were systematically characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), atomic force microscopy (AFM), spectroscopic ellipsometry (SE), and photoluminescence (PL). The XRD and AFM results illustrate that the deposited ZnO films evolved from an X-ray amorphous structure to the polycrystalline hexagonal wurtzite structure with increasing thickness and experienced a crystallographic plane improvement from (102) to the (110) non-polar phase during annealing. The dielectric functions of the whole layer are mainly affected by the dielectric responses near the surface of ZnO nanocrystals and show an upward trend with nanocrystal growth, induced by thickness and annealing temperature. The optical band gaps were also investigated and correlated with the structural properties. In the PL spectra, a strong ultraviolet luminescence (UVL) band and a weak visible green luminescence (GL) band were observed. The intensity ratio of UVL and GL-associated with crystal quality-agrees with the results acquired from other measurements. The two determinants for highly (110)-oriented non-polar ZnO films are the suppression of growth in the (002) direction by ion bombardment and the promotion of the (110) plane induced by diffusion energy during annealing.

  1. Low-bandgap, highly c-axis-oriented Al-doped ZnO thin films

    Science.gov (United States)

    Wen, Long; Kumar, Manish; Cho, Hyung Jun; Leksakul, Komgrit; Geon Han, Jeon

    2017-05-01

    Low-bandgap transparent conductive oxides will be of interest to researchers who wish to address the health hazards of blue radiation emission from electronic displays. Here, we present a single-step, low-temperature fast enough (throughput  >  60 nm min-1) process to grow highly c-axis-oriented crystalline Al-doped ZnO thin films via advanced plasma processing. Dual-power DC-magnetron sputtering plasma was employed for the synthesis of thin films. The addition of top power to a pre-existing rectangular power pushed additional ions to a confined plasma and increased the plasma density and electron temperature. The effect of this additional-ion pushing was systematically studied using the microstructure, surface properties, and electronic properties. As a result, bandgap reduction from 3.35 eV to 3.10 eV and tailoring of electrical resistivity (4.89  ×  10-4-8.32  ×  10-3 Ω cm) and Seebeck coefficients (21-48 µV K-1) were achieved in addition to excellent transparency. Given their properties, the obtained films show promise for multifunctional applications, such as in UV and near-blue radiation shielding, transparent conductive electrodes and low-temperature thermoelectrics.

  2. Double threshold behavior in a resonance-controlled ZnO random laser

    Directory of Open Access Journals (Sweden)

    Ryo Niyuki

    2017-03-01

    Full Text Available We observed unusual lasing characteristics, such as double thresholds and blue-shift of lasing peak, in a resonance-controlled ZnO random laser. From the analysis of lasing threshold carrier density, we found that the lasing at 1st and 2nd thresholds possibly arises from different mechanisms; the lasing at 1st threshold involves exciton recombination, whereas the lasing at 2nd threshold is caused by electron-hole plasma recombination, which is the typical origin of conventional random lasers. These phenomena are very similar to the transition from polariton lasing to photon lasing observed in a well-defined cavity laser.

  3. Tuning of deep level emission in highly oriented electrodeposited ZnO nanorods by post growth annealing treatments

    Science.gov (United States)

    Simimol, A.; Manikandanath, N. T.; Anappara, Aji A.; Chowdhury, Prasanta; Barshilia, Harish C.

    2014-08-01

    Highly dense and c-axis oriented zinc oxide (ZnO) nanorods with hexagonal wurtzite facets were deposited on fluorine doped tin oxide coated glass substrates by a simple and cost-effective electrodeposition method at low bath temperature (80 °C). The as-grown samples were then annealed at various temperatures (TA = 100-500 °C) in different environments (e.g., zinc, oxygen, air, and vacuum) to understand their photoluminescence (PL) behavior in the ultra-violet (UV) and the visible regions. The PL results revealed that the as-deposited ZnO nanorods consisted of oxygen vacancy (VO), zinc interstitial (Zni), and oxygen interstitial (Oi) defects and these can be reduced significantly by annealing in different environments at optimal annealing temperatures. However, the intensity of deep level emission increased for TA greater than the optimized values for the respective environments due to the introduction of various defect centers. For example, for TA ≥ 450 °C in the oxygen and air environments, the density of Oi defects increased, whereas, the green emission associated with VO is dominant in the vacuum annealed (TA = 500 °C) ZnO nanorods. The UV peak red shifted after the post-growth annealing treatments in all the environments and the vacuum annealed sample exhibited highest UV peak intensity. The observations from the PL data are supported by the micro-Raman spectroscopy. The present study gives new insight into the origin of different defects that exist in the electrodeposited ZnO nanorods and how these defects can be precisely controlled in order to get the desired emissions for the opto-electronic applications.

  4. Controlled growth of c-axis oriented ZnO nanorod array films by electrodeposition method and characterization.

    Science.gov (United States)

    Arslan, Andaç; Hür, Evrim; Ilican, Saliha; Caglar, Yasemin; Caglar, Mujdat

    2014-07-15

    ZnO nanorod array films were deposited from aqueous solution containing different concentrations (1×10(-2) M and 5×10(-3) M) Zn(NO3)2⋅6H2O and C6H12N4 and at different electrodeposition times (i.e., 15 min, 30 min, 60 min, 120 min and 180 min) using chronoamperometry method on p-Si substrate. Surface morphology and crystal structural properties of ZnO films were investigated by XRD and FESEM to select ZnO films which have optimum properties. The highest TC(hkl) value was observed in (002) plane for the film, which is deposited at 1×10(-2) M and 120 min. It is also observed that the highly oriented nanorods in this film are denser. Additionally, the conductivity type was determined by using Mott-Schottky which is electrochemical impedance spectroscopy method (EIS). On the other hand, to investigate the utility of obtained ZnO on p-Si (p-Si/n-ZnO) as supercapacitor electrode active material, the electrochemical storage properties of p-Si/ZnO was studied by electrochemical impedance spectroscopy and repeating chronopotentiometry methods. It is suggested from electrochemical tests results that p-Si/ZnO is a promising electrode materials for supercapacitor applications that required low voltage (V). Rectifiying behavior was observed from the I-V characteristic of nanorod array n-ZnO/p-Si heterojunction diode. The n value, Io and the ϕb were found to be 5.48, 1.93×10(-8) A and 0.75 eV, respectively. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Statistical properties of photon modes in random arrays of ZnO nano-needles

    Energy Technology Data Exchange (ETDEWEB)

    Minz, Christoph; Leipold, David; Runge, Erich [Technische Universitaet Ilmenau, 98693 Ilmenau (Germany)

    2011-07-01

    Localization of electromagnetic waves in random media received renewed interest in the last years. Recent ultrafast optical experiments indicate the existence of highly localized photon modes in a system of homogeneous, randomly distributed, vertically aligned ZnO nano-needles. In particular, hot spots in the spatial distribution of the second harmonic generation (SHG) were found. In this work, we discuss the optical near field, which we obtain from full 3D solutions of Maxwell's equations of a model system in time domain. The spatial distribution of the electric near-field and the squared electric near-field intensity are investigated with statistical methods. The results are compared to the experimental findings. We thank Manfred Maschek, Slawa Schmidt, Martin Silies and Christoph Lienau from the Carl von Ossietzky Universitaet Oldenburg as well as Takashi Yatsui, Kokoro Kitamura and Motoichi Ohtsu from the University of Tokyo for sharing their experimental data with us prior to publication.

  6. Scattering from randomly oriented scatterers with strong permittivity fluctuations

    Science.gov (United States)

    Yueh, S. H.; Kong, J. A.; Shin, R. T.

    1990-01-01

    Strong permittivity fluctuation theory is used to solve the problem of scattering from a medium composed of completely randomly oriented scatterers under a low frequency limit. Gaussian statistics are not assumed for the renormalized scattering sources. Numerical results on effective permittivity are illustrated for oblate and prolate spheroidal scatterers and compared with the results for spherical scatterers. The results are consistent with discrete scatterer theory. The effective permittivity of a random medium embedded with nonspherical scatterers shows a higher imaginary part than the spherical scatterer case with equal correlation volume. Under the distorted Born approximation, the polarimetric covariance matrix for the backscattered electric field is calculated for half-space randomly oriented scatterers. The nonspherical geometry of the scatterers shows significant effects on the cross-polarized backscattering returns, and the correlation coefficient between HH and VV returns. The polarimetric backscattering coefficients can provide useful information in distinguishing the geometry of scatterers.

  7. Intermittent spray pyrolytic growth of nanocrystalline and highly oriented transparent conducting ZnO thin films: Effect of solution spray rate

    Energy Technology Data Exchange (ETDEWEB)

    Mahajan, C.M., E-mail: c_mahajan9@yahoo.com [Department of Engineering Sciences and Humanities, Vishwakarma Institute of Technology, Pune 411 037 (India); School of Energy Studies, University of Pune, Pune 411 007 (India); Takwale, M.G. [School of Energy Studies, University of Pune, Pune 411 007 (India)

    2014-01-25

    Highlights: • ZnO films show enhancement in structural, optical and electrical properties. • Film orientation is altered from [0 0 2] to [1 0 1] direction for higher S{sub f} > 5 ml/min. • E{sub g} (eV) is influenced by variation in crystallinity, grain size and film thickness. • Nanocrystalline ZnO films are superior for TCO and optoelectronic applications. • FE-SEM and AFM study reveal growth of an array of vertically aligned ZnO nanorods. -- Abstract: Uniformly distributed jet of fine droplets was created with control of spray rate (S{sub f}) to deposit nanocrystalline ZnO thin films by spray pyrolysis technique. X-ray diffraction analysis indicated the polycrystalline film growth with most preferred orientation along c-axis [0 0 2] direction for S{sub f} ⩽ 4.5 ml/min, above which films favored [1 0 1] direction. FE-SEM and AFM analysis revealed the uniform vertical growth of ZnO nano-rods for S{sub f} = 2.5 ml/min and the film exhibited highest transmittance (95%) with lowest dark resistivity (∼10{sup −2} Ω-cm). The deposition rate increased due to rise in S{sub f}. Alteration of crystallinity, grain size and film thickness with variation in S{sub f} lead to variation of band-gap energy from 3.198 eV to 3.302 eV. ZnO film deposited at optimal S{sub f} = 2.5 ml/min exhibited maximum electrical conductivity σ = 78.8 Ω{sup −1}-cm{sup −1}, minimum sheet resistance R{sub s} = 2.04 × 10{sup 2} Ω/□ and highest figure of merit Φ{sub TC} = 2.93 × 10{sup −3} Ω{sup −1}.

  8. An effective low-temperature solution synthesis of Co-doped [0001]-oriented ZnO nanorods

    OpenAIRE

    Alnoor, Hatim; Savoyant, Adrien; Liu, Xianjie; Pozina, Galia; Willander, Magnus; Nur, Omer

    2017-01-01

    We demonstrate an efficient possibility to synthesize vertically aligned pure zinc oxide (ZnO) and Co-doped ZnO nanorods (NRs) using the low-temperature aqueous chemical synthesis (90 degrees C). Two different mixing methods of the synthesis solutions were investigated for the Co-doped samples. The synthesized samples were compared to pure ZnO NRs regarding the Co incorporation and crystal quality. Electron paramagnetic resonance (EPR) measurements confirmed the substitution of Co2+ inside th...

  9. Layered zinc hydroxide salts: delamination, preferred orientation of hydroxide lamellae, and formation of ZnO nanodiscs.

    Science.gov (United States)

    Demel, Jan; Pleštil, Josef; Bezdička, Petr; Janda, Pavel; Klementová, Mariana; Lang, Kamil

    2011-08-15

    Delamination of layered zinc hydroxide salts (LZH) into hydroxide layers provides nanobuilding blocs of a two-dimensional anisotropy. The methodology, extent of delamination, the size and stability of hydroxide lamellae are described in detail. The ability of lamellae to restack to form oriented hydroxide films depends on the solvent, original LZH salt, and conditions used for delamination. The most interesting results were obtained using LZH intercalated with dodecyl sulfate anions and LZH nitrate delaminated in butanol at 60 °C and in formamide at room temperature, respectively. The former method produces hydroxide lamellae of a lateral size of ca. 10-20 nm. The inner structure of the hydroxide layers is conserved and separated lamellae restack to the original layered structure of LZH dodecyl sulfate. The latter method yields lamellae with a size decreasing from 73.3 nm to 10 nm after a 2-week aging, while their thickness is nearly constant (2.6-3.8 nm). However, the use of formamide is complicated by the formation of Zn(II) formate. The major part of LZH intercalated with dodecyl sulfate anions is transformed during the delamination procedure to anisotropic ZnO nanoparticles, either needle-like particles prolonged in the [0 0 1] direction or disc-like particles flattened along the (0 0 1) plane. Copyright © 2011 Elsevier Inc. All rights reserved.

  10. Effect of orientation and density of hydroxide precursor films on performance of dye-sensitized ZnO solar cells

    National Research Council Canada - National Science Library

    KAJIHARA, Hisasuke; HAGIWARA, Manabu; FUJIHARA, Shinobu

    2016-01-01

    .... The increase in the film density resulted in the improvement of the open-circuit voltage and the fill factor of dye-sensitized solar cells using N719-loaded ZnO films as photoanodes. The light-to-electricity conversion efficiency of 3.49% was obtained in the DSSC using the present ZnO film.

  11. Highly efficient hybrid energy generator: coupled organic photovoltaic device and randomly oriented electrospun poly(vinylidene fluoride) nanofiber.

    Science.gov (United States)

    Park, Boongik; Lee, Kihwan; Park, Jongjin; Kim, Jongmin; Kim, Ohyun

    2013-03-01

    A hybrid architecture consisting of an inverted organic photovoltaic device and a randomly-oriented electrospun PVDF piezoelectric device was fabricated as a highly-efficient energy generator. It uses the inverted photovoltaic device with coupled electrospun PVDF nanofibers as tandem structure to convert solar and mechanical vibrations energy to electricity simultaneously or individually. The power conversion efficiency of the photovoltaic device was also significantly improved up to 4.72% by optimized processes such as intrinsic ZnO, MoO3 and active layer. A simple electrospinning method with the two electrode technique was adopted to achieve a high voltage of - 300 mV in PVDF piezoelectric fibers. Highly-efficient HEG using voltage adder circuit provides the conceptual possibility of realizing multi-functional energy generator whenever and wherever various energy sources are available.

  12. Failure process in heterogeneous materials with randomly oriented fibers

    Science.gov (United States)

    Sbiaai, H.; Hader, A.; Bakir, R.; Achik, I.; Tarras, I.; Boughaleb, Y.

    2017-06-01

    Our aim in this study is to investigate the failure process in heterogeneous materials with randomly oriented fibers. In our proposed system, the fiber bundle model assumes that all the fibers are randomly oriented in all directions relative to the vertical one. Our calculations are performed in the framework of the local load-sharing rule, which states that the applied load of a broken fiber is redistributed only to its neighboring ones. The results show that this system presents a greater resistance than the classical one where the fibers are arranged parallel to the applied load. We found that the density of the broken fibers exhibited a power law and was linearly correlated with the applied load and temperature. However, the results show that the failure process of the considered system is characterized by an avalanche phenomenon with two different regimes. We also studied the crossover behavior of lifetime of the materials versus both applied load and temperature. We compared these results with those obtained from the classical model.

  13. Antibacterial and barrier properties of oriented polymer films with ZnO thin films applied with atomic layer deposition at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Vähä-Nissi, Mika, E-mail: mika.vaha-nissi@vtt.fi [VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044, VTT (Finland); Pitkänen, Marja; Salo, Erkki; Kenttä, Eija [VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044, VTT (Finland); Tanskanen, Anne, E-mail: Anne.Tanskanen@aalto.fi [Aalto University, School of Chemical Technology, Department of Chemistry, Laboratory of Inorganic Chemistry, P.O. Box 16100, FI-00076 Aalto (Finland); Sajavaara, Timo, E-mail: timo.sajavaara@jyu.fi [University of Jyväskylä, Department of Physics, P.O. Box 35, FI-40014 Jyväskylä (Finland); Putkonen, Matti; Sievänen, Jenni; Sneck, Asko; Rättö, Marjaana [VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044, VTT (Finland); Karppinen, Maarit, E-mail: Maarit.Karppinen@aalto.fi [Aalto University, School of Chemical Technology, Department of Chemistry, Laboratory of Inorganic Chemistry, P.O. Box 16100, FI-00076 Aalto (Finland); Harlin, Ali [VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044, VTT (Finland)

    2014-07-01

    Concerns on food safety, and need for high quality and extended shelf-life of packaged foods have promoted the development of antibacterial barrier packaging materials. Few articles have been available dealing with the barrier or antimicrobial properties of zinc oxide thin films deposited at low temperature with atomic layer deposition (ALD) onto commercial polymer films typically used for packaging purposes. The purpose of this paper was to study the properties of ZnO thin films compared to those of aluminum oxide. It was also possible to deposit ZnO thin films onto oriented polylactic acid and polypropylene films at relatively low temperatures using ozone instead of water as an oxidizing precursor for diethylzinc. Replacing water with ozone changed both the structure and the chemical composition of films deposited on silicon wafers. ZnO films deposited with ozone contained large grains covered and separated probably by a more amorphous and uniform layer. These thin films were also assumed to contain zinc salts of carboxylic acids. The barrier properties of a 25 nm ZnO thin film deposited with ozone at 100 °C were quite close to those obtained earlier with ALD Al{sub 2}O{sub 3} of similar apparent thickness on similar polymer films. ZnO thin films deposited at low temperature indicated migration of antibacterial agent, while direct contact between ZnO and Al{sub 2}O{sub 3} thin films and bacteria promoted antibacterial activity. - Highlights: • Thin films were grown from diethylzinc also with ozone instead of water at 70 and 100 °C. • ZnO films deposited with diethylzinc and ozone had different structures and chemistries. • Best barrier properties obtained with zinc oxide films close to those obtained with Al{sub 2}O{sub 3} • Ozone as oxygen source provided better barrier properties at 100 °C than water. • Both aluminum and zinc oxide thin films showed antimicrobial activity against E. coli.

  14. An effective low-temperature solution synthesis of Co-doped [0001]-oriented ZnO nanorods

    Science.gov (United States)

    Alnoor, Hatim; Savoyant, Adrien; Liu, Xianjie; Pozina, Galia; Willander, Magnus; Nur, Omer

    2017-06-01

    We demonstrate an efficient possibility to synthesize vertically aligned pure zinc oxide (ZnO) and Co-doped ZnO nanorods (NRs) using the low-temperature aqueous chemical synthesis (90 °C). Two different mixing methods of the synthesis solutions were investigated for the Co-doped samples. The synthesized samples were compared to pure ZnO NRs regarding the Co incorporation and crystal quality. Electron paramagnetic resonance (EPR) measurements confirmed the substitution of Co2+ inside the ZnO NRs, giving a highly anisotropic magnetic Co2+ signal. The substitution of Zn2+ by Co2+ was observed to be combined with a drastic reduction in the core-defect (CD) signal (g ˜ 1.956) which is seen in pure ZnO NRs. As revealed by the cathodoluminescence (CL), the incorporation of Co causes a slight red-shift of the UV peak position combined with an enhancement in the intensity of the defect-related yellow-orange emission compared to pure ZnO NRs. Furthermore, the EPR and the CL measurements allow a possible model of the defect configuration in the samples. It is proposed that the as-synthesized pure ZnO NRs likely contain Zn interstitial (Zni+) as CDs and oxygen vacancy (VO) or oxygen interstitial (Oi) as surface defects. As a result, Co was found to likely occupy the Zni+, leading to the observed CDs reduction and hence enhancing the crystal quality. These results open the possibility of synthesis of highly crystalline quality ZnO NRs-based diluted magnetic semiconductors using the low-temperature aqueous chemical method.

  15. The role of Al, Ba, and Cd dopant elements in tailoring the properties of c-axis oriented ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Dilawar [Department of Physics GC University, Lahore 54000 (Pakistan); Center for Advanced Studies in Physics, GC University Lahore, Lahore 54000 (Pakistan); Butt, M.Z., E-mail: mzakriabutt@gmail.com [Center for Advanced Studies in Physics, GC University Lahore, Lahore 54000 (Pakistan); Arif, Bilal [Department of Physics, Faculty of Arts and Sciences, Firat University, 23169 Elazig (Turkey); Al-Ghamdi, Ahmed A. [Department of Physics, Faculty of Sciences, King Abdul Aziz University, Jeddah (Saudi Arabia); Yakuphanoglu, Fahrettin [Department of Physics, Faculty of Arts and Sciences, Firat University, 23169 Elazig (Turkey); Department of Physics, Faculty of Sciences, King Abdul Aziz University, Jeddah (Saudi Arabia)

    2017-02-01

    Highly c-axis oriented un-doped ZnO and Al-, Ba-, and Cd-doped ZnO thin films were successfully deposited on glass substrate employing sol-gel spin coating method. XRD analysis showed that all thin films possess hexagonal wurtzite structure with preferred orientation along c-axis. Field emission scanning electron microscope (FESEM) was used to study the morphology of thin films. The morphology consists of spherical and non-spherical shape grains. EDX analysis confirms the presence of O, Zn, Al, Ba, and Cd in the relevant thin films. The optical properties of thin films were studied using UV–Vis spectrometer. All thin films possess more than 85% optical transmittance in the visible region. Blue shift in optical band gap E{sub g} has been observed on doping with Al, whereas doping with Ba and Cd resulted in red shift of E{sub g}. Urbach energy E{sub u} of all doped ZnO thin films was found to have excellent correlation with their band gap energy E{sub g}. Moreover, E{sub g} increases while E{sub u} decreases on the increase in crystallite size D. Optical parameters E{sub g} and E{sub u} as well as structural parameters lattice strain and stacking fault probability also show excellent correlation with the B-factor or the mean-square amplitude of atomic vibrations of the dopant elements. Electrical conductivity measurement of the thin films was carried out using two-point probe method. The electrical conductivity was found to increase with the increase in crystallite orientation along c-axis.

  16. High-Hall-Mobility Al-Doped ZnO Films Having Textured Polycrystalline Structure with a Well-Defined (0001) Orientation.

    Science.gov (United States)

    Nomoto, Junichi; Makino, Hisao; Yamamoto, Tetsuya

    2016-12-01

    Five hundred-nanometer-thick ZnO-based textured polycrystalline films consisting of 490-nm-thick Al-doped ZnO (AZO) films deposited on 10-nm-thick Ga-doped ZnO (GZO) films exhibited a high Hall mobility (μ H) of 50.1 cm(2)/Vs with a carrier concentration (N) of 2.55 × 10(20) cm(-3). Firstly, the GZO films were prepared on glass substrates by ion plating with dc arc discharge, and the AZO films were then deposited on the GZO films by direct current magnetron sputtering (DC-MS). The GZO interface layers with a preferential c-axis orientation play a critical role in producing AZO films with texture development of a well-defined (0001) orientation, whereas 500-nm-thick AZO films deposited by only DC-MS showed a mixture of the c-plane and the other plane orientation, to exhibit a μ H of 38.7 cm(2)/Vs with an N of 2.22 × 10(20) cm(-3).

  17. Simulation of Young’s moduli for hexagonal ZnO [0 0 0 1]-oriented nanowires: first principles and molecular mechanical calculations

    Science.gov (United States)

    Bandura, Andrei V.; Evarestov, Robert A.; Lukyanov, Sergey I.; Piskunov, Sergei; Zhukovskii, Yuri F.

    2017-08-01

    Morphologically reproducible wurtzite-structured zinc oxide nanowires (ZnO NWs) can be synthesized by different methods. Since ZnO NWs have been found to possess piezoelectricity, a comprehensive study of their mechanical properties, e.g. deformations caused by external compression or stretching, is one of the actual tasks of this paper. We have calculated wurtzite-structured [0 0 0 1]-oriented ZnO NWs whose diameters have been varied within 1-5 nm and 1-20 nm ranges when using either ab initio (hybrid DFT-LCAO) or force-field (molecular mechanical) methods, respectively (the minimum diameter d NW of experimentally synthesized NWs has been estimated on average to be ~20 nm). When using both chosen calculation approaches, the values of Young’s moduli determined for the mentioned ranges of NW diameters have been found to be qualitatively compatible (168-169 GPa for 5 nm NW thickness), whereas results of molecular mechanical simulations on Y NW for 20 nm-thick NWs (160-162 GPa) have been qualitatively comparable with those experimentally measured along the [0 0 0 1] direction of NW loading. In all the cases, a gradual increase of the NW diameter has resulted in an asymptotic decrease of Young’s modulus consequently approaching that (Y b) of wurtzite-structured ZnO bulk along its [0 0 0 1] axis. The novelty of this study is that we combine the computation methods of quantum chemistry and molecular mechanics, while the majority of previous studies with the same aim have focused on the application of different classical molecular dynamical methods.

  18. Sonicated sol–gel preparation of nanoparticulate ZnO thin films with various deposition speeds: The highly preferred c-axis (0 0 2) orientation enhances the final properties

    Energy Technology Data Exchange (ETDEWEB)

    Malek, M.F., E-mail: firz_solarzelle@yahoo.com [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Mamat, M.H. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Khusaimi, Z. [NANO-SciTech Centre (NST), Institute of Science (IOS), Universiti Teknologi MARA UiTM, 40450 Shah Alam, Selangor (Malaysia); Sahdan, M.Z. [Microelectronic and Nanotechnology Centre (MiNT), Universiti Tun Hussein Onn Malaysia (UTHM), 86400 Batu Pahat, Johor (Malaysia); Musa, M.Z. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Zainun, A.R. [Faculty of Electrical and Electronics Engineering, Universiti Malaysia Pahang (UMP), Lebuhraya Tun Razak, 26300 Kuantan, Pahang (Malaysia); Suriani, A.B. [Department of Physics, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, 35900 Tanjung Malim, Perak (Malaysia); Md Sin, N.D. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Abd Hamid, S.B. [Nanotechnology and Catalysis Research Centre (NANOCAT), Universiti Malaya (UM), 50603 Kuala Lumpur (Malaysia); Rusop, M. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre (NST), Institute of Science (IOS), Universiti Teknologi MARA UiTM, 40450 Shah Alam, Selangor (Malaysia)

    2014-01-05

    Highlights: • Minimum stress of highly c-axis oriented ZnO was grown at suitable deposition speed. • The ZnO crystal orientation was influenced by strain/stress of the film. • Minimum stress/strain of ZnO film leads to lower defects. • Bandgap and defects were closely intertwined with strain/stress. • We report additional optical and electrical properties based on deposition speed. -- Abstract: Zinc oxide (ZnO) thin films have been deposited onto glass substrates at various deposition speeds by a sonicated sol–gel dip-coating technique. This work studies the effects of deposition speed on the crystallisation behaviour and optical and electrical properties of the resulting films. X-ray diffraction (XRD) analysis showed that thin films were preferentially oriented along the (0 0 2) c-axis direction of the crystal. The transformation sequence of strain and stress effects in ZnO thin films has also been studied. The films deposited at a low deposition speed exhibited a large compressive stress of 0.78 GPa, which decreased to 0.43 GPa as the deposition speed increased to 40 mm/min. Interestingly, the enhancement in the crystallinity of these films led to a significant reduction in compressive stress. All films exhibited an average transmittance of greater than 90% in the visible region, with absorption edges at ∼380 nm. The photoluminescence (PL) measurements indicated that the intensity of the emission peaks varied significantly with deposition speed. The optical band gap energy (E{sub g}) was evaluated as 3.276–3.289 eV, which increased with decreasing compressive stress along the c-axis. The energy band gap of the resulting ZnO films was found to be strongly influenced by the preferred c-axis (0 0 2) orientation.

  19. High coupling and high velocity surface acoustic waves using a c-axis oriented ZnO film on translucent Al2O3 ceramics

    Science.gov (United States)

    Takeda, Fumio; Shiosaki, Tadashi; Kawabata, Akira

    1983-07-01

    The layered structure comprising a c-axis normally oriented ZnO piezoelectric film and a translucent Al2O3 ceramic substrate which has a high surface-acoustic-wave velocity and a small surface roughness has given both a high phase velocity Vp and a high coupling k2 for the 0th (Rayleigh) mode, 1st (Sezawa) mode, and leaky mode surface acoustic waves. The measured maximum values of k2 are 3.6% for the 0th mode at h/λ=0.45 where Vp is 3.2 km/s, 5.7% for the 1st mode at h/λ=0.21 where Vp is 5.6 km/s, and 6.7% for the leaky mode at h/λ=0.16 where Vp is 6.2 km/s, where the interdigital transducers are located at the interface in measuring the above values, and also electrically floating plane metals are on top of the ZnO film for the last two values.

  20. A comparative structure and morphology study of Zn (1- x ) Cd x O solid solution grown on ZnO and different sapphire orientations

    Science.gov (United States)

    Fouzri, A.; Sallet, V.; Oumezzine, M.

    2011-09-01

    Zn (1- x) Cd xO solid solutions with a constant Cadmium flow 10 cc have been grown on ZnO, c-, a- and r-plane sapphire substrates using metal organic chemical vapor deposition (MO-CVD). The optical transmission spectra and energy band-gap equation established by Mikano et al. were used to estimate cadmium mole fraction of alloy. Lattice parameters and morphology of these films were examined using high resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM) as Cd incorporation and employed substrate. By comparison, we observe significant differences between Cd incorporation and morphologies depending on nature and substrate orientation but the hexagonal wurtzite structure is maintained. Higher Cd incorporation (11.2 at%) is obtained on Zn (1- x) Cd xO grown on r-plane sapphire, which is confirmed by the greatest energy shift (340 meV) to lower energy measured by room temperature photoluminescence. However, the lattice parameter c remains unchanged while parameter a is identical for films deposited on ZnO and r-plane sapphire substrates and for those deposited on c- and a-plane sapphire substrates.

  1. Effects of Low Ag Doping on Physical and Optical Waveguide Properties of Highly Oriented Sol-Gel ZnO Thin Films

    Directory of Open Access Journals (Sweden)

    Mohamed Dehimi

    2015-01-01

    Full Text Available A sol-gel dip-coating process was used to deposit almost stress-free highly c-axis oriented zinc oxide (ZnO thin films onto glass substrates. The effects of low silver doping concentration (Ag/Zn < 1% on the structural, morphological, optical, and waveguide properties of such films were investigated by X-ray diffraction (XRD, scanning electron microscopy (SEM, atomic force microscopy, UV-Visible spectrophotometry, and M-lines spectroscopy (MLS. XRD analysis revealed that all the films were in single phase and had a hexagonal wurtzite structure. The grain size values were calculated and found to be about 24–29 nm. SEM micrographs and AFM images have shown that film morphology and surface roughness were influenced by Ag doping concentration. According to UV-Vis. measurements all the films were highly transparent with average visible transmission values ranging from 80% to 86%. It was found that the Ag contents lead to widening of the band gap. MLS measurements at 632.8 nm wavelength put into evidence that all thin film planar waveguides demonstrate a well-guided fundamental mode for both transverse electric and transverse magnetic polarized light. Moreover, the refractive index of ZnO thin films was found to increase by Ag doping levels.

  2. Influence of anisotropic in-plane strain on the optical properties of (0001)-oriented GaN and ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Roeppischer, Marcus; Buchheim, Carsten; Goldhahn, Ruediger; Gobsch, Gerhard [Technical University Ilmenau, Institute of Physics (Germany); Furtmayr, Florian; Wassner, Thomas; Eickhoff, Martin [Technical University Munich, Walter-Schottky Institute (Germany)

    2007-07-01

    The growth of hexagonal (0001)-oriented GaN films on a-plane sapphire substrates causes an anisotropic in-plane strain. It originates from the different lattice constants and thermal expansion coefficients of the substrate parallel and perpendicular to the c-axis. Under those conditions the optical response of the GaN films depends on the light polarization within the surface plane. We have applied photoreflectance spectroscopy in order to study the polarization dependence of the oscillator strength for the free A and B excitonic transitions. The experimental results are in good agreement with theoretical calculations based on the Bir-Pikus strain Hamiltonian and the experimentally determined lattice constants. Corresponding investigations of ZnO films reveal a much lower polarization anisotropy.

  3. Robotic virtual reality simulation plus standard robotic orientation versus standard robotic orientation alone: a randomized controlled trial.

    Science.gov (United States)

    Vaccaro, Christine M; Crisp, Catrina C; Fellner, Angela N; Jackson, Christopher; Kleeman, Steven D; Pavelka, James

    2013-01-01

    The objective of this study was to compare the effect of virtual reality simulation training plus robotic orientation versus robotic orientation alone on performance of surgical tasks using an inanimate model. Surgical resident physicians were enrolled in this assessor-blinded randomized controlled trial. Residents were randomized to receive either (1) robotic virtual reality simulation training plus standard robotic orientation or (2) standard robotic orientation alone. Performance of surgical tasks was assessed at baseline and after the intervention. Nine of 33 modules from the da Vinci Skills Simulator were chosen. Experts in robotic surgery evaluated each resident's videotaped performance of the inanimate model using the Global Rating Scale (GRS) and Objective Structured Assessment of Technical Skills-modified for robotic-assisted surgery (rOSATS). Nine resident physicians were enrolled in the simulation group and 9 in the control group. As a whole, participants improved their total time, time to incision, and suture time from baseline to repeat testing on the inanimate model (P = 0.001, 0.003, virtual reality simulation improve surgical skills on an inanimate model, although this may be a function of the initial "practice" on the inanimate model and repeat testing of a known task. However, robotic virtual reality simulation training increases GRS pass rates consistent with improved robotic technical skills learned in a virtual reality environment.

  4. Growth of vertically aligned ZnO nanorods using textured ZnO films

    OpenAIRE

    Meléndrez Manuel; Martínez Eduardo; Solís-Pomar Francisco; Pérez-Tijerina Eduardo

    2011-01-01

    Abstract A hydrothermal method to grow vertical-aligned ZnO nanorod arrays on ZnO films obtained by atomic layer deposition (ALD) is presented. The growth of ZnO nanorods is studied as function of the crystallographic orientation of the ZnO films deposited on silicon (100) substrates. Different thicknesses of ZnO films around 40 to 180 nm were obtained and characterized before carrying out the growth process by hydrothermal methods. A textured ZnO layer with preferential direction in the norm...

  5. Magnetic field alignment of randomly oriented, high aspect ratio silicon microwires into vertically oriented arrays.

    Science.gov (United States)

    Beardslee, Joseph A; Sadtler, Bryce; Lewis, Nathan S

    2012-11-27

    External magnetic fields have been used to vertically align ensembles of silicon microwires coated with ferromagnetic nickel films. X-ray diffraction and image analysis techniques were used to quantify the degree of vertical orientation of the microwires. The degree of vertical alignment and the minimum field strength required for alignment were evaluated as a function of the wire length, coating thickness, magnetic history, and substrate surface properties. Nearly 100% of 100 μm long, 2 μm diameter, Si microwires that had been coated with 300 nm of Ni could be vertically aligned by a 300 G magnetic field. For wires ranging from 40 to 60 μm in length, as the length of the wire increased, a higher degree of alignment was observed at lower field strengths, consistent with an increase in the available magnetic torque. Microwires that had been exposed to a magnetic sweep up to 300 G remained magnetized and, therefore, aligned more readily during subsequent magnetic field alignment sweeps. Alignment of the Ni-coated Si microwires occurred at lower field strengths on hydrophilic Si substrates than on hydrophobic Si substrates. The magnetic field alignment approach provides a pathway for the directed assembly of solution-grown semiconductor wires into vertical arrays, with potential applications in solar cells as well as in other electronic devices that utilize nano- and microscale components as active elements.

  6. Modulation of field emission properties of znO nanorods during arc discharge.

    Science.gov (United States)

    Fang, F; Kennedy, J; Carder, D A; Futter, J; Murmu, P; Markwitz, A

    2010-12-01

    Zinc oxide (ZnO) nanorods have been synthesized via the arc discharge method. Different oxygen partial pressures were applied in the arc discharge chamber to modulate the field emission properties of the as-synthesized ZnO nanorods. Scanning electron microscopy (SEM) was carried out to analyze the morphology of the ZnO nanorods. The ion beam analysis technique of proton induced X-ray emission (PIXE) was performed to probe the impurities in ZnO nanorods. SEM images clearly revealed the formation of randomly oriented ZnO nanorods with diameters between 10-50 nm. It was found that the morphology and the electrical properties of the ZnO nanorods were dependent on the oxygen partial pressure during arc discharge. In addition enhanced UV-sensitive photoconductivity was found for ZnO nanorods synthesized at high oxygen partial pressure during arc discharge. The field emission properties of the nanorods were studied. The turn-on field, which is defined at a current density of 10 microA cm(-2), was about 3 V microm(-1) for ZnO nanorods synthesized at 99% oxygen partial pressure during arc discharge. The turn-on field for ZnO nanorods increased with the decrease of oxygen partial pressure during arc discharge. The simplicity of the synthesis route coupled with the modulation of field emission properties due to the arc discharge method make the ZnO nanorods a promising candidate for a low cost and compact cold cathode material.

  7. Microwave single-scattering properties of randomly oriented soft-ice hydrometeors

    Directory of Open Access Journals (Sweden)

    D. Casella

    2008-11-01

    Full Text Available Large ice hydrometeors are usually present in intense convective clouds and may significantly affect the upwelling radiances that are measured by satellite-borne microwave radiometers – especially, at millimeter-wavelength frequencies. Thus, interpretation of these measurements (e.g., for precipitation retrieval requires knowledge of the single scattering properties of ice particles. On the other hand, shape and internal structure of these particles (especially, the larger ones is very complex and variable, and therefore it is necessary to resort to simplifying assumptions in order to compute their single-scattering parameters.

    In this study, we use the discrete dipole approximation (DDA to compute the absorption and scattering efficiencies and the asymmetry factor of two kinds of quasi-spherical and non-homogeneous soft-ice particles in the frequency range 50–183 GHz. Particles of the first kind are modeled as quasi-spherical ice particles having randomly distributed spherical air inclusions. Particles of the second kind are modeled as random aggregates of ice spheres having random radii. In both cases, particle densities and dimensions are coherent with the snow hydrometeor category that is utilized by the University of Wisconsin – Non-hydrostatic Modeling System (UW-NMS cloud-mesoscale model. Then, we compare our single-scattering results for randomly-oriented soft-ice hydrometeors with corresponding ones that make use of: a effective-medium equivalent spheres, b solid-ice equivalent spheres, and c randomly-oriented aggregates of ice cylinders. Finally, we extend to our particles the scattering formulas that have been developed by other authors for randomly-oriented aggregates of ice cylinders.

  8. Graded index and randomly oriented core-shell silicon nanowires for broadband and wide angle antireflection

    Directory of Open Access Journals (Sweden)

    P. Pignalosa

    2011-09-01

    Full Text Available Antireflection with broadband and wide angle properties is important for a wide range of applications on photovoltaic cells and display. The SiOx shell layer provides a natural antireflection from air to the Si core absorption layer. In this work, we have demonstrated the random core-shell silicon nanowires with both broadband (from 400nm to 900nm and wide angle (from normal incidence to 60º antireflection characteristics within AM1.5 solar spectrum. The graded index structure from the randomly oriented core-shell (Air/SiOx/Si nanowires may provide a potential avenue to realize a broadband and wide angle antireflection layer.

  9. Characteristics of Carrier Transport and Crystallographic Orientation Distribution of Transparent Conductive Al-Doped ZnO Polycrystalline Films Deposited by Radio-Frequency, Direct-Current, and Radio-Frequency-Superimposed Direct-Current Magnetron Sputtering.

    Science.gov (United States)

    Nomoto, Junichi; Inaba, Katsuhiko; Kobayashi, Shintaro; Watanabe, Takeshi; Makino, Hisao; Yamamoto, Tetsuya

    2017-08-09

    We investigated the characteristics of carrier transport and crystallographic orientation distribution in 500-nm-thick Al-doped ZnO (AZO) polycrystalline films to achieve high-Hall-mobility AZO films. The AZO films were deposited on glass substrates at 200 °C by direct-current, radio-frequency, or radio-frequency-superimposed direct-current magnetron sputtering at various power ratios. We used sintered AZO targets with an Al₂O₃ content of 2.0 wt. %. The analysis of the data obtained by X-ray diffraction, Hall-effect, and optical measurements of AZO films at various power ratios showed that the complex orientation texture depending on the growth process enhanced the contribution of grain boundary scattering to carrier transport and of carrier sinks on net carrier concentration, resulting in the reduction in the Hall mobility of polycrystalline AZO films.

  10. Growth Method-Dependent and Defect Density-Oriented Structural, Optical, Conductive, and Physical Properties of Solution-Grown ZnO Nanostructures

    Science.gov (United States)

    Rana, Abu ul Hassan Sarwar; Lee, Ji Young; Shahid, Areej; Kim, Hyun-Seok

    2017-01-01

    It is time for industry to pay a serious heed to the application and quality-dependent research on the most important solution growth methods for ZnO, namely, aqueous chemical growth (ACG) and microwave-assisted growth (MAG) methods. This study proffers a critical analysis on how the defect density and formation behavior of ZnO nanostructures (ZNSs) are growth method-dependent. Both antithetical and facile methods are exploited to control the ZnO defect density and the growth mechanism. In this context, the growth of ZnO nanorods (ZNRs), nanoflowers, and nanotubes (ZNTs) are considered. The aforementioned growth methods directly stimulate the nanostructure crystal growth and, depending upon the defect density, ZNSs show different trends in structural, optical, etching, and conductive properties. The defect density of MAG ZNRs is the least because of an ample amount of thermal energy catered by high-power microwaves to the atoms to grow on appropriate crystallographic planes, which is not the case in faulty convective ACG ZNSs. Defect-centric etching of ZNRs into ZNTs is also probed and methodological constraints are proposed. ZNS optical properties are different in the visible region, which are quite peculiar, but outstanding for ZNRs. Hall effect measurements illustrate incongruent conductive trends in both samples. PMID:28891969

  11. Orientation-dependent low field magnetic anomalies and room-temperature spintronic material – Mn doped ZnO films by aerosol spray pyrolysis

    CSIR Research Space (South Africa)

    Nkosi, SS

    2013-12-01

    Full Text Available High quality un-doped and Mn-doped ZnO films deposited by a simple aerosol spray pyrolysis technique for 20 and 30 min were studied using electron paramagnetic resonance (EPR), X-ray diffraction (XRD) and atomic force microscopy (AFM) techniques...

  12. Cellular compatibility of RGD-modified chitosan nanofibers with aligned or random orientation

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yanyan; Lue Lanxin; Feng Zhangqi; Xiao Zhongdang; Huang Ningping, E-mail: nphuang@seu.edu.c, E-mail: zdxiao@seu.edu.c [State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096 (China)

    2010-10-01

    Aligned and randomly oriented chitosan nanofibers were prepared by electrospinning. The fibers were modified with the RGD cell-adhesive peptide through a heterobifunctional crosslinker containing a segment of poly(ethylene glycol) (PEG). PEG rendered the surface hydrophilic and provided flexible spacers, allowing the preservation of the bioactivity of further captured RGD peptides. NIH 3T3 cells were used to test the cellular compatibility of these chitosan nanofibrous scaffolds. Cell morphology and viability were investigated by SEM, fluorescent staining and cell counting. The results indicate that RGD-modified surfaces significantly improve the cellular compatibility of chitosan nanofibers and suggest a good candidate as a scaffold employed in tissue engineering.

  13. Public attitudes toward child undervaccination: A randomized experiment on evaluations, stigmatizing orientations, and support for policies.

    Science.gov (United States)

    Carpiano, Richard M; Fitz, Nicholas S

    2017-07-01

    Child undervaccination is a complex public health problem and a contentious social and political issue. Efforts to increase vaccination coverage require understanding how the public evaluates different reasons for child undervaccination, which may influence attitudes, stigmatizing behaviors, and support for vaccination policies. We conducted a vignette experiment with a United States national online sample (n = 1469) to investigate how and why different undervaccination actions shape evaluations (blame, anger, sympathy, differentness, credibility, dangerousness), stigmatizing orientations (social distance, discrimination), and support for particular policies (e.g., research funding, belief exemptions, fines). Each participant was randomly assigned to read one of four vignettes that described a mother who either refused vaccines, delayed vaccines, encountered social barriers to obtaining vaccines, or was up-to-date on vaccines for her child. Compared to the up-to-date condition, each undervaccination action predicted significantly more negative evaluations and stigmatizing orientations. Vaccine refusal was the most negatively appraised. Differences in social distance and discrimination were explained by negative evaluations about the parent. These evaluations and orientations predicted support for a range of policies. Negative parental evaluations were associated with increased support for more severe policies. We discuss the implications of these findings for addressing undervaccination and informing health scholarship on stigma. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Vibration Analysis of Randomly Oriented Carbon Nanotube Based on FGM Beam Using Timoshenko Theory

    Directory of Open Access Journals (Sweden)

    Mohammad Amin Rashidifar

    2015-02-01

    Full Text Available The carbon nanotube (CNT reinforced functionally graded materials (FGM are expected to be the new generation materials having wide range of unexplored potential applications in various technological areas such as aerospace and structural and chemical industry. The present work deals with the finite element modeling and free vibration analysis of CNT based functionally graded beam using three-dimensional Timoshenko beam theory. It has been assumed that the material properties of CNT based FG beam vary only along the thickness and these properties are evaluated by rule of mixture. The extended Hamilton principle has been applied to find out the governing equations of CNT based FG beam. Finite element method is used to solve governing equation with the exact shape functions. Initial analysis deals with CNTs assumed to be oriented along the length direction only. But practically it is not possible. So, further work deals with the free vibration analysis of functionally graded nanocomposite beams reinforced by randomly oriented straight single walled carbon nanotubes (SWCNTs. The Eshelby-Mori-Tanaka approach based on an equivalent fiber is used to investigate the material properties of the beam. Results are presented in tabular and graphical forms to show the effects of carbon nanotube orientations, slenderness ratios, and boundary conditions on the dynamic behavior of the beam.

  15. Real-Space x-ray tomographic reconstruction of randomly oriented objects with sparse data frames.

    Science.gov (United States)

    Ayyer, Kartik; Philipp, Hugh T; Tate, Mark W; Elser, Veit; Gruner, Sol M

    2014-02-10

    Schemes for X-ray imaging single protein molecules using new x-ray sources, like x-ray free electron lasers (XFELs), require processing many frames of data that are obtained by taking temporally short snapshots of identical molecules, each with a random and unknown orientation. Due to the small size of the molecules and short exposure times, average signal levels of much less than 1 photon/pixel/frame are expected, much too low to be processed using standard methods. One approach to process the data is to use statistical methods developed in the EMC algorithm (Loh & Elser, Phys. Rev. E, 2009) which processes the data set as a whole. In this paper we apply this method to a real-space tomographic reconstruction using sparse frames of data (below 10(-2) photons/pixel/frame) obtained by performing x-ray transmission measurements of a low-contrast, randomly-oriented object. This extends the work by Philipp et al. (Optics Express, 2012) to three dimensions and is one step closer to the single molecule reconstruction problem.

  16. Effect of NICU Department Orientation Program on Mother’s Anxiety: a Randomized Clinical Trial

    Directory of Open Access Journals (Sweden)

    Leila Valizadeh

    2016-09-01

    Full Text Available Introduction: Neonatal intensive care unit induces the high level of anxiety for mothers. The aim of this study was to evaluate the effectiveness of NICU orientation program on the anxiety of mothers who had preterm newborns hospitalized in NICU. Methods: This study was a randomized clinical trial (three parallel groups. Participants included 99 mothers with preterm newborns hospitalized in NICU of Al- Zahra hospital, affiliated to Tabriz University of Medical Sciences in 2015. Mothers were randomly assigned to one of three groups (film, booklet, and control. Mothers completed the State- Trait Anxiety Inventory before entering to the NICU, and then mothers in the experiment groups became familiar with the NICU environment through watching a film or reading booklet. After the first NICU visit, all mothers completed the STAI and Cattell's Anxiety Questionnaires. Data were analyzed using SPSS ver. 13 software. Results: There was no significant difference between three groups regarding state- trait anxiety before the intervention. After the first NICU visit, a significant reduction in maternal state anxiety was seen in the both experiment groups. There was no statistical significant difference regarding trait anxiety. Data obtained from Cattell's anxiety questionnaire after intervention, showed significant difference in state anxiety between groups. Conclusion: Employing film and booklet orientation strategy after preterm delivery can reduce the mother’s anxiety and beneficent for the mother, baby, family and health care system.

  17. Growth of vertically aligned ZnO nanorods using textured ZnO films

    Directory of Open Access Journals (Sweden)

    Meléndrez Manuel

    2011-01-01

    Full Text Available Abstract A hydrothermal method to grow vertical-aligned ZnO nanorod arrays on ZnO films obtained by atomic layer deposition (ALD is presented. The growth of ZnO nanorods is studied as function of the crystallographic orientation of the ZnO films deposited on silicon (100 substrates. Different thicknesses of ZnO films around 40 to 180 nm were obtained and characterized before carrying out the growth process by hydrothermal methods. A textured ZnO layer with preferential direction in the normal c-axes is formed on substrates by the decomposition of diethylzinc to provide nucleation sites for vertical nanorod growth. Crystallographic orientation of the ZnO nanorods and ZnO-ALD films was determined by X-ray diffraction analysis. Composition, morphologies, length, size, and diameter of the nanorods were studied using a scanning electron microscope and energy dispersed x-ray spectroscopy analyses. In this work, it is demonstrated that crystallinity of the ZnO-ALD films plays an important role in the vertical-aligned ZnO nanorod growth. The nanorod arrays synthesized in solution had a diameter, length, density, and orientation desirable for a potential application as photosensitive materials in the manufacture of semiconductor-polymer solar cells. PACS 61.46.Hk, Nanocrystals; 61.46.Km, Structure of nanowires and nanorods; 81.07.Gf, Nanowires; 81.15.Gh, Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.

  18. Growth of vertically aligned ZnO nanorods using textured ZnO films.

    Science.gov (United States)

    Solís-Pomar, Francisco; Martínez, Eduardo; Meléndrez, Manuel F; Pérez-Tijerina, Eduardo

    2011-09-07

    A hydrothermal method to grow vertical-aligned ZnO nanorod arrays on ZnO films obtained by atomic layer deposition (ALD) is presented. The growth of ZnO nanorods is studied as function of the crystallographic orientation of the ZnO films deposited on silicon (100) substrates. Different thicknesses of ZnO films around 40 to 180 nm were obtained and characterized before carrying out the growth process by hydrothermal methods. A textured ZnO layer with preferential direction in the normal c-axes is formed on substrates by the decomposition of diethylzinc to provide nucleation sites for vertical nanorod growth. Crystallographic orientation of the ZnO nanorods and ZnO-ALD films was determined by X-ray diffraction analysis. Composition, morphologies, length, size, and diameter of the nanorods were studied using a scanning electron microscope and energy dispersed x-ray spectroscopy analyses. In this work, it is demonstrated that crystallinity of the ZnO-ALD films plays an important role in the vertical-aligned ZnO nanorod growth. The nanorod arrays synthesized in solution had a diameter, length, density, and orientation desirable for a potential application as photosensitive materials in the manufacture of semiconductor-polymer solar cells. PACS: 61.46.Hk, Nanocrystals; 61.46.Km, Structure of nanowires and nanorods; 81.07.Gf, Nanowires; 81.15.Gh, Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.).

  19. Guiding the orientation of smooth muscle cells on random and aligned polyurethane/collagen nanofibers.

    Science.gov (United States)

    Jia, Lin; Prabhakaran, Molamma P; Qin, Xiaohong; Ramakrishna, Seeram

    2014-09-01

    Fabricating scaffolds that can simulate the architecture and functionality of native extracellular matrix is a huge challenge in vascular tissue engineering. Various kinds of materials are engineered via nano-technological approaches to meet the current challenges in vascular tissue regeneration. During this study, nanofibers from pure polyurethane and hybrid polyurethane/collagen in two different morphologies (random and aligned) and in three different ratios of polyurethane:collagen (75:25; 50:50; 25:75) are fabricated by electrospinning. The fiber diameters of the nanofibrous scaffolds are in the range of 174-453 nm and 145-419 for random and aligned fibers, respectively, where they closely mimic the nanoscale dimensions of native extracellular matrix. The aligned polyurethane/collagen nanofibers expressed anisotropic wettability with mechanical properties which is suitable for regeneration of the artery. After 12 days of human aortic smooth muscle cells culture on different scaffolds, the proliferation of smooth muscle cells on hybrid polyurethane/collagen (3:1) nanofibers was 173% and 212% higher than on pure polyurethane scaffolds for random and aligned scaffolds, respectively. The results of cell morphology and protein staining showed that the aligned polyurethane/collagen (3:1) scaffold promote smooth muscle cells alignment through contact guidance, while the random polyurethane/collagen (3:1) also guided cell orientation most probably due to the inherent biochemical composition. Our studies demonstrate the potential of aligned and random polyurethane/collagen (3:1) as promising substrates for vascular tissue regeneration. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  20. Deducing fast electron density changes in randomly orientated uncrystallized biomolecules in a pump-probe experiment.

    Science.gov (United States)

    Pande, K; Schwander, P; Schmidt, M; Saldin, D K

    2014-07-17

    We propose a method for deducing time-resolved structural changes in uncrystallized biomolecules in solution. The method relies on measuring the angular correlations of the intensities, when averaged over a large number of diffraction patterns from randomly oriented biomolecules in solution in a liquid solvent. The experiment is somewhat like a pump-probe version of an experiment on small angle X-ray scattering, except that the data expected by the algorithm are not just the radial variation of the averaged intensities. The differences of these correlation functions as measured from a photoexcited and dark structure enable the direct calculation of the difference electron density with a knowledge of only the dark structure. We exploit a linear relation we derive between the difference in these correlation functions and the difference electron density, applicable for small structural changes.

  1. Patient-oriented rehabilitation in the management of chronic mechanical neck pain: a randomized controlled trial.

    Science.gov (United States)

    Paoloni, M; Tavernese, E; Cacchio, A; Tattoli, M; Melis, L; Ronconi, R; Santilli, V

    2013-06-01

    Management of chronic mechanical neck pain (CMNP) still represents a challenge. A patient-oriented (Pa-O) therapeutic approach could be considered as the one in which therapies are scheduled at the start of each therapeutic session according to the patient's current physical status, and differs from a prescription-oriented (Pr-O) therapeutic approach, in which therapies are prescribed at the first medical referral and are not adjusted at any time during the treatment period. To determine if a Pa-O approach may be more beneficial for CMNP patients when compared to a Pr-O one. Randomized controlled trial. 220 CMNP outpatients randomized to either Pa-O group (N.=114) or Pr-O group (N.=106). Each group received 10 therapeutic sessions over 3 weeks. Primary outcome measures were pain assessment, evaluated by Visual-Analog-Scale (VAS), and disability level, evaluated by the Neck Pain and Disability Scale (NPDS-I). Secondary outcome measures included patients' response to treatment and treatment failures. Measurements were carried out at baseline (T0) and 1 month after treatment ended (T1). Data were analysed according to the intention-to-treat principle. Patients in both groups displayed at T1 a significant reduction in VAS and NPDS-I scores. The relative changes at T1 were greater in Pa-O group when compared with Pr-O group both for VAS (61.5% versus 48.8%; Pup in suffers from CMNP. However, the occurrence of a performance-bias due to the increased level of attention from physicians to patients in Pa-O group, cannot be ruled-out. A Pa-O approach should be considered for CMNP also in an outpatient facility.

  2. Effect of SiC Nano powder on Multiaxial Woven and Chopped Randomly Oriented Flax/Sisal Fiber Reinforced composites

    Directory of Open Access Journals (Sweden)

    Kalagi Ganesh R.

    2018-01-01

    Full Text Available A study has been carried out to investigate effect of SiC Nano powder on tensile and impact properties of Multiaxial layers of Flax and Sisal fiber reinforced composites and randomly oriented chopped Flax and Sisal fiber reinforced composites. It has been observed that tensile strength and impact strength were improved using 6% of SiC Nanopowder into Multiaxial layer (+45º/-45º, 0º/90º of Flax and Sisal where as randomly oriented chopped Flax and Sisal fiber reinforced composites are improved in its stiffnes for the same composition of fiber, epoxy and SiC Nano powder. SEM Analysis are done to analyse the distribution of SiC in both Multiaxial layers of Flax and Sisal fiber reinforced composites and randomly oriented chopped Flax and Sisal fiber reinforced composites.

  3. Study of structural and optical properties of ZnO films grown by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lemlikchi, S., E-mail: lemlikchi_safo@yahoo.fr [Advanced Technology Development Centre, Cite 20 Aout 1956 BP 17 Baba Hassen, Algiers (Algeria); Abdelli-Messaci, S.; Lafane, S.; Kerdja, T. [Advanced Technology Development Centre, Cite 20 Aout 1956 BP 17 Baba Hassen, Algiers (Algeria); Guittoum, A.; Saad, M. [Nuclear Research Centre of Algiers, 2 Bd Frantz-Fanon, Algiers (Algeria)

    2010-07-01

    Wurtzite zinc oxides films (ZnO) were deposited on silicon (0 0 1) and corning glass substrates using the pulsed laser deposition technique. The laser fluence, target-substrate distance, substrate temperature of 300 deg. C were fixed while varying oxygen pressures from 2 to 500 Pa were used. It is observed that the structural properties of ZnO films depend strongly on the oxygen pressure and the substrate nature. The film crystallinity improves with decreasing oxygen pressure. At high oxygen pressure, the films are randomly oriented, whereas, at low oxygen pressures they are well oriented along [0 0 1] axis for Si substrates and along [1 0 3] axis for glass substrates. A honeycomb structure is obtained at low oxygen pressures, whereas microcrystalline structures were obtained at high oxygen pressures. The effect of oxygen pressure on film transparency, band gap E{sub g} and Urbach energies was investigated.

  4. Preparation and characterization of ZnO and Fe-doped ZnO films by sol-gel method

    Directory of Open Access Journals (Sweden)

    Xin ZHANG

    2016-04-01

    Full Text Available ZnO and Fe-doped ZnO thin films are prepared on glass substrate by sol-gel method, and the surface morphology, structure and optical property are analyzed by scanning electron microscope (SEM, atomic force microscopy (AFM, X-ray diffraction (XRD and UV-Vis-NIR spectrophotometer. The results show that both films have a smooth surface and a hexagonal wurtzite structure with orienting along the (101 plane. Compared with the ZnO film, the surface of Fe-doped ZnO film becomes smoother, and its grain size decreases from 58.512 nm of the ZnO film to 36.460 nm. Moreover, after Fe doping, the orientation degree of (101 plane is weakened, and the optical band gap energy increases from 3.1 eV of the ZnO film to 3.4 eV.

  5. Analysis of Li-related defects in ZnO thin films influenced by ...

    Indian Academy of Sciences (India)

    Li-doped ZnO thin films were grown on quartz substrates by radio frequency magnetron sputtering and in situ annealing under O2 or Ar ambient. Li-related defects in ZnO films strongly depend on the annealing ambient. AFM and XRD indicated that ZnO films possessed a good crystallinity with -axis orientation, uniform ...

  6. Bi-functional nonlinearities in monodisperse ZnO nano-grains – Self-consistent transport and random lasing

    Energy Technology Data Exchange (ETDEWEB)

    Lubatsch, Andreas [Georg-Simon-Ohm University of Applied Sciences, Keßlerplatz 12, 90489 Nürnberg (Germany); Frank, Regine, E-mail: r.frank@uni-tuebingen.de [Institute for Theoretical Physics, Optics and Photonics, Eberhard-Karls-Universität, Auf der Morgenstelle 14, 72076 Tübingen (Germany)

    2014-08-20

    We report a quantum field theoretical description of light transport and random lasing. The Bethe-Salpeter equation is solved including maximally crossed diagrams and non-elastic scattering. This is the first theoretical framework that combines so called off-shell scattering and lasing in random media. We present results for the self-consistent scattering mean free path that varies over the width of the sample. Further we discuss the density dependent correlation length of self-consistent transport in disordered media composed of semi-conductor Mie scatterers.

  7. ZnO 1-D nanostructures: Low temperature synthesis and ...

    Indian Academy of Sciences (India)

    ZnO is one of the most important semiconductors having a wide variety of applications in photonic, field emission and sensing devices. In addition, it exhibits a wide variety of morphologies in the nano regime that can be grown by tuning the growth habit of the ZnO crystal. Among various nanostructures, oriented 1-D ...

  8. Generalized Pareto for Pattern-Oriented Random Walk Modelling of Organisms' Movements.

    Science.gov (United States)

    Bertrand, Sophie; Joo, Rocío; Fablet, Ronan

    2015-01-01

    How organisms move and disperse is crucial to understand how population dynamics relates to the spatial heterogeneity of the environment. Random walk (RW) models are typical tools to describe movement patterns. Whether Lévy or alternative RW better describes forager movements is keenly debated. We get around this issue using the Generalized Pareto Distribution (GPD). GPD includes as specific cases Normal, exponential and power law distributions, which underlie Brownian, Poisson-like and Lévy walks respectively. Whereas previous studies typically confronted a limited set of candidate models, GPD lets the most likely RW model emerge from the data. We illustrate the wide applicability of the method using GPS-tracked seabird foraging movements and fishing vessel movements tracked by Vessel Monitoring System (VMS), both collected in the Peruvian pelagic ecosystem. The two parameters from the fitted GPD, a scale and a shape parameter, provide a synoptic characterization of the observed movement in terms of characteristic scale and diffusive property. They reveal and quantify the variability, among species and individuals, of the spatial strategies selected by predators foraging on a common prey field. The GPD parameters constitute relevant metrics for (1) providing a synthetic and pattern-oriented description of movement, (2) using top predators as ecosystem indicators and (3) studying the variability of spatial behaviour among species or among individuals with different personalities.

  9. Generalized Pareto for Pattern-Oriented Random Walk Modelling of Organisms’ Movements

    Science.gov (United States)

    Bertrand, Sophie; Joo, Rocío; Fablet, Ronan

    2015-01-01

    How organisms move and disperse is crucial to understand how population dynamics relates to the spatial heterogeneity of the environment. Random walk (RW) models are typical tools to describe movement patterns. Whether Lévy or alternative RW better describes forager movements is keenly debated. We get around this issue using the Generalized Pareto Distribution (GPD). GPD includes as specific cases Normal, exponential and power law distributions, which underlie Brownian, Poisson-like and Lévy walks respectively. Whereas previous studies typically confronted a limited set of candidate models, GPD lets the most likely RW model emerge from the data. We illustrate the wide applicability of the method using GPS-tracked seabird foraging movements and fishing vessel movements tracked by Vessel Monitoring System (VMS), both collected in the Peruvian pelagic ecosystem. The two parameters from the fitted GPD, a scale and a shape parameter, provide a synoptic characterization of the observed movement in terms of characteristic scale and diffusive property. They reveal and quantify the variability, among species and individuals, of the spatial strategies selected by predators foraging on a common prey field. The GPD parameters constitute relevant metrics for (1) providing a synthetic and pattern–oriented description of movement, (2) using top predators as ecosystem indicators and (3) studying the variability of spatial behaviour among species or among individuals with different personalities. PMID:26172045

  10. Generalized Pareto for Pattern-Oriented Random Walk Modelling of Organisms' Movements.

    Directory of Open Access Journals (Sweden)

    Sophie Bertrand

    Full Text Available How organisms move and disperse is crucial to understand how population dynamics relates to the spatial heterogeneity of the environment. Random walk (RW models are typical tools to describe movement patterns. Whether Lévy or alternative RW better describes forager movements is keenly debated. We get around this issue using the Generalized Pareto Distribution (GPD. GPD includes as specific cases Normal, exponential and power law distributions, which underlie Brownian, Poisson-like and Lévy walks respectively. Whereas previous studies typically confronted a limited set of candidate models, GPD lets the most likely RW model emerge from the data. We illustrate the wide applicability of the method using GPS-tracked seabird foraging movements and fishing vessel movements tracked by Vessel Monitoring System (VMS, both collected in the Peruvian pelagic ecosystem. The two parameters from the fitted GPD, a scale and a shape parameter, provide a synoptic characterization of the observed movement in terms of characteristic scale and diffusive property. They reveal and quantify the variability, among species and individuals, of the spatial strategies selected by predators foraging on a common prey field. The GPD parameters constitute relevant metrics for (1 providing a synthetic and pattern-oriented description of movement, (2 using top predators as ecosystem indicators and (3 studying the variability of spatial behaviour among species or among individuals with different personalities.

  11. Promoting physical activity with goal-oriented mental imagery: a randomized controlled trial.

    Science.gov (United States)

    Chan, Carina K Y; Cameron, Linda D

    2012-06-01

    Self-regulation theory and research suggests that different types of mental imagery can promote goal-directed behaviors. The present study was designed to compare the efficacy of approach imagery (attainment of desired goal states) and process imagery (steps for enacting behavior) in promoting physical activity among inactive individuals. A randomized controlled trial was conducted with 182 inactive adults who received one of four interventions for generating mental images related to physical activity over a 4-week period, with Approach Imagery (approach versus neutral) and Process Imagery (process versus no process) as the intervention strategies. Participants received imagery training and practiced daily. Repeated measures ANOVAs revealed that Approach Imagery: (1) increased approach motivations for physical activity at Week 4; (2) induced greater intentions post-session, which subsequently induced more action planning at Week 4; (3) enhanced action planning when combined with process images at post-session and Week 1; and (4) facilitated more physical activity at Week 4 via action planning. These findings suggest that inducing approach orientation via mental imagery may be a convenient and low-cost technique to promote physical activity among inactive individuals.

  12. Influence of crystal shapes on radiative fluxes in visible wavelength: ice crystals randomly oriented in space

    Directory of Open Access Journals (Sweden)

    P. Chervet

    1996-08-01

    Full Text Available Radiative properties of cirrus clouds are one of the major unsolved problems in climate studies and global radiation budget. These clouds are generally composed of various ice-crystal shapes, so we tried to evaluate effects of the ice-crystal shape on radiative fluxes. We calculated radiative fluxes of cirrus clouds with a constant geometrical depth, composed of ice crystals with different shapes (hexagonal columns, bullets, bullet-rosettes, sizes and various concentrations. We considered ice particles randomly oriented in space (3D case and their scattering phase functions were calculated by a ray-tracing method. We calculated radiative fluxes for cirrus layers for different microphysical characteristics by using a discrete-ordinate radiative code. Results showed that the foremost effect of the ice-crystal shape on radiative properties of cirrus clouds was that on the optical thickness, while the variation of the scattering phase function with the ice shape remained less than 3% for our computations. The ice-water content may be a better choice to parameterize the optical properties of cirrus, but the shape effect must be included.

  13. Processing of X-ray snapshots from crystals in random orientations.

    Science.gov (United States)

    Kabsch, Wolfgang

    2014-08-01

    A functional expression is introduced that relates scattered X-ray intensities from a still or a rotation snapshot to the corresponding structure-factor amplitudes. The new approach was implemented in the program nXDS for processing monochromatic diffraction images recorded by a multi-segment detector where each exposure could come from a different crystal. For images containing indexable spots, the intensities of the expected reflections and their variances are obtained by profile fitting after mapping the contributing pixel contents to the Ewald sphere. The varying intensity decline owing to the angular distance of the reflection from the surface of the Ewald sphere is estimated using a Gaussian rocking curve. This decline is dubbed `Ewald offset correction', which is well defined even for still images. Together with an image-scaling factor and other corrections, an explicit expression is defined that predicts each recorded intensity from its corresponding structure-factor amplitude. All diffraction parameters, scaling and correction factors are improved by post-refinement. The ambiguous case of a lower point group than the lattice symmetry is resolved by a method reminiscent of the technique of `selective breeding'. It selects the indexing alternative for each image that yields, on average, the highest correlation with intensities from all other images. Processing a test set of rotation images by XDS and treating the same images by nXDS as snapshots of crystals in random orientations yields data of comparable quality, clearly indicating an anomalous signal from Se atoms.

  14. Bilateral robotic priming before task-oriented approach in subacute stroke rehabilitation: a pilot randomized controlled trial.

    Science.gov (United States)

    Hsieh, Yu-Wei; Wu, Ching-Yi; Wang, Wei-En; Lin, Keh-Chung; Chang, Ku-Chou; Chen, Chih-Chi; Liu, Chien-Ting

    2017-02-01

    To investigate the treatment effects of bilateral robotic priming combined with the task-oriented approach on motor impairment, disability, daily function, and quality of life in patients with subacute stroke. A randomized controlled trial. Occupational therapy clinics in medical centers. Thirty-one subacute stroke patients were recruited. Participants were randomly assigned to receive bilateral priming combined with the task-oriented approach (i.e., primed group) or to the task-oriented approach alone (i.e., unprimed group) for 90 minutes/day, 5 days/week for 4 weeks. The primed group began with the bilateral priming technique by using a bimanual robot-aided device. Motor impairments were assessed by the Fugal-Meyer Assessment, grip strength, and the Box and Block Test. Disability and daily function were measured by the modified Rankin Scale, the Functional Independence Measure, and actigraphy. Quality of life was examined by the Stroke Impact Scale. The primed and unprimed groups improved significantly on most outcomes over time. The primed group demonstrated significantly better improvement on the Stroke Impact Scale strength subscale ( p = 0.012) and a trend for greater improvement on the modified Rankin Scale ( p = 0.065) than the unprimed group. Bilateral priming combined with the task-oriented approach elicited more improvements in self-reported strength and disability degrees than the task-oriented approach by itself. Further large-scale research with at least 31 participants in each intervention group is suggested to confirm the study findings.

  15. Local radial basis function meshless scheme for vector radiative transfer in participating media with randomly oriented axisymmetric particles.

    Science.gov (United States)

    Sun, Jie; Yi, Hong-Liang; Tan, He-Ping

    2016-02-20

    A local radial basis function meshless scheme (LRBFM) is developed to solve polarized radiative transfer in participating media containing randomly oriented axisymmetric particles in which radial basis functions augmented with polynomial basis are employed to construct the trial functions, and the vector radiative-transfer equation based on the discrete-ordinates approach is discretized directly by collocation method. The LRBFM belongs to a class of truly meshless methods that do not need any mesh or any numerical integration scheme. Performances of the LRBFM are verified with analytical solutions and other numerical results reported earlier in the literature via five various test cases. The predicted angular distribution of brightness temperature and Stokes vector by the LRBFM agree very well with the benchmark. It is demonstrated that the LRBFM is accurate to solve vector radiative transfer in participating media with randomly oriented axisymmetric particles.

  16. Superhydrophobic ZnAl double hydroxide nanostructures and ZnO films on Al and glass substrates

    Energy Technology Data Exchange (ETDEWEB)

    De, Debasis, E-mail: debasis.de@bcrec.ac.in [Electronics and Instrumentation Engineering Department, Dr. B C Roy Engineering College, Durgapur, West Bengal 713206 (India); Sarkar, D.K. [Centre Universitaire de Recherche sur l' Aluminium (CURAL), L' Université du Québec à Chicoutimi, 555 Blvd. Université, Chicoutimi, Saguenay, Québec G7H 2B1 (Canada)

    2017-01-01

    Superhydrophobic nanostructured ZnAl: layered double hydroxides (LDHs) and ZnO films have been fabricated on Al and glass substrates, respectively, by a simple and cost effective chemical bath deposition technique. Randomly oriented hexagonal patterned of ZnAl: LDHs thin nanoplates are clearly observed on Al-substrate in the scanning electron microscopic images. The average size of these hexagonal plates is ∼4 μm side and ∼30 nm of thickness. While on the glass substrate, a oriented hexagonal patterned ZnO nanorods (height ∼5 μm and 1 μm diameter) are observed and each rod is further decorated throughout the top few nanometers with several nanosteps. At the top of the nanorod, a perfectly hexagonal patterned ZnO surface with ∼250 nm sides is observed. The tendency to form hexagonal morphological features is due to the hexagonal crystal structure of ZnO confirmed from X-ray diffraction patterns and transmission electron microscopy image. The ZnAl: LDHs and/or ZnO coated substrates have been passivated by using stearic acid (SA) molecules. Infrared spectra of passivated ZnAl: LDHs coated substrates confirm the presence of SA. X-ray diffraction pattern also corroborates the results of infrared spectrum. The contact angle of the as prepared samples is zero. The superhydrophobicity is achieved by observing contact angle of ∼161° with a hysteresis of ∼4° for Al-substrate. On the glass substrate, a higher contact angle of ∼168° with a lower hysteresis of ∼3° is observed. A lower surface roughness of ∼4.93 μm is measured on ZnAl: LDHs surface layer on the Al substrate as compare to a higher surface roughness of 6.87 μm measured on ZnO layer on glass substrate. The superhydrophobicity of passivated nanostructured films on two different substrates is observed due to high surface roughness and low surface energy. - Highlights: • ZnAl: layered double hydroxides (LDHs) nanoplates are fabricated on Al substrate. • ZnO nanorods are fabricated on

  17. Task-Oriented Training with Computer Games for People with Rheumatoid Arthritis or Hand Osteoarthritis: A Feasibility Randomized Controlled Trial.

    Science.gov (United States)

    Srikesavan, Cynthia Swarnalatha; Shay, Barbara; Szturm, Tony

    2016-09-13

    To examine the feasibility of a clinical trial on a novel, home-based task-oriented training with conventional hand exercises in people with rheumatoid arthritis or hand osteoarthritis. To explore the experiences of participants who completed their respective home exercise programmes. Thirty volunteer participants aged between 30 and 60 years and diagnosed with rheumatoid arthritis or hand osteoarthritis were proposed for a single-center, assessor-blinded, randomized controlled trial ( ClinicalTrials.gov : NCT01635582). Participants received task-oriented training with interactive computer games and objects of daily life or finger mobility and strengthening exercises. Both programmes were home based and were done four sessions per week with 20 minutes each session for 6 weeks. Major feasibility outcomes were number of volunteers screened, randomized, and retained; completion of blinded assessments, exercise training, and home exercise sessions; equipment and data management; and clinical outcomes of hand function. Reaching the recruitment target in 18 months and achieving exercise compliance >80% were set as success criteria. Concurrent with the trial, focus group interviews explored experiences of those participants who completed their respective programmes. After trial initiation, revisions in inclusion criteria were required to promote recruitment. A total of 17 participants were randomized and 15 were retained. Completion of assessments, exercise training, and home exercise sessions; equipment and data collection and management demonstrated excellent feasibility. Both groups improved in hand function outcomes and exercise compliance was above 85%. Participants perceived both programmes as appropriate and acceptable. Participants who completed task-oriented training also agreed that playing different computer games was enjoyable, engaging, and motivating. Findings demonstrate initial evidence on recruitment, feasibility of trial procedures, and acceptability of

  18. Anodized ZnO nanostructures for photoelectrochemical water splitting

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Mao-Chia [Institute of Materials Science and Engineering, National Central University, Taoyuan 32001, Taiwan (China); Wang, TsingHai [Department of Biomedical Engineering and Environment Sciences, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Wu, Bin-Jui [Institute of Materials Science and Engineering, National Central University, Taoyuan 32001, Taiwan (China); Lin, Jing-Chie, E-mail: jclin4046@gmail.com [Institute of Materials Science and Engineering, National Central University, Taoyuan 32001, Taiwan (China); Wu, Ching-Chen [Green Energy and Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu 310, Taiwan (China)

    2016-01-01

    Highlights: • ZnO nanostructures were synthesized by electrochemical anodic process. • The parameter of ZnO nanostructure was anodic potential. • The model of growth of ZnO nanostructure was investigated. - Abstract: Zinc oxide (ZnO) nanostructures were fabricated on the polished zinc foil by anodic deposition in an alkaline solution containing 1.0 M NaOH and 0.25 M Zn(NO{sub 3}){sub 2}. Potentiostatic anodization was conducted at two potentials (−0.7 V in the passive region and −1.0 V in the active region vs. SCE) which are higher than the open circuit potential (−1.03 V vs. SCE) and as-obtained ZnO nanostrcutures were investigated focusing on their structural, optical, electrical and photoelectrochemical (PEC) characteristics. All samples were confirmed ZnO by X-ray photoelectron spectroscopy and Raman spectra. Observations in the SEM images clearly showed that ZnO nanostructures prepared at −0.7 V vs. SCE were composed of nanowires at while those obtained at −1.0 V vs. SCE possessed nanosheets morphology. Result from transmission electron microscope and X-ray diffraction patterns suggested that the ZnO nanowires belonged to single crystalline with a preferred orientation of (0 0 2) whereas the ZnO nanosheets were polycrystalline. Following PEC experiments indicated that ZnO nanowires had higher photocurrent density of 0.32 mA/cm{sup 2} at 0.5 V vs. SCE under 100 mW/cm{sup 2} illumination. This value was about 1.9 times higher than that of ZnO nanosheets. Observed higher photocurrent was likely due to the single crystalline, preferred (0 0 2) orientation, higher carrier concentration and lower charge transfer resistance.

  19. Effects of Coping-Oriented Couples Therapy on Depression: A Randomized Clinical Trial

    Science.gov (United States)

    Bodenmann, Guy; Plancherel, Bernard; Beach, Steven R. H.; Widmer, Kathrin; Gabriel, Barbara; Meuwly, Nathalie; Charvoz, Linda; Hautzinger, Martin; Schramm, Elisabeth

    2008-01-01

    The aim of this study was to evaluate the effectiveness of treating depression with coping-oriented couples therapy (COCT) as compared with cognitive-behavioral therapy (CBT; A. T. Beck, C. Ward, & M. Mendelson, 1961) and interpersonal psychotherapy (IPT; M. M. Weissman, J. C. Markowitz, & G. L. Klerman, 2000). Sixty couples, including 1…

  20. Shape dependency of the extinction and absorption cross sections of dust aerosols modeled as randomly oriented spheroids

    Directory of Open Access Journals (Sweden)

    R. Wagner

    2011-09-01

    Full Text Available We present computational results on the shape dependency of the extinction and absorption cross sections of dustlike aerosol particles that were modeled as randomly oriented spheroids. Shape dependent variations in the extinction cross sections are largest in the size regime that is governed by the interference structure. Elongated spheroids best fitted measured extinction spectra of re-dispersed Saharan dust samples. For dust particles smaller than 1.5 μm in diameter and low absorption potential, shape effects on the absorption cross sections are very small.

  1. Ultraviolet electroluminescence from ZnO /p-Si heterojunctions

    Science.gov (United States)

    Chen, Peiliang; Ma, Xiangyang; Yang, Deren

    2007-03-01

    Nominally undoped ZnO films were deposited by reactive sputtering on the lightly boron-doped (p-) and heavily boron-doped (p+) silicon substrates. The sputtered ZnO films were identified to be highly ⟨002⟩ oriented in crystallinity and n type in electrical conductivity. The current-voltage (I-V) characteristics revealed that the ZnO /p--Si heterojunction exhibited well-defined rectifying behavior while the ZnO /p+-Si heterojunction did not possess rectifying function. As for the ZnO /p+-Si heterojunction, it was electroluminescent to a certain extent in the visible region under sufficient forward bias with the positive voltage on the silicon substrate, while it emitted ultraviolet light characteristics of near-band-edge emission of ZnO under the reverse bias, which significantly dominated the visible emission. In contrast to the ZnO /p+-Si heterojunction, the ZnO /p--Si heterojunction did not exhibit detectable electroluminescence (EL) under either forward or reverse bias. The I-V characteristics and EL mechanism of the above-mentioned heterojunctions have been tentatively explained in terms of the energy-band structures of the heterojunctions.

  2. ZnO nanorods: growth mechanism and anisotropic functionalization

    Science.gov (United States)

    Pacholski, Claudia; Kornowski, Andreas; Weller, Horst

    2004-10-01

    We report on the wet-chemical synthesis of ZnO nanoparticles and their functionalization with metal colloids by photocatalytic reduction of metal ions. Different morphologies of ZnO nanoparticles were prepared by using different precursor concentrations and zinc sources such as zinc acetate, zinc propanoate and zinc decanoate. Spherical ZnO nanoparticles were produced at low concentrations and with zinc precursors having long alkylchains. The formation of elongated particles was achieved by using zinc acetate and high precursor concentrations. We found that ZnO nanorods were grown via oriented attachment of pre-formed quasi-spherical particles. This growth mechanism occurs at almost ambient temperature and in the first step, pearl chain like structures of 5 nm particles are formed, which coarse by condensation and finally grow - assisted by Ostwald ripening - to almost perfect single crystalline rods with length up to 300 nm. These nanorods were metallizied with silver and platinum by photocatalytic reduction of the appropriate metal ions on pre-formed ZnO nanorods. The deposition of metal took place at different locations of the ZnO nanorods and depended on the metal source. Positively charged silver ions were preferentially reduced to silver colloids at one end of the ZnO nanorods and led to anisotropic functionalized nanoparticles. Using a negatively charged platinum complex instead of silver ions generated a statistical coverage of the ZnO nanorods.

  3. Hydrothermal Growth of Vertically Aligned ZnO Nanorods Using a Biocomposite Seed Layer of ZnO Nanoparticles

    Directory of Open Access Journals (Sweden)

    Zafar Hussain Ibupoto

    2013-08-01

    Full Text Available Well aligned ZnO nanorods have been prepared by a low temperature aqueous chemical growth method, using a biocomposite seed layer of ZnO nanoparticles prepared in starch and cellulose bio polymers. The effect of different concentrations of biocomposite seed layer on the alignment of ZnO nanorods has been investigated. ZnO nanorods grown on a gold-coated glass substrate have been characterized by X-ray diffraction (XRD and field emission scanning electron microscopy (FESEM techniques. These techniques have shown that the ZnO nanorods are well aligned and perpendicular to the substrate, and grown with a high density and uniformity on the substrate. Moreover, ZnO nanorods can be grown with an orientation along the c-axis of the substrate and exhibit a wurtzite crystal structure with a dominant (002 peak in an XRD spectrum and possessed a high crystal quality. A photoluminescence (PL spectroscopy study of the ZnO nanorods has revealed a conventional near band edge ultraviolet emission, along with emission in the visible part of the electromagnetic spectrum due to defect emission. This study provides an alternative method for the fabrication of well aligned ZnO nanorods. This method can be helpful in improving the performance of devices where alignment plays a significant role.

  4. Economic evaluation of schema therapy and clarification-oriented psychotherapy for personality disorders: a multicenter, randomized controlled trial.

    Science.gov (United States)

    Bamelis, Lotte L M; Arntz, Arnoud; Wetzelaer, Pim; Verdoorn, Ryanne; Evers, Silvia M A A

    2015-11-01

    To compare from a societal perspective the cost-effectiveness and cost-utility of schema therapy, clarification-oriented psychotherapy, and treatment as usual for patients with avoidant, dependent, obsessive-compulsive, paranoid, histrionic, and/or narcissistic personality disorder. A multicenter, randomized controlled trial, single-blind parallel design, was conducted between May 2006 and December 2011 in 12 Dutch mental health institutes. Data from 320 patients (diagnosed according to DSM-IV criteria) randomly assigned to schema therapy (n = 145), treatment as usual (n = 134), or clarification-oriented psychotherapy (n = 41) were analyzed. Costs were repeatedly measured during 36 months by interview and patient registries. Primary outcome measures were proportion of recovered patients as measured with the Structured Clinical Interview for DSM-IV Axis II Personality Disorders for the cost-effectiveness analysis, and quality-adjusted life-years (QALYs) for the cost-utility analysis. Bootstrap replications in the cost-effectiveness and the cost-utility planes were used to estimate the probability that one treatment was more cost-effective than the other. Mixed gamma regression on net monetary benefit for different levels of willingness to pay for extra effects was used as sensitivity analysis. Additional sensitivity analyses were done to assess robustness of the results. Due to higher clinical effects and lower costs, schema therapy was dominant over the other treatments in the cost-effectiveness analyses. Schema therapy has the probability of being the most cost-effective treatment (78% at €0 to 96% at €37,500 [$27,375] willingness to pay per extra recovery). Treatment as usual was more cost-effective than clarification-oriented psychotherapy due to lower costs. In the cost-utility analysis, schema therapy had a stable 75% probability of being cost-effective. Sensitivity analyses confirmed these findings. The results support the cost-effectiveness of schema

  5. Growth of ZnO thin films on GaAs by pulsed laser deposition

    NARCIS (Netherlands)

    Craciun, V.; Elders, J.; Gardeniers, Johannes G.E.; Geretovsky, J.; Boyd, Ian W.

    1995-01-01

    ZnO thin films have been grown on GaAs substrates using the pulsed laser deposition technique with or without a photodeposited SiO2 buffer layer. The presence of the SiO2 layer has a beneficial effect on the crystalline quality of the grown ZnO films. Highly c-axis oriented ZnO films having a full

  6. Fabrication of Well-Aligned ZnO Nanorods Using a Composite Seed Layer of ZnO Nanoparticles and Chitosan Polymer

    Directory of Open Access Journals (Sweden)

    Anees A. Ansari

    2013-09-01

    Full Text Available In this study, by taking the advantage of both inorganic ZnO nanoparticles and the organic material chitosan as a composite seed layer, we have fabricated well-aligned ZnO nanorods on a gold-coated glass substrate using the hydrothermal growth method. The ZnO nanoparticles were characterized by the Raman spectroscopic techniques, which showed the nanocrystalline phase of the ZnO nanoparticles. Different composites of ZnO nanoparticles and chitosan were prepared and used as a seed layer for the fabrication of well-aligned ZnO nanorods. Field emission scanning electron microscopy, energy dispersive X-ray, high-resolution transmission electron microscopy, X-ray diffraction, and infrared reflection absorption spectroscopic techniques were utilized for the structural characterization of the ZnO nanoparticles/chitosan seed layer-coated ZnO nanorods on a gold-coated glass substrate. This study has shown that the ZnO nanorods are well-aligned, uniform, and dense, exhibit the wurtzite hexagonal structure, and are perpendicularly oriented to the substrate. Moreover, the ZnO nanorods are only composed of Zn and O atoms. An optical study was also carried out for the ZnO nanoparticles/chitosan seed layer-coated ZnO nanorods, and the obtained results have shown that the fabricated ZnO nanorods exhibit good crystal quality. This study has provided a cheap fabrication method for the controlled morphology and good alignment of ZnO nanorods, which is of high demand for enhancing the working performance of optoelectronic devices.

  7. Resource-oriented coaching for reduction of examination-related stress in medical students: an exploratory randomized controlled trial.

    Science.gov (United States)

    Kötter, Thomas; Niebuhr, Frank

    2016-01-01

    The years spent in acquiring medical education is considered a stressful period in the life of many students. Students whose mental health deteriorates during this long period of study are less likely to become empathic and productive physicians. In addition to other specific stressors, academic examinations seem to further induce medical school-related stress and anxiety. Combined group and individual resource-oriented coaching early in medical education might reduce examination-related stress and anxiety and, consequently, enhance academic performance. Good quality evidence, however, remains scarce. In this study, therefore, we explored the question of whether coaching affects examination-related stress and health in medical students. We conducted a randomized controlled trial. Students who registered for the first medical academic examination in August 2014 at the University of Lübeck were recruited and randomized into three groups. The intervention groups 1 and 2 received a 1-hour psychoeducative seminar. Group 1 additionally received two 1-hour sessions of individual coaching during examination preparation. Group 3 served as a control group. We compared changes in self-rated general health (measured by a single item), anxiety and depression (measured by the hospital anxiety and depression scale), as well as medical school stress (measured by the perceived medical school stress instrument). In order to further investigate the influence of group allocation on perceived medical school stress, we conducted a linear regression analysis. We saw a significant deterioration of general health and an increase in anxiety and depression scores in medical students while preparing for an examination. We found a small, but statistically significant, effect of group allocation on the development of perceived medical school stress. However, we could not differentiate between the effects of group coaching only and group coaching in combination with two sessions of individual

  8. Object-oriented Markov random model for classification of high resolution satellite imagery based on wavelet transform

    Science.gov (United States)

    Hong, Liang; Liu, Cun; Yang, Kun; Deng, Ming

    2013-07-01

    The high resolution satellite imagery (HRSI) have higher spatial resolution and less spectrum number, so there are some "object with different spectra, different objects with same spectrum" phenomena. The objective of this paper is to utilize the extracted features of high resolution satellite imagery (HRSI) obtained by the wavelet transform(WT) for segmentation. WT provides the spatial and spectral characteristics of a pixel along with its neighbors. The object-oriented Markov random Model in the wavelet domain is proposed in order to segment high resolution satellite imagery (HRSI). The proposed method is made up of three blocks: (1) WT-based feature extrcation.the aim of extraction of feature using WT for original spectral bands is to exploit the spatial and frequency information of the pixels; (2) over-segmentation object generation. Mean-Shift algorithm is employed to obtain over-segmentation objects; (3) classification based on Object-oriented Markov Random Model. Firstly the object adjacent graph (OAG) can be constructed on the over-segmentation objects. Secondly MRF model is easily defined on the OAG, in which WT-based feature of pixels are modeled in the feature field model and the neighbor system, potential cliques and energy functions of OAG are exploited in the labeling model. Experiments are conducted on one HRSI dataset-QuickBird images. We evaluate and compare the proposed approach with the well-known commercial software eCognition(object-based analysis approach) and Maximum Likelihood(ML) based pixels. Experimental results show that the proposed the method in this paper obviously outperforms the other methods.

  9. Magnetic localization and orientation of the capsule endoscope based on a random complex algorithm

    Directory of Open Access Journals (Sweden)

    He XQ

    2015-04-01

    Full Text Available Xiaoqi He,1 Zizhao Zheng,1,2 Chao Hu1 1Ningbo Institute of Technology, Zhejiang University, Ningbo, People's Republic of China; 2Taiyuan University of Science and Technology, Taiyuan, People's Republic of China Abstract: The development of the capsule endoscope has made possible the examination of the whole gastrointestinal tract without much pain. However, there are still some important problems to be solved, among which, one important problem is the localization of the capsule. Currently, magnetic positioning technology is a suitable method for capsule localization, and this depends on a reliable system and algorithm. In this paper, based on the magnetic dipole model as well as magnetic sensor array, we propose nonlinear optimization algorithms using a random complex algorithm, applied to the optimization calculation for the nonlinear function of the dipole, to determine the three-dimensional position parameters and two-dimensional direction parameters. The stability and the antinoise ability of the algorithm is compared with the Levenberg–Marquart algorithm. The simulation and experiment results show that in terms of the error level of the initial guess of magnet location, the random complex algorithm is more accurate, more stable, and has a higher “denoise” capacity, with a larger range for initial guess values. Keywords: wireless capsule endoscope, magnet, optimization 

  10. Emergency Department Management of Sepsis Patients: A Randomized, Goal-Oriented, Noninvasive Sepsis Trial.

    Science.gov (United States)

    Kuan, Win Sen; Ibrahim, Irwani; Leong, Benjamin S H; Jain, Swati; Lu, Qingshu; Cheung, Yin Bun; Mahadevan, Malcolm

    2016-03-01

    The noninvasive cardiac output monitor and passive leg-raising maneuver has been shown to be reasonably accurate in predicting fluid responsiveness in critically ill patients. We examine whether using a noninvasive protocol would result in more rapid lactate clearance after 3 hours in patients with severe sepsis and septic shock in the emergency department. In this open-label randomized controlled trial, 122 adult patients with sepsis and serum lactate concentration of greater than or equal to 3.0 mmol/L were randomized to receive usual care or intravenous fluid bolus administration guided by measurements of change of stroke volume index, using the noninvasive cardiac output monitor after passive leg-raising maneuver. The primary outcome was lactate clearance of more than 20% at 3 hours. Secondary outcomes included mortality, length of hospital and ICU stay, and total hospital cost. Analysis was intention to treat. Similar proportions of patients in the randomized intervention group (70.5%; N=61) versus control group (73.8%; N=61) achieved the primary outcome, with a relative risk of 0.96 (95% confidence interval [CI] 0.77 to 1.19). Secondary outcomes were similar in both groups (P>.05 for all comparisons). Hospital mortality occurred in 6 patients (9.8%) each in the intervention and control groups on or before 28 days (relative risk=1.00; 95% CI 0.34 to 2.93). Among a subgroup of patients with underlying fluid overload states, those in the intervention group tended to receive clinically significantly more intravenous fluids at 3 hours (difference=975 mL; 95% CI -450 to 1,725 mL) and attained better lactate clearance (difference=19.7%; 95% CI -34.6% to 60.2%) compared with the control group, with shorter hospital lengths of stay (difference=-4.5 days; 95% CI -9.5 to 2.5 days). Protocol-based fluid resuscitation of patients with severe sepsis and septic shock with the noninvasive cardiac output monitor and passive leg-raising maneuver did not result in better

  11. ZnO(101) films by pulsed reactive crossed-beam laser ablation

    Indian Academy of Sciences (India)

    Administrator

    PRCLA) to deposit a (101) oriented. ZnO film. In this method, a supersonic jet of oxygen pulse is made to cross the laser plume from a zinc metal target while being carried to the Si(111) substrate. The obtained deposit was nanocrystalline ZnO as ...

  12. Influence of annealing temperature on ZnO thin films grown by dual ...

    Indian Academy of Sciences (India)

    Administrator

    X-ray diffraction (XRD) measurements showed that all ZnO films have (002) preferred orientation. Full-width at half-maximum (FWHM) of XRD from the (002) crystal plane was observed to reach to a minimum value of 0⋅139° from ZnO film, annealed at 600 °C. Photoluminescence (PL) measurements demonstrated sharp ...

  13. Structural, optical and electrical properties of ZnO thin films prepared ...

    Indian Academy of Sciences (India)

    ZnO thin films have been prepared using zinc acetate precursor by spray pyrolytic decomposition of zinc acetate on glass substrates at 450 °C. Effect of precursor concentration on structural and optical properties has been investigated. ZnO films are polycrystalline with (002) plane as preferential orientation. The optical ...

  14. Seed-mediated growth of ZnO nanorods on multiwalled carbon nanotubes.

    Science.gov (United States)

    Li, Changqing; Jin, Zhong; Chu, Haibin; Li, Yan

    2008-09-01

    The heterostructures of ZnO nanorods on multiwalled carbon nanotubes (MWNTs) were fabricated by a seed-mediated growth method. First, the surfaces of the carbon nanotubes (CNTs) were coated in situ with mono-dispersed ZnO nanocrystals of about 7 nm by the reaction of zinc acetate and sodium hydroxide. These nanocrystals were then served as the seeds for further growth of ZnO nanorods. In the second step, ZnO nanorods were grown on MWNTs coated with ZnO nanocrystals in an aqueous solution of zinc nitrate and equimolar hexamethylenetetramine at 85 degrees C. Typically, the ZnO nanorods had the length of 300-600 nm and the diameter of 40-140 nm and took a random direction on the outside walls of MWNTs. The morphology of the ZnO nanorods was dependent on pH, reactant concentration, and growing time.

  15. Selective growth of ZnO thin film nanostructures: Structure, morphology and tunable optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Krishnakanth, Katturi Naga; Sunandana, C. S. [School of Physics, University of Hyderabad, Hyderabad-50046 (India); Rajesh, Desapogu, E-mail: rajesh.esapogu@gmail.com, E-mail: mperd@nus.edu.sg [School of Physics, University of Hyderabad, Hyderabad-50046 (India); Dept. of Mechanical Engineering, National University of Singapore (Singapore)

    2016-05-23

    The ZnO nanostructures (spherical, rod shape) have been successfully fabricated via a thermal evaporation followed by dip coating method. The pure, doped ZnO thin films were characterized by X-ray powder diffraction (XRD) and field emission scanning electron microscopy (FESEM) and UV-Vis spectroscopy, respectively. A possible growth mechanism of the spherical, rod shape ZnO nanostructures are discussed. XRD patterns revealed that all films consist of pure ZnO phase and were well crystallized with preferential orientation towards (002) direction. Doping by PVA, PVA+Cu has effective role in the enhancement of the crystalline quality and increases in the band gap.

  16. Insights into post-annealing and silver doping effects on the internal microstructure of ZnO nanoparticles through X-ray diffraction probe

    Science.gov (United States)

    Obeydavi, Ali; Dastafkan, Kamran; Rahimi, Mohammad; Ghadam Dezfouli, Mohammad Amin

    2017-07-01

    ZnO nanoparticles were synthesized via Pechini method at various post-annealing temperatures (400°, 500°, and 600 °C) and silver doping concentrations (Zn:Ag molar ratios of 30, 20, and 10). Multifarious microstructural features including crystallite size, size-strain based broadening, residual stress, preferential orientation, crystallinity degree, lattice parameters, unit cell variation, and stacking fault probability were surveyed through phase analysis, Williamson-Hall plot, texture coefficient and unit cell calculations. X-ray probing verified good crystallinity with a hexagonal close pack Wurtzite morphology. Williamson-Hall analysis exhibited distributions of crystallite size and microstrain as well as their contributions on the line broadening of the host ZnO and guest Ag phases upon annealing-doping treatments. Textural analysis revealed the alteration in anisotropic crystallinity of the host phase and transformation of the preferred directions, (100) and (101), as function of annealing-doping processes. Besides, while guest Ag phase was shown to be polycrystalline with randomly orientated crystals at moderate concentration with respect to thermal treatment, preferential orientation went through a major change, (220) to (111), with increment in Ag loadings. Under identical synthetic conditions, the distinction in the lattice constants and unit cell variation between pure and doped ZnO nanoparticles was enforced and results verified major impressionability via annealing and doping factors.

  17. Pre and post annealed low cost ZnO nanorods on seeded substrate

    Science.gov (United States)

    Nordin, M. N.; Kamil, Wan Maryam Wan Ahmad

    2017-05-01

    We wish to report the photonic band gap (where light is confined) in low cost ZnO nanorods created by two-step chemical bath deposition (CBD) method where the glass substrates were pre-treated with two different seeding thicknesses, 100 nm (sample a) and 150 nm (sample b), of ZnO using radio frequency magnetron sputtering. Then the samples were annealed at 600°C for 1 hour in air before and after immersed into the chemical solution for CBD process. To observe the presence of photonic band gap on the sample, UV-Visible-NIR spectrophotometer was utilized and showed that sample a and sample b both achieved wide band gap between 240 nm and 380 nm, within the UV range for typical ZnO, however sample b provided a better light confinement that may be attributed by the difference in average nanorods size. Field Emission Scanning Electron Microscope (FESEM) of the samples revealed better oriented nanorods uniformly scattered across the surface when substrates were coated with 100 nm of seeding layer whilst the 150 nm seeding sample showed a poor distribution of nanorods probably due to defects in the sample. Finally, the crystal structure of the ZnO crystallite is revealed by employing X-ray diffraction and both samples showed polycrystalline with hexagonal wurtzite structure that matched with JCPDS No. 36-1451. The 100 nm pre-seeded samples was recognized to have bigger average crystallite size, however sample b was suggested as having a higher crystalline quality. In conclusion, the sample b is recognized as a better candidate for future photonic applications due to its more apparent of photonic band gap and this may be contributed by more random distribution of the nanorods as observed in FESEM images as well as higher crystalline quality as suggested from XRD measurements.

  18. UV irradiation assisted growth of ZnO nanowires on optical fiber surface

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Bo; Shi, Tielin; Liao, Guanglan; Li, Xiaoping; Huang, Jie; Zhou, Temgyuan; Tang, Zirong, E-mail: zirong@mail.hust.edu.cn

    2017-06-01

    Highlights: • A new fabrication process combined a hydrothermal process with UV irradiation from optical fiber is developed. • The growth of ZnO nanowires is efficient in the utilization of UV light. • A novel hybrid structure which integrates ZnO nanowires on optical fiber surface is synthesized. • The UV assisted growth of ZnO nanowires shows preferred orientation and better quality. • A mechanism of growing ZnO nanowires under UV irradiation is proposed. - Abstract: In this paper, a novel approach was developed for the enhanced growth of ZnO nanowires on optical fiber surface. The method combined a hydrothermal process with the efficient UV irradiation from the fiber core, and the effects of UV irradiation on the growth behavior of ZnO nanowires were investigated. The results show that UV irradiation had great effects on the preferred growth orientation and the quality of the ZnO nanowires. The crystallization velocity along the c-axis would increase rapidly with the increase of the irradiation power, while the growth process in the lateral direction was marginally affected by the irradiation. The structure of ZnO nanowires also shows less oxygen vacancy with UV irradiation of higher power. The developed approach is applicable for the efficient growth of nanowires on the fiber surface, and the ZnO nanowires/optical fiber hybrid structures have great potentials for a wide variety of applications such as optical fiber sensors and probes.

  19. Resource-oriented coaching for reduction of examination-related stress in medical students: an exploratory randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Kötter T

    2016-08-01

    Full Text Available Thomas Kötter,1 Frank Niebuhr2 1Institute of Social Medicine and Epidemiology, 2Institute of Family Medicine, University of Lübeck, Lübeck, Germany Introduction: The years spent in acquiring medical education is considered a stressful period in the life of many students. Students whose mental health deteriorates during this long period of study are less likely to become empathic and productive physicians. In addition to other specific stressors, academic examinations seem to further induce medical school-related stress and anxiety. Combined group and individual resource-oriented coaching early in medical education might reduce examination-related stress and anxiety and, consequently, enhance academic performance. Good quality evidence, however, remains scarce. In this study, therefore, we explored the question of whether coaching affects examination-related stress and health in medical students.Methods: We conducted a randomized controlled trial. Students who registered for the first medical academic examination in August 2014 at the University of Lübeck were recruited and randomized into three groups. The intervention groups 1 and 2 received a 1-hour psychoeducative seminar. Group 1 additionally received two 1-hour sessions of individual coaching during examination preparation. Group 3 served as a control group. We compared changes in self-rated general health (measured by a single item, anxiety and depression (measured by the hospital anxiety and depression scale, as well as medical school stress (measured by the perceived medical school stress instrument. In order to further investigate the influence of group allocation on perceived medical school stress, we conducted a linear regression analysis.Results: We saw a significant deterioration of general health and an increase in anxiety and depression scores in medical students while preparing for an examination. We found a small, but statistically significant, effect of group allocation on

  20. The effect of integrated emotion-oriented care versus usual care on elderly persons with dementia in the nursing home and on nursing assistants: a randomized clinical trial

    NARCIS (Netherlands)

    Finnema, E.J.; Dr�es, R.M.; Ettema, T.P.; Ooms, M.E.; Adèr, H.J.; Ribbe, M.W.; van Tilburg, W.

    2005-01-01

    Objectives: To examine the effect of integrated emotion-oriented care on nursing home residents with dementia and nursing assistants. Design: A multi-site randomized clinical trial with matched groups, and measurements at baseline and after seven months. Setting: Sixteen psychogeriatric wards in

  1. The effect of integrated emotion-oriented care versus usual care on elderly persons with dementia in the nursing home and on nursing assistants: a randomized clinical trial

    NARCIS (Netherlands)

    Finnema, E.J.; Dr�es, R.M.; Ettema, T.P.; Ooms, M.E.; Adèr, H.J.; Ribbe, M.W.; Tilburg, van W.

    2005-01-01

    OBJECTIVES: To examine the effect of integrated emotion-oriented care on nursing home residents with dementia and nursing assistants. DESIGN: A multi-site randomized clinical trial with matched groups, and measurements at baseline and after seven months. SETTING: Sixteen psychogeriatric wards in

  2. Effects of carbon defects on ZnO nanorods directly grown on graphene

    Science.gov (United States)

    Honda, Mitsuhiro; Tokuda, Fuyuki; Ichikawa, Yo

    2017-11-01

    The correlation between carbon defects and the density of ZnO nanorods directly grown on graphene was studied. Thermal annealing was performed to vary the defect density of graphene on which ZnO nanorods were directly grown via hydrothermal synthesis. We found that ZnO nanorods were densely distributed on a highly defective graphene. Furthermore, specific defect sites were observed to provide upright ZnO nanorods. Raman spectroscopy revealed that the thermally induced defect corresponds to a carbon vacancy, which is expected to provide a reactive graphene surface where precursors can be easily attached to trigger the nucleation and further growth of ZnO nanorods. The local measurement of defects is believed to elucidate the key parameters for the growth of highly oriented ZnO nanorods.

  3. Structural interpretation of chemically synthesized ZnO nanorod and its application in lithium ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, Samapti; Sain, Sumanta [Materials Science Division, Department of Physics, The University of Burdwan, Golapbag, Burdwan 713104, West Bengal (India); Yoshio, Masaki [Advanced Research and Education Centre, Saga University, 1341 Yoga-machi, Saga 840-0047 (Japan); Kar, Tanusree [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, West Bengal (India); Gunawardhana, Nanda, E-mail: nandagunawardhana@pdn.ac.lk [International Research Centre, Senate Building, University of Peradeniya, Peradeniya 20400 (Sri Lanka); Pradhan, Swapan Kumar, E-mail: skpradhan@phys.buruniv.ac.in [Materials Science Division, Department of Physics, The University of Burdwan, Golapbag, Burdwan 713104, West Bengal (India)

    2015-02-28

    Graphical abstract: - Highlights: • ZnO nanorods are synthesized at room temperature via a simple chemical route. • Growth direction of ZnO nanorods has been determined along 〈0 0 2〉. • ZnO nanorods constructed anode shows a high discharge capacity in first cycle. • It retains good reversible capacity compared to other ZnO morphologies. - Abstract: ZnO nanorods are synthesized at room temperature via a simple chemical route without using any template or capping agent and its importance is evaluated as a suitable candidate for anode material in lithium ion battery. Structural and microstructure characterizations of these nanorods are made by analyzing the X-ray diffraction data employing the Rietveld method of powder structure refinement. It reveals that the ZnO nanorods are grown up with a preferred orientation and elongated along 〈0 0 2〉. FESEM images reveal that these uniform cylindrical shaped nanorods are of different lengths and diameters. These synthesized ZnO nanorods are tested as an anode material for lithium ion batteries. The nano grain size of the ZnO rods results in less volume expansion and/or contraction during the alloying/de-alloying process and causes in good cyclability. In addition, synthesized ZnO nanorods deliver high charge/discharge capacities compared to other reported ZnO materials.

  4. Development of nanostructured ZnO thin film via electrohydrodynamic atomization technique and its photoconductivity characteristics.

    Science.gov (United States)

    Duraisamy, Navaneethan; Kwon, Ki Rin; Jo, Jeongdai; Choi, Kyung-Hyun

    2014-08-01

    This article presents the non-vacuum technique for the preparation of nanostructured zinc oxide (ZnO) thin film on glass substrate through electrohydrodynamic atomization (EHDA) technique. The detailed process parameters for achieving homogeneous ZnO thin films are clearly discussed. The crystallinity and surface morphology of ZnO thin film are investigated by X-ray diffraction and field emission scanning electron microscopy. The result shows that the deposited ZnO thin film is oriented in the wurtzite phase with void free surface morphology. The surface roughness of deposited ZnO thin film is found to be ~17.8 nm. The optical properties of nanostructured ZnO thin films show the average transmittance is about 90% in the visible region and the energy band gap is found to be 3.17 eV. The surface chemistry and purity of deposited ZnO thin films are analyzed by fourier transform infrared and X-ray photoelectron spectroscopy, conforming the presence of Zn-O in the deposited thin films without any organic moiety. The photocurrent measurement of nanostructured ZnO thin film is examined in the presence of UV light illumination with wavelength of 365 nm. These results suggest that the deposited nanostructured ZnO thin film through EHDA technique possess promising applications in the near future.

  5. Room temperature photoluminescence properties of ZnO nanorods grown by hydrothermal reaction

    Energy Technology Data Exchange (ETDEWEB)

    Iwan, S., E-mail: iwan-sugihartono@unj.ac.id [Jurusan Fisika, FMIPA-UNJ, Rawamangun, Jakarta (Indonesia); Prodi Ilmu Material, Departemen Fisika, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia); Fauzia, Vivi [Prodi Ilmu Material, Departemen Fisika, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia); Umar, A. A. [Institute of Microengineering and Nanoelectronics, Universiti Kebangsaan Malaysia, UKM Bangi, Selangor (Malaysia); Sun, X. W. [School of Electrical & Electronic Engineering, Nanyang Technological University, Nanyang Avenue (Singapore)

    2016-04-19

    Zinc oxide (ZnO) nanorods were fabricated by a hydrothermal reaction on silicon (Si) substrate at 95 °C for 6 hours. The ZnO seed layer was fabricated by depositing ZnO thin films on Si substrates by ultrasonic spray pyrolisis (USP). The annealing effects on crystal structure and optical properties of ZnO nanorods were investigated. The post-annealing treatment was performed at 800 °C with different environments. The annealed of ZnO nanorods were characterized by X-ray diffraction (XRD) and photoluminescence (PL) in order to analyze crystal structure and optical properties, respectively. The results show the orientations of [002], [101], [102], and [103] diffraction peaks were observed and hexagonal wurtzite structure of ZnO nanorods were vertically grown on Si substrates. The room temperature PL spectra show ultra-violet (UV) and visible emissions. The annealed of ZnO nanorods in vacuum condition (3.8 × 10{sup −3} Torr) has dominant UV emission. Meanwhile, non-annealed of ZnO nanorods has dominant visible emission. It was expected that the annealed of ZnO in vacuum condition suppresses the existence of native defects in ZnO nanorods.

  6. Structural studies of ZnO nanostructures by varying the deposition parameters

    Science.gov (United States)

    Yunus, S. H. A.; Sahdan, M. Z.; Ichimura, M.; Supee, A.; Rahim, S.

    2017-01-01

    The effect of Zinc Oxide (ZnO) thin film on the growth of ZnO nanorods (NRs) was investigated. The structures of ZnO NRs were synthesized by chemical bath deposition (CBD) method in aqueous solution of N2O6Zn.6H2O and C6H12N4 at 90°C of deposition temperature. One of the ZnO NRs samples was deposited on a ZnO seed layer coated on a glass substrate to investigate the properties of ZnO NRs without receiving effect of other materials. Next, for diode application, the ZnO NRs was deposited on tin monosulfide (SnS) coated on indium-tin-oxide (ITO) coated glass substrate (SnS/ITO). The next, the ZnO structural properties were studied from surface morphology, X-ray diffractometer (XRD) spectra, and chemical composition by using field emission scanning electron microscope (FESEM), XRD and energy dispersive X-ray Spectroscopy (EDX). The growth of ZnO NRs on ZnO seed layer was investigated by ZnO seed layer condition while the growth of ZnO NRs on SnS/ITO was investigated by deposition time and deposition temperature parameters. From FESEM images, aligned ZnO NRs were obtained, and the diameters of ZnO NRs were 0.024-3.94 µm. The SnS thin film was affected by the diameter of ZnO NRs which are the ZnO NRs grow on SnS thin films has a larger diameter compared to ZnO NRs grow on ZnO seed layer. Besides that, all of ZnO peaks observed from XRD corresponding to the wurzite structure and preferentially oriented along the c-axis. In addition, EDX shows a high composition of zinc (Zn) and oxygen (O) signals, which indicated that the NRs are indeed made up of Zn and O.

  7. Standard practice for X-Ray determination of retained austenite in steel with near random crystallographic orientation

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2003-01-01

    1.1 This practice covers the determination of retained austenite phase in steel using integrated intensities (area under peak above background) of X-ray diffraction peaks using chromium Kα or molybdenum Kα X-radiation. 1.2 The method applies to carbon and alloy steels with near random crystallographic orientations of both ferrite and austenite phases. 1.3 This practice is valid for retained austenite contents from 1 % by volume and above. 1.4 If possible, X-ray diffraction peak interference from other crystalline phases such as carbides should be eliminated from the ferrite and austenite peak intensities. 1.5 Substantial alloy contents in steel cause some change in peak intensities which have not been considered in this method. Application of this method to steels with total alloy contents exceeding 15 weight % should be done with care. If necessary, the users can calculate the theoretical correction factors to account for changes in volume of the unit cells for austenite and ferrite resulting from vari...

  8. Influence of annealing on polymeric precursor derived ZnO thin films on sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Choppali, Uma, E-mail: umachoppali@gmail.com [Department of Mathematics and Science, Collin College, Frisco, TX 75035 (United States); Kougianos, Elias; Mohanty, Saraju P. [NanoSystem Design Laboratory (NSDL), University of North Texas, Denton, TX 76203 (United States); Gorman, Brian P. [Colorado Center for Advanced Ceramics, Dept. of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO 80401 (United States)

    2013-10-31

    Zinc oxide (ZnO) thin films on c-sapphire substrates were synthesized by spin-coating aqueous polymeric precursors. The effects of annealing at 1000 °C on crystallinity, surface morphology, and optical properties of ZnO thin films, with varying thicknesses, were studied. Single-layered ZnO thin films are polycrystalline with wurtzite structure and preferentially oriented along the (002) plane. X-ray diffraction pattern also reveals the presence of spinel zinc aluminate (ZnAl{sub 2}O{sub 4}) peaks. ZnO films have highly faceted granular morphology. Multilayered ZnO films, annealed twice at 1000 °C, do not exhibit any ZnO peaks but only ZnAl{sub 2}O{sub 4} peaks. Moreover, the surface morphology was smooth with ridges. These films do not exhibit the band gap or ultra-violet emission photoluminescence characteristics of ZnO. On annealing, there is an interfacial reaction between ZnO and sapphire resulting in ZnAl{sub 2}O{sub 4}. - Highlights: • Multilayer polymeric precursor derived ZnO film is annealed at 1000 °C on c-sapphire. • X-Ray diffraction (XRD) pattern of ZnO film annealed at 1000 °C shows ZnO peaks. • XRD pattern of ZnO films twice-annealed at 1000 °C shows only ZnAl{sub 2}O{sub 4} peaks. • Optical characterization of the multilayered films does not show ZnAl{sub 2}O{sub 4} peaks. • On annealing twice at 1000 °C, ZnO reacts with the c-sapphire to form ZnAl{sub 2}O{sub 4}.

  9. Effect of oriental medicine music therapy on patients with Hwa-byung: a study protocol for a randomized controlled trial.

    Science.gov (United States)

    Park, Jeong-Su; Park, Sunju; Cheon, Chun-Hoo; Jang, Bo-Hyoung; Lee, Song-Hee; Lee, Seung-Hyun; Chung, Sun-Yong; Kim, Jong-Woo; Jeon, Chan-Yong; Park, Jong-Hyeong; Shin, Yong-Cheol; Ko, Seong-Gyu

    2012-09-11

    Hwa-byung, a Korean culture-bound syndrome with both psychological and somatic symptoms, is also known as 'anger syndrome'. It includes various physical symptoms including anxiety, a feeling of overheating, a sensation of pressure on the chest, heart palpitations, respiratory stuffiness, insomnia, and anxiety. The proposed study is a single-center, double-blind, randomized, controlled trial with two parallel arms: an oriental medicine music therapy (OMMT) group and a control music therapy (CMT) group. In total, 48 patients will be enrolled into the trial. The first visit will be the screening visit. At baseline (visit 2), all participants fulfilling both the inclusion and the exclusion criteria will be split and randomly divided into two equal groups: the OMMT and the CMT (n = 24 each). Each group will receive treatment sessions over the course of 4 weeks, twice per week, for eight sessions in total. The primary outcome is the State-Trait Anxiety Inventory (STAI), and the secondary outcomes are the Hwa-byung scale (H-scale), the Center for Epidemiologic Studies Depression Scale (CES-D), the Hwa-byung visual analogue scale (H-VAS) for primary symptoms, the World Health Organization Quality of Life scale, brief version (WHOQOL-BREF), and levels of salivary cortisol. Patients will be asked to complete questionnaires at the baseline visit (visit 2), after the last treatment session (visit 9), and at 4 weeks after the end of all trial sessions (visit 10). From the baseline (visit 2) through the follow-up (visit 10), the entire process will take a total of 53 days. This proposed study targets patients with Hwa-byung, especially those who have exhibited symptoms of anxiety. Therefore, the primary outcome is set to measure the level of anxiety. OMMT is music therapy combined with traditional Korean medicinal theories. Unlike previously reported music therapies, for which patients simply listen to music passively, in OMMT, patients actively move their bodies and play the

  10. Effect of oriental medicine music therapy on patients with Hwa-byung: a study protocol for a randomized controlled trial

    Science.gov (United States)

    2012-01-01

    Background Hwa-byung, a Korean culture-bound syndrome with both psychological and somatic symptoms, is also known as ‘anger syndrome’. It includes various physical symptoms including anxiety, a feeling of overheating, a sensation of pressure on the chest, heart palpitations, respiratory stuffiness, insomnia, and anxiety. Methods/design The proposed study is a single-center, double-blind, randomized, controlled trial with two parallel arms: an oriental medicine music therapy (OMMT) group and a control music therapy (CMT) group. In total, 48 patients will be enrolled into the trial. The first visit will be the screening visit. At baseline (visit 2), all participants fulfilling both the inclusion and the exclusion criteria will be split and randomly divided into two equal groups: the OMMT and the CMT (n = 24 each). Each group will receive treatment sessions over the course of 4 weeks, twice per week, for eight sessions in total. The primary outcome is the State-Trait Anxiety Inventory (STAI), and the secondary outcomes are the Hwa-byung scale (H-scale), the Center for Epidemiologic Studies Depression Scale (CES-D), the Hwa-byung visual analogue scale (H-VAS) for primary symptoms, the World Health Organization Quality of Life scale, brief version (WHOQOL-BREF), and levels of salivary cortisol. Patients will be asked to complete questionnaires at the baseline visit (visit 2), after the last treatment session (visit 9), and at 4 weeks after the end of all trial sessions (visit 10). From the baseline (visit 2) through the follow-up (visit 10), the entire process will take a total of 53 days. Discussion This proposed study targets patients with Hwa-byung, especially those who have exhibited symptoms of anxiety. Therefore, the primary outcome is set to measure the level of anxiety. OMMT is music therapy combined with traditional Korean medicinal theories. Unlike previously reported music therapies, for which patients simply listen to music passively, in OMMT, patients

  11. Effect of oriental medicine music therapy on patients with Hwa-byung: a study protocol for a randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Park Jeong-Su

    2012-09-01

    Full Text Available Abstract Background Hwa-byung, a Korean culture-bound syndrome with both psychological and somatic symptoms, is also known as ‘anger syndrome’. It includes various physical symptoms including anxiety, a feeling of overheating, a sensation of pressure on the chest, heart palpitations, respiratory stuffiness, insomnia, and anxiety. Methods/design The proposed study is a single-center, double-blind, randomized, controlled trial with two parallel arms: an oriental medicine music therapy (OMMT group and a control music therapy (CMT group. In total, 48 patients will be enrolled into the trial. The first visit will be the screening visit. At baseline (visit 2, all participants fulfilling both the inclusion and the exclusion criteria will be split and randomly divided into two equal groups: the OMMT and the CMT (n = 24 each. Each group will receive treatment sessions over the course of 4 weeks, twice per week, for eight sessions in total. The primary outcome is the State-Trait Anxiety Inventory (STAI, and the secondary outcomes are the Hwa-byung scale (H-scale, the Center for Epidemiologic Studies Depression Scale (CES-D, the Hwa-byung visual analogue scale (H-VAS for primary symptoms, the World Health Organization Quality of Life scale, brief version (WHOQOL-BREF, and levels of salivary cortisol. Patients will be asked to complete questionnaires at the baseline visit (visit 2, after the last treatment session (visit 9, and at 4 weeks after the end of all trial sessions (visit 10. From the baseline (visit 2 through the follow-up (visit 10, the entire process will take a total of 53 days. Discussion This proposed study targets patients with Hwa-byung, especially those who have exhibited symptoms of anxiety. Therefore, the primary outcome is set to measure the level of anxiety. OMMT is music therapy combined with traditional Korean medicinal theories. Unlike previously reported music therapies, for which patients simply listen to music passively, in

  12. Preferential growth of ZnO thin films by the atomic layer deposition technique

    Science.gov (United States)

    Pung, Swee-Yong; Choy, Kwang-Leong; Hou, Xianghui; Shan, Chongxin

    2008-10-01

    Preferred orientation of ZnO thin films deposited by the atomic layer deposition (ALD) technique could be manipulated by deposition temperature. In this work, diethyl zinc (DEZn) and deionized water (H2O) were used as a zinc source and oxygen source, respectively. The results demonstrated that (10.0) dominant ZnO thin films were grown in the temperature range of 155-220 °C. The c-axis crystal growth of these films was greatly suppressed. Adhesion of anions (such as fragments of an ethyl group) on the (00.2) polar surface of the ZnO thin film was believed to be responsible for this suppression. In contrast, (00.2) dominant ZnO thin films were obtained between 220 and 300 °C. The preferred orientations of (10.0) and (00.2) of the ZnO thin films were examined by XRD texture analysis. The texture analysis results agreed well with the alignments of ZnO nanowires (NWs) which were grown from these ZnO thin films. In this case, the nanosized crystals of ZnO thin films acted as seeds for the growth of ZnO nanowires (NWs) by chemical vapor deposition (CVD) process. The highly (00.2) textured ZnO thin films deposited at high temperatures, such as 280 °C, contained polycrystals with the c axis perpendicular to the substrate surface and provided a good template for the growth of vertically aligned ZnO NWs.

  13. The Influence of Coping-oriented Hypnotic Suggestions on Chronic Pain in Patients with Spinal Cord Injury (SCI): A Randomized Controlled Study

    DEFF Research Database (Denmark)

    Knudsen, Lone; Kjøgx, Heidi; Kasch, Helge

    Background and aims: Coping-oriented hypnotic suggestions aimed at reducing pain catastrophizing have been shown to reduce pain in people with chronic tension-type headache and experimental pain in healthy volunteers during hypnosis (Kjøgx et al., 2016). However, the effect on pain post-hypnosis...... is unknown. The aim is to investigate the effect of coping-oriented hypnotic suggestions on chronic pain post-hypnosis. Methods: Seventy-five SCI-patients with chronic pain (>3, NRS 0-10) are randomized into one of three conditions; 1) coping-oriented hypnosis plus current treatment, 2) neutral hypnosis plus...... Strategies Questionnaire), pain catastrophizing (Pain Catastrophizing Scale), anxiety and depression (Hospital Anxiety and Depression Scale). Patients’ global impression of change and side effects of the hypnosis are also assessed for 14 days post-intervention. Results: Preliminary results will be presented...

  14. Mn-doped ZnO nanocrystals synthesized by sonochemical method: Structural, photoluminescence, and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Othman, A.A., E-mail: aaelho@yahoo.com [Assiut University, Faculty of Science, Department of Physics, Assiut 71516 (Egypt); Osman, M.A. [Assiut University, Faculty of Science, Department of Physics, Assiut 71516 (Egypt); Ibrahim, E.M.M. [Sohag University, Faculty of Science, Department of Physics, Sohag 82524 (Egypt); Ali, Manar A.; Abd-Elrahim, A.G. [Assiut University, Faculty of Science, Department of Physics, Assiut 71516 (Egypt)

    2017-05-15

    Highlights: • Mn-doped ZnO nanostructures were synthesized by the sonochemical method. • Structural, morphological, optical, photoluminescence and magnetic properties were investigated. • Mn-doped ZnO nanostructures reveal a blue shift of the optical band gap. • Photoluminescence spectra of Mn-doped ZnO nanostructures show quenching in the emission intensity. • Mn-doped ZnO nanostructures exhibit ferromagnetic ordering at room temperature. - Abstract: This work reports the synthesis of Mn-doped ZnO nanostructures using ice-bath assisted sonochemical technique. The impact of Mn-doping on structural, morphological, optical, and magnetic properties of ZnO nanostructures is studied. The morphological study shows that the lower doped samples possess mixtures of nanosheets and nanorods while the increase in Mn content leads to improvement of an anisotropic growth in a preferable orientation to form well-defined edge rods at Mn content of 0.04. UV–vis absorption spectra show that the exciton peak in the UV region is blue shifted due to Mn incorporation into the ZnO lattice. Doping ZnO with Mn ions leads to a reduction in the PL intensity due to a creation of more non-radiative recombination centers. The magnetic measurements show that the Mn-doped ZnO nanostructures exhibit ferromagnetic ordering at room temperature, as well as variation of the Mn content can significantly affect the ferromagnetic behavior of the samples.

  15. Shape controlled Sn doped ZnO nanostructures for tunable optical emission and transport properties

    Directory of Open Access Journals (Sweden)

    T. Rakshit

    2013-11-01

    Full Text Available Pure and Sn doped ZnO nanostructures have been grown on SiO2/Si substrates by vapor-solid technique without using any catalysts. It has been found that the morphology of the nanostructures depend strongly on the growth temperature and doping concentration. By proper tuning of the growth temperature, morphology of pure ZnO can be changed from tetrapods to multipods. On the other hand, by varying the doping concentration of Sn in ZnO, the morphology can be tuned from tetrapods to flower-like multipods to nanowires. X-ray diffraction pattern reveals that the nanostructures have a preferred (0002 growth orientation, and they are tensile strained with the increase of Sn doping in ZnO. Temperature-dependent photoluminescence characteristics of these nanostructures have been investigated in the range from 10 to 300 K. Pure ZnO tetrapods exhibited less defect state emissions than that of pure ZnO multipods. The defect emission is reduced with low concentration of Sn doping, but again increases at higher concentration of doping because of increased defects. Transport properties of pure and Sn doped ZnO tetrapods have been studied using complex-plane impedance spectroscopy. The contribution from the arms and junctions of a tetrapod could be distinguished. Sn doped ZnO samples showed lower conductivity but higher relaxation time than that of pure ZnO tetrapods.

  16. Core stability exercise is as effective as task-oriented motor training in improving motor proficiency in children with developmental coordination disorder: a randomized controlled pilot study.

    Science.gov (United States)

    Au, Mei K; Chan, Wai M; Lee, Lin; Chen, Tracy Mk; Chau, Rosanna Mw; Pang, Marco Yc

    2014-10-01

    To compare the effectiveness of a core stability program with a task-oriented motor training program in improving motor proficiency in children with developmental coordination disorder (DCD). Randomized controlled pilot trial. Outpatient unit in a hospital. Twenty-two children diagnosed with DCD aged 6-9 years were randomly allocated to the core stability program or the task-oriented motor program. Both groups underwent their respective face-to-face training session once per week for eight consecutive weeks. They were also instructed to carry out home exercises on a daily basis during the intervention period. Short Form of the Bruininks-Oseretsky Test of Motor Proficiency (Second Edition) and Sensory Organization Test at pre- and post-intervention. Intention-to-treat analysis revealed no significant between-group difference in the change of motor proficiency standard score (P=0.717), and composite equilibrium score derived from the Sensory Organization Test (P=0.100). Further analysis showed significant improvement in motor proficiency in both the core stability (mean change (SD)=6.3(5.4); p=0.008) and task-oriented training groups (mean change(SD)=5.1(4.0); P=0.007). The composite equilibrium score was significantly increased in the task-oriented training group (mean change (SD)=6.0(5.5); P=0.009), but not in the core stability group (mean change(SD) =0.0(9.6); P=0.812). In the task-oriented training group, compliance with the home program was positively correlated with change in motor proficiency (ρ=0.680, P=0.030) and composite equilibrium score (ρ=0.638, P=0.047). The core stability exercise program is as effective as task-oriented training in improving motor proficiency among children with DCD. © The Author(s) 2014.

  17. Omitted data in randomized controlled trials for anxiety and depression: A systematic review of the inclusion of sexual orientation and gender identity.

    Science.gov (United States)

    Heck, Nicholas C; Mirabito, Lucas A; LeMaire, Kelly; Livingston, Nicholas A; Flentje, Annesa

    2017-01-01

    The current study examined the frequency with which randomized controlled trials (RCTs) of behavioral and psychological interventions for anxiety and depression include data pertaining to participant sexual orientation and nonbinary gender identities. Using systematic review methodology, the databases PubMed and PsycINFO were searched to identify RCTs published in 2004, 2009, and 2014. Random selections of 400 articles per database per year (2,400 articles in total) were considered for inclusion in the review. Articles meeting inclusion criteria were read and coded by the research team to identify whether the trial reported data pertaining to participant sexual orientation and nonbinary gender identities. Additional trial characteristics were also identified and indexed in our database (e.g., sample size, funding source). Of the 232 articles meeting inclusion criteria, only 1 reported participants' sexual orientation, and zero articles included nonbinary gender identities. A total of 52,769 participants were represented in the trials, 93 of which were conducted in the United States, and 43 acknowledged the National Institutes of Health as a source of funding. Despite known mental health disparities on the basis of sexual orientation and nonbinary gender identification, researchers evaluating interventions for anxiety and depression are not reporting on these important demographic characteristics. Reporting practices must change to ensure that our interventions generalize to lesbian, gay, bisexual, and transgender persons. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  18. Effects of task-oriented robot training on arm function, activity, and quality of life in chronic stroke patients: a randomized controlled trial.

    Science.gov (United States)

    Timmermans, Annick A A; Lemmens, Ryanne J M; Monfrance, Maurice; Geers, Richard P J; Bakx, Wilbert; Smeets, Rob J E M; Seelen, Henk A M

    2014-03-31

    Over fifty percent of stroke patients experience chronic arm hand performance problems, compromising independence in daily life activities and quality of life. Task-oriented training may improve arm hand performance after stroke, whereby augmented therapy may lead to a better treatment outcome. Technology-supported training holds opportunities for increasing training intensity. However, the effects of robot-supported task-oriented training with real life objects in stroke patients are not known to date. The aim of the present study was to investigate the effectiveness and added value of the Haptic Master robot combined with task-oriented arm hand training in chronic stroke patients. In a single-blind randomized controlled trial, 22 chronic stroke patients were randomly allocated to receive either task-oriented robot-assisted arm-hand training (experimental group) or task-oriented non-robotic arm-hand training (control group). For training, the T-TOAT (Technology-supported Task-Oriented Arm Training) method was applied. Training was provided during 8 weeks, 4 times/week, 2 × 30 min/day. A significant improvement after training on the Action Research Arm Test (ARAT) was demonstrated in the experimental group (p = 0.008). Results were maintained until 6 months after cessation of the training. On the perceived performance measure (Motor Activity Log (MAL)), both, the experimental and control group improved significantly after training (control group p = 0.008; experimental group p = 0.013). The improvements on MAL in both groups were maintained until 6 months after cessation of the training. With regard to quality of life, only in the control group a significant improvement after training was found (EuroQol-5D p = 0.015, SF-36 physical p = 0.01). However, the improvement on SF-36 in the control group was not maintained (p = 0.012). No between-group differences could be demonstrated on any of the outcome measures. Arm hand performance improved in chronic stroke

  19. Properties of In–N codoped p-type ZnO nanorods grown through a two-step chemical route

    Energy Technology Data Exchange (ETDEWEB)

    Duta, M.; Mihaiu, S.; Munteanu, C. [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Anastasescu, M., E-mail: manastasescu@icf.ro [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Osiceanu, P.; Marin, A.; Preda, S. [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Nicolescu, M., E-mail: mnicolescu2006@yahoo.com [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Modreanu, M. [Tyndall National Institute, University College, Cork (Ireland); Zaharescu, M.; Gartner, M. [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania)

    2015-07-30

    Highlights: • p-Type ZnO film codoped with In, N on glass substrate was obtained. • The films were prepared by sol–gel followed by hydrothermal method. • Influence of annealing regimes on opto-electrical properties was studied. • Thin films morphology consists of interconnected, randomly oriented nanorods. • 3.31 × 10{sup 17} cm{sup −3}carrier concentration and 85% transmission were obtained at 500 °C. - Abstract: By codoping with a donor–acceptor pair through a two-step chemical method we have succeed to obtain p-type ZnO thin films on glass. Firstly, a thin undoped ZnO seed layer was deposited by sol–gel method followed by the deposition of In–N codoped ZnO film obtained through the hydrothermal technique. The influence of post-deposition annealing temperature (100 °C, 300 °C and 500 °C) on the samples was investigated from a structural, chemical, morphological and optoelectrical point of view. X-ray diffractometry (XRD), infrared ellipsometry and X-ray photoelectron spectroscopy (XPS) analyses have confirmed the codoped nature of the ZnO thin films. The XRD pattern analysis has established the films have wurtzite nanocrystalline structure, the crystallite sizes varying between 10 nm and 13 nm with the annealing temperature. Continuous and homogenous films with nanorods surface morphology has been obtained, as visualized by scanning electron microscopy measurements. Hall Effect measurements have established that all samples, regardless of annealing temperature, showed p-type conduction due to the successful incorporation of nitrogen in the film, with the highest carrier concentration registered at 500 °C. This is in good correlation with the nitrogen content in the films as revealed from XPS. In all samples, the XPS depth profiling has shown a nitrogen gradient with higher elemental concentration at the surface.

  20. Photoluminescence study of ZnO films codoped with nitrogen and tellurium

    Science.gov (United States)

    Porter, H. L.; Muth, J. F.; Narayan, J.; Foreman, John V.; Everitt, Henry O.

    2006-12-01

    Epitaxial ZnO films codoped with tellurium and nitrogen were grown by pulsed laser deposition on c-axis oriented sapphire substrates. The codoping strategy allowed the resistivity of the films to be controlled over several orders of magnitude and may prove useful in the development of ZnO based light emitters. Photoluminescence studies of tellurium-doped, nitrogen-doped, tellurium and nitrogen codoped, and undoped ZnO films were conducted. Strong room temperature photoluminescence and stimulated emission were observed in the undoped and Te-doped films, but not in codoped films. Time-resolved photoluminescence measurements indicated that carrier lifetime was significantly reduced in doped ZnO as compared to undoped ZnO.

  1. Electrically pumped waveguide lasing from ZnO nanowires.

    Science.gov (United States)

    Chu, Sheng; Wang, Guoping; Zhou, Weihang; Lin, Yuqing; Chernyak, Leonid; Zhao, Jianze; Kong, Jieying; Li, Lin; Ren, Jingjian; Liu, Jianlin

    2011-07-03

    Ultraviolet semiconductor lasers are widely used for applications in photonics, information storage, biology and medical therapeutics. Although the performance of gallium nitride ultraviolet lasers has improved significantly over the past decade, demand for lower costs, higher powers and shorter wavelengths has motivated interest in zinc oxide (ZnO), which has a wide direct bandgap and a large exciton binding energy. ZnO-based random lasing has been demonstrated with both optical and electrical pumping, but random lasers suffer from reduced output powers, unstable emission spectra and beam divergence. Here, we demonstrate electrically pumped Fabry-Perot type waveguide lasing from laser diodes that consist of Sb-doped p-type ZnO nanowires and n-type ZnO thin films. The diodes exhibit highly stable lasing at room temperature, and can be modelled with finite-difference time-domain methods.

  2. Structural, optical and photocatalytic properties of flower-like ZnO nanostructures prepared by a facile wet chemical method

    Directory of Open Access Journals (Sweden)

    Sini Kuriakose

    2013-11-01

    Full Text Available Flower-like ZnO nanostructures were synthesized by a facile wet chemical method. Structural, optical and photocatalytic properties of these nanostructures have been studied by X-ray diffraction (XRD, scanning electron microscopy (SEM, transmission electron microscopy (TEM, photoluminescence (PL and UV–vis absorption spectroscopy. SEM and TEM studies revealed flower-like structures consisting of nanosheets, formed due to oriented attachment of ZnO nanoparticles. Flower-like ZnO structures showed enhanced photocatalytic activity towards sun-light driven photodegradation of methylene blue dye (MB as compared to ZnO nanoparticles. XRD, UV–vis absorption, PL, FTIR and TEM studies revealed the formation of Zn(OH2 surface layer on ZnO nanostructures upon ageing. We demonstrate that the formation of a passivating Zn(OH2 surface layer on the ZnO nanostructures upon ageing deteriorates their efficiency to photocatalytically degrade of MB.

  3. Low-temperature solution growth of ZnO nanotube arrays

    Directory of Open Access Journals (Sweden)

    Ki-Woong Chae

    2010-12-01

    Full Text Available Single crystal ZnO nanotube arrays were synthesized at low temperature in an aqueous solution containing zinc nitrate and hexamethylenetetramine. It was found that the pH value of the reaction solution played an important role in mediating the growth of ZnO nanostructures. A change in the growth temperature might change the pH value of the solution and bring about the structure conversion of ZnO from nanorods to nanotubes. It was proposed that the ZnO nanorods were initially formed while the reaction solution was at a relatively high temperature (~90 °C and therefore enriched with colloidal Zn(OH2, which allowed a fast growth of ZnO nanocrystals along the [001] orientation to form nanorods. A decrease in the reaction temperature yielded a supersaturated solution, resulting in an increase in the concentration of OH− ions as well as the pH value of the solution. Colloidal Zn(OH2 in the supersaturated solution trended to precipitate. However, because of a slow diffusion process in view of the low temperature and low concentration of the colloidal Zn(OH2, the growth of the (001 plane of ZnO nanorods was limited and only occurred at the edge of the nanorods, eventually leading to the formation of a nanotube shape. In addition, it was demonstrated that the pH might impact the surface energy difference between the polar and non-polar faces of the ZnO crystal. Such a surface energy difference became small at high pH and hereby the prioritized growth of ZnO crystal along the [001] orientation was suppressed, facilitating the formation of nanotubes. This paper demonstrates a new strategy for the fabrication of ZnO nanotubes on a large scale and presents a more comprehensive understanding of the growth of tube-shaped ZnO in aqueous solution at low temperature.

  4. Recent advances in ZnO nanostructures and thin films for biosensor applications: Review

    Energy Technology Data Exchange (ETDEWEB)

    Arya, Sunil K., E-mail: sunilarya333@gmail.com [Bioelectronics Program, Institute of Microelectronics, A-Star 11 Science Park Road, Singapore Science Park II, Singapore 117685 (Singapore); Saha, Shibu [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Ramirez-Vick, Jaime E. [Engineering Science and Materials Department, University of Puerto Rico, Mayaguez, PR 00681 (United States); Gupta, Vinay [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Bhansali, Shekhar [Department of Electrical and Computer Engineering, Florida International University, Miami, FL (United States); Singh, Surinder P., E-mail: singh.uprm@gmail.com [National Physical Laboratory, Dr K.S. Krishnan Marg, New Delhi 110012 (India)

    2012-08-06

    Graphical abstract: ZnO nanostructures have shown binding of biomolecules in desired orientation with improved conformation and high biological activity, resulting in enhanced sensing characteristics. Furthermore, their compatibility with complementary metal oxide semiconductor technology for constructing integrated circuits makes them suitable candidate for future small integrated biosensor devices. This review highlights various approaches to synthesize ZnO nanostructures and thin films, and their applications in biosensor technology. Highlights: Black-Right-Pointing-Pointer This review highlights various approaches to synthesize ZnO nanostructures and thin films. Black-Right-Pointing-Pointer Article highlights the importance of ZnO nanostructures as biosensor matrix. Black-Right-Pointing-Pointer Article highlights the advances in various biosensors based on ZnO nanostructures. Black-Right-Pointing-Pointer Article describes the potential of ZnO based biosensor for new generation healthcare devices. - Abstract: Biosensors have shown great potential for health care and environmental monitoring. The performance of biosensors depends on their components, among which the matrix material, i.e., the layer between the recognition layer of biomolecule and transducer, plays a crucial role in defining the stability, sensitivity and shelf-life of a biosensor. Recently, zinc oxide (ZnO) nanostructures and thin films have attracted much interest as materials for biosensors due to their biocompatibility, chemical stability, high isoelectric point, electrochemical activity, high electron mobility, ease of synthesis by diverse methods and high surface-to-volume ratio. ZnO nanostructures have shown the binding of biomolecules in desired orientations with improved conformation and high biological activity, resulting in enhanced sensing characteristics. Furthermore, compatibility with complementary metal oxide semiconductor technology for constructing integrated circuits makes ZnO

  5. Synthesis of Imine-Bearing ZnO Nanoparticle Thin Films and Characterization of Their Structural, Morphological and Optical Properties.

    Science.gov (United States)

    Kaur, Narinder; Sharma, Sanjeev K; Kim, Deuk Young; Sharma, Hemant; Singh, Narinder

    2015-10-01

    We are presenting the first report on the fabrication of imine-bearing ZnO nanoparticle thin films grown on Corning glass by spin coating. The sol was prepared by dissolving imine-bearing ZnO nanoparticles in dimethylsulfoxide (DMSO). The thickness of the films was manipulated to be 125-200 nm. The X-ray diffraction (XRD) analysis showed hexagonal wurtzite structure of imine-bearing ZnO nanoparticles thin films with a (002) preferential orientation. The stretching of chemical bonds of the imine linkage and Zn-O in imine-bearing ZnO nanoparticle thin films was confirmed by Fourier transform infrared spectroscopy (FTIR). The grain size of the films increased with increasing the thickness of the films due to the number of coatings and subsequently dried at 200 °C. The transmittance of imine-bearing ZnO nanoparticle thin films was observed to be ≥94%, which was in close agreement to pure ZnO thin films in the visible region. The bandgap of imine-bearing ZnO nanoparticle thin films (3.04 eV), evaluated from Tauc's plot, was observed to be lower than that of pure ZnO (3.21 eV), which is attributed to the interaction of the ZnO nanoparticles with the imine receptor.

  6. Facile synthesis of mesoporous nanocrystalline ZnO bipyramids and spheres: Characterization, and photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan, Priya; Subramanian, Balaji [Laboratoire de recherche en matériaux et Micro-spectroscopies Raman et FTIR, Université de Moncton, Campus de Shippagan, Shippagan, NB, E8S 1P6 Canada (Canada); Djaoued, Yahia, E-mail: yahia.djaoued@umoncton.ca [Laboratoire de recherche en matériaux et Micro-spectroscopies Raman et FTIR, Université de Moncton, Campus de Shippagan, Shippagan, NB, E8S 1P6 Canada (Canada); Robichaud, Jacques [Laboratoire de recherche en matériaux et Micro-spectroscopies Raman et FTIR, Université de Moncton, Campus de Shippagan, Shippagan, NB, E8S 1P6 Canada (Canada); Sharma, Tanu; Bruning, Ralf [Department of Physcis, Mount Alison University, Sackville, NB, E4L 1E6 Canada (Canada)

    2015-04-01

    A facile and versatile polyol mediated solvo-thermal process using zinc acetate has been adopted for the synthesis of mesoporous ZnO nanomaterials having novel morphologies. Polyols used in this study, i.e. ethylene glycol (EG) and polyethylene glycols (PEG) of molecular weight 200 and 400, not only act as solvents but also as structure directing agents. The synthesis using EG leads to the formation of novel square bipyramidal zinc glycolate intermediate, which upon thermal treatment is converted into a nanocrystalline (NC) wurtzite ZnO structure, preserving the square bipyramidal morphology. Zinc glycolate upon hot water treatment (∼85 °C), results in the formation of NC wurtzite ZnO having a bicone morphology. However, when the synthesis is carried out by replacing EG with PEG-200 or 400, NC wurtzite ZnO having spherical morphologies have been directly isolated. In the case of PEG-200, the NC ZnO spheres displayed radially oriented nanorod features on the surface. A mechanism of formation of these ZnO morphologies is proposed. The synthesized ZnO materials have been used as catalysts for the photodegradation of crystal violet dye under UV-B and UV-C irradiation. The catalytic behavior of the ZnO samples is explained based on their porosity, crystallinity, and microstructure. - Highlights: • A polyol facilitated process using zinc acetate was used to obtain mesoporous ZnO. • These mesoporous ZnO materials exhibited square bipyramids and spheres morphologies. • Ethylene glycol and PEG-200 mediated ZnO samples presented higher degradation rates. • Crystallinity takes precedence over surface area in photodegradation.

  7. Multi-step resistive switching behavior of Li-doped ZnO resistance random access memory device controlled by compliance current

    Science.gov (United States)

    Lin, Chun-Cheng; Tang, Jian-Fu; Su, Hsiu-Hsien; Hong, Cheng-Shong; Huang, Chih-Yu; Chu, Sheng-Yuan

    2016-06-01

    The multi-step resistive switching (RS) behavior of a unipolar Pt/Li0.06Zn0.94O/Pt resistive random access memory (RRAM) device is investigated. It is found that the RRAM device exhibits normal, 2-, 3-, and 4-step RESET behaviors under different compliance currents. The transport mechanism within the device is investigated by means of current-voltage curves, in-situ transmission electron microscopy, and electrochemical impedance spectroscopy. It is shown that the ion transport mechanism is dominated by Ohmic behavior under low electric fields and the Poole-Frenkel emission effect (normal RS behavior) or Li+ ion diffusion (2-, 3-, and 4-step RESET behaviors) under high electric fields.

  8. Multi-step resistive switching behavior of Li-doped ZnO resistance random access memory device controlled by compliance current

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chun-Cheng [Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Department of Mathematic and Physical Sciences, R.O.C. Air Force Academy, Kaohsiung 820, Taiwan (China); Tang, Jian-Fu; Su, Hsiu-Hsien [Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Hong, Cheng-Shong; Huang, Chih-Yu [Department of Electronic Engineering, National Kaohsiung Normal University, Kaohsiung 802, Taiwan (China); Chu, Sheng-Yuan, E-mail: chusy@mail.ncku.edu.tw [Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 701, Taiwan (China)

    2016-06-28

    The multi-step resistive switching (RS) behavior of a unipolar Pt/Li{sub 0.06}Zn{sub 0.94}O/Pt resistive random access memory (RRAM) device is investigated. It is found that the RRAM device exhibits normal, 2-, 3-, and 4-step RESET behaviors under different compliance currents. The transport mechanism within the device is investigated by means of current-voltage curves, in-situ transmission electron microscopy, and electrochemical impedance spectroscopy. It is shown that the ion transport mechanism is dominated by Ohmic behavior under low electric fields and the Poole-Frenkel emission effect (normal RS behavior) or Li{sup +} ion diffusion (2-, 3-, and 4-step RESET behaviors) under high electric fields.

  9. Economic evaluation of schema therapy and clarification-oriented psychotherapy for personality disorders: A multicenter, randomized controlled trial

    NARCIS (Netherlands)

    Bamelis, L.L.M.; Arntz, A.; Wetzelaer, P.; Verdoorn, R.; Evers, S.M.A.A.

    2015-01-01

    Purpose: To compare from a societal perspective the cost-effectiveness and cost-utility of schema therapy, clarification-oriented psychotherapy, and treatment as usual for patients with avoidant, dependent, obsessive-compulsive, paranoid, histrionic, and/or narcissistic personality disorder. Method:

  10. Development of gas sensors using ZnO nanostructures

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Different ZnO nanostructures such as nanowires, nanobelts and tetrapods have been grown and used for preparation of thick film (with random grain boundaries) as well as isolated nano- wire/nanobelt gas sensors. Sensitivity of different type of sensors has been studied to H2S and NO gases. The results show ...

  11. Development of gas sensors using ZnO nanostructures

    Indian Academy of Sciences (India)

    Different ZnO nanostructures such as nanowires, nanobelts and tetrapods have been grown and used for preparation of thick film (with random grain boundaries) as well as isolated nanowire/nanobelt gas sensors. Sensitivity of different type of sensors has been studied to H2S and NO gases. The results show that the ...

  12. Fabrication of ZnO photonic amorphous diamond nanostructure from parrot feathers for modulated photoluminescence properties

    Science.gov (United States)

    Zhang, Zhengli; Yu, Ke; Liao, Na; Yin, Haihong; Lou, Lei; Yu, Qian; Liao, Yuanyuan; Zhu, Ziqiang

    2011-12-01

    A ZnO photonic amorphous diamond nanostructure was successfully synthesised using a feather barb of the Rosy-Faced Lovebird as supporting template via a facile sol-gel process. Different from ordered structures, an isotropic PBG around 500 nm was evidenced from reflectance spectra and an optical metallurgical microscopy image, which overlaps with the visible emission peak of ZnO. As a result, the inhibition of visible emission inside the PBG and the enhancement of UV emission at the PBG edges have both been observed, which is independent from the incident angle. Moreover, the rapid thermal annealing can also help improve the crystallinity of ZnO and raise the UV/visible emission ratio without affecting the structure. These results can be very useful for the study of the modification of the optical emission properties of ZnO and other semiconductor materials as well as research on ZnO random lasing.

  13. Electric Characteristics of the Carbon Nanotube Network Transistor with Directly Grown ZnO Nanoparticles.

    Science.gov (United States)

    Kim, Un Jeong; Bae, Gi Yoon; Suh, Dong Ik; Park, Wanjun

    2016-03-01

    We report on the electrical characteristics of field effect transistors fabricated with random networks of single-walled carbon nanotubes with surfaces modified by ZnO nanoparticles. ZnO nanoparticles are directly grown on single-walled carbon nanotubes by atomic layer deposition using diethylzinc (DEZ) and water. Electrical observations show that ZnO nanoparticles act as charge transfer sources that provide electrons to the nanotube channel. The valley position in ambipolar transport of nanotube transistors is negatively shifted for 3V due to the electronic n-typed property of ZnO nanoparticles. However, the Raman resonance remains invariant despite the charge transfer effect produced by ZnO nanoparticles.

  14. ZnO films grown by MOCVD on GaAs substrates: Effects of a Zn buffer deposition on interface, structural and morphological properties

    Science.gov (United States)

    Agouram, S.; Martínez-Tomás, M. C.; Muñoz-Sanjosé, V.

    2009-04-01

    Integration of ZnO with the well-developed GaAs technology presents several aspects that need to be previously analyzed and considered. The large lattice mismatch between ZnO and GaAs and its different crystallographic structure lead to many structural defects. In addition, their potential chemical reactivity is another source of complexity and an academic challenge. Recently some interesting contributions on this subject have been carried out by Liu and co-workers. As an additional step to the knowledge of the ZnO/GaAs heterostructure, we have deepened on the study of the morphology and orientation of ZnO thin films grown by atmospheric pressure metal-organic chemical vapour deposition (AP-MOCVD) on GaAs(1 0 0) and GaAs(1 1 1)A substrates with and without a Zn buffer pre-deposition on them. The analysis has been made as a function of growth temperature and precursors ratio. Structural, morphological and compositional characterizations have been made by X-ray diffraction (XRD), high-resolution X-ray diffraction (HRXRD), scanning electron microscopy (SEM), energy dispersive X-ray microanalysis (EDX) and X-ray photoemission spectroscopy (XPS). ZnO layers present an out-of-plane (0 0 0 1) preferred orientation, while the in-plane orientation has a random distribution. The layers are constituted by large tilted columnar grains with a top angle of around 55° indicating that the planes which constitute the conic heads are the {1 0 1¯ 1} ones. ZnO films grown after a previous Zn deposition exhibit a less compact morphology. In some cases and depending on growth conditions, interfacial processes with crystallization of extrinsic phases have been observed by XRD, revealing the presence of a body centred tetragonal phase of Zn 3As 2. In order to get an insight into these interfacial effects, EDX on cross-sectional views of the interface has been carried out. Strain measurements indicate a tensile nature of the biaxial stress, which is reduced by a factor two when the Zn

  15. Structural and Morphology of ZnO Nanorods Synthesized Using ZnO Seeded Growth Hydrothermal Method and Its Properties as UV Sensing

    Science.gov (United States)

    Ridhuan, Nur Syafinaz; Abdul Razak, Khairunisak; Lockman, Zainovia; Abdul Aziz, Azlan

    2012-01-01

    In this study, zinc oxide (ZnO) nanorod arrays were synthesized using a simple hydrothermal reaction on ZnO seeds/n-silicon substrate. Several parameters were studied, including the heat-treatment temperature to produce ZnO seeds, zinc nitrate concentration, pH of hydrothermal reaction solution, and hydrothermal reaction time. The optimum heat-treatment temperature to produce uniform nanosized ZnO seeds was 400°C. The nanorod dimensions depended on the hydrothermal reaction parameters. The optimum hydrothermal reaction parameters to produce blunt tip-like nanorods (770 nm long and 80 nm in top diameter) were 0.1 M zinc nitrate, pH 7, and 4 h of growth duration. Phase analysis studies showed that all ZnO nanorods exhibited a strong (002) peak. Thus, the ZnO nanorods grew in a c-axis preferred orientation. A strong ultraviolet (UV) emission peak was observed for ZnO nanorods grown under optimized parameters with a low, deep-level emission peak, which indicated high optical property and crystallinity of the nanorods. The produced ZnO nanorods were also tested for their UV-sensing properties. All samples responded to UV light but with different sensing characteristics. Such different responses could be attributed to the high surface-to-volume ratio of the nanorods that correlated with the final ZnO nanorods morphology formed at different synthesis parameters. The sample grown using optimum synthesis parameters showed the highest responsivity of 0.024 A/W for UV light at 375 nm under a 3 V bias. PMID:23189199

  16. Preparation and Characteristic of Relative-Humidity Sensors Based on Laterally Grown ZnO Nanowires

    Science.gov (United States)

    Tsai, Fu-Shou; Wang, Shui-Jinn; Tu, Yung-Chun; Lin, Tseng-Hsing

    2013-06-01

    The use of laterally oriented zinc oxide nanowires (ZnO NWs) grown by a hydrothermal growth (HTG) method for relative-humidity (RH) sensing devices at room temperature (RT) is demonstrated. Sensing response under various RH conditions (12-96%) at RT is presented and discussed. A humidity sensor based on laterally oriented ZnO NWs with a sensing response (R12%/R96%) as high as 2.2 was obtained at RT. The RT-operable humidity-sensing characteristics with comparably good sensitivity of the proposed humidity sensors is attributed to the full utilization of the entire NW surface, because the current path is aligned with the orientation of the bridged lateral ZnO NWs during the humidity sensing application, thus making possible.

  17. Preparation and characterization of ZnO microcantilever for nanoactuation

    Science.gov (United States)

    Wang, Peihong; Du, Hejun; Shen, Shengnan; Zhang, Mingsheng; Liu, Bo

    2012-03-01

    Zinc oxide [ZnO] thin films are deposited using a radiofrequency magnetron sputtering method under room temperature. Its crystalline quality, surface morphology, and composition purity are characterized by X-ray diffraction [XRD], atomic force microscopy [AFM], field-emission scanning electron microscopy [FE-SEM], and energy-dispersive X-ray spectroscopy [EDS]. XRD pattern of the ZnO thin film shows that it has a high c-axis-preferring orientation, which is confirmed by a FE-SEM cross-sectional image of the film. The EDS analysis indicates that only Zn and O elements are contained in the ZnO film. The AFM image shows that the film's surface is very smooth and dense, and the surface roughness is 5.899 nm. The microcantilever (Au/Ti/ZnO/Au/Ti/SiO2/Si) based on the ZnO thin film is fabricated by micromachining techniques. The dynamic characterizations of the cantilever using a laser Doppler vibrometer show that the amplitude of the cantilever tip is linear with the driving voltage, and the amplitude of this microcantilever's tip increased from 2.1 to 13.6 nm when the driving voltage increased from 0.05 to 0.3 Vrms. The calculated transverse piezoelectric constant d 31 of the ZnO thin film is -3.27 pC/N. This d 31 is high compared with other published results. This ZnO thin film will be used in smart slider in hard disk drives to do nanoactuation in the future.

  18. Surface morphology evolution with fabrication parameters of ZnO nanowires toward emission properties enhancement

    Science.gov (United States)

    Belhaj, Marwa; Dridi, Cherif; Habba, Yamina Ghozlene; Capo-Chichi, Martine; Leprince-Wang, Yamin

    2017-12-01

    ZnO nanowire (NW) arrays were successfully grown on pre-seeded indium Tin oxide (ITO)-coated glass substrate using hydrothermal synthesis. Herein, the effects of ZnO seed layer density on the performance of ZnO NWs were investigated in details. The orientation and the dimension of ZnO NWs were found to depend on seeded substrate density as shown by scanning electron microscopy (SEM) micrographs which revealed that the typical morphology with the most uniform size can be obtained. From the X-ray diffraction (XRD) measurement, it can be seen that hexagonal c -axis oriented NWs were grown. The resonant Raman scattering was also investigated in details. It confirmed the wurtzite structure of the NW arrays and expected for good optical properties. The optical band gaps of synthesized ZnO NWs were found to decrease comparing to bulk ZnO and as function of seed layer. The photoluminescence (PL) spectra at room temperature have shown strong UV excitonic emission and weak deep-level emissions which reveal that the as-grown NW arrays have good optical properties with limited deep-level defects.

  19. Deposition conditions for the growth of textured ZnO thin films by aerosol CVD process

    OpenAIRE

    Deschanvres, J.-L.; Bochu, B.; Joubert, J.-C.

    1993-01-01

    The crystalline orientation of ZnO thin films deposited by an aerosol CVD process is studied with regard to the experimental conditions. The quality of the C-axis oriented growth depended on the substrate temperature, on the deposition rate and also on the hygrometric degree of the carrier gas. The quality of the gold sublayer influenced also the quality of the ZnO textured growth. Under a dry gas mixture N2-O2 at 495°C and with a deposition rate of 35Å/mn, the texture ratio was less than -3....

  20. ZnO Film Photocatalysts

    Directory of Open Access Journals (Sweden)

    Bosi Yin

    2014-01-01

    Full Text Available We have synthesized high-quality, nanoscale ultrathin ZnO films at relatively low temperature using a facile and effective hydrothermal approach. ZnO films were characterized by scanning electron microscope (SEM, X-ray diffraction (XRD, Raman spectroscopy, photoluminescence spectra (PL, and UV-vis absorption spectroscopy. The products demonstrated 95% photodegradation efficiency with Congo red (CR after 40 min irradiation. The photocatalytic degradation experiments of methyl orange (MO and eosin red also were carried out. The results indicate that the as-obtained ZnO films might be promising candidates as the excellent photocatalysts for elimination of waste water.

  1. Optical and morphological properties of graphene sheets decorated with ZnO nanowires via polyol enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Vinay, E-mail: winn201@gmail.com; Rajaura, Rajveer Singh, E-mail: winn201@gmail.com [Centre for Converging Technologies, University of Rajasthan, Jaipur - 302004 (India); Sharma, Preetam K.; Srivastava, Subodh; Vijay, Y. K. [Department of Physics, Thin Film and Membrane Science Lab., University of Rajasthan, Jaipur - 302004 (India); Sharma, S. S. [Department of Physics, Govt. Women Engineering College, Ajmer- 305002 (India)

    2014-04-24

    Graphene-ZnO nanocomposites have proven to be very useful materials for photovoltaic and sensor applications. Here, we report a facile, one-step in situ polymerization method for synthesis of graphene sheets randomly decorated with zinc oxide nanowires using ethylene glycol as solvent. We have used hydrothermal treatment for growth of ZnO nanowires. UV-visible spectra peak shifting around 288nm and 307 nm shows the presence of ZnO on graphene structure. Photoluminiscence spectra (PL) in 400nm-500nm region exhibits the luminescence quenching effect. Scanning electron microscopy (SEM) image confirms the growth of ZnO nanowires on graphene sheets.

  2. Optimization of growth conditions of ZnO nano thin films by chemical double dip technique

    Energy Technology Data Exchange (ETDEWEB)

    Vijayan, Thirukonda Anandamoorthy; Chandramohan, Rathinam; Thirumalai, Jagannathan [Department of Physics, Sree Sevugan Annamalai College, Devakottai-630 303 (India); Valanarasu, Santiyagu [Department of Physics, Ananda College, Devakottai-630 303 (India); Venkateswaran, Sivasuriyan [Department of Chemistry, Sree Sevugan Annamalai College, Devakottai-630 303 (India); Mahalingam, Thaiyan [Department of Physics, Alagappa University, Karaikudi-630 003 (India); Srikumar, Subbiah Ramachandran [Department of Physics, Kalasalingam University, Krishnankoil-626 190 (India)], E-mail: chandru17@yahoo.com

    2008-07-01

    Zinc oxide (ZnO) nano thin films have been deposited by the chemical double-dip technique using aqueous ZnSO{sub 4} and NaOH solutions. The ZnO films were characterized in terms of surface morphology by x-ray diffraction, energy-dispersive x-ray analysis (EDX), the use of a scanning electron microscope (SEM) and atomic force microscope (AFM) for surface morphology. The films exhibited a smooth morphology. The chemical states of oxygen and zinc in the ZnO nano thin films were also investigated by x-ray photoelectron spectroscopy (XPS). In the present investigations, highly textured ZnO thin films with a preferential (002)-orientation were prepared on glass substrates. The deposition conditions were optimized to obtain device-quality films for practical applications.

  3. Transition metal implanted ZnO. A correlation between structure and magnetism

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Shengqiang

    2008-07-01

    Nowadays ferromagnetism is often found in potential diluted magnetic semiconductor systems. However, many authors question the origin of this ferromagnetism, i.e. if the observed ferromagnetism stems from ferromagnetic precipitates rather than from carriermediated magnetic coupling of ionic impurities, as required for a diluted magnetic semiconductor. In this thesis, this question will be answered for transition-metal implanted ZnO single crystals. Magnetic secondary phases, namely metallic Fe, Co and Ni nanocrystals, are formed inside ZnO. They are - although difficult to detect by common approaches of structural analysis - responsible for the observed ferromagnetism. Particularly Co and Ni nanocrystals are crystallographically oriented with respect to the ZnO matrix. Their structure phase transformation and corresponding evolution of magnetic properties upon annealing have been established. Finally, an approach, pre-annealing ZnO crystals at high temperature before implantation, has been demonstrated to sufficiently suppress the formation of metallic secondary phases. (orig.)

  4. Synthesis and annealing study of RF sputtered ZnO thin film

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Shushant Kumar, E-mail: singhshushant86@gmail.com; Sharma, Himanshu [Department of Physics, Malaviya National Institute of Technology, Jaipur, JLN Marg, Malaviya Nagar, Jaipur-302017 (India); Singhal, R. [Department of Physics and Materials Research Centre, Malaviya National Institute of Technology Jaipur, JLN Marg, Malaviya Nagar, Jaipur-302017 (India); Kumar, V. V. Siva; Avasthi, D. K. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi-110067 (India)

    2016-05-23

    In this paper, we have investigated the annealing effect on optical and structural properties of ZnO thin films, synthesized by RF magnetron sputtering. ZnO thin films were deposited on glass and silicon substrates simultaneously at a substrate temperature of 300 °C using Argon gas in sputtering chamber. Thickness of as deposited ZnO thin film was found to be ~155 nm, calculated by Rutherford backscattering spectroscopy (RBS). These films were annealed at 400 °C and 500 °C temperature in the continuous flow of oxygen gas for 1 hour in tube furnace. X-ray diffraction analysis confirmed the formation of hexagonal wurtzite structure of ZnO thin film along the c-axis (002) orientation. Transmittance of thin films was increased with increasing the annealing temperature estimated by UV-visible transmission spectroscopy. Quality and texture of the thin films were improved with annealing temperature, estimated by Raman spectroscopy.

  5. Characteristics of strontium-doped ZnO films on love wave filter applications

    Energy Technology Data Exchange (ETDEWEB)

    Water, Walter [Department of Electronic Englineering, National Formosa University, No 64, Wen-Hwa Rd., Hu-Wei, Yunlin, Taiwan (China)]. E-mail: wwater@nfu.edu.tw; Yan, Y.-S. [Department of Electrical Engineering, Tung Nan Institute of Technology, No 152, Sec. 3 PeiShen Rd., Shenkeng, Taipei, Taiwan (China)

    2007-06-13

    The effect of dopant concentrations in strontium-doped ZnO films on Love wave filter characteristics was investigated. Strontium-doped ZnO films with a c-axis preferred orientation were grown on ST-cut quartz by radio frequency magnetron sputtering. The crystalline structures and surface morphology of films were studied by X-ray diffraction, scanning electron microscopy and atomic force microscopy. The electromechanical coupling coefficient, dielectric constant, and temperature coefficient of frequency of filters were then determined using a network analyzer. A uniform crystalline structure and smooth surface of the ZnO films were obtained at the 1-2 mol% strontium dopant level. The electromechanical coupling coefficient of the 1 mol% strontium-doped ZnO film reaches a maximum of 0.61%, and the temperature coefficient of frequency declines to + 12.87 ppm/deg. C at a 1.5 mol% strontium dopant level.

  6. Influence of stress in ZnO thin films on its biosensing application.

    Science.gov (United States)

    Saha, Shibu; Tomar, Monika; Gupta, Vinay

    2015-11-01

    Highly c-axis oriented zinc oxide (ZnO) thin films deposited by radio frequency (RF) magnetron sputtering, under varying ambient atmosphere (oxygen and argon reactive gas mixture), were studied for biosensing application. The as-grown ZnO thin films were found to be under compressive stress. Glucose oxidase was chosen as model enzyme for studying biosensing response properties of the ZnO thin films. The present study reveals a good correlation between stress induced during thin film growth and its biosensing response characteristic. The bio-electrodes based on ZnO thin films which are under the influence of higher stress, show better sensitivity and higher enzyme loading along with a prolonged shelf life. The study highlights the importance of physical properties of thin film matrix on its biosensing application. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Templated self-assembly of ZnO films on monolayer patterns with nanoscale resolution.

    Science.gov (United States)

    Bauermann, Luciana Pitta; Gerstel, Peter; Bill, Joachim; Walheim, Stefan; Huang, Cheng; Pfeifer, Joerg; Schimmel, Thomas

    2010-03-16

    Lithographically defined self-growing ZnO films were prepared by a bioinspired chemical bath deposition technique (CBD). We observed a high selectivity of ZnO deposition: Teflon-like per-fluoro-decyl-trichlorosilane (FDTS) monolayers repelled ZnO primary particles, whereas amino-functionalized areas of the substrate were selectively covered by a highly anisotropic, oriented, and compact ZnO film with a thickness of 50 nm. The size of the primary particles in our methanol-based solution was approximately 2.5 nm. On the amino substrate they formed agglomerates not larger than 30 nm. Monolayer patterns made by polymer blend lithography were templated with an edge resolution of 30 nm. By using a specialized derivative of microcontact printing, we prepared layout-defined silane templates, which reliably determined the growth of a layout-defined, patterned oxide film with submicrometer lateral resolution.

  8. Effect of growth durations on the formation of ZnO nanorods prepared using continuous microwave heating technique

    Science.gov (United States)

    Jumali, Mohammad Hafizuddin Hj; Lee, Hock Beng; Abbas, Haidr Abdulzahra

    2017-05-01

    The effect of growth durations on the formation of ZnO nanorods thin film under continuous microwave irradiation was investigated. ZnO nanorods were synthesized using a microwave-assisted seed mediated growth method. ZnO nanoseed layer was prepared on Si substrate using a sol-gel technique. The microwave-assisted seed mediated growth of ZnO nanorods was conducted at different growth durations, namely 15, 20 and 30 min by fixing the irradiation power at 110 W. XRD diffractogram shows that the hexagonal wurtzite crystal structure for all the samples exhibited a preferred growth orientation along the c-axis. FESEM micrographs reveal with increasing heating duration, the average diameter of ZnO nanorods increased considerably and contrarily, the surface density of nanorods reduced. PL analysis suggests that an extended growth duration has resulted in the creation of defects in nanorods films owing to the insufficient supply of precursor ions during growth process.

  9. ZnO films grown by pulsed-laser deposition on soda lime glass substrates for the ultraviolet inactivation of Staphylococcus epidermidis biofilms

    Directory of Open Access Journals (Sweden)

    Jean-Paul Mosnier, Richard J O'Haire, Enda McGlynn, Martin O Henry, Stephen J McDonnell, Maria A Boyle and Kevin G McGuigan

    2009-01-01

    Full Text Available We found that a ZnO film of 2 μm thickness which was laser-deposited at room temperature onto a plain soda lime glass substrate, exhibits notable antibacterial activity against a biofilm of Staphylococcus epidermidis when back-illuminated by a UVA light source with a peak emission wavelength of about 365 nm. X-ray diffraction (XRD, scanning electron microscopy (SEM, atomic force microscopy (AFM, UV-visible absorption spectroscopy, Raman spectroscopy and x-ray photoemission spectroscopy (XPS were used to characterize the ZnO films before and after the interactions with the biofilm and the ultraviolet light, respectively. The as-deposited film was highly textured with the wurtzite (0002 in-plane orientation (c-axis perpendicular to ZnO surface and had a surface rms roughness of 49.7 nm. In the as-deposited film, the Zn to O ratio was 1 to 0.95. After the UV and biofilm treatments, the ZnO film surface had become rougher (rms roughness 68.1 nm and presented uniform micron-sized pitting randomly distributed, while the zinc to oxygen ratio had become 1 to 2.2. In this case, both the UV-visible and Raman spectra pointed to degradation of the structural quality of the material. On the strength of these data, we propose a model for the mediation of the bactericidal activity in which the photogeneration of highly oxidizing species and the presence of active surface defect sites both play an important role. This study is of particular interest for the acute problem of disinfection of pathogenic biofilms which form on medical device/implant surfaces.

  10. ZnO films grown by pulsed-laser deposition on soda lime glass substrates for the ultraviolet inactivation of Staphylococcus epidermidis biofilms

    Energy Technology Data Exchange (ETDEWEB)

    Mosnier, Jean-Paul; O' Haire, Richard J; McGlynn, Enda; Henry, Martin O [National Centre for Plasma Science and Technology and School of Physical Sciences, Dublin City University, Glasnevin, Dublin 9 (Ireland); McDonnell, Stephen J [Surface and Interface Research Laboratory, School of Physical Sciences, Dublin City University, Glasnevin, Dublin 9 (Ireland); Boyle, Maria A; McGuigan, Kevin G, E-mail: jean-paul.mosnier@dcu.i [Department of Physiology and Medical Physics, The Royal College of Surgeons in Ireland, St Stephen' s Green, Dublin 2 (Ireland)

    2009-08-15

    We found that a ZnO film of 2 {mu}m thickness which was laser-deposited at room temperature onto a plain soda lime glass substrate, exhibits notable antibacterial activity against a biofilm of Staphylococcus epidermidis when back-illuminated by a UVA light source with a peak emission wavelength of about 365 nm. X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), UV-visible absorption spectroscopy, Raman spectroscopy and x-ray photoemission spectroscopy (XPS) were used to characterize the ZnO films before and after the interactions with the biofilm and the ultraviolet light, respectively. The as-deposited film was highly textured with the wurtzite (0002) in-plane orientation (c-axis perpendicular to ZnO surface) and had a surface rms roughness of 49.7 nm. In the as-deposited film, the Zn to O ratio was 1 to 0.95. After the UV and biofilm treatments, the ZnO film surface had become rougher (rms roughness 68.1 nm) and presented uniform micron-sized pitting randomly distributed, while the zinc to oxygen ratio had become 1 to 2.2. In this case, both the UV-visible and Raman spectra pointed to degradation of the structural quality of the material. On the strength of these data, we propose a model for the mediation of the bactericidal activity in which the photogeneration of highly oxidizing species and the presence of active surface defect sites both play an important role. This study is of particular interest for the acute problem of disinfection of pathogenic biofilms which form on medical device/implant surfaces.

  11. ZnO films grown by pulsed-laser deposition on soda lime glass substrates for the ultraviolet inactivation of Staphylococcus epidermidis biofilms

    Science.gov (United States)

    Mosnier, Jean-Paul; O'Haire, Richard J.; McGlynn, Enda; Henry, Martin O.; McDonnell, Stephen J.; Boyle, Maria A.; McGuigan, Kevin G.

    2009-08-01

    We found that a ZnO film of 2 μm thickness which was laser-deposited at room temperature onto a plain soda lime glass substrate, exhibits notable antibacterial activity against a biofilm of Staphylococcus epidermidis when back-illuminated by a UVA light source with a peak emission wavelength of about 365 nm. X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), UV-visible absorption spectroscopy, Raman spectroscopy and x-ray photoemission spectroscopy (XPS) were used to characterize the ZnO films before and after the interactions with the biofilm and the ultraviolet light, respectively. The as-deposited film was highly textured with the wurtzite (0002) in-plane orientation (c-axis perpendicular to ZnO surface) and had a surface rms roughness of 49.7 nm. In the as-deposited film, the Zn to O ratio was 1 to 0.95. After the UV and biofilm treatments, the ZnO film surface had become rougher (rms roughness 68.1 nm) and presented uniform micron-sized pitting randomly distributed, while the zinc to oxygen ratio had become 1 to 2.2. In this case, both the UV-visible and Raman spectra pointed to degradation of the structural quality of the material. On the strength of these data, we propose a model for the mediation of the bactericidal activity in which the photogeneration of highly oxidizing species and the presence of active surface defect sites both play an important role. This study is of particular interest for the acute problem of disinfection of pathogenic biofilms which form on medical device/implant surfaces.

  12. A Randomized Trial to Measure the Efficacy of Applying Task Oriented Role Assignment to Improve Neonatal Resuscitation

    Science.gov (United States)

    2017-05-06

    DEPARTMENT OF THE AIR FORCE 59TH MEDICAL W ING (AETC) JOINT BASE SAN ANTONIO - LACKLAND TEXAS MEMORANOUMFORSGVT ATTN: MAJ CARRIE LITKE-WAGER...Author Litke· Wager, Carrie 0-4/Major 959/CSPS/ 59MDW/SGVT b. Mu, Thornton 0-5/LTC MCH E-ZDP-N SA MMC c. Delaney, Heather 0-4/ MAJ MCHE-ZDP-N SA MMC d...78234-2715 15 June 2016 Maj Carrie Litke-Wager, MD Brooke Army Medical Center Institutional Review Board A Randomized Trial to Measure the

  13. A Comparative Study on Structural and Optical Properties of ZnO Micro-Nanorod Arrays Grown on Seed Layers Using Chemical Bath Deposition and Spin Coating Methods

    Directory of Open Access Journals (Sweden)

    Sibel MORKOÇ KARADENİZ

    2016-11-01

    Full Text Available In this study, Zinc Oxide (ZnO seed layers were prepared on Indium Tin Oxide (ITO substrates by using Chemical Bath Deposition (CBD method and Sol-gel Spin Coating (SC method. ZnO micro-nanorod arrays were grown on ZnO seed layers by using Hydrothermal Synthesis method. Seed layer effects of structural and optical properties of ZnO arrays were characterized. X-ray diffractometer (XRD, Scanning Electron Microscopy (SEM and Ultraviolet Visible (UV-Vis Spectrometer were used for analyses. ZnO micro-nanorod arrays consisted of a single crystalline wurtzite ZnO structure for each seed layer. Besides, ZnO rod arrays were grown smoothly and vertically on SC seed layer, while ZnO rod arrays were grown randomly and flower like structures on CBD seed layer. The optical absorbance peaks found at 422 nm wavelength in the visible region for both ZnO arrays. Optical bandgap values were determined by using UV-Vis measurements at 3.12 and 3.15 eV for ZnO micro-nanorod arrays on CBD seed layer and for ZnO micro-nanorod arrays on SC-seed layer respectively.DOI: http://dx.doi.org/10.5755/j01.ms.22.4.13443

  14. Epitaxial ZnO Thin Films on a-Plane Sapphire Substrates Grown by Ultrasonic Spray-Assisted Mist Chemical Vapor Deposition

    Science.gov (United States)

    Nishinaka, Hiroyuki; Kamada, Yudai; Kameyama, Naoki; Fujita, Shizuo

    2009-12-01

    High-quality epitaxial ZnO thin films were grown by an ultrasonic spray-assisted mist chemical vapor deposition (CVD) on a-plane sapphire substrates with ZnO buffer layers. The ZnO thin films were grown with c-axis orientation without notable rotational domains. Surface morphologies and electrical properties were markedly improved as an effect of the ZnO buffer layers. The mobility in the ZnO epitaxial (main) layer was estimated to be 90 cm2/(V·s), which is reasonably high compared with those in ZnO layers grown by CVD processes. Photoluminescence at a low temperature (4.5 K) revealed a free A-exiton peak, and that at room temperature showed a strong band-edge peak with little deep-level luminescence.

  15. Algorithm for Reconstruction of 3D Images of Nanorice Particles from Diffraction Patterns of Two Particles in Independent Random Orientations with an X-ray Laser

    Directory of Open Access Journals (Sweden)

    Sung Soon Kim

    2017-06-01

    Full Text Available The method of angular correlations recovers quantities from diffraction patterns of randomly oriented particles, as expected to be measured with an X-ray free electron laser (XFEL, proportional to quadratic functions of the spherical harmonic expansion coefficients of the diffraction volume of a single particle. We have previously shown that it is possible to reconstruct a randomly oriented icosahedral or helical virus from the average over all measured diffraction patterns of such correlations. We point out in this paper that a structure of even simpler particles of 50 Å or so in diameter and consisting of heavier atomic elements (to enhance scattering that has been used as a test case for reconstructions from XFEL diffraction patterns can also be solved by this technique. Even though there has been earlier work on similar objects (prolate spheroids, one advantage of the present technique is its potential to also work with diffraction patterns not only due to single particles as has been suggested on the basis on nonoverlapping delta functions of angular scattering. Accordingly, we calculated from the diffraction patterns the angular momentum expansions of the pair correlations and triple correlations for general particle images and reconstructed those images in the standard way. Although the images looked pretty much the same, it is not totally clear to us that the angular correlations are exactly the same as different numbers of particles due to the possibility of constructive or destructive interference between the scattered waves from different particles. It is of course known that, for a large number of particles contributing to a diffraction parttern, the correlations converge to that of a single particle. It could be that the lack of perfect agreement between the images reconstructed with one and two particles is due to uncancelling constructive and destructive conditions that are not found in the case of solution scattering.

  16. Efficacy of a Peer-Led, Recovery-Oriented Shared Decision-Making System: A Pilot Randomized Controlled Trial.

    Science.gov (United States)

    Yamaguchi, Sosei; Taneda, Ayano; Matsunaga, Asami; Sasaki, Natsuki; Mizuno, Masashi; Sawada, Yumiko; Sakata, Masuhiro; Fukui, Satoe; Hisanaga, Fumie; Bernick, Peter; Ito, Junichiro

    2017-12-01

    The effects of a comprehensive shared decision-making system based on the CommonGround approach and incorporating peer support and a computerized decision aid were investigated. A pilot randomized controlled trial with six-month follow-up was conducted in Japan. Fifty-six outpatients with mental illness were randomly allocated to a shared decision-making system (intervention) group or treatment as usual (control) group. The implementation process and several outcomes were compared between groups. The core components and processes of shared decision making were observed in the intervention group more frequently than in the control group. The intervention group also reported a significantly more positive participants' view of the relationship with their doctor than the control group. The intervention did not have a significant effect on most clinical and recovery-related outcomes. The shared decision-making system appeared to partly improve patients' perceptions of communication and relationships with doctors but did not have a significant effect on other patient-level outcomes.

  17. Electrochemical synthesis of one-dimensional ZnO nanostructures on ZnO seed layer for DSSC applications

    Science.gov (United States)

    Marimuthu, T.; Anandhan, N.; Thangamuthu, R.

    2018-01-01

    Electrochemical deposition of vertically aligned zinc oxide (ZnO) nanorods were prepared on ZnO seeded fluorine doped tin oxide (FTO) substrate in the solutions consisting of different concentrations of hexamethylenetetramine (HMTA). The electrochemical, structural, morphological, vibrational and optical properties were characterized by cyclic voltammetry (CV), X-ray diffraction (XRD), scanning electron microscope (SEM), Raman spectroscopy and photoluminescence (PL) spectroscopy, respectively. CV curves confirm that metallic zinc phase is not deposited as the HMTA concentration is about 9 mM in a deposition solution. XRD patterns of the as-prepared films show that the increasing HMTA concentrations from 0 mM to 9 mM not only increase the formation of zinc hydrate chloride (Zn5(OH)8Cl2·H2O) but also decrease and finally disappear the metallic Zn deposition. After the as-prepared films annealed at 450 ° C, the crystalline phases of Zn and Zn5(OH)8Cl2·H2O are completely converted to ZnO hexagonal wurtzite phase with high intense growth (002) plane orientation. SEM images support that the vertical growth of ZnO nanostructures (nanorods and petals) with a few flowers is found to be in the cordillera structure as the films are deposited in the solutions consisting of 3 mM, 6 mM and 9 mM HMTA respectively. Raman and PL spectra confirm that the ZnO film deposited in the solution consisting of 9 mM HMTA has a higher crystalline nature with lesser atomic defects and is also higher c-axis growth than that of other films deposited in the solutions consisting of 0 mM, 3 mM and 6 mM, respectively. UV-vis absorbance spectra corroborate that the ZnO film deposited in the solution consisting of 9 mM HMTA shows a high dye absorbance as compared with other films. The efficiency of DSSCs based on ZnO photoanodes deposited in the solutions consisting of 0 mM and 9 mM HMTA was 1.79 and 3.75%, respectively. Electrochemical impedance spectra revealed that DSSC based on ZnO photoanode

  18. The PULSAR Specialist Care protocol: a stepped-wedge cluster randomized control trial of a training intervention for community mental health teams in recovery-oriented practice.

    Science.gov (United States)

    Shawyer, Frances; Enticott, Joanne C; Brophy, Lisa; Bruxner, Annie; Fossey, Ellie; Inder, Brett; Julian, John; Kakuma, Ritsuko; Weller, Penelope; Wilson-Evered, Elisabeth; Edan, Vrinda; Slade, Mike; Meadows, Graham N

    2017-05-08

    Recovery features strongly in Australian mental health policy; however, evidence is limited for the efficacy of recovery-oriented practice at the service level. This paper describes the Principles Unite Local Services Assisting Recovery (PULSAR) Specialist Care trial protocol for a recovery-oriented practice training intervention delivered to specialist mental health services staff. The primary aim is to evaluate whether adult consumers accessing services where staff have received the intervention report superior recovery outcomes compared to adult consumers accessing services where staff have not yet received the intervention. A qualitative sub-study aims to examine staff and consumer views on implementing recovery-oriented practice. A process evaluation sub-study aims to articulate important explanatory variables affecting the interventions rollout and outcomes. The mixed methods design incorporates a two-step stepped-wedge cluster randomized controlled trial (cRCT) examining cross-sectional data from three phases, and nested qualitative and process evaluation sub-studies. Participating specialist mental health care services in Melbourne, Victoria are divided into 14 clusters with half randomly allocated to receive the staff training in year one and half in year two. Research participants are consumers aged 18-75 years who attended the cluster within a previous three-month period either at baseline, 12 (step 1) or 24 months (step 2). In the two nested sub-studies, participation extends to cluster staff. The primary outcome is the Questionnaire about the Process of Recovery collected from 756 consumers (252 each at baseline, step 1, step 2). Secondary and other outcomes measuring well-being, service satisfaction and health economic impact are collected from a subset of 252 consumers (63 at baseline; 126 at step 1; 63 at step 2) via interviews. Interview-based longitudinal data are also collected 12 months apart from 88 consumers with a psychotic disorder

  19. Improvements in Orientation and Balancing Abilities in Response to One Month of Intensive Slackline-Training. A Randomized Controlled Feasibility Study.

    Science.gov (United States)

    Dordevic, Milos; Hökelmann, Anita; Müller, Patrick; Rehfeld, Kathrin; Müller, Notger G

    2017-01-01

    Background: Slackline-training has been shown to improve mainly task-specific balancing skills. Non-task specific effects were assessed for tandem stance and preferred one-leg stance on stable and perturbed force platforms with open eyes. It is unclear whether transfer effects exist for other balancing conditions and which component of the balancing ability is affected. Also, it is not known whether slackline-training can improve non-visual-dependent spatial orientation abilities, a function mainly supported by the hippocampus. Objective: To assess the effect of one-month of slackline-training on different components of balancing ability and its transfer effects on non-visual-dependent spatial orientation abilities. Materials and Methods: Fifty subjects aged 18-30 were randomly assigned to the training group (T) (n = 25, 23.2 ± 2.5 years; 12 females) and the control group (C) (n = 25, 24.4 ± 2.8 years; 11 females). Professional instructors taught the intervention group to slackline over four consecutive weeks with three 60-min-trainings in each week. Data acquisition was performed (within 2 days) by blinded investigators at the baseline and after the training. Main outcomes Improvement in the score of a 30-item clinical balance test (CBT) developed at our institute (max. score = 90 points) and in the average error distance (in centimeters) in an orientation test (OT), a triangle completion task with walking and wheelchair conditions for 60°, 90°, and 120°. Results: Training group performed significantly better on the closed-eyes conditions of the CBT (1.6 points, 95% CI: 0.6 to 2.6 points vs. 0.1 points, 95% CI: -1 to 1.1 points; p = 0.011, [Formula: see text] = 0.128) and in the wheelchair (vestibular) condition of the OT (21 cm, 95% CI: 8-34 cm vs. 1 cm, 95% CI: -14-16 cm; p = 0.049, [Formula: see text] = 0.013). Conclusion: Our results indicate that one month of intensive slackline training is a novel approach for enhancing clinically relevant balancing

  20. Comparison of Cognitive Orientation to daily Occupational Performance and conventional occupational therapy on occupational performance in individuals with stroke: A randomized controlled trial.

    Science.gov (United States)

    Ahn, Si-Nae; Yoo, Eun-Young; Jung, Min-Ye; Park, Hae-Yean; Lee, Ji-Yeon; Choi, Yoo-Im

    2017-01-01

    Cognitive Orientation to daily Occupational Performance (CO-OP) approach based on cognitive strategy in occupational therapy. To investigate the effects of CO-OP approach on occupational performance in individuals with hemiparetic stroke. This study was designed as a 5-week, randomized, single-blind. Forty-three participants who had a diagnosis of first stroke were enrolled in this study. The participants were randomly assigned to the experimental group (n = 20) or the control group (n = 23). The experimental group conducted CO-OP approach while the control group conducted conventional occupational therapy based on occupational performance components. This study measured Canadian Occupational Performance Measure (COPM) and Performance Quality Rating Scale (PQRS). Outcome measurements were performed at baseline and post-intervention. After training, the scores of COPM and PQRS in trained task were significantly higher for the score in the experimental group than the control group. In addition, the non-trained task was significantly higher for the score in the experimental group than the control group in COPM and the PQRS. This study suggests that the CO-OP approach is beneficial effects on the occupational performance to improvement in individuals with hemiparetic stroke, and have positive effects on generalization and transfer of acquired skills.

  1. Effects of motive-oriented therapeutic relationship in early-phase treatment of borderline personality disorder: a pilot study of a randomized trial.

    Science.gov (United States)

    Kramer, Ueli; Berger, Thomas; Kolly, Stéphane; Marquet, Pierre; Preisig, Martin; de Roten, Yves; Despland, Jean-Nicolas; Caspar, Franz

    2011-04-01

    Motive-oriented therapeutic relationship (MOTR, also called complementary therapeutic relationship) was postulated to be a particularly helpful therapeutic ingredient in the early-phase treatment of patients with personality disorders, in particular borderline personality disorder (BPD). The present pilot study of randomized controlled trial using an add-on design aims to investigate the effects of MOTR in early-phase treatment (up to session 10), with BPD patients on therapeutic alliance, session impact, and outcome. In total, N = 25 patients participated in the study. BPD patients were randomly allocated to a manual-based investigation process in 10 sessions or to the same investigation process infused with MOTR. Adherence ratings were performed and yielded satisfactory results. The results suggested a specific effectiveness of MOTR on the interpersonal problem area, on the quality of the therapeutic alliance and the quality of the therapeutic relationship, as rated by the patient. These results may have important clinical implications for the early-phase treatment of patients presenting with BPD.

  2. Effects of motive-oriented therapeutic relationship in a ten-session general psychiatric treatment of borderline personality disorder: a randomized controlled trial.

    Science.gov (United States)

    Kramer, Ueli; Kolly, Stéphane; Berthoud, Laurent; Keller, Sabine; Preisig, Martin; Caspar, Franz; Berger, Thomas; de Roten, Yves; Marquet, Pierre; Despland, Jean-Nicolas

    2014-01-01

    Motive-oriented therapeutic relationship (MOTR) was postulated to be a particularly helpful therapeutic ingredient in the early treatment phase of patients with personality disorders, in particular with borderline personality disorder (BPD). The present randomized controlled study using an add-on design is the first study to test this assumption in a 10-session general psychiatric treatment with patients presenting with BPD on symptom reduction and therapeutic alliance. A total of 85 patients were randomized. They were either allocated to a manual-based short variant of the general psychiatric management (GPM) treatment (in 10 sessions) or to the same treatment where MOTR was deliberately added to the treatment. Treatment attrition and integrity analyses yielded satisfactory results. The results of the intent-to-treat analyses suggested a global efficacy of MOTR, in the sense of an additional reduction of general problems, i.e. symptoms, interpersonal and social problems (F1, 73 = 7.25, p < 0.05). However, they also showed that MOTR did not yield an additional reduction of specific borderline symptoms. It was also shown that a stronger therapeutic alliance, as assessed by the therapist, developed in MOTR treatments compared to GPM (Z55 = 0.99, p < 0.04). These results suggest that adding MOTR to psychiatric and psychotherapeutic treatments of BPD is promising. Moreover, the findings shed additional light on the perspective of shortening treatments for patients presenting with BPD. © 2014 S. Karger AG, Basel.

  3. Mindfulness-Oriented Recovery Enhancement versus CBT for co-occurring substance dependence, traumatic stress, and psychiatric disorders: Proximal outcomes from a pragmatic randomized trial.

    Science.gov (United States)

    Garland, Eric L; Roberts-Lewis, Amelia; Tronnier, Christine D; Graves, Rebecca; Kelley, Karen

    2016-02-01

    In many clinical settings, there is a high comorbidity between substance use disorders, psychiatric disorders, and traumatic stress. Novel therapies are needed to address these co-occurring issues efficiently. The aim of the present study was to conduct a pragmatic randomized controlled trial comparing Mindfulness-Oriented Recovery Enhancement (MORE) to group Cognitive-Behavioral Therapy (CBT) and treatment-as-usual (TAU) for previously homeless men residing in a therapeutic community. Men with co-occurring substance use and psychiatric disorders, as well as extensive trauma histories, were randomly assigned to 10 weeks of group treatment with MORE (n = 64), CBT (n = 64), or TAU (n = 52). Study findings indicated that from pre-to post-treatment MORE was associated with modest yet significantly greater improvements in substance craving, post-traumatic stress, and negative affect than CBT, and greater improvements in post-traumatic stress and positive affect than TAU. A significant indirect effect of MORE on decreasing craving and post-traumatic stress by increasing dispositional mindfulness was observed, suggesting that MORE may target these issues via enhancing mindful awareness in everyday life. This pragmatic trial represents the first head-to-head comparison of MORE against an empirically-supported treatment for co-occurring disorders. Results suggest that MORE, as an integrative therapy designed to bolster self-regulatory capacity, may hold promise as a treatment for intersecting clinical conditions. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Effect of precursor solutions on ZnO film via solution precursor plasma spray and corresponding gas sensing performances

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Z.X., E-mail: zexin.yu@utbm.fr [Univ Bourgogne Franche Comte, CNRS, Lab ICB, UMR 6303, Site UTBM, F-90010 Belfort (France); Ma, Y.Z., E-mail: yangzhou.ma@outlook.com [School of Materials Science and Engineering, Anhui University of Technology, Ma’anshan 243002 (China); Zhao, Y.L. [Univ Bourgogne Franche Comte, CNRS, Lab ICB, UMR 6303, Site UTBM, F-90010 Belfort (France); Huang, J.B.; Wang, W.Z. [Key Lab of Safety Science of Pressurized System, Ministry of Education, School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237 (China); Moliere, M.; Liao, H.L. [Univ Bourgogne Franche Comte, CNRS, Lab ICB, UMR 6303, Site UTBM, F-90010 Belfort (France)

    2017-08-01

    Highlights: • C-axis preferential oriented grown ZnO films were firstly deposited via SPPS with different solutions. • ZnO films were hydrophobic due to cauliflower and honeycomb-like surface morphologies with high surface specific area. • Gas detecting performance of (002) plane oriented ZnO was predicted and compared by “first principle calculation method”. - Abstract: Solution precursor plasma spraying (SPPS) as a novel thermal spray method was employed to deposit nano-structured ZnO thin film using different formulations of the precursor solution. This article focuses on the influence of the solution composition on the preferential orientation of crystal growth, on crystal size and surface morphology of the resulting ZnO films. The trend of preferential growth along (002) lattice plane of ZnO film was studied by slow scanning X-ray diffraction using a specific coefficient P{sub (002).} It appears that the thermal spray process promotes the buildup of ZnO films preferentially oriented along the c-axis. The shape of single particle tends to change from round shaped beads to hexagonal plates by increasing the volume ratio of ethanol in the solvent. Both cauliflower and honeycomb-like surface morphologies featuring high specific surface area and roughness were obtained through the SPPS process by varying solution composition. These ZnO films are hydrophobic with contact angle as high as 136°, which is seemingly associated with micro reliefs developing high surface specific area. Then the gas sensing performances of ZnO films preferentially oriented along (002) face were tentatively predicted using the “first principle calculation method” and were compared with those of conventional films that are mainly oriented along the (101) face. The (002) face displays better hydrogen adsorption capability than the (101) face with much larger resulting changes in electrical resistance. In conclusion, the c-axis oriented ZnO films obtained through SSPS have

  5. Development and surface characterization of a glucose biosensor based on a nanocolumnar ZnO film

    Science.gov (United States)

    Rodrigues, A.; Castegnaro, M. V.; Arguello, J.; Alves, M. C. M.; Morais, J.

    2017-04-01

    Highly oriented nanostructured ZnO films were grown on the surface of stainless steel plates (ZnO/SS) by chemical bath deposition (CBD). The films consisted of vertically aligned ZnO nanocolumns, ∼1 μm long and ∼80 nm wide, as observed by SEM (scanning electron microscopy) and FIB (focused ion beam). XRD (X-ray diffraction) confirmed the c-axis preferred orientation of the ZnO columns, which were functionalized with the glucose oxidase (GOx) enzyme into a biosensor of glucose. The electrochemical response studied by CV (cyclic voltammetry) proved that the biosensor was capable of detecting glucose from 1.5 up to 16 mM concentration range. XPS (X-ray photoelectron spectroscopy) analysis, excited with synchrotron radiation, probed the atom specific chemical environment at the electrode's surface and shed some light on the nature of the ZnO-GOx interaction.

  6. Feeling Thanks and Saying Thanks: A Randomized Controlled Trial Examining If and How Socially Oriented Gratitude Journals Work.

    Science.gov (United States)

    O'Connell, Brenda H; O'Shea, Deirdre; Gallagher, Stephen

    2017-10-01

    This study examined the effect of a reflective interpersonal gratitude journal, a reflective-behavioral interpersonal gratitude journal and an active control journal, on primary qualities of well-being and depression. Participants (n = 192; 67.2% female) completed this 3-month longitudinal randomized controlled design. Participants in the reflective-behavioral condition experienced the greatest improvements in affect balance and reductions in depression at immediate posttest. Both gratitude interventions improved affect balance at 1 month, compared to the control. Changes in affect balance for those in the reflective-behavioral condition were mediated by the rate at which people expressed gratitude in their existing relationships. This effect was moderated by participant's baseline depressive status. Expressing felt gratitude to others appears to be a crucial step in deriving benefits, and these benefits may not be limited to the emotionally healthy. Given the applied popularity of gratitude interventions, understanding not only if but also how they work is essential. © 2017 Wiley Periodicals, Inc.

  7. ZnO UV Detectors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Radiation-hard UV detectors will be developed with ZnO in Phase I efforts by MOXtronics, Inc. (MOX). ZnO is a very suitable material for fabrication of high-speed,...

  8. Mechanistic study of ZnO nanorod array electrodeposition

    Energy Technology Data Exchange (ETDEWEB)

    El Belghiti, H.; Pauporte, T.; Lincot, D. [Laboratoire d' Electrochimie et Chimie Analytique, UMR7575, Ecole Nationale Superieure de Chimie de Paris-Universite Paris 6 (France)

    2008-10-15

    The growth of ZnO nanorods by electrodeposition from oxygenated aqueous mixture of zinc chloride and potassium chloride is studied experimentally as a function of the deposition time, zinc concentration and the substrate. These parameters influence markedly the characteristics of the deposits (rod density, aspect ratio, orientation). A mechanistic model is presented in order to explain the formation of ZnO nanorod arrays by electrodeposition. The model is based on the effect of zinc concentration on the interfacial pH at the electrode surface and then on the charged stable zinc species able to react with the growing film. The charge of the complex seems to be the key parameter which stops the lateral growth and then significantly increases the aspect ratio of the single crystalline nanorods. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Structural and Optical Properties of Eu Doped ZnO Nanorods prepared by Pulsed Laser Deposition

    KAUST Repository

    Alarawi, Abeer

    2014-06-23

    Nano structured wide band gap semiconductors have attracted attention of many researchers due to their potential electronic and optoelectronic applications. In this thesis, we report successful synthesis of well aligned Eu doped ZnO nano-rods prepared, for the first time to our knowledge, by pulsed laser deposition (PLD) without any catalyst. X-ray diffraction (XRD) patterns shows that these Eu doped ZnO nanorods are grown along the c-axis of ZnO wurtzite structure. We have studied the effect of the PLD growth conditions on forming vertically aligned Eu doped ZnO nanorods. The structural properties of the material are investigated using a -scanning electron microscope (SEM). The PLD parameters must be carefully controlled in order to obtain c-axis oriented ZnO nanorods on sapphire substrates, without the use of any catalyst. The experiments conducted in order to identify the optimal growth conditions confirmed that, by adjusting the target-substrate distance, substrate temperature, laser energy and deposition duration, the nanorod size could be successfully controlled. Most importantly, the results indicated that the photoluminescence (PL) properties reflect the quality of the ZnO nanorods. These parameters can change the material’s structure from one-dimensional to two-dimensional however the laser energy and frequency affect the size and the height of the nanorods; the xygen pressure changes the density of the nanorods.

  10. Synthesis of ZnO nanopencils using wet chemical method and its investigation as LPG sensor

    Energy Technology Data Exchange (ETDEWEB)

    Shimpi, Navinchandra G., E-mail: navin_shimpi@rediffmail.com [Department of Chemistry, University of Mumbai, Santacruz (East), Mumbai-400098 (India); Jain, Shilpa [Department of Chemistry, University of Mumbai, Santacruz (East), Mumbai-400098 (India); Karmakar, Narayan [Department of Physics, University of Mumbai, Santacruz (East), Mumbai-400098 (India); Shah, Akshara [Department of Chemistry, University of Mumbai, Santacruz (East), Mumbai-400098 (India); Kothari, D.C. [Department of Physics, University of Mumbai, Santacruz (East), Mumbai-400098 (India); National Centre for Nanosciences & Nanotechnology, University of Mumbai, Santacruz (East), Mumbai-400098 (India); Mishra, Satyendra [University Institute of Chemical Technology, North Maharashtra University, Jalgaon (India)

    2016-12-30

    Highlights: • Synthesis using a simple and cost-effective wet chemical process. • Uniform, monodispersed and pure nanoparticles. • Pencil shaped rods with sharp tips. • Understanding of Growth mechanism. • Efficient LPG sensing with high response. • Morphology dependent sensing. - Abstract: ZnO nanopencils (NPCs) were prepared by a novel wet chemical process, using triethanolamine (TEA) as a mild base, which is relatively simple and cost effective method as compared to hydrothermal method. ZnO NPCs were characterized using powder X-ray diffraction (XRD), Fourier Transform Infra-Red (FTIR) spectroscopy in mid-IR and far-IR regions, X-ray Photoelectron Spectroscopy (XPS), UV–vis (UV–vis) absorption spectroscopy, room temperature Photoluminescence (PL) spectroscopy and Field Emission Scanning Electron Microscopy (FESEM). ZnO NPCs obtained, were highly pure, uniform and monodispersed.XRD pattern indicated hexagonal unit cell structure with preferred orientation along the c-axis. Sensing behaviour of ZnO NPCs was studied towards Liquefied Petroleum Gas (LPG) at different operating temperatures. The study shows that ZnO NPCs were most sensitive and promising candidate for detection of LPG at 250 °C with gas sensitivity > 60%. The high response towards LPG is due to high surface area of ZnO NPCs and their parallel alignment.

  11. Structural properties of ZnO layers deposited on glass substrates by PECVD

    Science.gov (United States)

    Kitova, S.; Kazakov, R.; Danev, G.

    2012-03-01

    Thin ZnO layers were grown by metal-organic plasma-enhanced CVD (RF - 13.56 MHz) on glass substrates without and with ZnO seed film. The properties of the ZnO layers obtained were studied in dependence of the partial oxygen pressure by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results obtained show that by controlling the partial oxygen pressure during the layer growth one can control the crystallinity and texture of the layers obtained on pure glass substrates. It was found that ZnO layers deposited at low O2 pressure have well-developed grain structures with a predominant c-axis phase and better crystalline quality than that of the samples obtained at high partial oxygen pressure. In the presence of ZnO seed films, the formation of c-axis phase and its quality are less dependent on partial PO2. Nanorods with good alignment and orientated vertically with respect to the substrate surface can be observed in the layers deposited on glass substrates with ZnO seeds and substrate temperature of 400 °C at low content of O2 in the plasma. This behavior is interpreted in the framework of the so-called preferential nucleation and preferential grain growth.

  12. Synthesis and characterization of Sb doped ZnO thin films for photodetector application

    Science.gov (United States)

    Mohite, S. V.; Rajpure, K. Y.

    2014-02-01

    We report properties of metal-semiconductor-metal (MSM) photoconductive UV detectors based on Sb-doped ZnO thin films. Highly c-axis oriented Sb-doped ZnO thin films were prepared by spray pyrolysis technique onto glass substrates. Optical properties and photocurrent measurements were carried out to study optoelectronic properties of Sb-doped ZnO thin films. These films are highly transparent in visible region and exhibit a steep absorption edge at 365 nm. The electrical resistivity measurement showed semiconducting behaviors of Sb-doped ZnO thin films. All Sb-doped ZnO thin films exhibit n-type electrical conductivity. I-V characteristics of photodetector devices were analyzed by applying 5 V bias. The 3% Sb doped ZnO photodetector shows higher responsivity of 5.1 A/W at 365 nm under 10 μW/cm2 photo-illumination. In order to check the maximal (for the rise) or minimal (for the fall) level of photocurrent, the results on photodetector for 30 s ON and OFF cycles of illumination have been reported.

  13. Mobile Augmented Reality as a Feature for Self-Oriented, Blended Learning in Medicine: Randomized Controlled Trial

    Science.gov (United States)

    2017-01-01

    Background Advantages of mobile Augmented Reality (mAR) application-based learning versus textbook-based learning were already shown in a previous study. However, it was unclear whether the augmented reality (AR) component was responsible for the success of the self-developed app or whether this was attributable to the novelty of using mobile technology for learning. Objective The study’s aim was to test the hypothesis whether there is no difference in learning success between learners who employed the mobile AR component and those who learned without it to determine possible effects of mAR. Also, we were interested in potential emotional effects of using this technology. Methods Forty-four medical students (male: 25, female: 19, mean age: 22.25 years, standard deviation [SD]: 3.33 years) participated in this study. Baseline emotional status was evaluated using the Profile of Mood States (POMS) questionnaire. Dermatological knowledge was ascertained using a single choice (SC) test (10 questions). The students were randomly assigned to learn 45 min with either a mobile learning method with mAR (group A) or without AR (group B). Afterwards, both groups were again asked to complete the previous questionnaires. AttrakDiff 2 questionnaires were used to evaluate the perceived usability as well as pragmatic and hedonic qualities. For capturing longer term effects, after 14 days, all participants were again asked to complete the SC questionnaire. All evaluations were anonymous, and descriptive statistics were calculated. For hypothesis testing, an unpaired signed-rank test was applied. Results For the SC tests, there were only minor differences, with both groups gaining knowledge (average improvement group A: 3.59 [SD 1.48]; group B: 3.86 [SD 1.51]). Differences between both groups were statistically insignificant (exact Mann Whitney U, U=173.5; P=.10; r=.247). However, in the follow-up SC test after 14 days, group A had retained more knowledge (average decrease of the

  14. Mobile Augmented Reality as a Feature for Self-Oriented, Blended Learning in Medicine: Randomized Controlled Trial.

    Science.gov (United States)

    Noll, Christoph; von Jan, Ute; Raap, Ulrike; Albrecht, Urs-Vito

    2017-09-14

    Advantages of mobile Augmented Reality (mAR) application-based learning versus textbook-based learning were already shown in a previous study. However, it was unclear whether the augmented reality (AR) component was responsible for the success of the self-developed app or whether this was attributable to the novelty of using mobile technology for learning. The study's aim was to test the hypothesis whether there is no difference in learning success between learners who employed the mobile AR component and those who learned without it to determine possible effects of mAR. Also, we were interested in potential emotional effects of using this technology. Forty-four medical students (male: 25, female: 19, mean age: 22.25 years, standard deviation [SD]: 3.33 years) participated in this study. Baseline emotional status was evaluated using the Profile of Mood States (POMS) questionnaire. Dermatological knowledge was ascertained using a single choice (SC) test (10 questions). The students were randomly assigned to learn 45 min with either a mobile learning method with mAR (group A) or without AR (group B). Afterwards, both groups were again asked to complete the previous questionnaires. AttrakDiff 2 questionnaires were used to evaluate the perceived usability as well as pragmatic and hedonic qualities. For capturing longer term effects, after 14 days, all participants were again asked to complete the SC questionnaire. All evaluations were anonymous, and descriptive statistics were calculated. For hypothesis testing, an unpaired signed-rank test was applied. For the SC tests, there were only minor differences, with both groups gaining knowledge (average improvement group A: 3.59 [SD 1.48]; group B: 3.86 [SD 1.51]). Differences between both groups were statistically insignificant (exact Mann Whitney U, U=173.5; P=.10; r=.247). However, in the follow-up SC test after 14 days, group A had retained more knowledge (average decrease of the number of correct answers group A: 0

  15. Development and surface characterization of a glucose biosensor based on a nanocolumnar ZnO film

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, A., E-mail: adriana.rodrigues@partner.kit.edu [Instituto de Física − UFRGS, P.O. Box 15051, 91501-970 Porto Alegre, RS (Brazil); Castegnaro, M.V. [Instituto de Física − UFRGS, P.O. Box 15051, 91501-970 Porto Alegre, RS (Brazil); Arguello, J.; Alves, M.C.M. [Instituto de Química − UFRGS, P.O. Box 15003, 91501-970 Porto Alegre, RS (Brazil); Morais, J., E-mail: jonder@if.ufrgs.br [Instituto de Física − UFRGS, P.O. Box 15051, 91501-970 Porto Alegre, RS (Brazil)

    2017-04-30

    Highlights: • Glucose biosensor based on self-assembled nanocolumnar ZnO deposited on stainless steel. • XPS applied to investigate the GOx immobilization on the ZnO nanocolumns surface. • Observable chemical shifts on O1s and Zn2p corroborates enzime immobilization. - Abstract: Highly oriented nanostructured ZnO films were grown on the surface of stainless steel plates (ZnO/SS) by chemical bath deposition (CBD). The films consisted of vertically aligned ZnO nanocolumns, ∼1 μm long and ∼80 nm wide, as observed by SEM (scanning electron microscopy) and FIB (focused ion beam). XRD (X-ray diffraction) confirmed the c-axis preferred orientation of the ZnO columns, which were functionalized with the glucose oxidase (GOx) enzyme into a biosensor of glucose. The electrochemical response studied by CV (cyclic voltammetry) proved that the biosensor was capable of detecting glucose from 1.5 up to 16 mM concentration range. XPS (X-ray photoelectron spectroscopy) analysis, excited with synchrotron radiation, probed the atom specific chemical environment at the electrode’s surface and shed some light on the nature of the ZnO-GOx interaction.

  16. Structure and lattice dynamics of group-V-elements in ZnO; Struktur und Gitterdynamik von Gruppe-V-Elementen in ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Friedrich, Felice

    2010-02-15

    The main focus of this thesis is a fundamental and systematic investigation of mechanisms, which prevent stable p-type doping of ZnO. In this context, compensation by impurities, the formation of defect complexes and phase separations, which limit the doping efficiency, are discussed. With regard to the electronic compensation by impurities, a substitution of commonly used sapphire substrates with isoelectric MgO substrates is investigated. Thus, diffusion of Al donor atoms into the ZnO layer can be circumvented. It is shown that undoped, c-oriented ZnO thin-films can be grown epitaxially on (111)-MgO substrates by pulsed-laser deposition (PLD). Due to the smaller lattice mismatch of c-oriented ZnO on (111)-MgO the full width at half maximum of the E{sub 2}{sup high} phonon in Raman spectra was 1 cm{sup -1} smaller compared to ZnO layers grown on sapphire indicating a higher crystalline quality. The charge carrier concentration was reduced from 5 x 10{sup 18} to 7 x 10{sup 16} cm{sup -3}. On (100)-MgO substrates m-oriented unpolar as well as s-oriented ZnO thin-films were grown. Here, the growth is limited by the low surface mobility of the adatoms, which leads to a columnar growth mode. In addition, the variation of the thin-film morphology upon increasing deposition pressure was analyzed. A growth model is derived, which considers the influence of the deposition pressure on the nucleation density and the PLD plasma plume. This model provides an excellent qualitative description of the observed morphology of the ZnO films. These findings provide further insight into the difficulties that govern the doping of ZnO with antimony (Sb). The presence of Sb reduces the surface mobility of Zn adatoms. As a result, an amorphous film structure was observed for samples that contained an Sb concentration above 1 at.%. Furthermore, the preferential incorporation of Sb in grain boundaries leads to local phase separations, which strongly reduce the doping efficiency. Raman

  17. Impairment-oriented training or Bobath therapy for severe arm paresis after stroke: a single-blind, multicentre randomized controlled trial.

    Science.gov (United States)

    Platz, T; Eickhof, C; van Kaick, S; Engel, U; Pinkowski, C; Kalok, S; Pause, M

    2005-10-01

    To study the effects of augmented exercise therapy time for arm rehabilitation as either Bobath therapy or the impairment-oriented training (Arm BASIS training) in stroke patients with arm severe paresis. Single blind, multicentre randomized control trial. Three inpatient neurorehabilitation centres. Sixty-two anterior circulation ischaemic stroke patients. Random assignment to three group: (A) no augmented exercise therapy time, (B) augmented exercise therapy time as Bobath therapy and (C) augmented exercise therapy time as Arm BASIS training. Fugl-Meyer arm motor score. Secondary measure: Action Research Arm Test (ARA). Ancillary measures: Fugl-Meyer arm sensation and joint motion/pain scores and the Ashworth Scale (elbow flexors). An overall effect of augmented exercise therapy time on Fugl-Meyer scores after four weeks was not corroborated (mean and 95% confidence interval (CI) of change scores: no augmented exercise therapy time (n=20) 8.8, 5.2-12.3; augmented exercise therapy time (n=40) 9.9, 6.8-13.9; p = 0.2657). The group who received the augmented exercise therapy time as Arm BASIS training (n=20) had, however, higher gains than the group receiving the augmented exercise therapy time as Bobath therapy (n=20) (mean and 95% CI of change scores: Bobath 7.2, 2.6-11.8; BASIS 12.6, 8.4-16.8; p = 0.0432). Passive joint motion/pain deteriorated less in the group who received BASIS training (mean and 95% CI of change scores: Bobath -3.2, -5.2 to -1.1; BASIS 0.1, -1.8-2.0; p = 0.0090). ARA, Fugl-Meyer arm sensation, and Ashworth Scale scores were not differentially affected. The augmented exercise therapy time as Arm BASIS training enhanced selective motor control. Type of training was more relevant for recovery of motor control than therapeutic time spent.

  18. Noninvasive bipolar double-pulsed-field-gradient NMR reveals signatures for pore size and shape in polydisperse, randomly oriented, inhomogeneous porous media.

    Science.gov (United States)

    Shemesh, Noam; Ozarslan, Evren; Adiri, Tal; Basser, Peter J; Cohen, Yoram

    2010-07-28

    Noninvasive characterization of pore size and shape in opaque porous media is a formidable challenge. NMR diffusion-diffraction patterns were found to be exceptionally useful for obtaining such morphological features, but only when pores are monodisperse and coherently placed. When locally anisotropic pores are randomly oriented, conventional diffusion NMR methods fail. Here, we present a simple, direct, and general approach to obtain both compartment size and shape even in such settings and even when pores are characterized by internal field gradients. Using controlled porous media, we show that the bipolar-double-pulsed-field-gradient (bp-d-PFG) methodology yields diffusion-diffraction patterns from which pore size can be directly obtained. Moreover, we show that pore shape, which cannot be obtained by conventional methods, can be directly inferred from the modulation of the signal in angular bp-d-PFG experiments. This new methodology significantly broadens the types of porous media that can be studied using noninvasive diffusion-diffraction NMR.

  19. Photocatalytic efficiency of reusable ZnO thin films deposited by sputtering technique

    Energy Technology Data Exchange (ETDEWEB)

    Ahumada-Lazo, R.; Torres-Martínez, L.M. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Civil, Departamento de Ecomateriales y Energía, Av. Universidad S/N Ciudad Universitaria, San Nicolás de los Garza, Nuevo León C.P. 66450, México (Mexico); Ruíz-Gómez, M.A. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Civil, Departamento de Ecomateriales y Energía, Av. Universidad S/N Ciudad Universitaria, San Nicolás de los Garza, Nuevo León C.P. 66450, México (Mexico); Departmento de Física Aplicada, CINVESTAV-IPN, Antigua Carretera a Progreso km 6, Mérida, Yucatán 97310, México (Mexico); Vega-Becerra, O.E. [Centro de Investigación en Materiales Avanzados S.C, Alianza norte 202, Parque de Investigación e Innovación Tecnológica, C.P. 66600 Apodaca Nuevo León, México (Mexico); and others

    2014-12-15

    Graphical abstract: - Highlights: • Decolorization of Orange G dye using highly c-axis-oriented ZnO thin films. • The flake-shaped film shows superior and stable photoactivity at a wide range of pH. • The highest photodecolorization was achieved at pH of 7. • The exposure of (101) and (100) facets enhanced the photoactivity. • ZnO thin films exhibit a promising performance as recyclable photocatalysts. - Abstract: The photocatalytic activity of ZnO thin films with different physicochemical characteristics deposited by RF magnetron sputtering on glass substrate was tested for the decolorization of orange G dye aqueous solution (OG). The crystalline phase, surface morphology, surface roughness and the optical properties of these ZnO films were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM) and UV–visible spectroscopy (UV–Vis), respectively. The dye photodecolorization process was studied at acid, neutral and basic pH media under UV irradiation of 365 nm. Results showed that ZnO films grow with an orientation along the c-axis of the substrate and exhibit a wurtzite crystal structure with a (002) preferential crystalline orientation. A clear relationship between surface morphology and photocatalytic activity was observed for ZnO films. Additionally, the recycling photocatalytic abilities of the films were also evaluated. A promising photocatalytic performance has been found with a very low variation of the decolorization degree after five consecutive cycles at a wide range of pH media.

  20. Polarized photoluminescence study of whispering gallery mode polaritons in ZnO microcavity

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Liaoxin; Chen, Zhanghai; Ren, Qijun; Zhou, Weihang; Bai, Lihui; Shen, Xuechu [Surface Physics Laboratory, Department of Physics, Fudan University, Shanghai (China); Yu, Ke; Zhu, Z.Q. [Department of Electronic Engineering, East China Normal University, Shanghai (China)

    2009-01-15

    Polariton effect and its polarization dependence were studied in ZnO tapered whispering gallery (WG) microcavity at room temperature. By scanning the excitation along the tapered arm of ZnO tetrapod with different polarizations, the photo-exciton coupling strength were continuingly tuned and thus the resonant interaction between the WG optical modes and the excitons with different dipole orientation are clearly resolved. The experimental observations were well described by the plane wave model with excitonic polariton dispersions. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Growth and investigation of antifungal properties of ZnO nanorod arrays on the glass

    Energy Technology Data Exchange (ETDEWEB)

    Eskandari, M., E-mail: msnano1361@yahoo.co [Nanomaterial Research Group, Academic Center for Education, Culture and Research (ACECR) on TMU, Tehran (Iran, Islamic Republic of); Haghighi, N. [Department of physics, Tehran University, Tehran (Iran, Islamic Republic of); Ahmadi, V. [Department of Electrical Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Haghighi, F.; Mohammadi, SH.R. [Department of Mycology, Tarbiat Modares University, Tehran (Iran, Islamic Republic of)

    2011-01-01

    In this study, we have investigated the antifungal activity of ZnO nanorods prepared by the chemical solution method against Candida albicans. In the study, Zinc oxide nanorods have been deposited on glass substrates using the chemical solution method. The as-grown samples are characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). X-ray diffraction (XRD) showed zinc oxide nanorods grown in (0 0 2) orientation. The antifungal results indicated that ZnO nanorod arrays exhibit stable properties after two months and play an important role in the growth inhibitory of Candida albicans.

  2. Low Temperature Plasma Enhanced CVD Synthesis of Piezoactive ZnO Films

    OpenAIRE

    Tabenskaya, T.; Ovsyannikov, V.; Mazurenko, E.

    1995-01-01

    Plasma-enhanced organometallic chemical vapour deposition process has been developed to obtain piezoelectric ZnO films with a highly preferred orientation of the crystallites on sapphire and on SiO2/Si substrates. The volatile organic precursor of zinc acetylacetonate Zn(AA)2 decomposes under r.f. discharge plasma at low temperature in controlled atmosphere of Ar+O2 gas mixture. The optimal deposition conditions of high quality ZnO film were deduced and investigated. The films obtained have h...

  3. Study of the surface properties of ZnO nanocolumns used for thin-film solar cells

    Directory of Open Access Journals (Sweden)

    Neda Neykova

    2017-02-01

    Full Text Available Densely packed ZnO nanocolumns (NCs, perpendicularly oriented to the fused-silica substrates were directly grown under hydrothermal conditions at 90 °C, with a growth rate of around 0.2 μm/h. The morphology of the nanostructures was visualized and analyzed by scanning electron microscopy (SEM. The surface properties of ZnO NCs and the binding state of present elements were investigated before and after different plasma treatments, typically used in plasma-enhanced CVD solar cell deposition processes, by X-ray photoelectron spectroscopy (XPS. Photothermal deflection spectroscopy (PDS was used to investigate the optical and photoelectrical characteristics of the ZnO NCs, and the changes induced to the absorptance by the plasma treatments. A strong impact of hydrogen plasma treatment on the free-carrier and defect absorption of ZnO NCs has been directly detected in the PDS spectra. Although oxygen plasma treatment was proven to be more efficient in the surface activation of the ZnO NC, the PDS analysis showed that the plasma treatment left the optical and photoelectrical features of the ZnO NCs intact. Thus, it was proven that the selected oxygen plasma treatment can be of great benefit for the development of thin film solar cells based on ZnO NCs.

  4. Study of the surface properties of ZnO nanocolumns used for thin-film solar cells.

    Science.gov (United States)

    Neykova, Neda; Stuchlik, Jiri; Hruska, Karel; Poruba, Ales; Remes, Zdenek; Pop-Georgievski, Ognen

    2017-01-01

    Densely packed ZnO nanocolumns (NCs), perpendicularly oriented to the fused-silica substrates were directly grown under hydrothermal conditions at 90 °C, with a growth rate of around 0.2 μm/h. The morphology of the nanostructures was visualized and analyzed by scanning electron microscopy (SEM). The surface properties of ZnO NCs and the binding state of present elements were investigated before and after different plasma treatments, typically used in plasma-enhanced CVD solar cell deposition processes, by X-ray photoelectron spectroscopy (XPS). Photothermal deflection spectroscopy (PDS) was used to investigate the optical and photoelectrical characteristics of the ZnO NCs, and the changes induced to the absorptance by the plasma treatments. A strong impact of hydrogen plasma treatment on the free-carrier and defect absorption of ZnO NCs has been directly detected in the PDS spectra. Although oxygen plasma treatment was proven to be more efficient in the surface activation of the ZnO NC, the PDS analysis showed that the plasma treatment left the optical and photoelectrical features of the ZnO NCs intact. Thus, it was proven that the selected oxygen plasma treatment can be of great benefit for the development of thin film solar cells based on ZnO NCs.

  5. Tuning the Surface Morphologies and Properties of ZnO Films by the Design of Interfacial Layer

    Science.gov (United States)

    Li, Yaping; Wang, Hui-Qiong; Zhou, Hua; Du, Damin; Geng, Wei; Lin, Dingqu; Chen, Xiaohang; Zhan, Huahan; Zhou, Yinghui; Kang, Junyong

    2017-09-01

    Wurtzite ZnO films were grown on MgO(111) substrates by plasma-assisted molecular beam epitaxy (MBE). Different initial growth conditions were designed to monitor the film quality. All the grown ZnO films show highly (0001)-oriented textures without in-plane rotation, as illustrated by in situ reflection high-energy electron diffraction (RHEED) and ex situ X-ray diffraction (XRD). As demonstrated by atomic force microscopy (AFM) images, "ridge-like" and "particle-like" surface morphologies are observed for the ZnO films grown in a molecular O2 atmosphere with and without an initial deposition of Zn adatoms, respectively, before ZnO growth with oxygen plasma. This artificially designed interfacial layer deeply influences the final surface morphology and optical properties of the ZnO film. From room-temperature photoluminescence (PL) measurements, a strong defect-related green luminescence band appears for the ZnO film with a "particle-like" morphology but was hardly observed in the films with flat "ridge-like" surface morphologies. Our work suggests that the ZnO crystallinity can be improved and defect luminescence can be reduced by designing interfacial layers between substrates and epilayers.

  6. The influence of Cu-doping on structural, optical and photocatalytic properties of ZnO nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Polat, İsmail [Department of Energy Systems Engineering, Faculty of Technology, Karadeniz Technical University, 61830 Trabzon (Turkey); Yılmaz, Salih [Department of Materials Engineering, Faculty of Engineering and Natural Sciences, Adana Science and Technology University, 01180 Adana (Turkey); Altın, İlknur [Department of Chemistry, Faculty of Science, Karadeniz Technical University, 61080 Trabzon (Turkey); Bacaksız, Emin [Department of Physics, Faculty of Science, Karadeniz Technical University, 61080 Trabzon (Turkey); Sökmen, Münevver, E-mail: msokmen@ktu.edu.tr [Department of Chemistry, Faculty of Science, Karadeniz Technical University, 61080 Trabzon (Turkey)

    2014-12-15

    Undoped and Cu-doped ZnO nanorods with different copper contents were produced on glass substrates. The structural and optical properties of the samples were investigated through X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL) measurements. Irrespective of the Cu content in ZnO nanorods, X-ray diffraction results showed that all the ZnO nanorods had a hexagonal structure with a strong preferred orientation along (002) direction. SEM results indicated that increasing Cu content caused a change from the pyramidal geometry to a hexagonal rod shape in the morphology of ZnO. Photoluminescence measurements exhibited two emission bands in the spectra: one sharp ultraviolet luminescence at ∼379 nm and one broad visible emission ranging from 400 to 720 nm. The photocatalytic properties of undoped and Cu-doped ZnO nanorods synthesized by a chemical bath deposition method were studied for the first time in this study by using photocatalytic degradation of methylene blue (MB, 9.4 × 10{sup −6} M) as a model chemical. - Highlights: • Production of undoped ZnO and Cu-doped ZnO nanorods (between 1 and 3 at.%). • All the samples were produced by a chemical bath deposition method. • Cu-doping caused a change from pyramidal geometry to hexagonal rods. • Determination of the photocatalytic action of produced materials.

  7. Characteristics of surface acoustic waves in (11\\bar 2 0)ZnO film/ R-sapphire substrate structures

    Science.gov (United States)

    Wang, Yan; Zhang, ShuYi; Xu, Jing; Xie, YingCai; Lan, XiaoDong

    2018-02-01

    (11\\bar 2 0)ZnO film/ R-sapphire substrate structure is promising for high frequency acoustic wave devices. The propagation characteristics of SAWs, including the Rayleigh waves along [0001] direction and Love waves along [1ī00] direction, are investigated by using 3 dimensional finite element method (3D-FEM). The phase velocity ( v p), electromechanical coupling coefficient ( k 2), temperature coefficient of frequency ( TCF) and reflection coefficient ( r) of Rayleigh wave and Love wave devices are theoretically analyzed. Furthermore, the influences of ZnO films with different crystal orientation on SAW properties are also investigated. The results show that the 1st Rayleigh wave has an exceedingly large k 2 of 4.95% in (90°, 90°, 0°) (11\\bar 2 0)ZnO film/ R-sapphire substrate associated with a phase velocity of 5300 m/s; and the 0th Love wave in (0°, 90°, 0°) (11\\bar 2 0)ZnO film/ R-sapphire substrate has a maximum k 2 of 3.86% associated with a phase velocity of 3400 m/s. And (11\\bar 2 0)ZnO film/ R-sapphire substrate structures can be used to design temperature-compensated and wide-band SAW devices. All of the results indicate that the performances of SAW devices can be optimized by suitably selecting ZnO films with different thickness and crystal orientations deposited on R-sapphire substrates.

  8. Texture of obliquely sputtered ZnO thin films

    Science.gov (United States)

    Červeň, I.; Lacko, T.; Novotný, I.; Tvarožek, V.; Harvanka, M.

    1993-08-01

    A series of ZnO polycrystalline thin films were prepared on Si(100)/SiO 2/TiN substrates by radio frequency (RF) sputtering at various angles between the sputter direction and the substrate normal. The X-ray diffraction θ/2 θ scans confirmed the expected c-orientation of the films, depending at some extent on the angle of sputtering. The limited pole figures, obtained by rocking-curve measurement, show a slight deviation of the texture axis from the substrate normal direction, which increase with the sputtering angle. The texture axis is inclined not toward the sputtering direction, as was expected, but quite opposite.

  9. Carrier concentration dependent optical and electrical properties of Ga doped ZnO hexagonal nanocrystals.

    Science.gov (United States)

    Saha, Manas; Ghosh, Sirshendu; Ashok, Vishal Dev; De, S K

    2015-06-28

    Colloidal trivalent gallium (Ga) doped zinc oxide (ZnO) hexagonal nanocrystals have been prepared to introduce more carrier concentration into the wide band gap of ZnO. The dopant (Ga) modifies the morphology and size of ZnO nanocrystals. Low content of Ga enhances the optical band gap of ZnO due to excess carrier concentration in the conduction band of ZnO. The interaction among free carriers arising from higher concentration of Ga gives rise to narrowing of the band gap. Surface plasmon resonance absorption appears in the infrared region due to excessive carrier concentration. A broad emission band consists of blue, yellow and green colors associated with different native defects of ZnO. Intrinsic defects and extrinsic dopant Ga control the defect related emission spectrum in the visible region. Replacement of Zn by Ga induces a room temperature metallic state in a degenerate semiconductor. Cationic disorder leads to metal-semiconductor transition at low temperature strongly dependent on the concentration of Ga. Pure semiconducting behavior up to about 80 K is observed for the highest amount of Ga. Temperature dependent metal-semiconductor transition has been interpreted by localization of charge carriers due to disorder arising from random Ga substitution.

  10. (Er, Yb)-co-doped multifunctional ZnO transparent hybrid materials: fabrication, luminescent and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Yang Lixin; Liu Peng; Liu Fangmin; Ge Shuibing [Department of Physics, Soochow University, Suzhou 215006 (China); Wang Xuefeng; Liu Bin; Shi Yi; Zhang Rong [Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Li Zhaoguo; Song Fengqi, E-mail: xfwang@nju.edu.cn [Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093 (China)

    2011-04-20

    We report the successful fabrication of (Er{sup 3+}, Yb{sup 3+})-co-doped ZnO transparent hybrid materials by controlling compositions and crystallization. The singly precipitated ZnO nanocrystals were preferentially oriented along the c-axis on the glass surface, leading to an intense luminescence at the bandgap energy of ZnO. The Er{sup 3+} and Yb{sup 3+} ions assembled around the low-phonon-energy ZnO nanocrystals, achieving an enhanced two-photon upconversion emission in the visible region. In addition, the glass ceramic exhibited typical paramagnetism with antiferromagnetic interactions. The multifunctional combination in such a low-cost, easily shapable and environmentally friendly bulk material may find a wide range of device applications.

  11. Optical and structural properties of ZnO hexagonal rods prepared by thermal chemical vapor deposition technique

    Directory of Open Access Journals (Sweden)

    A Reyhani

    2014-11-01

    Full Text Available In this research, ZnO nanostructure hexagonal pyramid rods with high optical and structural quality were synthesized by the simple thermal chemical vapor deposition of Zn powder without a metal catalyst. Surface morphologies were characterized by scanning electron microscopy (SEM. XRD analyses demonstrated that ZnO hexagonal pyramid rods had a wurtzite structure with the orientation of (002. Investigation of optical properties of samples by photoluminescence spectrum exhibited a sharp UV emission peak at 380nm. The quality and composition of the ZnO pyramid rods were characterized using the Fourier transform infrared spectrum (FTIR at room temperature. In addition, the growth mechanism of ZnO hexagonal rods is also briefly discussed.

  12. Effect of in situ Al doping on structure and optical properties of ZnO nanowires grown by MOCVD

    Science.gov (United States)

    Souissi, H.; Jabri, S.; Souissi, A.; Lusson, A.; Galtier, P.; Meftah, A.; Sallet, V.; Oueslati, M.

    2018-01-01

    Al-doped ZnO nanowires (NWs) were grown on C-axis oriented sapphire by metal organic chemical vapor deposition using dimethylzinc–triethylamine (DMZn–TEN), nitrogen dioxide (NO2) and TMAl as zinc, oxygen and aluminum doping sources respectively. The NWs morphology has been characterized by scanning electron microscopy and transmission electron microscopy. The photoluminescence (PL) spectra exhibit a strong excitonic transition bond that confirms the Al incorporation in the ZnO NWs. Raman results support PL conclusion by showing additional modes in Al-doped ZnO NWs at nearly 270, 510, 579 and 641 cm‑1. The micro-Raman scattering analysis along a single Al-doped ZnO needle-like NW shows an increase of the Al concentration from the basis to the tip of the wire.

  13. Oxygen pressure effect on optical properties and dye degradation of ZnO nanostructured films prepared by sputtering

    Science.gov (United States)

    Neelakanta Reddy, I.; Gobi Saravanan, K.; Venkata Reddy, Ch; Cho, Migyung; Shim, Jaesool; Kim, Dongseob

    2017-09-01

    The effect of oxygen pressure on structural, morphological and photocatalytic properties of ZnO nanostructured films deposited on glass substrates via RF magnetron sputtering was investigated. The structural, morphology and oxidation states of the films were investigated by x-ray diffraction, scanning electron microscopy, atomic force microscopy, and x-ray photoelectron spectroscopy. UV-vis spectroscopy and photoluminescence spectroscopy were used to analyze the degradation and optical properties of ZnO thin films. The grown films showed wurtzite hexagonal crystalline nanostructures with a favored orientation along the direction of (0 0 2) lattice plane. The morphology images showed a hierarchical ZnO nanostructured films with various shapes from circulars to foils and even much more multifaceted circular shapes and triangular sheets-like shapes by varying the oxygen pressure. The foil type ZnO nanostructured films showed significant photocatalytic activity concerning the degradation of methyl orange, mainly due to their surface-to-volume ratio.

  14. Effects of deposition conditions on the structural and acoustic characteristics of (1120) ZnO thin films on R-sapphire substrates.

    Science.gov (United States)

    Wang, Yan; Wasa, Kiyotaka; Zhang, Shu-yi

    2012-08-01

    (1120) ZnO films with the c-axis lying in the plane deposited on R-sapphire substrates by RF magnetron sputtering are studied. The focusing investigation is the effect of substrate positions in the sputtering on structural and acoustic characteristics of the ZnO films. The crystallographic characteristics of the films are characterized by X-ray diffraction analysis. It is found that the crystalline orientation of ZnO films varies with the variation of substrate position deviated from the normal direction of the anode center and there is an optimized deviation position. To investigate the variations of acoustic characteristics of these piezoelectric ZnO films, multilayered structures are prepared to fabricate shear-mode highovertone bulk acoustic resonators (HBARs). The results show that the electromechanical coupling coefficient k(15) of the (1120) ZnO films obtained at the optimized position approaches a maximum.

  15. Nanostructured ‘Anastacia’ flowers for Zn coating by electrodepositing ZnO at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Alves, Marta M., E-mail: martamalves@tecnico.ulisboa.pt [ICEMS Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1049-001, Lisboa (Portugal); Santos, Catarina F.; Carmezim, Maria J. [ICEMS Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1049-001, Lisboa (Portugal); EST Setúbal, DEM, Instituto Politécnico de Setúbal, Campus IPS, 2910 Setúbal (Portugal); Montemor, Maria F. [ICEMS Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1049-001, Lisboa (Portugal)

    2015-03-30

    Graphical abstract: - Highlights: • Functional coating of Zn with ZnO ‘Anastacia’ flowers. • Flowers are composed by nano-hexagonal units of single-crystal wurtzite ZnO. • The growth mechanism of these flowers is discussed. • Room temperature yield cost-effective electrodeposited ZnO ‘Anastacia’ flowers. - Abstract: Functional coatings composed of ZnO, a new flowered structured denominated as ‘Anastacia’ flowers, were successfully obtained through a facile and green one-step electrodeposition approach on Zn substrate. Electrodeposition was performed at constant cathodic potential, in Zn(NO{sub 3}){sub 2} aqueous solution, at pH 6 and at room temperature. The resulting ZnO thin uniform layer, with an average thickness of 300 nm, bearing top 3D hierarchical nanostructures that compose ‘Anastacia’ flowers, was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman. The results reveal a nano-architecture structure composed by nano-hexagonal units of single-crystal wurtzite ZnO structure with a [0 0 0 1] growth direction along the longitudinal particles axis. Other morphological features, sphere-like, rod-like and random distributed hexagons were also obtained by varying the electrodeposition time as observed by SEM. The Raman spectroscopy revealed the typical peak of ZnO wurtzite for all the obtained morphologies. Coatings wettability was studied and the different morphologies display distinct water contact angles with the ‘Anastacia’ flowers coating showing a wettability of 110°. These results pave the way for simple and low-cost routes for the production of novel functionalized coatings of ZnO over Zn, with potential for biomedical devices.

  16. Arm rehabilitation in post stroke subjects: A randomized controlled trial on the efficacy of myoelectrically driven FES applied in a task-oriented approach.

    Science.gov (United States)

    Jonsdottir, Johanna; Thorsen, Rune; Aprile, Irene; Galeri, Silvia; Spannocchi, Giovanna; Beghi, Ettore; Bianchi, Elisa; Montesano, Angelo; Ferrarin, Maurizio

    2017-01-01

    Motor recovery of persons after stroke may be enhanced by a novel approach where residual muscle activity is facilitated by patient-controlled electrical muscle activation. Myoelectric activity from hemiparetic muscles is then used for continuous control of functional electrical stimulation (MeCFES) of same or synergic muscles to promote restoration of movements during task-oriented therapy (TOT). Use of MeCFES during TOT may help to obtain a larger functional and neurological recovery than otherwise possible. Multicenter randomized controlled trial. Eighty two acute and chronic stroke victims were recruited through the collaborating facilities and after signing an informed consent were randomized to receive either the experimental (MeCFES assisted TOT (M-TOT) or conventional rehabilitation care including TOT (C-TOT). Both groups received 45 minutes of rehabilitation over 25 sessions. Outcomes were Action Research Arm Test (ARAT), Upper Extremity Fugl-Meyer Assessment (FMA-UE) scores and Disability of the Arm Shoulder and Hand questionnaire. Sixty eight subjects completed the protocol (Mean age 66.2, range 36.5-88.7, onset months 12.7, range 0.8-19.1) of which 45 were seen at follow up 5 weeks later. There were significant improvements in both groups on ARAT (median improvement: MeCFES TOT group 3.0; C-TOT group 2.0) and FMA-UE (median improvement: M-TOT 4.5; C-TOT 3.5). Considering subacute subjects (time since stroke < 6 months), there was a trend for a larger proportion of improved patients in the M-TOT group following rehabilitation (57.9%) than in the C-TOT group (33.2%) (difference in proportion improved 24.7%; 95% CI -4.0; 48.6), though the study did not meet the planned sample size. This is the first large multicentre RCT to compare MeCFES assisted TOT with conventional care TOT for the upper extremity. No adverse events or negative outcomes were encountered, thus we conclude that MeCFES can be a safe adjunct to rehabilitation that could promote recovery of

  17. Arm rehabilitation in post stroke subjects: A randomized controlled trial on the efficacy of myoelectrically driven FES applied in a task-oriented approach.

    Directory of Open Access Journals (Sweden)

    Johanna Jonsdottir

    Full Text Available Motor recovery of persons after stroke may be enhanced by a novel approach where residual muscle activity is facilitated by patient-controlled electrical muscle activation. Myoelectric activity from hemiparetic muscles is then used for continuous control of functional electrical stimulation (MeCFES of same or synergic muscles to promote restoration of movements during task-oriented therapy (TOT. Use of MeCFES during TOT may help to obtain a larger functional and neurological recovery than otherwise possible.Multicenter randomized controlled trial.Eighty two acute and chronic stroke victims were recruited through the collaborating facilities and after signing an informed consent were randomized to receive either the experimental (MeCFES assisted TOT (M-TOT or conventional rehabilitation care including TOT (C-TOT. Both groups received 45 minutes of rehabilitation over 25 sessions. Outcomes were Action Research Arm Test (ARAT, Upper Extremity Fugl-Meyer Assessment (FMA-UE scores and Disability of the Arm Shoulder and Hand questionnaire.Sixty eight subjects completed the protocol (Mean age 66.2, range 36.5-88.7, onset months 12.7, range 0.8-19.1 of which 45 were seen at follow up 5 weeks later. There were significant improvements in both groups on ARAT (median improvement: MeCFES TOT group 3.0; C-TOT group 2.0 and FMA-UE (median improvement: M-TOT 4.5; C-TOT 3.5. Considering subacute subjects (time since stroke < 6 months, there was a trend for a larger proportion of improved patients in the M-TOT group following rehabilitation (57.9% than in the C-TOT group (33.2% (difference in proportion improved 24.7%; 95% CI -4.0; 48.6, though the study did not meet the planned sample size.This is the first large multicentre RCT to compare MeCFES assisted TOT with conventional care TOT for the upper extremity. No adverse events or negative outcomes were encountered, thus we conclude that MeCFES can be a safe adjunct to rehabilitation that could promote recovery

  18. Nuclear magnetic relaxation induced by exchange-mediated orientational randomization: Longitudinal relaxation dispersion for a dipole-coupled spin-1/2 pair

    Science.gov (United States)

    Chang, Zhiwei; Halle, Bertil

    2013-10-01

    In complex biological or colloidal samples, magnetic relaxation dispersion (MRD) experiments using the field-cycling technique can characterize molecular motions on time scales ranging from nanoseconds to microseconds, provided that a rigorous theory of nuclear spin relaxation is available. In gels, cross-linked proteins, and biological tissues, where an immobilized macromolecular component coexists with a mobile solvent phase, nuclear spins residing in solvent (or cosolvent) species relax predominantly via exchange-mediated orientational randomization (EMOR) of anisotropic nuclear (electric quadrupole or magnetic dipole) couplings. The physical or chemical exchange processes that dominate the MRD typically occur on a time scale of microseconds or longer, where the conventional perturbation theory of spin relaxation breaks down. There is thus a need for a more general relaxation theory. Such a theory, based on the stochastic Liouville equation (SLE) for the EMOR mechanism, is available for a single quadrupolar spin I = 1. Here, we present the corresponding theory for a dipole-coupled spin-1/2 pair. To our knowledge, this is the first treatment of dipolar MRD outside the motional-narrowing regime. Based on an analytical solution of the spatial part of the SLE, we show how the integral longitudinal relaxation rate can be computed efficiently. Both like and unlike spins, with selective or non-selective excitation, are treated. For the experimentally important dilute regime, where only a small fraction of the spin pairs are immobilized, we obtain simple analytical expressions for the auto-relaxation and cross-relaxation rates which generalize the well-known Solomon equations. These generalized results will be useful in biophysical studies, e.g., of intermittent protein dynamics. In addition, they represent a first step towards a rigorous theory of water 1H relaxation in biological tissues, which is a prerequisite for unravelling the molecular basis of soft

  19. Structural, morphological and electroluminescence studies of Zno:Co nanophosphor

    Science.gov (United States)

    Singh, Anju; Vishwakarma, H. L.

    2016-09-01

    The nanoparticles of zinc oxide (ZnO) doped with various concentrations of cobalt (Co) were synthesized by chemical precipitation method in the presence of capping agent polyvinylpyrrolidone (PVP). The effect of doping concentration on structural and morphological properties has been studied by X-ray diffraction (XRD) and scanning electron microscope (SEM). Cell volume, bond length, texture coefficient, lattice constants and dislocation density are also studied. Here, we also compared the interplaner spacing and relative peak intensities from their standard values with different angles. Crystallite sizes have been calculated by Debye-Scherrer's formula whose values are decreasing with increase in cobalt content up to 3 %. It has been seen that the growth orientation of the prepared ZnO nanorods was (101). The XRD analysis also ensures that ZnO has a hexagonal (wurtzite) crystal structure. The electroluminescence (EL) cells were prepared by placing pure and cobalt-doped ZnO nanoparticles between ITO-coated conducting glass plate and aluminium foil. Alternating voltage of various frequencies was applied, and EL brightness at different voltages was measured and corresponding current was also recorded. The voltage dependence of electroluminescence (EL) brightness of the ZnO:Co shows exponential increase. The linear voltage-current characteristic indicates ohmic nature. The EL brightness at a particular voltage is found to increase by increasing Co doping, but for higher percentage of Co the EL brightness is reduced. It is also seen that Co does not influence the threshold voltage. The brightness is also affected by increasing the frequency of AC signal.

  20. Growth of Horizonatal ZnO Nanowire Arrays on Any Substrate

    KAUST Repository

    Qin, Yong

    2008-12-04

    A general method is presented for growing laterally aligned and patterned ZnO nanowire (NW) arrays on any substrate as long as it is flat. The orientation control is achieved using the combined effect from ZnO seed layer and the catalytically inactive Cr (or Sn) layer for NW growth. The growth temperature (< 100 °C) is so low that the method can be applied to a wide range of substrates that can be inorganic, organic, single crystal, polycrystal, or amorphous. The laterally aligned ZnO NW arrays can be employed for various applications, such as gas sensor, field effect transistor, nanogenerator, and flexible electronics. © 2008 American Chemical Society.

  1. Polystyrene sphere monolayer assisted electrochemical deposition of ZnO nanorods with controlable surface density

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, D., E-mail: daniel.ramirez@ucv.c [Laboratorio de Electroquimica, Pontificia Universidad Catolica de Valparaiso, Valparaiso (Chile); Gomez, H. [Laboratorio de Electroquimica, Pontificia Universidad Catolica de Valparaiso, Valparaiso (Chile); Lincot, D. [Institute de Recherche et Developpement sur l' Energie Photovoltaique-IRDEP, 6 Quai Watier 78401, Chatou Cedex (France)

    2010-02-15

    In this paper we report the zinc oxide nanorods (ZnO NRs) growth by electrochemical deposition onto polycrystalline gold electrodes modified with assemblies of polystyrene sphere monolayers (PSSMs). Growth occurs through the interstitial spaces between the hexagonally close packed spheres. ZnO NRs nucleate in the region where three adjacent spheres leave a space, being able to grow and projected over the PSSMs. The nanorod surface density (N{sub NR}) shows a linear dependence with respect to a PS sphere diameter selected. XRD analysis shows these ZnO NRs are highly oriented along the (0 0 2) plane (c-axis). This open the possibility to have electronic devices with mechanically supported nanometric materials.

  2. Quantitative and simultaneous analysis of the polarity of polycrystalline ZnO seed layers and related nanowires grown by wet chemical deposition

    Energy Technology Data Exchange (ETDEWEB)

    Guillemin, Sophie; Parize, Romain; Carabetta, Joseph; Cantelli, Valentina; Albertini, David; Gautier, Brice; Brémond, Georges; Fong, Dillon D.; Renevier, Hubert; Consonni, Vincent

    2017-01-30

    The polarity in ZnO nanowires is an important issue since it strongly affects surface configuration and reactivity, nucleation and growth, electro-optical properties, and nanoscaleengineering device performances. However, measuring statistically the polarity of ZnO nanowire arrays grown by chemical bath deposition and elucidating its correlation with the polarity of the underneath polycrystalline ZnO seed layer grown by the sol–gel process represents a major difficulty. To address that issue, we combine resonant x-ray diffraction (XRD) at Zn K-edge using synchrotron radiation with piezoelectric force microscopy and polarity-sensitive chemical etching to statistically investigate the polarity of more than 107 nano-objects both on the macroscopic and local microscopic scales, respectively. By using high temperature annealing under an argon atmosphere, it is shown that the compact, highly c-axis oriented ZnO seed layer is more than 92% Zn-polar and that only a few small O-polar ZnO grains with an amount less than 8% are formed. Correlatively, the resulting ZnO nanowires are also found to be Zn-polar, indicating that their polarity is transferred from the c-axis oriented ZnO grains acting as nucleation sites in the seed layer. These findings pave the way for the development of new strategies to form unipolar ZnO nanowire arrays as a requirement for a number of nanoscaleengineering devices like piezoelectric nanogenerators. They also highlight the great advantage of resonant XRD as a macroscopic, non-destructive method to simultaneously and statistically measure the polarity of ZnO nanowire arrays and of the underneath ZnO seed layer.

  3. Quantitative and simultaneous analysis of the polarity of polycrystalline ZnO seed layers and related nanowires grown by wet chemical deposition

    Science.gov (United States)

    Guillemin, Sophie; Parize, Romain; Carabetta, Joseph; Cantelli, Valentina; Albertini, David; Gautier, Brice; Brémond, Georges; Fong, Dillon D.; Renevier, Hubert; Consonni, Vincent

    2017-03-01

    The polarity in ZnO nanowires is an important issue since it strongly affects surface configuration and reactivity, nucleation and growth, electro-optical properties, and nanoscale-engineering device performances. However, measuring statistically the polarity of ZnO nanowire arrays grown by chemical bath deposition and elucidating its correlation with the polarity of the underneath polycrystalline ZnO seed layer grown by the sol-gel process represents a major difficulty. To address that issue, we combine resonant x-ray diffraction (XRD) at Zn K-edge using synchrotron radiation with piezoelectric force microscopy and polarity-sensitive chemical etching to statistically investigate the polarity of more than 107 nano-objects both on the macroscopic and local microscopic scales, respectively. By using high temperature annealing under an argon atmosphere, it is shown that the compact, highly c-axis oriented ZnO seed layer is more than 92% Zn-polar and that only a few small O-polar ZnO grains with an amount less than 8% are formed. Correlatively, the resulting ZnO nanowires are also found to be Zn-polar, indicating that their polarity is transferred from the c-axis oriented ZnO grains acting as nucleation sites in the seed layer. These findings pave the way for the development of new strategies to form unipolar ZnO nanowire arrays as a requirement for a number of nanoscale-engineering devices like piezoelectric nanogenerators. They also highlight the great advantage of resonant XRD as a macroscopic, non-destructive method to simultaneously and statistically measure the polarity of ZnO nanowire arrays and of the underneath ZnO seed layer.

  4. DFT calculations on electronic properties of ZnO thin films deposited by spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Cordeiro, J.M.; Reynoso, V.C.; Azevedo, D.H.M. [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), SP (Brazil)

    2016-07-01

    Full text: Introduction - Thin films of Zinc oxide (ZnO) has a wide range of technological applications, as transparent conducting electrodes in solar cells, flat panel displays, and sensors, for example. More recently applications in optoelectronics, like light emitter diodes and laser diodes, due to its large band gap, are been explored. Studies of ZnO thin films are important for these applications. Methodology - In this study thin films of ZnO have been deposited by spray pyrolysis on glass substrate. The films were characterized by XRD and UV-VIS techniques and the electronic properties as a function of the film thickness have been investigated by DFT calculations with B3LYP hybrid potential implemented in the CRYSTAL09 code. Results - The diffractograms obtained for the ZnO thin films as a function of the thickness are shown. The films exhibit a hexagonal wurtzite structure with preferred c-axis orientation in (002) direction of ZnO crystal. A quantum mechanical approach based on the periodic Density Functional Theory (DFT), with B3LYP hybrid potential was used to investigate the electronic structure of the films as a function of the thickness. The CRYSTAL09 code has been used for the calculations on the wurtzite hexagonal structure of ZnO - spatial group P63mc. For optimizing the geometry of the pure ZnO crystal, the experimental lattice parameters were got as follows: a= 0.325 nm, b= 0.325 nm, c= 0.5207 nm with c/a= 1.602. Considering to the calculations of the band structure, it is suggested that the semiconducting properties of ZnO arises from the overlapping of the 4s orbital of the conducting band of Zn and the 2p orbital of the top of valence band of O. Conclusions - The structure of ZnO thin film deposited on glass substrate present preferential orientation in (002) direction. Variation in the optical properties as a function of the film thickness was observed. The band gap energy was determined from optical analysis to be ∼ 3.27 eV. The refractive

  5. ZnO nanocoral reef grown on porous silicon substrates without catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Abdulgafour, H.I., E-mail: hind_alshaikh@yahoo.com [School of Physics, University Sains Malaysia 11800 Penang (Malaysia); Yam, F.K.; Hassan, Z.; AL-Heuseen, K.; Jawad, M.J. [School of Physics, University Sains Malaysia 11800 Penang (Malaysia)

    2011-05-05

    Research highlights: > Porous silicon (PS) technology is utilized to grow coral reef-like ZnO nanostructures on the surface of Si substrates. > Flower-like aligned ZnO nanorods are fabricated directly onto the silicon substrates through zinc powder evaporation using a simple thermal evaporation method without a catalyst for comparison. > The PL spectra show that for ZnO nanocoral reefs the UV emission shifts slightly towards lower frequency. > This non-catalyst growth technique on the rough surface of substrates may have potential applications in the fabrication of nanoelectronic and nanooptical devices. - Abstract: Porous silicon (PS) technology is utilized to grow coral reef-like ZnO nanostructures on the surface of Si substrates with rough morphology. Flower-like aligned ZnO nanorods are also fabricated directly onto the silicon substrates through zinc powder evaporation using a simple thermal evaporation method without a catalyst for comparison. The characteristics of these nanostructures are investigated using field-emission scanning electron microscopy, grazing-angle X-ray diffraction (XRD), and photoluminescence (PL) measurements of structures grown on both Si and porous Si substrates. The texture coefficient obtained from the XRD spectra indicates that the coral reef-like nanostructures are highly oriented on the porous silicon substrate with decreasing nanorods length and diameter from 800-900 nm to 3.5-5.5 {mu}m and from 217-229 nm to 0.6-0.7 {mu}m, respectively. The PL spectra show that for ZnO nanocoral reefs the UV emission shifts slightly towards lower frequency and the intensity increase with the improvement of ZnO crystallization. This non-catalyst growth technique on the rough surface of substrates may have potential applications in the fabrication of nanoelectronic and nanooptical devices.

  6. Aqueous chemical growth of free standing vertical ZnO nanoprisms, nanorods and nanodiskettes with improved texture co-efficient and tunable size uniformity

    Energy Technology Data Exchange (ETDEWEB)

    Ram, S.D.G. [Bharath Niketan Engineering College, Department of Physics, Aundipatti (India); Ravi, G.; Mahalingam, T. [Alagappa University, Department of Physics, Karaikudi (India); Athimoolam, A. [Fatima Michael College of Engineering and Technology, Department of Physics, Madurai (India); Kulandainathan, M.A. [Central Electro Chemical Research Institute, Karaikudi (India)

    2011-12-15

    Tuning the morphology, size and aspect ratio of free standing ZnO nanostructured arrays by a simple hydrothermal method is reported. Pre-coated ZnO seed layers of two different thicknesses ({approx}350 nm or 550 nm) were used as substrates to grow ZnO nanostructures for the study. Various parameters such as chemical ambience, pH of the solution, strength of the Zn{sup 2+} atoms and thickness of seed bed are varied to analyze their effects on the resultant ZnO nanostructures. Vertically oriented hexagonal nanorods, multi-angular nanorods, hexagonal diskette and popcorn-like nanostructures are obtained by altering the experimental parameters. All the produced nanostructures were analysed by X-ray powder diffraction analysis and found to be grown in the (002) orientation of wurtzite ZnO. The texture co-efficient of ZnO layer was improved by combining a thick seed layer with higher cationic strength. Surface morphological studies reveal various nanostructures such as nanorods, diskettes and popcorn-like structures based on various preparation conditions. The optical property of the closest packed nanorods array was recorded by UV-VIS spectrometry, and the band gap value simulated from the results reflect the near characteristic band gap of ZnO. The surface roughness profile taken from the Atomic Force Microscopy reveals a roughness of less than 320 nm. (orig.)

  7. Wafer-Scale High-Throughput Ordered Growth of Vertically Aligned ZnO Nanowire Arrays

    KAUST Repository

    Wei, Yaguang

    2010-09-08

    This article presents an effective approach for patterned growth of vertically aligned ZnO nanowire (NW) arrays with high throughput and low cost at wafer scale without using cleanroom technology. Periodic hole patterns are generated using laser interference lithography on substrates coated with the photoresist SU-8. ZnO NWs are selectively grown through the holes via a low-temperature hydrothermal method without using a catalyst and with a superior control over orientation, location/density, and as-synthesized morphology. The development of textured ZnO seed layers for replacing single crystalline GaN and ZnO substrates extends the large-scale fabrication of vertically aligned ZnO NW arrays on substrates of other materials, such as polymers, Si, and glass. This combined approach demonstrates a novel method of manufacturing large-scale patterned one-dimensional nanostructures on various substrates for applications in energy harvesting, sensing, optoelectronics, and electronic devices. © 2010 American Chemical Society.

  8. On-chip surface modified nanostructured ZnO as functional pH sensors

    Science.gov (United States)

    Zhang, Qing; Liu, Wenpeng; Sun, Chongling; Zhang, Hao; Pang, Wei; Zhang, Daihua; Duan, Xuexin

    2015-09-01

    Zinc oxide (ZnO) nanostructures are promising candidates as electronic components for biological and chemical applications. In this study, ZnO ultra-fine nanowire (NW) and nanoflake (NF) hybrid structures have been prepared by Au-assisted chemical vapor deposition (CVD) under ambient pressure. Their surface morphology, lattice structures, and crystal orientation were investigated by scanning electron microscopy (SEM), x-ray diffraction (XRD), and transmission electron microscopy (TEM). Two types of ZnO nanostructures were successfully integrated as gate electrodes in extended-gate field-effect transistors (EGFETs). Due to the amphoteric properties of ZnO, such devices function as pH sensors. We found that the ultra-fine NWs, which were more than 50 μm in length and less than 100 nm in diameter, performed better in the pH sensing process than NW-NF hybrid structures because of their higher surface-to-volume ratio, considering the Nernst equation and the Gouy-Chapman-Stern model. Furthermore, the surface coating of (3-Aminopropyl)triethoxysilane (APTES) protects ZnO nanostructures in both acidic and alkaline environments, thus enhancing the device stability and extending its pH sensing dynamic range.

  9. Study on the Optoelectronic Properties of UV Luminescent Polymer: ZnO Nanoparticles Dispersed PANI

    Directory of Open Access Journals (Sweden)

    J. Kayathri

    2013-01-01

    Full Text Available The present work is focused on the synthesis and characterization of a new polymer thin film material suitable for emissive layer in polymer light-emitting diodes. Thin films of polyaniline and ZnO nanoparticles dispersed polyaniline have been prepared and investigated for the suitability of emissive layer in polymer light emitting diodes. ZnO nanoparticles have been synthesized using wet chemical method and characterized using powder X-ray diffraction. Diffraction pattern reveals that the ZnO nanoparticles are grown in hexagonal wurtzite structure with the preferential orientation of (001 plane. Polyaniline was synthesized using potassium persulphate (initiator at room temperature. ZnO nanoparticles are then dispersed in different doping level (5%, 10%, 15% 20% and 50% with polyaniline. Thin films of ZnO dispersed polyaniline (PANI/ZnO were prepared and characterized using scanning electron microscopy in order to investigate the surface morphology of the film. The optical characteristics and the suitability of film as emissive layer were analyzed using UV-visible absorption and fluorescence spectroscopy.

  10. Homogeneous vertical ZnO nanorod arrays with high conductivity on an in situ Gd nanolayer

    KAUST Repository

    Flemban, Tahani H.

    2015-10-30

    We demonstrate a novel, one-step, catalyst-free method for the production of size-controlled vertical highly conductive ZnO nanorod (NR) arrays with highly desirable characteristics by pulsed laser deposition using a Gd-doped ZnO target. Our study shows that an in situ transparent and conductive Gd nanolayer (with a uniform thickness of ∼1 nm) at the interface between a lattice-matched (11-20) a-sapphire substrate and ZnO is formed during the deposition. This nanolayer significantly induces a relaxation mechanism that controls the dislocation distribution along the growth direction; which consequently improves the formation of homogeneous vertically aligned ZnO NRs. We demonstrate that both the lattice orientation of the substrate and the Gd characteristics are important in enhancing the NR synthesis, and we report precise control of the NR density by changing the oxygen partial pressure. We show that these NRs possess high optical and electrical quality, with a mobility of 177 cm2 (V s)-1, which is comparable to the best-reported mobility of ZnO NRs. Therefore, this new and simple method has significant potential for improving the performance of materials used in a wide range of electronic and optoelectronic applications.

  11. Skill-building through Task-Oriented Motor Practice (STOMP) intervention for activities of daily living: study protocol for a randomized, single blinded clinical trial.

    Science.gov (United States)

    Ciro, C A; Stoner, J; Prodan, C; Hershey, L

    2016-01-01

    Progressive disability in activities of daily living (ADL) is inevitable for people with Alzheimer's disease and related dementias (ADRD). Attempts to slow or prevent ADL disability have been unsuccessful despite making progress in behavioral training methods. Missing from this research is an emphasis on how we maximize a patient's engagement during training and the rigorous examination of implementation protocols (dosing and training methods) which may advantage learning in people with ADRD. Our team addressed this gap with the development of the STOMP (Skill-building through Task-Oriented Motor Practice) intervention which creates methods for obtaining ADL goals that support "personhood" and tests high-intensity protocols that appear to advantage learning and sustained learning over time. Through this study, we aim to evaluate differential outcomes by dose levels as well as assess the moderating effects of attention to task during training. Randomized-controlled trial with 32 participants with dementia assigned to either the original, intensive STOMP protocol (3 hours/day, 5 days/week for 2 weeks) or a less-intensive STOMP protocol (1 hour/day, 2 days/week for 2 weeks) delivered by an occupational therapy assistant in the home. ADL training is delivered using motor learning theory techniques of blocked practice, continuous verbal praise, errorless learning and intense dosing schedules. Inclusion criteria: English speaking, adults 50-80 years old that live with a legally-authorized representative that can provide consent, who can follow a one-step command, have three ADL goals they want to address and can participate in an intense therapy protocol. Exclusions include diagnoses of Creutzfeldt-Jakob Dementia, delirium or receptive/global aphasia. Recruitment will occur through direct mailing, physician referral and media/support group presentations. Blinded occupational therapists will complete baseline, post-intervention and 3-month follow-up assessments in the

  12. Strain mismatch induced tilted heteroepitaxial (000l) hexagonal ZnO films on (001) cubic substrates

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Bo Soo [Department of Applied Physics, Hanyang University Ansan (Korea, Republic of); Stan, Liliana; Usov, Igor O.; DePaula, Raymond F.; Arendt, Paul N.; Nastasi, Michael; Jia, Quanxi [Los Alamos National Laboratory, Los Alamos, NM (United States); Lee, Jung-Kun [Department of Mechanical Engineering and Materials Science, University of Pittsburgh, PA (United States); Harriman, Tres A.; Lucca, Don A. [School of Mechanical and Aerospace Engineering, Oklahoma State University Stillwater, OK (United States); MacManus-Driscoll, Judith L. [Department of Materials Science and Metallurgy, University of Cambridge (United Kingdom); Park, Bae Ho [Division of Quantum Phases and Devices, Department of Physics, Konkuk University Seoul (Korea, Republic of)

    2011-12-15

    A novel strain mismatch induced tilted epitaxy method has been demonstrated for producing high quality (000l) hexagonal films on (001) cubic substrates. Highly oriented hexagonal (000l) ZnO films are grown on cubic (001) MgO substrates using Sm{sub 0.28}Zr{sub 0.72}O{sub 2-{delta}} (SZO) as a template. The large lattice mismatch of >13% between the obvious crystallographic matching directions of the template and substrate means that cube-on-cube epitaxy is energetically unfavorable, leading to growth instead of two high index, low energy compact planes, close to the {l_brace}111{r_brace} orientation. These planes give three different in-plane orientations resulting from coincidence site lattice matching (12 in-plane orientations in total) and provide a pseudo-hexagonal symmetry surface for the ZnO to grow on. The texture of the ensuing (000l) ZnO layer is markedly improved over the template. The work opens up both a new avenue for growing technologically important hexagonal structures on a range of readily available, (001) cubic substrates, as well as showing that there are wide possibilities for heteroepitaxial growth of a range of dissimilar materials. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Realization of p -ZnO thin films by GaP codoping

    Science.gov (United States)

    Gowrishankar, S.; Balakrishnan, L.; Elanchezhiyan, J.; Balasubramanian, T.; Gopalakrishnan, N.

    2011-11-01

    An attempt has been made to realize p-ZnO by directly doping (codoping) GaP into ZnO thin films. GaP codoped ZnO thin films of different concentrations (1, 2 and 4 mol%) have been grown by RF magnetron sputtering. The grown films on sapphire substrate have been characterized by X-ray diffraction (XRD), Hall measurement, Photoluminescence (PL) and Energy dispersive spectroscopy (EDS) to validate the p-type conduction. XRD result shows that all the films have been preferentially oriented along (0 0 2) orientation. The decrease of full-width at half maximum (FWHM) with increase in GaP doping depicts the decrease in native donor defects. Hall measurement shows that among the three films, 2 and 4 mol% GaP doped ZnO shows p-conductivity due to the sufficient amount of phosphorous incorporation. It has been found that low resistivity (2.17 Ωcm) and high hole concentration (1.8×10 18 cm -3) for 2% GaP codoped ZnO films due to best codoping. The red shift in near-band-edge (NBE) emission and donar-acceptor-pair (DAP) and neutral acceptor bound recombination (A°X) observed by room temperature and low temperature (10 K) PL, respectively, well acknowledged the formation of p-ZnO. The incorporated phosphorous in the film has been also confirmed by EDS analysis.

  14. Effects of laser wavelength and fluence on the growth of ZnO thin films by pulsed laser deposition

    NARCIS (Netherlands)

    Craciun, V.; Amirhaghi, S.; Craciun, D.; Elders, J.; Gardeniers, Johannes G.E.; Boyd, Ian W.

    Transparent, electrically conductive and c-axis oriented ZnO thin films have been grown by the pulsed laser deposition (PLD) technique on silicon and Corning glass substrates employing either a KrF excimer laser (λ = 248 nm) or a frequency-doubled Nd:YAG laser (λ = 532 nm). The crystalline

  15. Polarization induced conductive AFM on cobalt doped ZnO nanostructures

    Science.gov (United States)

    Sahoo, Pradosh Kumar; Mangamma, G.; Rajesh, A.; Kamruddin, M.; Dash, S.

    2017-05-01

    In the present work cobalt doped ZnO (CZO) nanostructures (NS) have been synthesized by of sol-gel and spin coating process. After the crystal phase confirmation by GIXRD and Raman spectroscopy, Conductive Atomic Force Microscopy (C-AFM) measurement was performed on CZO NS which shows the random distribution of electrically conducting zones on the surface of the material exhibiting current in the range 4-170 pA. We provide the possible mechanisms for variation in current distribution essential for quantitative understanding of transport properties of ZnO NS in doped and undoped forms.

  16. Low temperature carving of ZnO nanorods into nanotubes for dye-sensitized solar cell application

    Energy Technology Data Exchange (ETDEWEB)

    Dehghan Nayeri, Fatemeh, E-mail: F.d.nayeri@ut.ac.ir; Kolahdouz, Mohammadreza; Asl-Soleimani, Ebrahim; Mohajerzadeh, S.

    2015-06-05

    Highlights: • Large scale arrays of highly oriented ZnO NTs have been fabricated and investigated. • The DSSCs made of these 2.5 μm NRs and NTs resulted in conversion efficiencies of 0.34% and 0.9%, respectively. • EIS measurements have demonstrated that the NTs could acquire a higher electron lifetime compared to NRs. • Twofold electron lifetime electron accompanied by half electron transport time for ZnO NTs compared to NRs. - Abstract: High aspect ratio zinc oxide (ZnO) nanotubes (NT) were synthesized based on a two-steps approach. In the first step, ZnO nanorod (NR) arrays were prepared by chemical bath deposition from an aqueous of zinc nitrate. In the second step, the cores of ZnO NRs were carved selectively in a KCl solution, resulting in the formation of a tubular structure. The influence of KCL concentration, temperature, and immersion time on the ZnO NT formation process was completely characterized and investigated. 12.5 μm NRs and NTs have been utilized to manufacture dye-sensitized solar cells (DSSCs) and as a result, conversion efficiencies of 1.06% and 2.87% were obtained, respectively. Electrochemical impedance spectroscopy measurements have demonstrated that the NTs could acquire a higher electron lifetime compared to NRs which causes a faster electron collection. The overall improvement in NT-based DSSC performance demonstrates a new approach to enhance the efficiency of dye-sensitized solar cells.

  17. ZnO UV Detectors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — High-efficiency UV detectors will be developed in the Phase II program with ZnO and its alloy (ZnBeO). ZnO and ZnBeO are a very suitable material for fabrication of...

  18. Synthesis of ZnO Nanowires and Their Photovoltaic Application: ZnO Nanowires/AgGaSe2 Thin Film Core-Shell Solar Cell

    Directory of Open Access Journals (Sweden)

    Elif Peksu

    2015-01-01

    Full Text Available In this investigation, hydrothermal technique was employed for the synthesis of well-aligned dense arrays of ZnO nanowires (NWs on a wide range of substrates including silicon, soda-lime glass (SLG, indium tin oxide, and polyethylene terephthalate (PET. Results showed that ZnO NWs can be successfully grown on any substrate that can withstand the growth temperature (~90°C and precursor solution chemicals. Results also revealed that there was a strong impact of growth time and ZnO seed layer deposition route on the orientation, density, diameter, and uniformity of the synthesized nanowires. A core-shell n-ZnO NWs/p-AgGaSe2 (AGS thin film solar cell was fabricated as a device application of synthesized ZnO nanowires by decoration of nanowires with ~700 nm thick sputtering deposited AGS thin film layer, which demonstrated an energy conversion efficiency of 1.74% under 100 mW/cm2 of simulated solar illumination.

  19. Superhydrophobic and anti-reflective ZnO nanorod-coated FTO transparent conductive thin films prepared by a three-step method

    Energy Technology Data Exchange (ETDEWEB)

    Li, Bao-jia, E-mail: li_bjia@126.com [School of Materials Science and Engineering, Jiangsu University, Zhenjiang, 212013 (China); Jiangsu Provincial Key Laboratory of Center for Photon Manufacturing Science and Technology, Jiangsu University, Zhenjiang, 212013 (China); Huang, Li-jing; Ren, Nai-fei [Jiangsu Provincial Key Laboratory of Center for Photon Manufacturing Science and Technology, Jiangsu University, Zhenjiang, 212013 (China); School of Mechanical Engineering, Jiangsu University, Zhenjiang, 212013 (China); Kong, Xia; Cai, Yun-long; Zhang, Jie-lu [Jiangsu Tailong Reduction Box Co. Ltd., Taixing, 225400 (China)

    2016-07-25

    A ZnO nanorod-coated FTO film was prepared by sputtering an AZO layer on FTO glass, thermal annealing of the AZO/FTO film, and hydrothermal growth of ZnO nanorods at 70 °C on the annealed AZO/FTO film using zinc foils as zinc source. Two other ZnO nanorod-coated FTO films were also prepared by hydrothermal growths of ZnO nanorods on the FTO glass and the unannealed AZO/FTO film respectively for comparison purpose. The results were observed in detail using X-ray diffraction, scanning electron microscopy, water contact/sliding angle measurement, spectrophotometry and four-point probe measurement. The ZnO nanorods on the annealed AZO/FTO film were found to exhibit denser distribution and better orientation than those on the FTO glass and the unannealed AZO/FTO film. As a result, the ZnO nanorod-coated annealed AZO/FTO film demonstrated superhydrophobicity, high transparency and low reflectance in the visible range. Also this film had the lowest sheet resistance of 4.0 Ω/sq, implying its good electrical conductivity. This investigation provides a valuable reference for developing multifunctional transparent conductive films. - Highlights: • ZnO nanorod-coated annealed AZO/FTO film was obtained by a three-step method. • FTO and unannealed AZO/FTO films were also used as substrates for comparison. • ZnO nanorods on the annealed AZO/FTO film were denser and more vertically-oriented. • The ZnO nanorod-coated annealed AZO/FTO film (Z/TA-FTO) had superhydrophobicity. • The Z/TA-FTO exhibited high transparency, low reflectance and good conductivity.

  20. c-plane ZnO on a-plane sapphire: Inclusion of (1 1 bar 01) domains

    Science.gov (United States)

    Madel, M.; Neusser, G.; Simon, U.; Mizaikoff, B.; Thonke, K.

    2015-06-01

    The influence of metal-free ZnO nanoseed-layers on the growth of ZnO films on a-plane sapphire substrates by chemical vapor deposition (CVD) is investigated. For epitaxial films with a high density of (1 1 bar 01) inclusions we find a twofold orientation of these inclusions with the epitaxial relationships (11 2 bar 0) Al2O3 ∥(1 1 bar 01) ZnO and (10 1 bar 4) Al2O3 ∥(0001)ZnO. HRXRD measurements show that these inclusions are tilted by approx. 1.45° towards the sapphire substrate as a result of strain relaxation during heteroepitaxial growth. Numerical simulations with ANSYS confirm this as the energetically favorable situation. Detailed HRXRD and EBSD studies show that the occurrence of (1 1 bar 01) oriented nanocrystallites during nucleation is responsible for the formation of dislocations, and that the nucleation process has a pronounced influence on the crystal quality of c-plane ZnO films grown on a-plane sapphire.

  1. Randomized controlled trial of a family-oriented self-management program to improve self-efficacy, glycemic control and quality of life among Thai individuals with Type 2 diabetes.

    Science.gov (United States)

    Wichit, Nutchanath; Mnatzaganian, George; Courtney, Mary; Schulz, Paula; Johnson, Maree

    2017-01-01

    We evaluated a theoretically-derived family-oriented intervention aimed to improve self-efficacy, self-management, glycemic control and quality of life in individuals living with Type 2 diabetes in Thailand. In a single-blinded randomized controlled trial, 140 volunteer individuals with Type 2 diabetes, recruited from a diabetes clinic in rural Thailand, were randomly allocated to intervention and control arms. Those in the intervention arm received routine care plus a family-oriented program that included education classes, group discussions, a home visit, and a telephone follow-up while the control arm only received routine care. Improvement in outcomes over time (baseline, Week 3, and Week 13 following intervention) was evaluated using Generalized Estimating Equations multivariable analyses. Except for age, no between-group significant differences were observed in all other baseline characteristics. Diabetes self-efficacy, self-management, and quality of life improved in the intervention arm but no improvement was observed in the controls. In the risk-adjusted multivariable models, compared to the controls, the intervention arm had significantly better self-efficacy, self-management, outcome expectations, and diabetes knowledge (plife or glycemic control, however, in the risk-adjusted multivariable models, higher self-management scores were associated with significantly decreased HbA1c levels (plife (pfamily-oriented program improved patients' self-efficacy and self-management, which in turn could decrease HbA1c levels. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  2. Polyelectrolyte-assisted preparation and characterization of nanostructured ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Shijun

    2005-05-15

    The present work focuses on the synthesis and characterization of nanostructured ZnO thin films onto silicon wafers modified by self-assembled-monolayers via chemical bath deposition. Two precursor solutions were designed and used for the film deposition, in which two different polymers were introduced respectively to control the growth of the ZnO colloidal particles in solution. ZnO films were deposited from an aqueous solution containing zinc salt and hexamethylenetetramine (HMTA) in the presence of a graft-copolymer (P (MAA{sub 0.50}-co(MAA-EO{sub 20}){sub 0.50}){sub 70}). A film-formation-diagram was established based on the results obtained by scanning electron microscopy (SEM) and atomic force microscopy (AFM), which describes the influence of the concentration of HMTA and copolymer on the ZnO film formation. According to the film morphology, film formation can be classified into three categories: (a) island-like films, (b) uniform films and (c) canyon-like films. The ZnO films annealed at temperatures of 450 C, 500 C, 600 C and 700 C were examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). After annealing, the films are polycrystalline ZnO with wurtzite structure. XRD measurements indicate that with increasing annealing temperature, the average grain size increases accordingly and the crystallinity of the films is improved. Upon heating to 600 C, the ZnO films exhibit preferred orientation with c-axis normal to substrate, whereas the films annealed at 700 C even show a more explicit texture. By annealing at temperatures above 600 C the ZnO film reacts with the substrate to form an interfacial layer of Zn{sub 2}SiO{sub 4}, which grows thicker at elevated annealing temperatures. The ZnO films annealed at 600 C and 700 C show strong UV emission. Another non-aqueous solution system for ZnO thin film deposition was established, in which 2- propanol was used as a solvent and Zn(CH3COO){sub 2}.2H{sub 2}O as well as NaOH as reactants

  3. Effect of ZnO doping on the structural and optical properties of ...

    Indian Academy of Sciences (India)

    Abstract. BaWO4 doped with ZnO (2, 3, 5, 7 and 10 wt%) nanostructured films are prepared on quartz substrates by pulsed laser ablation. The films are post annealed at. 900°C. GIXRD analysis of the post-annealed films reveal the change of orientation of scheelite tetragonal crystal growth from 1 1 2 reflection plane to 0 0 4 ...

  4. Spectroscopic characterization and docking studies of ZnO nanoparticle modified with BSA

    Energy Technology Data Exchange (ETDEWEB)

    Ledesma, Ana E., E-mail: anael@unse.edu.ar [CITSE-UNSE, CONICET, FCEyT, RN 9, km 1125, 4206 Santiago del Estero (Argentina); Chemes, Doly María [INQUINOA, UNT, CONICET, FBQyF, San Lorenzo 456, San Miguel de Tucumán CPA T4000ILI, Tucumán (Argentina); Frías, María de los Angeles [Laboratory of Biointerphases and Biomimetic Systems, (CITSE) National University of Santiago del Estero and CONICET, 4206, RN 9- Km 1125, Santiago del Estero (Argentina); Guauque Torres, Maria del Pilar [CITSE-UNSE, CONICET, FCEyT, RN 9, km 1125, 4206 Santiago del Estero (Argentina)

    2017-08-01

    Highlights: • The ZnO NPs have synthesized at moderate temperature and conjugated with BSA to elucidate the characteristics of best binding site in the protein cavity. • The Docking studies have successfully applied to identify the amino acids residues involved in the interaction. • The cytotoxicity of ZnO NPs and ZnO-BSA NPs and esterase-like activity of the protein have evaluated, with very promising results for medical applications. - Abstract: Nanoparticles (NP) into a biological environment are an interesting topic for diagnosis and therapy in applications for medicine or environment and the knowledge about this interaction is important from the perspective of safe use of nanomaterials. In the current study, we characterized the type of interaction and the orientation of bovine serum albumin (BSA) adsorbed on ZnO nanoparticle surfaces as a function of size, using molecular docking. To probe experimentally different theoretical hypothesis about the interaction, ZnO-NPs were prepared in aqueous solution, and then were bioconjugated with BSA. Transmission electron microscopy (TEM) and Raman spectroscopy confirm the spherical shape of NP and the irreversible adsorption of BSA on NP surface. Raman and Infrared spectroscopy (FTIR) reveal that BSA interaction with ZnO nanoparticle produced a conformational rearrangement into protein, observing changes in Tyr and Trp environment, a minor percentage of α-helix structure and a more extended chain. The fluorescence analysis demonstrated that when BSA concentration higher than 30 μM is used the signal due to the self-oligomerization of protein overlaps with the ZnO nanoparticle emission. The results predicted that the most probable interaction site is near to domain IB and IIA and ionic interactions are the major responsible for the binding. Thermal stability studies reveals that the denaturalization temperature of BSA increase from 57 °C to 65 °C in presence of ZnO NP and their esterase-like activity was

  5. Highly textured and transparent RF sputtered Eu2O3 doped ZnO films

    Directory of Open Access Journals (Sweden)

    Remadevi Sreeja Sreedharan

    2015-03-01

    Full Text Available Background: Zinc oxide (ZnO is a wide, direct band gap II-VI oxide semiconductor. ZnO has large exciton binding energy at room temperature, and it is a good host material for obtaining visible and infrared emission of various rare-earth ions. Methods: Europium oxide (Eu2O3 doped ZnO films are prepared on quartz substrate using radio frequency (RF magnetron sputtering with doping concentrations 0, 0.5, 1, 3 and 5 wt%. The films are annealed in air at a temperature of 773 K for 2 hours. The annealed films are characterized using X-ray diffraction (XRD, micro-Raman spectroscopy, atomic force microscopy, ultraviolet (UV-visible spectroscopy and photoluminescence (PL spectroscopy. Results: XRD patterns show that the films are highly c-axis oriented exhibiting hexagonalwurtzite structure of ZnO. Particle size calculations using Debye-Scherrer formula show that average crystalline size is in the range 15–22 nm showing the nanostructured nature of the films. The observation of low- and high-frequency E2 modes in the Raman spectra supports the hexagonal wurtzite structure of ZnO in the films. The surface morphology of the Eu2O3 doped films presents dense distribution of grains. The films show good transparency in the visible region. The band gaps of the films are evaluated using Tauc plot model. Optical constants such as refractive index, dielectric constant, loss factor, and so on are calculated using the transmittance data. The PL spectra show both UV and visible emissions. Conclusion: Highly textured, transparent, luminescent Eu2O3 doped ZnO films have been synthesized using RF magnetron sputtering. The good optical and structural properties and intense luminescence in the ultraviolet and visible regions from the films suggest their suitability for optoelectronic applications.

  6. Synthesis and conductivity enhancement of Al-doped ZnO nanorod array thin films.

    Science.gov (United States)

    Hsu, Chih-Hsiung; Chen, Dong-Hwang

    2010-07-16

    Al-doped ZnO (AZO) nanorod array thin films with various Al/Zn molar ratios were synthesized by chemical bath deposition. The resultant AZO nanorods were well-aligned at the glass substrate, growing vertically along the c-axis [001] direction. In addition, they had an average diameter of 64.7 +/- 16.8 nm and an average length of about 1.0 microm with the structure of wurtzite-type ZnO. Analyses of energy dispersive x-ray spectra and x-ray photoelectron spectra indicated that Al atoms had been doped into the ZnO crystal lattice. The doping of Al atoms did not result in significant changes in the structure and crystal orientation, but the electrical resistivity was found to increase first and then decrease with increasing Al content owing to the increase of carrier concentration and the decrease of mobility. In addition, the transmission in the visible region increased but the increase was reduced at higher Al doping levels. After hydrogen treatment, the morphology of the AZO nanorod array thin films remained unchanged. However, the electrical resistivity decreased significantly due to the formation of oxygen vacancies and interstitial hydrogen atoms. When the real Al/Zn molar ratio was about 3.7%, the conductivity was enhanced about 1000 times and a minimum electrical resistivity of 6.4 x 10( - 4) Omega cm was obtained. In addition, the transmission of the ZnO nanorod array thin film in the visible region was significantly increased but the increase was less significant for the AZO nanorod array thin film, particularly at higher Al doping levels. In addition, the current-voltage curves of the thin film devices with ZnO or AZO nanorod arrays revealed that AZO had a higher current response than ZnO and hydrogen treatment led to a more significant enhancement of current responses (about 100-fold).

  7. Effects of the oriental herbal medicine Bofu-tsusho-san in obesity hypertension: a multicenter, randomized, parallel-group controlled trial (ATH-D-14-01021.R2).

    Science.gov (United States)

    Azushima, Kengo; Tamura, Kouichi; Haku, Sona; Wakui, Hiromichi; Kanaoka, Tomohiko; Ohsawa, Masato; Uneda, Kazushi; Kobayashi, Ryu; Ohki, Kohji; Dejima, Toru; Maeda, Akinobu; Hashimoto, Tatsuo; Oshikawa, Jin; Kobayashi, Yusuke; Nomura, Koichiro; Azushima, Chieko; Takeshita, Yasuyo; Fujino, Ryota; Uchida, Ken; Shibuya, Ken; Ando, Daisaku; Tokita, Yasuo; Fujikawa, Tetsuya; Toya, Yoshiyuki; Umemura, Satoshi

    2015-05-01

    There is no clinical evidence that supports the benefit of integrative medicine, defined as combination therapy of oriental and western medicine, on obesity-related hypertension. This study evaluates the efficacy of Bofu-tsusho-san (BOF), an oriental herbal medicine, on the ambulatory blood pressure (BP) profile in hypertensive patients with obesity. The study design was a multicenter, randomized, open-label, parallel-group controlled trial in 107 hypertensive patients with obesity. Participants were randomly assigned to receive either the conventional control therapy or BOF add-on therapy. In both groups antihypertensive therapy was aimed at achieving the target clinic BP. The primary outcome was change in the ambulatory BP profile from baseline to 24 weeks after randomization. Daytime systolic BP variability, an important parameter of ambulatory BP profile, was decreased in the BOF group, and the difference in the changes in daytime systolic BP variability was significant between the BOF and control group (Control vs BOF; the change from baseline in daytime systolic BP variability, 1.0±3.3 vs -1.0±3.3%; p=0.006). The BOF add-on therapy effectively improved the ambulatory BP variability. This is the first report suggesting that an integrative medicine approach may exert favorable effects on obesity-related hypertension compared with conventional pharmaceutical treatment. UMIN000003878. Copyright © 2015 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

  8. Synthesis and characterization of porous structured ZnO thin film for dye sensitized solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Marimuthu, T.; Anandhan, N., E-mail: anandhan-kn@rediffmail.com; Mummoorthi, M. [School of Physics, Alagappa University, Karaikudi – 630 003 (India); Dharuman, V. [Department of Bioelectronics and Biosensors, Alagappa University, Karaikudi – 630 003 (India)

    2016-05-23

    Zinc oxide (ZnO) and zinc oxide/eosin yellow (ZnO/EY) thin films were potentiostatically deposited onto fluorine doped tin oxide (FTO) glass substrate. Effect of eosin yellow dye on structural, morphological and optical properties was studied. X-ray diffraction patterns, micro Raman spectra and photoluminescence (PL) spectra reveal hexagonal wurtzite structure with less atomic defects in 101 plane orientation of the ZnO/EY film. Scanning electron microscopy (SEM) images show flower for ZnO and porous like structure for ZnO/EY thin film, respectively. DSSC was constructed and evaluated by measuring the current density verses voltage curve.

  9. Vertically aligned ZnO nanowire arrays in Rose Bengal-based dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Pradhan, Basudev; Batabyal, Sudip K.; Pal, Amlan J. [Indian Association for the Cultivation of Science, Department of Solid State Physics, Kolkata 700032 (India)

    2007-05-23

    We fabricate dye-sensitized solar cells (DSSC) using vertically oriented, high density, and crystalline array of ZnO nanowires, which can be a suitable alternative to titanium dioxide nanoparticle films. The vertical nanowires provide fast routes or channels for electron transport to the substrate electrode. As an alternative to conventional ruthenium complex, we introduce Rose Bengal dye, which acts as a photosensitizer in the dye-sensitized solar cells. The dye energetically matches the ZnO with usual KI-I{sub 2} redox couple for dye-sensitized solar cell applications. (author)

  10. The effect of Cu dopant on morphological, structural and optical properties of ZnO nanorods grown on indium tin oxide substrate

    Science.gov (United States)

    Marselie, J.; Fauzia, V.; Sugihartono, I.

    2017-04-01

    Zinc oxide (ZnO) is a promising semiconductor due to its tunable optical properties. Among semiconductor nanostructures, one-dimensional structure such as ZnO nanorods becomes the main focus due to their wide potential application. Cu doped ZnO has attracted much attention recently because of its interesting properties, such as room temperature ferromagnetism, multiferroics properties and green emission. In this work, we deposited ZnO nanoseeds on indium tin oxide coated glass substrates and then ZnO nanorods were grown and doped with three different Cu concentrations (1, 4 and 7 at. %) by hydrothermal method. The scanning electron microscope showed that ZnO nanorod were grown with a hexagonal shape with diverse growth orientation. The X-ray diffraction analysis reveals that the addition of Cu doping tends to decrease the crystallite size and the lattice parameter. Generally, Cu doping reduces the absorbance at ultraviolet wavelength region except on the ZnO nanorods with 4% Cu. The addition of Cu also increases the bandgap energy and decreases the luminescence intensity in UV and visible regions, that is a sign that number of radiative transitions and the natural defects have been reduced.

  11. Characterization of ZnO thin films grown on different p-Si substrate elaborated by solgel spin-coating method

    Energy Technology Data Exchange (ETDEWEB)

    Chebil, W., E-mail: Chbil.widad@live.fr [Laboratoire Physico-chimie des Matériaux, Unité de Service Commun de Recherche “High resolution X-ray diffractometer”, Département de Physique, Université de Monastir, Faculté des Sciences de Monastir, Avenue de l’Environnement, 5019 Monastir (Tunisia); Fouzri, A. [Laboratoire Physico-chimie des Matériaux, Unité de Service Commun de Recherche “High resolution X-ray diffractometer”, Département de Physique, Université de Monastir, Faculté des Sciences de Monastir, Avenue de l’Environnement, 5019 Monastir (Tunisia); Institut Supérieur des Sciences Appliquées et de Technologie de Sousse, Université de Sousse (Tunisia); Fargi, A. [Laboratoire de Microélectronique et Instrumentation, Faculté des Sciences de Monastir, Université de Monastir, Avenue de l’environnement, 5019 Monastir (Tunisia); Azeza, B.; Zaaboub, Z. [Laboratoire Micro-Optoélectroniques et Nanostructures, Faculté des Sciences de Monastir, Université de Monastir, Avenue de l' environnement, 5019 Monastir (Tunisia); and others

    2015-10-15

    Highlights: • High quality ZnO thin films grown on different p-Si substrates were successful obtained by sol–gel process. • PL measurement revealed that ZnO thin film grown on porous Si has the better optical quality. • I–V characteristics for all heterojunctions exhibit successful diode formation. • The diode ZnO/PSi shows a better photovoltaic effect under illumination with a maximum {sub Voc} of 0.2 V. - Abstract: In this study, ZnO thin films are deposited by sol–gel technique on p-type crystalline silicon (Si) with [100] orientation, etched silicon and porous silicon. The structural analyses showed that the obtained thin films were polycrystalline with a hexagonal wurtzite structure and preferentially oriented along the c-axis direction. Morphological study revealed the presence of rounded and facetted grains irregularly distributed on the surface of all samples. PL spectra at room temperature revealed that ZnO thin film grown on porous Si has a strong UV emission with low defects in the visible region comparing with ZnO grown on plat Si and etched Si surface. The heterojunction parameters were evaluated from the (I–V) under dark and illumination at room temperature. The ideality factor, barrier height and series resistance of heterojunction grown on different p-Si substrates are determined by using different methods. Best electrical properties are obtained for ZnO layer deposited on porous silicon.

  12. ZnO nanocrystals and allied materials

    CERN Document Server

    Okada, Tatsuo

    2014-01-01

    ZnO has been the central theme of research in the past decade due to its various applications in band gap engineering, and textile and biomedical industries. In nanostructured form, it offers ample opportunities to realize tunable optical and optoelectronic properties and it was also termed as a potential material to realize room temperature ferromagnetism. This book presents 17 high-quality contributory chapters on ZnO related systems written by experts in this field. These chapters will help researchers to understand and explore the varied physical properties to envisage device applications of ZnO in thin film, heterostructure and nanostructure forms.

  13. Second-harmonic generation of ZnO nanoparticles synthesized by laser ablation of solids in liquids

    Science.gov (United States)

    Rocha-Mendoza, Israel; Camacho-López, Santiago; Luna-Palacios, Yryx Y.; Esqueda-Barrón, Yasmín; Camacho-López, Miguel A.; Camacho-López, Marco; Aguilar, Guillermo

    2018-02-01

    We report the synthesis of small zinc oxide nanoparticles (ZnO NPs) based colloidal suspensions and the study of second-harmonic generation from aggregated ZnO NPs deposited on glass substrates. The colloidal suspensions were obtained using the laser ablation of solids in liquids technique, ablating a Zn solid target immersed in acetone as the liquid medium, with ns-laser pulses (1064 nm) of a Nd-YAG laser. The per pulse laser fluence, the laser repetition rate frequency and the ablation time were kept constant. The absorption evolution of the obtained suspensions was optically characterized through absorption spectroscopy until stabilization. Raman spectroscopy, SEM and HRTEM were used to provide evidence of the ZnO NPs structure. HRTEM results showed that 5-8 nm spheroids ZnO NPs were obtained. Strong second-harmonic signal is obtained from random ZnO monocrystalline NPs and from aggregated ZnO NPs, suggesting that the high efficiency of the nonlinear process may not depend on the NPs size or aggregation state.

  14. Aluminum as catalyst for ZnO nanostructures growth

    Energy Technology Data Exchange (ETDEWEB)

    Zandalazini, C., E-mail: zc@famaf.unc.edu.ar [Laboratorio de Física del Sólido, Departamento de Física, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina); Villafuerte, M. [Laboratorio de Física del Sólido, Departamento de Física, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina); Oliva, M. [Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina); Grupo de Ciencia de Materiales, Facultad de Matemática, Astronomía, y Física, Universidad Nacional de Córdoba (Argentina); Heluani, S.P. [Laboratorio de Física del Sólido, Departamento de Física, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán (Argentina)

    2015-05-15

    Highlights: • The efficiency of aluminum as catalyst to grow ZnO nanostructures is proved. • Aluminum as a new catalyst is proposed due to its reduced economic cost. • VSS growth mechanism is the main mechanism using Al as catalyst. • Abrupt diameter change of NWs is discussed due to Al-assisted growth. - Abstract: We report the growth of Al-catalyzed ZnO nanowires (NWs) using a thermal evaporation technique. Before the growth, the substrates were covered with a distribution of Al nano-island that act as seeds. We found that the density of NWs increases as the density of seeds is increased, confirming the catalyst properties of Al. The critical parameters of growth are the substrate temperature, oxygen partial pressure and the thickness of the initial Al layer from which the seeds are formed. The results showed that the oxygen pressure has a strong influence on the structural characteristics: the nanowires exhibit a preferential orientation in the (0 0 l)-planes when they are grown at low oxygen flow, and they become polycrystalline when a high concentration of oxygen in the flow is used. We consider that the growth occurs via a vapor-solid-solid (VSS) process as the predominant growth mechanism.

  15. Dielectric function of very thin nano-granular ZnO layers with different states of growth.

    Science.gov (United States)

    Gilliot, Mickaël; Hadjadj, Aomar; En Naciri, Aotmane

    2015-04-01

    Zinc oxide (ZnO) layers consisting of grains closely packed together are grown using a solgel synthesis and spin-coating deposition process. The morphologies are characterized by atomic force microscopy and X-ray diffraction, and their optical properties are investigated by spectroscopic ellipsometry at the different stages of the growth process. The optical observations are correlated with evolution of morphology and orientation. Two remarkable evolutions are observed: gradual evolution of morphology, crystallinity, and excitonic contribution with the first deposition steps; and transformation from a poorly oriented to a c-axis oriented crystalline state featuring a large contribution of bound excitons after thermal annealing. A modified Elliott model is used to obtain the optical parameters of ZnO, including bandgap and exciton energies. A simple growth mechanism is proposed to explain the evolution of the layers in accordance with the different deposition steps.

  16. Parametric analysis of the growth of colloidal ZnO nanoparticles synthesized in alcoholic medium

    Energy Technology Data Exchange (ETDEWEB)

    Fonseca, A. S. [National Research Centre for the Working Environment (Denmark); Figueira, P. A.; Pereira, A. S. [Universidade de Aveiro, Departamento de Química—CICECO (Portugal); Santos, R. J. [Universidade do Porto, Laboratory of Separation and Reaction Engineering-Laboratory of Catalysis and Materials (LSRE-LCM), Faculdade de Engenharia (Portugal); Trindade, T. [Universidade de Aveiro, Departamento de Química—CICECO (Portugal); Nunes, M. I., E-mail: isanunes@ua.pt [Universidade de Aveiro, Centre for Environmental and Marine Studies (CESAM), Dep. de Ambiente e Ordenamento (Portugal)

    2017-02-15

    The growth kinetics of nanosized ZnO was studied considering the influence of different parameters (mixing degree, temperature, alcohol chain length, reactant concentration and Zn/OH ratios) on the synthesis reaction and modelling the outputs using typical kinetic growth models, which were then evaluated by means of a sensitivity analysis. The Zn/OH ratio, the temperature and the alcohol chain length were found to be essential parameters to control the growth of ZnO nanoparticles, whereas zinc acetate concentration (for Zn/OH = 0.625) and the stirring during the ageing stage were shown to not have significant influence on the particle size growth. This last operational parameter was for the first time investigated for nanoparticles synthesized in 1-pentanol, and it is of outmost importance for the implementation of continuous industrial processes for mass production of nanosized ZnO and energy savings in the process. Concerning the nanoparticle growth modelling, the results show a different pattern from the more commonly accepted diffusion-limited Ostwald ripening process, i.e. the Lifshitz–Slyozov–Wagner (LSW) model. Indeed, this study shows that oriented attachment occurs during the early stages whereas for the later stages the particle growth is well represented by the LSW model. This conclusion contributes to clarify some controversy found in the literature regarding the kinetic model which better represents the ZnO NPs’ growth in alcoholic medium.

  17. Morphology and wettability of ZnO nanostructures prepared by hydrothermal method on various buffer layers

    Science.gov (United States)

    Li, Bao-jia; Huang, Li-jing; Zhou, Ming; Ren, Nai-fei

    2013-12-01

    Zinc oxide (ZnO) nanostructures were prepared by hydrothermal method on glass substrates with various buffer layers: Ag, Al, aluminum-doped zinc oxide (AZO) and tin-doped indium oxide (ITO). The structure, morphology and wettability of the ZnO nanostructured surfaces were investigated by using X-ray diffraction, scanning electron microscopy and water contact angle (WCA) analysis methods, respectively. All the nanostructures grown on glass with various buffer layers exhibited strong growth orientation along the (1 0 1) plane. The nature of the buffer layer was found to have remarkable effect on the morphology and wettability of the ZnO nanostructures. Whether the buffer layers were hydrophilic or low hydrophobic, all the ZnO nanostructures grown on the various buffer layers showed high hydrophobic property, and that grown on the AZO buffer layer even exhibited superhydrophobicity with a WCA of 151.1°. This work may provide a scientific basis for self-cleaning ZnO-based optoelectronic device applications.

  18. Synthesis of assembled ZnO structures by precipitation method in aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Sepulveda-Guzman, S. [Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, UANL Km. 10 de la nueva carretera al Aeropuerto Internacional de Monterrey, PIIT Monterrey, Apodaca NL (Mexico); Facultad de Ingenieria Mecanica y Electrica de la UANL, Ciudad Universitaria San Nicolas de los Garza, Nuevo Leon C.P. 66451 (Mexico)], E-mail: ssepulveda@mail.uanl.mx; Reeja-Jayan, B. [Texas Materials Institute, University of Texas at Austin, 1 University Station C0803 (United States); Rosa, E. de la [Centro de Investigaciones en Optica, A.C. Loma del Bosque 115 Col. Lomas del Campestre, Leon Gto. C.P. 37150 (Mexico); Torres-Castro, A.; Gonzalez-Gonzalez, V. [Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, UANL Km. 10 de la nueva carretera al Aeropuerto Internacional de Monterrey, PIIT Monterrey, Apodaca NL (Mexico); Facultad de Ingenieria Mecanica y Electrica de la UANL, Ciudad Universitaria San Nicolas de los Garza, Nuevo Leon C.P. 66451 (Mexico); Jose-Yacaman, M. [Physics and Astronomy Department, University of Texas at San Antonio, 1604 Campus San Antonio, TX 78249 (United States)

    2009-05-15

    In this work, arrays of submicron ZnO structures were successfully synthesized using a one-step aqueous precipitation method. Snowflake-like and flower-like morphologies were obtained by changing the reaction temperature. X-ray diffraction (XRD) patterns indicated that the ZnO arrays have a wurtzite crystal structure. A possible growth mechanism based on the analysis done by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and high-angle annular dark field (HAADF) is proposed. Our findings suggest that the growth mechanism of the ZnO arrays is by self-aggregation, and that such an oriented aggregation is enhanced by increasing the reaction temperature. The results also revealed that the aggregation process introduces several structural defects such as differences in mass distribution and crystalline structure. In order to study the surface chemical composition the samples were also characterized by XPS. The results showed the presence of Zn(OH){sub 2} and absorbed carbon species on the ZnO surface. In addition, the photoluminescence characterization showed that on UV excitation ({lambda} = 360 nm) all samples present the characteristic UV emission centered at 390 nm, and for the sample synthesized at 60 deg. C, a visible emission was also observed.

  19. Recent advances in ZnO nanostructures and thin films for biosensor applications: review.

    Science.gov (United States)

    Arya, Sunil K; Saha, Shibu; Ramirez-Vick, Jaime E; Gupta, Vinay; Bhansali, Shekhar; Singh, Surinder P

    2012-08-06

    Biosensors have shown great potential for health care and environmental monitoring. The performance of biosensors depends on their components, among which the matrix material, i.e., the layer between the recognition layer of biomolecule and transducer, plays a crucial role in defining the stability, sensitivity and shelf-life of a biosensor. Recently, zinc oxide (ZnO) nanostructures and thin films have attracted much interest as materials for biosensors due to their biocompatibility, chemical stability, high isoelectric point, electrochemical activity, high electron mobility, ease of synthesis by diverse methods and high surface-to-volume ratio. ZnO nanostructures have shown the binding of biomolecules in desired orientations with improved conformation and high biological activity, resulting in enhanced sensing characteristics. Furthermore, compatibility with complementary metal oxide semiconductor technology for constructing integrated circuits makes ZnO nanostructures suitable candidate for future small integrated biosensor devices. This review highlights recent advances in various approaches towards synthesis of ZnO nanostructures and thin films and their applications in biosensor technology. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. Parametric analysis of the growth of colloidal ZnO nanoparticles synthesized in alcoholic medium

    Science.gov (United States)

    Fonseca, A. S.; Figueira, P. A.; Pereira, A. S.; Santos, R. J.; Trindade, T.; Nunes, M. I.

    2017-02-01

    The growth kinetics of nanosized ZnO was studied considering the influence of different parameters (mixing degree, temperature, alcohol chain length, reactant concentration and Zn/OH ratios) on the synthesis reaction and modelling the outputs using typical kinetic growth models, which were then evaluated by means of a sensitivity analysis. The Zn/OH ratio, the temperature and the alcohol chain length were found to be essential parameters to control the growth of ZnO nanoparticles, whereas zinc acetate concentration (for Zn/OH = 0.625) and the stirring during the ageing stage were shown to not have significant influence on the particle size growth. This last operational parameter was for the first time investigated for nanoparticles synthesized in 1-pentanol, and it is of outmost importance for the implementation of continuous industrial processes for mass production of nanosized ZnO and energy savings in the process. Concerning the nanoparticle growth modelling, the results show a different pattern from the more commonly accepted diffusion-limited Ostwald ripening process, i.e. the Lifshitz-Slyozov-Wagner (LSW) model. Indeed, this study shows that oriented attachment occurs during the early stages whereas for the later stages the particle growth is well represented by the LSW model. This conclusion contributes to clarify some controversy found in the literature regarding the kinetic model which better represents the ZnO NPs' growth in alcoholic medium.

  1. Microstructural and optical characteristics of solution-grown Ga-doped ZnO nanorod arrays.

    Science.gov (United States)

    Wang, Huihu; Baek, Seonghoon; Song, Jaejin; Lee, Jonghyuck; Lim, Sangwoo

    2008-02-20

    Highly oriented Ga-doped zinc oxide (ZnO) nanorod arrays have been prepared on a ZnO-buffered silicon substrate in an aqueous solution, which is a mixture of methenamine (C(6)H(12)N(4)), zinc nitrate hexahydrate (Zn(NO(3))(2)·6H(2)O), and gallium nitrate hydrate (Ga(NO(3))(3)·xH(2)O). The microstructure characteristics and optical properties of the nanorod arrays were analyzed using different characterization techniques including field-emission scanning electron microscopy (FESEM), x-ray photoelectron spectroscopy (XPS), and photoluminescence (PL). The experimental results show that the morphology, density, and surface compositions of ZnO nanorod arrays are sensitive to the concentration of gallium nitrate hydrate. The PL spectra of all ZnO nanorod arrays show three different emissions, including UV (ultraviolet), yellow, and NIR (near infrared) emissions. With the increase in the Ga doping level, the luminescence quality of ZnO nanorods has been improved. The peak of UV emission has a small redshift, which can be ascribed to the combined effect of size and Ga doping. Furthermore, Ga doping has caused defects that respond to NIR emission.

  2. Spectroscopic characterization and docking studies of ZnO nanoparticle modified with BSA

    Science.gov (United States)

    Ledesma, Ana E.; Chemes, Doly María; Frías, María de los Angeles; Guauque Torres, Maria del Pilar

    2017-08-01

    Nanoparticles (NP) into a biological environment are an interesting topic for diagnosis and therapy in applications for medicine or environment and the knowledge about this interaction is important from the perspective of safe use of nanomaterials. In the current study, we characterized the type of interaction and the orientation of bovine serum albumin (BSA) adsorbed on ZnO nanoparticle surfaces as a function of size, using molecular docking. To probe experimentally different theoretical hypothesis about the interaction, ZnO-NPs were prepared in aqueous solution, and then were bioconjugated with BSA. Transmission electron microscopy (TEM) and Raman spectroscopy confirm the spherical shape of NP and the irreversible adsorption of BSA on NP surface. Raman and Infrared spectroscopy (FTIR) reveal that BSA interaction with ZnO nanoparticle produced a conformational rearrangement into protein, observing changes in Tyr and Trp environment, a minor percentage of α-helix structure and a more extended chain. The fluorescence analysis demonstrated that when BSA concentration higher than 30 μM is used the signal due to the self-oligomerization of protein overlaps with the ZnO nanoparticle emission. The results predicted that the most probable interaction site is near to domain IB and IIA and ionic interactions are the major responsible for the binding. Thermal stability studies reveals that the denaturalization temperature of BSA increase from 57 °C to 65 °C in presence of ZnO NP and their esterase-like activity was improved.

  3. A back-illuminated heterojunctions ultraviolet photodetector based on ZnO film

    Science.gov (United States)

    Jiang, Xiandong; Li, Dawei; Yang, Wenjun; Wang, Jiming; Lin, Xu; Huang, Ziqiang

    2010-10-01

    In this paper, we present the investigation of a back-illuminated heterojunctions ultraviolet detector, which were fabricated by depositing Ag-doped ZnO based (ZnO-TiO2) thin film on transparent conductive layer of ITO coated quartz substrate though the reactive radio-frequency (RF) magnetron sputtering at higher oxygen pressure. The p-n junction characteristic is confirmed by current-voltage (I-V) measurements. The turn-on voltage was 6 V, with a low leakage current under reverse bias (-5 V), corresponding values was just 0.2 nA . It is clearly showed the rectifying characteristics of typical p-n junction's rectifier behaviors. The structural, component and UV (365 nm, 1400 μW/cm2) photoresponse properties were explored by X-ray diffraction (XRD), Scanning Electron Microscope (SEM), X-ray energy dispersive spectrometer (EDS) and Tektronix oscilloscope. The results showed that: Ag in substitution form in the ZnO lattice, Ag doping concentration is low, the sample is highly c-axis preferred orientation, With the increase in doped Ag volume, ZnO film of 002 peaks no longer appear. The surface of the Ag doped ZnO based film exhibits a smooth surface and very dense structure, no visible pores and defects over the film were observed.The ultraviolet response time measurements showed rise and fall time are several seconds Level.

  4. Enhanced output voltage generation via ZnO nanowires (50 nm): Effect of diameter thinning on voltage enhancement

    Science.gov (United States)

    Ahmad, Mansoor; Iqbal, Muhammad Azhar; Kiely, Janice; Luxton, Richard; Jabeen, Musarrat

    2017-05-01

    50 nm ZnO nanowires were grown on indium tin oxide (ITO) coated poly ethylene terephthalate (PET) substrates by adapting facile aqueous growth technique using low temperature and vacuum conditions. Prior to growth of ZnO nanowires, pure hexagonal wurtzite structured seed layer was grown on flexible substrates. Surface morphology of nanostructure has been examined by scanning electron microscopy (SEM). Vertical growth orientation has been evidenced in XRD patterns. Minute external mechanical force ( 50 nN) has produced periodic voltage peaks. 2.5 nm and 7.5 nm thick sputtered Pt electrode have been tested to obtain output voltages. 50 nm ZnO nanowires has produced a maximum output voltage of 2.717 volts having an output power density of 397.1 mW/cm2. By squeezing the diameter, we have reduced reverse leakage current through nanowires and enhanced output voltage.

  5. Dye-sensitized solar cell based on spray deposited ZnO thin film: performance analysis through DFT approach.

    Science.gov (United States)

    Parthiban, R; Balamurugan, D; Jeyaprakash, B G

    2015-02-05

    A dye-sensitized solar cell based on a spray deposited zinc oxide (ZnO) photoanode with Evans blue as a sensitizer was fabricated. Structural analysis confirms the hexagonal wurtzite phase of the ZnO photoanode with c-axis orientation. Surface morphology of the ZnO photoanode shows uniform distribution of spherically-shaped grains, ranging from 18 nm to 25 nm. The power conversion efficiency of the device was measured as 0.1%. Density functional theory was adopted to study the observed photovoltaic performance of the fabricated device. The analysis of the electronic properties of Evans blue dye showed that it has a pronounced effect on the observed device performance. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. A hierarchically assembled mesoporous ZnO hemisphere array and hollow microspheres for photocatalytic membrane water filtration.

    Science.gov (United States)

    Pan, Jia Hong; Zhang, Xiwang; Du, Alan J; Bai, Hongwei; Ng, Jiawei; Sun, Darren

    2012-05-28

    A mesoporous ZnO hemisphere array has been prepared via a topotactic transition of Zn(4)(OH)(6)CO(3)·H(2)O (ZCHH) by chemical bath deposition. Each hemisphere is comprised of a radially oriented nanoflake shell grown on the hemispherical interior. Reaction time-dependent SEM analysis shows that the morphological formation of ZCHH involves a deposition-growth-secondary growth-redeposition procedure. Upon calcination, ZCHH readily decomposes to nanocrystalline wurtzite-phase ZnO without significant change in morphology, and the release of CO(2) and H(2)O from ZCHH creates an additional mesoporous structure in both hemispherical interior and nanoflake shell. A similar process but without using a substrate has been developed for synthesis of mesoporous ZnO hollow microspheres in powder form. Both the elaborated superstructured photocatalysts consisting of mesoporous nanoflakes have been demonstrated to exhibit excellent performances in the photocatalytic membrane filtration.

  7. The growth of ubiquitous ZnO rods on PMMA-coated substrate by solution-immersion method at different annealing temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Aadila, A., E-mail: aadilaazizali@gmail.com; Asib, N. A. M.; Afaah, A. N.; Husairi, F. S.; Khusaimi, Z., E-mail: zurai142@salam.edu.my [NANO-Scitech Centre, Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Mohamed, R.; Rusop, M. [NANO-Scitech Centre, Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); NANO-Electronic Centre, Faculty of Electrical Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia)

    2016-07-06

    In this work, solution-immersion method was used to grow ZnO rods on PMMA-coated substrate. For this purpose, 0.15 M of zinc nitrate hexahydrate (Zn(NO{sub 3}){sub 2}.6H{sub 2}O) and hexamethylenetetramine (C{sub 6}H{sub 12}N{sub 4}) were used to growth of ZnO films at different annealing temperatures (room temperature, 80, 100, 120 and 140 °C). The morphology of the films was investigated by Scanning Electron Microscope (SEM) and optical properties were studied by Ultraviolet (UV-Vis) Spectroscopy. SEM analysis showed ubiquitous growth of ZnO rods that became better aligned and more closely-packed as the annealing temperature increased. As the annealing temperature exceeds 100 °C, the rods tend to merge to adjacent particles and the UV absorption decreased for the sample at higher temperatures (120 °C and 140 °C). Good absorption and better orientation of ZnO was obtained for the sample annealed at 100 °C due to the film possess better distribution and these improved orientation of particles caused the light to be effectively scattered on the sample. Both surface morphology and UV was significantly affected by the change in annealing temperatures thus thermal effect played a dominant role in shaping and improving the orientation of ZnO rods on PMMA-coated and its UV absorption.

  8. ZnO nanostructures and their applications

    CERN Document Server

    Xiaowei, Sun

    2011-01-01

    This book focuses on the various functional properties and potential applications of one-dimensional ZnO nanostructures, from basic principles to our most recent discoveries. It comprises experimental analysis of various properties of ZnO nanostructures, preparation techniques, research methods, and some promising applications. The areas of focus include ZnO-based gas/biochemical sensing devices, field emitters, solar cells, light-emitting diodes, e-papers, and single-nanowire-based transistors.

  9. Electrochemical Synthesis of ZnO Nanorods/Nanotubes/Nanopencils on Transparent Aluminium-Doped Zinc Oxide Thin Films for Photocatalytic Applications.

    Science.gov (United States)

    Le, Thi Ngoc Tu; Pham, Tan Thi; Ngo, Quang Minh; Vu, Thi Hanh Thu

    2015-09-01

    We report an electrochemical synthesis of homogeneous and well-aligned ZnO nanorods (NRs) on transparent conducting aluminium-doped zinc oxide (AZO) thin films as electrodes. The selected ZnO NRs was then chemically corroded in HCl and KCl aqueous solutions to form nanopencils (NPs), and nanotubes (NTs), respectively. A DC magnetron sputtering was employed to fabricate AZO thin films at various thicknesses. The obtained AZO thin films have a c-direction orientation, transmittance above 80% in visible region, and sheet resistance approximately 40 Ω/sq. They are considered to be relevant as electrodes and seeding layers for electrochemical. The ZnO NRs are directly grown on the AZOs without a need of catalysts or additional seeding layers at temperature as low as 85 degrees C. Their shapes are strongly associated with the AZO thickness that provides a valuable way to control the diameter of ZnO NRs grown atop. With the addition of HCI and KCl aqueous solutions, ZnO NRs were modified their shape to NPs and NTs with the reaction time, respectively. All the ZnO NRs, NPs, and NTs are preferred to grow along c-direction that indicates a lattice matching between AZO thin films and ZnO nanostructrures. Photoluminescence spectra and XRD patterns show that they have good crystallinities. A great photocatalytic activity of ZnO nanostructures promises potential application in environmental treatment and protection. The ZnO NTs exhibits a higher photocatalysis than others possibly due to the oxygen vacancies on the surface and the polarizability of Zn2+ and O2-.

  10. Microstructural Study of ZnO Nanostructures by Rietveld Analysis

    Directory of Open Access Journals (Sweden)

    Francisco Pola-Albores

    2011-01-01

    Full Text Available ZnO nanorods were synthesized by induced seeds by chemical bath deposition using hexamethylenetetramine (HMT as a precipitant agent and zinc nitrate (ZN as Zn2+ source at 90°C. The influence of reactants ratio was studied from 2 to 0.25 ZN/HMT molar. The results obtained by scanning electron microscopy confirm that the diameter of nanorods was affected directly by the concentration of both zinc and OH− sources. Nanotubes (hollow nanorods were obtained with high HMT concentrations and were turning over nanorods as HMT concentration decreased. Microstructural information was obtained by Rietveld refinement of grazing incidence X-ray diffraction data. These results evidence low-textured materials with oriented volumes less than 18% coming from (101 planes in Bragg condition.

  11. Optical and electrical characteristics of aluminum-doped ZnO thin films prepared by solgel technique

    Science.gov (United States)

    Jiménez-González, A. E.; Soto Urueta, Jose A.; Suárez-Parra, R.

    1998-09-01

    Pure and aluminum-doped ZnO thin films of high quality were prepared by the solgel deposition method. ZnO thin films are formed by a three-step decomposition of the chemical complex (Zn(CH 3COO) 2·2H 2O) to ZnO. The aluminum doping was achieved by the addition of AlCl 3·2H 2O and Al(NO 3) 3·9H 2O in the methanol solution of the chemical complex at an atomic ratio of Al/Zn=10 -3-10 -2. The films are transparent (90% optical transmittance) in the near UV, VIS and near IR ranges. X-ray diffraction analysis indicates that the crystallites of both ZnO and ZnO : Al thin films are preferentially oriented along the c-axis, [0 0 2] direction of the hexagonal crystal structure. The electrical conductivity of ZnO thin films increases with film thickness, under selected heat treatments and with aluminum doping. The dark conductivity and photoconductivity values of the films are in the range 10-100 [Ω cm] -1, which are considered adequate for certain solar cell and electrochromic applications. Measurements of the activation energy show that pure and aluminum doped ZnO thin films have generally one donor level around 50 meV and another at 120 meV below the conduction band. These results are used to explain the high electrical conductivity of the films.

  12. Optical and electrical characteristics of aluminum-doped ZnO thin films prepared by solgel technique

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez-Gonzalez, A.E.; Soto Urueta, Jose A.; Suarez-Parra, R. [Centro de Investigacion en Energia, UNAM, Apartado postal 34, 62580 Temixco, Morelos (Mexico)

    1998-09-01

    Pure and aluminum-doped ZnO thin films of high quality were prepared by the solgel deposition method. ZnO thin films are formed by a three-step decomposition of the chemical complex (Zn(CH{sub 3}COO){sub 2}{center_dot}2H{sub 2}O) to ZnO. The aluminum doping was achieved by the addition of AlCl{sub 3}{center_dot}2H{sub 2}O and Al(NO{sub 3}){sub 3}{center_dot}9H{sub 2}O in the methanol solution of the chemical complex at an atomic ratio of Al/Zn=10{sup -3}-10{sup -2}. The films are transparent (90% optical transmittance) in the near UV, VIS and near IR ranges. X-ray diffraction analysis indicates that the crystallites of both ZnO and ZnO : Al thin films are preferentially oriented along the c-axis, [0 0 2] direction of the hexagonal crystal structure. The electrical conductivity of ZnO thin films increases with film thickness, under selected heat treatments and with aluminum doping. The dark conductivity and photoconductivity values of the films are in the range 10-100 [{Omega} cm]{sup -1}, which are considered adequate for certain solar cell and electrochromic applications. Measurements of the activation energy show that pure and aluminum doped ZnO thin films have generally one donor level around 50 meV and another at 120 meV below the conduction band. These results are used to explain the high electrical conductivity of the films

  13. Synthesis and characterization of nanostructured undoped and Sn-doped ZnO thin films via sol–gel approach

    Energy Technology Data Exchange (ETDEWEB)

    Aydin, H., E-mail: cihataydin_26@hotmail.com [Department of Metallurgical and Materials Engineering, Engineering Faculty, Tunceli University, Tunceli 62000 (Turkey); El-Nasser, H.M. [Department of Physics, Al al-Bayt University, Mafraq (Jordan); Aydin, C. [Department of Metallurgy and Materials Engineering, Faculty of Technology, Firat University, Elazig 23119 (Turkey); Al-Ghamdi, Ahmed A. [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Yakuphanoglu, F. [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Department of Physics, Faculty of Science, Firat University, Elazig 23119 (Turkey); Nanoscience and Nanotechnology Laboratory, Firat University, Elazig 23119 (Turkey)

    2015-09-30

    Graphical abstract: - Highlights: • Sn-doped ZnO films were prepared via facile sol–gel spin coating method. • The grain size of the films changes from 39.23 to 71.84 nm with Sn doping. • The refractive index dispersion of the films obeys the single oscillator model. - Abstract: Thin films of Sn-doped ZnO were prepared via facile sol–gel spin coating method. The structural and optical properties of the films were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and UV-VIS-NIR spectrophotometer. The X-ray results confirmed that all the ZnO thin films are polycrystalline with a hexagonal wurtzite structure with a preferential orientation of (002) plane. The crystallite size and lattice parameter values of the films were obtained. Atomic force microscopy results indicate that the Sn-doped ZnO films have the nanostructure. The grain size values of the films were found to vary from 39.23 to 71.84 nm with Sn doping. The nanostructure of the Sn-doped ZnO films was also confirmed by scanning electron microcopy. The optical bandgaps of the films were calculated for the various Sn contents. The refractive index dispersion curves obey the single oscillator model. The optical constants and dispersion parameters of the ZnO films were changed with Sn doping. The obtained results suggest that the structural and optical properties of ZnO films can be controlled by Sn doping.

  14. Electrodeposition and characterization of ZnO thin films using sodium thiosulfate as an additive for photovoltaic solar cells

    Science.gov (United States)

    Rahal, Hassiba; Kihal, Rafiaa; Affoune, Abed Mohamed; Ghers, Mokhtar; Djazi, Faycal

    2017-06-01

    Zinc oxide thin films have been grown by electrodeposition technique onto Cu and ITO-coated glass substrates from an aqueous zinc nitrate solution with addition of sodium thiosulfate at 90 °C. The effects of sodium thiosulfate on the electrochemical deposition of ZnO were investigated by cyclic voltammetry and chronoamperometry techniques. Deposited films were obtained at -0.60 V vs. SCE and characterized by XRD, SEM, FTIR, optical, photoelectrochemical and electrical measurements. Thickness of the deposited film was measured to be 357 nm. X-ray diffraction results indicated that the synthesized ZnO has a pure hexagonal wurtzite structure with a marked preferential orientation along (002) plane. FTIR results confirmed the presence of ZnO films at peak 558 cm-1. SEM images showed uniform, compact morphology without any cracks and films composed of large flower-like ZnO agglomerates with star-shape. Optical properties of ZnO reveal a high optical transmission (> 80 % ) and high absorption coefficient (α > {10}5 {{cm}}-1) in visible region. The optical energy band gap was found to be 3.28 eV. Photoelectrochemical measurements indicated that the ZnO films had n-type semiconductor conduction. Electrical properties of ZnO films showed a low electrical resistivity of 6.54 {{Ω }}\\cdot {cm}, carrier concentration of -1.3× {10}17 {{cm}}-3 and mobility of 7.35 cm2 V-1 s-1. Project supported by the Algerian Ministry of Higher Education and Scientific Research, Algeria (No. J0101520090018).

  15. Investigation into the antibacterial behaviour of suspensions of ZnO nanoparticles (ZnO nanofluids)

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Lingling; Jiang Yunhong; Ding Yulong [University of Leeds, Institute of Particle Science and Engineering (United Kingdom)], E-mail: y.ding@leeds.ac.uk; Povey, Malcolm [University of Leeds, Procter Department of Food Science (United Kingdom); York, David [Procter and Gamble Newcastle Technical Centre (United Kingdom)

    2007-06-15

    The antibacterial behaviour of suspensions of zinc oxide nanoparticles (ZnO nanofluids) against E. Coli has been investigated. ZnO nanoparticles from two sources are used to formulate nanofluids. The effects of particle size, concentration and the use of dispersants on the antibacterial behaviour are examined. The results show that the ZnO nanofluids have bacteriostatic activity against E. coli. The antibacterial activity increases with increasing nanoparticle concentration and increases with decreasing particle size. Particle concentration is observed to be more important than particle size under the conditions of this work. The results also show that the use of two types of dispersants (Polyethylene Glycol (PEG) and Polyvinylpyrolidone (PVP)) does not affect much the antibacterial activity of ZnO nanofluids but enhances the stability of the suspensions. SEM analyses of the bacteria before and after treatment with ZnO nanofluids show that the presence of ZnO nanoparticles damages the membrane wall of the bacteria. Electrochemical measurements using a model DOPC monolayer suggest some direct interaction between ZnO nanoparticles and the bacteria membrane at high ZnO concentrations.

  16. Synthesis of 1-D ZnO nanorods and polypyrrole/1-D ZnO ...

    Indian Academy of Sciences (India)

    ... Fourier transform-infrared spectroscopy (FTIR), X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM), which gave the evidence of 1-D ZnO nanorods, polymerization of pyrrole monomer and strong interaction between PPy and 1-D ZnO nanorods, respectively. Photocatalytic activity of 1-D ZnO ...

  17. Effect of lattice strain on structural and optical properties of ZnO nanorods grown by hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Gautam, Khyati, E-mail: khyati34@gmail.com; Nirwal, Varun Singh; Singh, Joginder; Peta, Koteswara Rao; Bhatnagar, P. K. [Department of Electronic Science, University of Delhi South Campus, Benito Juarez Road, New Delhi-110021 (India); Singh, Inderpreet [Department of Electronics, SGTB KhalsaCollege, University of Delhi, Delhi-110007 (India)

    2016-05-06

    In this work, we have synthesized ZnO nanorods over ZnO seeds/ITO/glass substrate by the facile hydrothermal method. ZnO seeds are grown at different temperatures ranging from 150°C to 550°C in steps of 100°C. We have studied the effect of strain on the structural and optical properties of ZnO nanorods. It was observed that the growth temperature of seed layer has an influence over the lattice strain present in the nanorods. The as synthesized nanorods were characterized by scanning electron microscope (SEM), x-ray diffraction (XRD) and photoluminescence (PL). SEM images confirm the formation of dense arrays of vertically aligned nanorods on seeds which are grown at 350°C. In addition to this, XRD patterns reveal that these ZnO nanorods are preferentially oriented along (002) direction. The strain analysis based on the XRD results reveals that the minimum value of strain is obtained at 350°C which is attributed to the improved crystalline quality of the interface of seed layer and nanorods leading to their c-axis alignment and enhancement of ultraviolet emission as observed in the PL spectra.

  18. The role of substrates on the structural, optical, and morphological properties of ZnO nanotubes prepared by spray pyrolysis.

    Science.gov (United States)

    Vijayalakshmi, K; Karthick, K

    2014-03-01

    ZnO films were deposited onto glass, ITO coated glass, and sapphire substrate by spray pyrolysis, and subsequently annealed at the same temperature of 400°C for 3 h. The role of substrate on the properties of ZnO films was investigated. The structural and optical properties of the films were investigated by X-ray diffractometer (XRD) and photoluminescence (PL) spectrophotometer, respectively. The surface morphology of the nanostructured ZnO film was investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Crystallographic properties revealed that the ZnO films deposited on sapphire and ITO substrates exhibit a strong c-axis orientation of grains with hexagonal wurtzite structure. Extremely high UV emission intensity was determined in the film on ITO. The different luminescence behaviors was discussed, which would be caused by least value of strain in the film. Films grown on different substrates revealed differences in the morphology. ZnO films on ITO and sapphire substrates revealed better morphology than that of the film on glass. AFM images of the films prepared on ITO show uniform distribution of grains with large surface roughness, suitable for application in dye sensitized solar cells. Copyright © 2013 Wiley Periodicals, Inc.

  19. Investigation of the correlation between dielectric function, thickness and morphology of nano-granular ZnO very thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gilliot, Mickaël, E-mail: mickael.gilliot@univ-reims.fr [Laboratoire d' Ingénierie et Sciences des Matériaux, Université de Reims Champagne-Ardenne (France); Hadjadj, Aomar [Laboratoire d' Ingénierie et Sciences des Matériaux, Université de Reims Champagne-Ardenne (France); Martin, Jérôme [Laboratoire de Nanotechnologie et d' Instrumentation Optique, Université de Technologie de Troyes (France)

    2015-12-31

    Thin nano-granular ZnO layers were prepared using a sol–gel synthesis and spin-coating deposition process with a thickness ranging between 20 and 120 nm. The complex dielectric function (ϵ) of the ZnO film was determined from spectroscopic ellipsometry measurements. Up to a critical thickness close to 60 nm, the magnitude of both the real and the imaginary parts of ϵ rapidly increases and then slowly tends to values closer to the bulk ZnO material. This trend suggests a drastic change in the film porosity at both sides of this critical thickness, due to the pre-heating and post-crystallization processes, as confirmed by additional characterization of the structure and the morphology of the ZnO films. - Highlights: • c-Axis oriented ZnO thin films were grown with different morphological states. • The morphology and structures are controlled by controlling the thickness. • The optical properties are correlated to morphological evolution. • Two growth behaviors and property evolutions are identified around a critical thickness.

  20. Microwave Assisted Growth of ZnO Nanorods and Nanopolypods Nanostructure Thin Films for Gas and Explosives Sensing

    Directory of Open Access Journals (Sweden)

    A. K. Singh

    2013-01-01

    Full Text Available The growth of uniformly distributed and densely packed array of zinc oxide (ZnO nanorods (NRs and nanorods (NRs/nanopolypods (NPPs was successfully achieved through microwave-assisted chemical route at low temperature. The ZnO NRs and NRs/NPPs were characterized using X-ray diffraction (XRD, scanning electron microscope (SEM, energy dispersive X-ray analysis (EDX, and UV-Vis absorption spectroscopy. The ZnO NRs were of 100–150 nm diameter and 0.5–1 μm length, while the NPPs were of diameter about 150–200 nm and 1.5–2 μm pod length. The prepared films are polycrystalline in nature and highly oriented along (002 plane with a hexagonal wurtzite structure. These films were studied for the sensing properties of liquefied petroleum gas (LPG, oxygen, and hazardous explosives, that is, 2,4,6-trinitrotoluene (TNT and cyclotrimethylenetrinitramines (RDX, in the temperature ranges of 25–425 °C and 100–200 °C, respectively. The grown nanostructure films showed reliable stable response to several on-off cycles, and reduction in sensor recovery time was found with the increase in temperature. ZnO NRs and NRs/NPPs showed better sensitivity and recovery time for both LPG and oxygen, as compared to the literature-reported results for ZnO thin films.

  1. Pattern recognition in bees : orientation discrimination

    NARCIS (Netherlands)

    Hateren, J.H. van; Srinivasan, M.V.; Wait, P.B.

    1990-01-01

    Honey bees (Apis mellifera, worker) were trained to discriminate between two random gratings oriented perpendicularly to each other. This task was quickly learned with vertical, horizontal, and oblique gratings. After being trained on perpendicularly-oriented random gratings, bees could discriminate

  2. Aggregation and growth of ZnO quantum dots prepared from sol-gel chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Santilli, C.V.; Pulcinelli, S.H.; Caetano, B.L. [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Araraquara, SP (Brazil); Briois, V.B [Synchrotron SOLEIL, Saint-Aubin (France)

    2016-07-01

    Full text: Herein we discuss in depth the mechanisms of growth control of ZnO quantum dots (Q-dot) prepared from the zinc oxy-acetate ethanolic solution by the addition of LiOH. Through in situ monitoring of Q-dot radii and of aggregation index calculated from UV-Vis absorption spectra and small-angle X-ray scattering (SAXS) the aggregation and growth of ZnO nanocrystal was well described from two kinetic models: during the first step (t< 50 min) the structural evolution is controlled by the coalescence caused by the oriented attachment between the nanocrystal aggregates while at the advanced time (t> 50 min) the Q-dot coarsening follows the Ostwald ripening (OR) mechanism. From the higher oriented attachment efficiency observed here as compared with early reported synthesis using NaOH and KOH, we propose an universal mechanism to control coalescence and coarsening of ZnO nanocrystal provided from the shield caused by the adsorption of the alkali cation. From X-ray diffraction and transmission electron microscopy results we demonstrate that this mechanism is also useful to prepare Q-dot powders with controlled size. (author)

  3. Characterization Of Microwave Obtained Zno Thin Films By RF Magnetron Sputtering

    Directory of Open Access Journals (Sweden)

    Roger Ondo-Ndong

    2015-02-01

    Full Text Available Abstract We have grown ZnO thin films on glass and Si 001 substrates by r.f magnetron sputtering using metallic zinc target. The crystalline property of the films were observed to vary with the structural properties used. X-ray diffraction XRD measurement showed that the substrate temperature ZnO films exhibited preferred c-axis oriented 002. A study has been made of the influence parameters prepared on the film refractive index. They exhibited the refractive index of 1.97 a c-axis orientation of below 0.32 FWHM of X-ray rocking curves and an energy gap of 3.3 eV at room temperature. It was found that a RF power of 50 W target to substrate distance 70 mm very low gas pressures of 3.35x10-3 Torr in argon and oxygen mixed gas atmosphere giving to ZnO thin films a good homogeneity and a high crystallinity. The network analyzer shows losses are -5dB at a k33 0.26 experimental.

  4. Photoirradiation Caused Controllable Wettability Switching of Sputtered Highly Aligned c-Axis-Oriented Zinc Oxide Columnar Films

    Directory of Open Access Journals (Sweden)

    P. W. Chi

    2014-01-01

    Full Text Available This study presents the microstructure morphology and UV photoirradiation coupling effects of the c-axis-oriented zinc oxide (ZnO columnar films. Highly aligned c-axis-oriented films have been deposited onto glass substrates at room temperature by radio-frequency (RF magnetron sputtering without introducing any oxygen source under different sputtering powers ranging from 50 to 150 W. Self-assembled ZnO columnar structures that were successfully obtained belong to wurtzite structure, and the corresponding columnar structures and crystalline orientation were confirmed by the FE-SEM and XRD, respectively. All the ZnO columnar films exhibit good transparency with a visible light averaged transmittance over 82%. According to water contact angle (CA measurement, ZnO columnar films exhibit hydrophobic behavior. After exposing to photoirradiation under ultraviolet (UV environment, all the ZnO samples showed remarkable transition from hydrophobic to superhydrophilic surfaces and could return to their original hydrophobicity after being placed in the dark. It is demonstrated that the controllable wettability of ZnO columnar films under changing between the UV photoirradiation and dark storage is due to the surface charges accumulation and discharging processes. As a result, this study could provide important applications for many fields such as ZnO-based hybrid sensors/solar cells functional devices with photoirradiation disinfection surfaces accompanied with reversible wettability switches.

  5. Scattering Intensity and Directionality Probed Along Individual Zinc Oxide Nanorods with Precisely Controlled Light Polarization and Nanorod Orientation

    Directory of Open Access Journals (Sweden)

    Daniel S. Choi

    2015-06-01

    Full Text Available We elucidated the light-matter interaction of individual ZnO NRs with a monochromatic beam of linearly polarized light that scatters elastically from the ZnO NRs by performing forward scattering and back-aperture imaging in a dark-field setting. We precisely controlled the electric field vector of the incident light and the NR orientation within the plane of light interaction during both modes of measurement, and spatially resolved the scattering response from different interaction points along the NR long axis. We then discerned, for the first time, the effects of light polarization, analyzer angle, and NR orientation on the intensity and directionality of the optical responses both qualitatively and quantitatively along the length of the single ZnO NRs. We identified distinctive scattering profiles from individual ZnO NRs subject to incident light polarization with controlled NR orientation from the forward dark-field scattering and back-aperture imaging modes. The fundamental light interaction behavior of ZnO NRs is likely to govern their functional outcomes in photonics, optoelectronics, and sensor devices. Hence, our efforts provided much needed insight into unique optical responses from individual 1D ZnO nanomaterials, which could be highly beneficial in developing next-generation optoelectronic systems and optical biodetectors with improved device efficiency and sensitivity.

  6. Superhydrophobic ZnO networks with high water adhesion

    OpenAIRE

    Florica, Camelia; Preda, Nicoleta; Enculescu, Monica; Zgura, Irina; Socol, Marcela; Enculescu, Ionut

    2014-01-01

    ZnO structures were deposited using a simple chemical bath deposition technique onto interdigitated electrodes fabricated by a conventional photolithography method on SiO2/Si substrates. The X-ray diffraction studies show that the ZnO samples have a hexagonal wurtzite crystalline structure. The scanning electron microscopy observations prove that the substrates are uniformly covered by ZnO networks formed by monodisperse rods. The ZnO rod average diameter and length were tuned by controlling ...

  7. Performance Improvement of Ultraviolet Sensor of ZnO Nanorod Arrays

    Science.gov (United States)

    Yang, Xiaopeng; Qiu, Zhiwen; Li, Xia; Lu, Jianguo; Cao, Bingqiang

    2013-12-01

    In this letter, large-area, high-quality, evenly distributed, and vertically oriented Na-doped ZnO nanorod arrays (NRAs:Na) are prepared by chemical vapor deposition. The properties of the relevant ultraviolet sensors are studied, indicating that by providing an intrinsic ZnO coating via the hydrothermal method and annealing treatment, the performance of the sensors could be improved dramatically. Photoluminescence analyses show that Na doping suppressed the green emission of NRAs:Na, which is commonly ascribed to the singly VO located at the surface of the nanorods. For the optimized NRAs:Na sensors with a core-shell structure, the VO-Oi annihilation mechanism is proposed to interpret the reduction of the persistent photocurrent.

  8. Hydrothermally Grown ZnO Micro/Nanotube Arrays and Their Properties

    Directory of Open Access Journals (Sweden)

    Shen Guozhen

    2009-01-01

    Full Text Available Abstract We reported the optical and wettability properties of aligned zinc oxide micro/nanotube arrays, which were synthesized on zinc foil via a simple hydrothermal method. As-synthesized ZnO micro/nanotubes have uniform growth directions along the [0001] orientations with diameters in the range of 100–700 nm. These micro/nanotubes showed a strong emission peak at 387 nm and two weak emission peaks at 422 and 485 nm, respectively, and have the hydrophobic properties with a contact angle of 121°. Single ZnO micro/nanotube-based field-effect transistor was also fabricated, which shows typical n-type semiconducting behavior.

  9. Effect of polyvinyl alcohol on electrochemically deposited ZnO thin films for DSSC applications

    Science.gov (United States)

    Marimuthu, T.; Anandhan, N.

    2017-05-01

    Nanostructures of zinc oxide (ZnO) thin film are electrochemically deposited in the absence and presence of polyvinyl alcohol (PVA) on fluorine doped tin oxide (FTO) substrate. X-ray diffraction (XRD) patterns and Raman spectroscopy confirmed the formation of hexagonal structure of ZnO. The film prepared in the presence of PVA showed a better crystallinity and its crystalline growth along the (002) plane orientation. Field emission scanning electron microscope (FE-SEM) images display nanowire arrays (NWAs) and sponge like morphology for films prepared in the absence and presence of PVA, respectively. Photoluminescence (PL) spectra depict the film prepared in the presence PVA having less atomic defects with good crystal quality compared with other film. Dye sensitized solar cell (DSSC) is constructed using low cost eosin yellow dye and current-voltage (J-V) curve is recorded for optimized sponge like morphology based solar cell.

  10. Fabrication and characterization of solution processed vertically aligned ZnO microrods

    Energy Technology Data Exchange (ETDEWEB)

    Gadallah, A.-S., E-mail: agadallah@niles.edu.eg [Laboratoire de Nanotechnologie et d’Instrumentation Optique, Institut Charles Delaunay, CNRS UMR 6279, Université de Technologie de Troyes, 12 rue Marie Curie, BP 2060, 10010 Troyes Cedex (France); Department of Laser Sciences and Interactions, National Institute of Laser Enhanced Sciences, Cairo University, 12613 Giza (Egypt)

    2014-08-30

    Simple and effective cost high quality vertically aligned densely packed ZnO microrods have been prepared using solution processed two-step deposition process, specifically sol–gel spin coating combined with chemical bath deposition. X-ray diffraction pattern and scanning electron microscope show that there has been preferential crystal orientation along c-axis and the growth of the microrods has occurred normal to the glass substrate and the facets of the these microrods are hexagons. Photoluminescence measurements showed an emission band in the UV region and another weak band in the visible region with the emission intensity of UV band grows superlinearly with the excitation intensity. The film shows an electrical resistivity of 136 Ω cm as evaluated from four-point probe method. The fabricated film has been used as UV detector through Au/SiO{sub 2}/ZnO structure on glass substrate as the structure shows higher current under illumination compared to without illumination.

  11. Nano-scaled diffusional or dislocation creep analysis of single-crystal ZnO

    Directory of Open Access Journals (Sweden)

    P. H. Lin

    2016-09-01

    Full Text Available The nanoindentation time-dependent creep experiments with different peak loads are conducted on c-plane (0001, a-plane (112¯0 and m-plane (101¯0 of single-crystal ZnO. Under nano-scaled indentation, the creep behavior is crystalline orientation-dependent. For the creep on (0001, the stress exponent at low loads is ∼1 and at high loads ∼4. The stress exponents under all loads are within 3∼7 for the creep on (112¯0 and (101¯0. This means that diffusion mechanism and dislocation mechanism is operative for different planes and loads. The relative difficulty of dislocations activation is an additional factor leading to the occurring of diffusion creep on the c-plane of single-crystal ZnO.

  12. Fabrication and Characterization of ZnO Nanowire Arrays with an Investigation into Electrochemical Sensing Capabilities

    Directory of Open Access Journals (Sweden)

    Jessica Weber

    2008-01-01

    Full Text Available ZnO nanowire arrays were grown on a Si (100 substrate using the vapor-liquid-solid (VLS method. ZnO nanowires were characterized by XRD, SEM, bright field TEM, and EDS. They were found to have a preferential orientation along the c-axis. The as-prepared sample was functionalized with glucose oxidase by physical adsorption. FTIR was taken before and after functionalization to verify the presence of the attached enzyme. Electrochemical measurements were performed on the nanowire array by differential pulse voltammetry in the range of −0.6 to 0.4 V. The nanoarray sensor displayed high sensitivity to glucose in the range of 1.0 ×10−4 to 1.0 ×10−2 mol L−1.

  13. Thin Solid Films Topical Special Issue on ZnO related transparent conductive oxides

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Jinn P.; Endo, Tamio; Ellmer, Klaus; Gessert, Tim; Ginley, David

    2016-04-01

    World-wide research activities on ZnO and related transparent conductive oxides (TCO) in thin film, nanostructured, and multilayered forms are driven by the vast potential of these materials for optoelectronic, microelectronic, and photovoltaic applications. Renewed interest in ZnO applications is partly stimulated by cost reduction in material processing and device development. One of the most important issues is doping and alloying with Al, Ga, In, Sn, etc. in order to tune properties. When highly doped, these materials are used as transparent-conducting contacts on solar cells, as well as in catalytic, spintronic, and surface acoustic wave devices. Film growth conditions, including substrate type and orientation, growth temperature, deposition rate, and ambient atmosphere, all play important roles in determining structural, electrical, magnetic, and optical properties.

  14. Structural, morphological and photoluminescence properties of W-doped ZnO nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Ngom, B.D., E-mail: bdngom@tlabs.ac.za [Groupes de physique du Solide et Sciences des Materiaux (GPSSM), Faculte des Sciences et Techniques Universite Cheikh Anta Diop de Dakar (UCAD), B.P. 25114, Dakar-Fann Dakar (Senegal); NANO-Sciences Laboratories, Materials Research Group, iThemba LABS, National Research Foundation (South Africa); Sakho, O. [Groupes de physique du Solide et Sciences des Materiaux (GPSSM), Faculte des Sciences et Techniques Universite Cheikh Anta Diop de Dakar (UCAD), B.P. 25114, Dakar-Fann Dakar (Senegal); Manyala, N. [Department of Physics, Institute of Materials, University of Pretoria, Pretoria (South Africa); Kana, J.B. [Departement de physique, Universite Yaounde 1, Yaounde (Cameroon); Mlungisi, N. [NANO-Sciences Laboratories, Materials Research Group, iThemba LABS, National Research Foundation (South Africa); Guerbous, L. [Nuclear Research Center of Algiers - CRNA, 02 Bd Frantz Fanon BP 399 Alger Gare, Algiers (Algeria); Fasasi, A.Y. [Centre for Energy Research and Development, Obafemi Awolowo University, Ile-Ife, Osun State (Nigeria); Maaza, M. [NANO-Sciences Laboratories, Materials Research Group, iThemba LABS, National Research Foundation (South Africa); Beye, A.C. [Groupes de physique du Solide et Sciences des Materiaux (GPSSM), Faculte des Sciences et Techniques Universite Cheikh Anta Diop de Dakar (UCAD), B.P. 25114, Dakar-Fann Dakar (Senegal)

    2009-05-30

    W-doped ZnO nanostructures were synthesized at substrate temperature of 600 deg. C by pulsed laser deposition (PLD), from different wt% of WO{sub 3} and ZnO mixed together. The resulting nanostructures have been characterized by X-ray diffraction, scanning electron microscopy, atomic force microscopy and photoluminescence for structural, surface morphology and optical properties as function of W-doping. XRD results show that the films have preferred orientation along a c-axis (0 0 L) plane. We have observed nanorods on all samples, except that W-doped samples show perfectly aligned nanorods. The nanorods exhibit near-band-edge (NBE) ultraviolet (UV) and violet emissions with strong deep-level blue emissions and green emissions at room temperature.

  15. Comparison between ZnO nanowires grown by chemical vapor deposition and hydrothermal synthesis

    Science.gov (United States)

    Podrezova, L. V.; Porro, S.; Cauda, V.; Fontana, M.; Cicero, G.

    2013-11-01

    Vertically aligned zinc oxide nanowires (NWs) were synthesized by two different techniques: chemical vapor deposition (CVD) and hydrothermal synthesis. To compare the effects of different growth conditions, both F-doped SnO2 (FTO) coated-glass and silicon wafers were used as substrates. Before NWs growth, all the substrates were covered with a ZnO seed layer film obtained with the same procedure, which acts as nucleation site for the subsequent growth of the nanowires both during CVD and hydrothermal synthesis. We studied the influence of the two synthesis techniques and the growth duration on the final morphology, orientation, and density of the ZnO NWs using electron microscopy and X-ray diffraction, while the NWs optical quality was addressed by UV-Vis spectroscopy. By discussing advantages and disadvantages of both synthesis methods, we finally show that the application purpose often drives the choice of the NWs growth process and the substrate to be used.

  16. Realizing field-dependent conduction in ZnO nanowires without annealing

    Science.gov (United States)

    Burke-Govey, C. P.; Castanet, U.; Warring, H.; Nau, A.; Ruck, B. J.; Majimel, J.; Plank, N. O. V.

    2017-03-01

    We report on the low-temperature fabrication of field-effect transistors by bridging pre-patterned electrodes using ZnO nanowires grown in situ, which operate without requiring post-growth processing or annealing. The devices show good performance using as-grown nanowires, with on-off ratios of 105 and threshold voltages of 2 V. Electron microscopy shows the field-dependent nanowires hierarchically nucleate from larger ZnO nanorods, and both are oriented along a common c-axis. A high nanowire surface-to-volume ratio allows depleting electron traps on the nanowire surface to compensate intrinsic electron donors present throughout the nanowire bulk. This eliminates the need to reduce the electron concentration through high-temperature annealing, making the nanowires naturally field-dependent in their as-grown state.

  17. Comprehensive study of ZnO nanostructures grown using chemical bath deposition: from growth to application

    Science.gov (United States)

    Urgessa, Z. N.; Murape, D. M.; Oluwafemi, O. S.; Venter, A.; Wagner, M.; Botha, J. R.

    2011-12-01

    ZnO nanostructures were grown using a simple and environmentally friendly chemical bath deposition technique on pre-treated p-type silicon substrate at temperatures below 100°C. The effects of growth parameters like seed layer density, growth time, growth temperature, precursor concentration and annealing temperature on the structural, morphological, electrical and optical properties of ZnO nanorods were systematically studied using field emission scanning electron microscopy, X-ray diffraction, photoluminescence spectroscopy and current-voltage measurements. A variety of architectures is demonstrated, ranging from single crystalline nanoparticles and c-axis orientated nanorods to highly compact crystalline thin films. Post-growth annealing at different temperatures profoundly affects the optical properties of the nanorods by, for example, reducing hydrogen- and intrinsic defect-related emission. The rectifying properties of the ZnO/Si heterojunction are discussed.

  18. Synthesis and red-shifted photoluminescence of single-crystalline ZnO nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Deng Yuan [School of Chemistry and Environment, BeiHang University, Beijing 100083 (China)], E-mail: dengyuan@buaa.edu.cn; Wang Guangsheng; Li Na [School of Chemistry and Environment, BeiHang University, Beijing 100083 (China); Guo Lin [School of Chemistry and Environment, BeiHang University, Beijing 100083 (China)], E-mail: guolin@buaa.edu.cn

    2009-01-15

    Local-oriented single-crystalline ZnO nanowires have been synthesized in large scale by a simple microemulsion method in the presence of sulfonate-polystyrene (S-PS) and dodecyl benzene sulfonic acid sodium salt (DBS). The as-prepared product is characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), infrared (IR) spectra and photoluminescence (PL) spectrum. The nanowires exhibit a local congregation and preferentially grow along the [0 0 2] facet. FT-IR spectrum indicates that S-PS is adsorbed on the surface of ZnO nanowires. The PL spectrum shows evidently red-shifted ultraviolet (UV) emission.

  19. Patient orientation and professional orientation of Dutch dentists.

    Science.gov (United States)

    Bruers, J Josef M; Felling, Albert J A; Truin, Gert Jan; van't Hof, Martin A; van Rossum, Ger M J M

    2004-04-01

    By providing dental health care, dentists dedicate themselves to the preservation and/or improvement of oral health in their patients. By adequately carrying out this care providers' role, dentists will gain recognition, esteem and respect from both patients and colleagues. This analysis aims to assess the patient and professional orientation of dentists and investigate which of their personal and practice characteristics can be regarded determining for these two aspects of their role as care providers. In the year 2000, data was collected via a written questionnaire sent to a random, stratified sample of 790 dentists, of whom 607 (77%) responded. Multivariate regression analysis shows that the preventive treatment concept, professional satisfaction and the number of hours per week that household tasks are performed are positive determinants for dentists' patient orientation. Also, the longer dentists are active in their profession, the more patient oriented they will be, and with more hours per week support from oral hygienists they are less patient oriented. As for professional orientation, dentists' preventive treatment concept and their professional satisfaction can also be considered positive determinants. Furthermore, dentists are more profession oriented when their partner works in the practice, with more hours per week support from oral hygienist(s) and with more collaboration contacts with other care providers. Compared to men, women are on average less profession oriented. Among Dutch dentists, there exist clear differences in the way they take on their role as care providers with regard to patient orientation and professional orientation.

  20. Orienteering club

    CERN Multimedia

    Club d'orientation

    2015-01-01

    Course d'orientation La reprise des courses d’orientation était attendue dans la région puisque près de 150 coureurs ont participé à la première épreuve automnale organisée par le club d’orientation du CERN sur le site de La Faucille. Les circuits ont été remportés par Yann Locatelli du club d’Orientation Coeur de Savoie avec 56 secondes d’avance sur Damien Berguerre du club SOS Sallanches pour le parcours technique long, Marie Vuitton du club CO CERN (membre également de l’Equipe de France Jeune) pour le parcours technique moyen avec presque 4 minutes d’avance sur Jeremy Wichoud du club Lausanne-Jorat, Victor Dannecker pour le circuit technique court devant Alina Niggli, Elliot Dannecker pour le facile moyen et Alice Merat sur le facile court, tous membres du club O’Jura. Les résultats comp...

  1. Preparation of ZnO nanocrystals via ultrasonic irradiation

    DEFF Research Database (Denmark)

    Qian, D.; Jiang, Jianzhong; Hansen, P. L.

    2003-01-01

    A simple and rapid process has been developed for the preparation of nanometer-sized ZnO crystals via ultrasonic irradiation, by which pure ZnO nanocrystals with an average size of 6 nm and narrow size distribution can be synthesized in a short time and without using any solvents...... for the precipitation of ZnO....

  2. Synthesis and optical characteristics of ZnO nanocrystals

    Indian Academy of Sciences (India)

    The average crystal size of the as prepared ZnO nanopowder is determined by XRD and the values are in good agreement with the TEM analysis. UV absorption spectra revealed the absorption at wavelength < 370 nm indicating the smaller size of ZnO nanoparticles. The quality and purity of ZnO nanomaterial crystalline ...

  3. Intrinsic Ferromagnetism in Eu doped ZnO

    OpenAIRE

    Assadi, M. H. N.; Zhang, Y. B.; Ionescu, M.; Photongkam, P.; Li, S.

    2010-01-01

    We report room temperature ferromagnetism in as-implanted Eu doped ZnO (ZnO:Eu). To address the origin of ferromagnetism ab initio calculations of ZnO:Eu system are performed. Results show that the ferromagnetism is induced by ZnO point defects as Eu ions in perfect ZnO tend to align antiferromagnetically.

  4. Ultrasonic-assisted fabrication of superhydrophobic ZnO nanowall ...

    Indian Academy of Sciences (India)

    2017-06-09

    Jun 9, 2017 ... ics, photonics and energy conversion applications. Okyay et al [6] grew ZnO nanorods on ZnO ... applications. As per the literature review, there are no reports regarding the growth of ZnO nanowalls on glass ... sonic waves (Ultrasonic Processor, Sonics and Systems, 500. W, 20 kHz at 20% efficiency) were ...

  5. A comprehensive picture in the view of atomic scale on piezoelectricity of ZnO tunnel junctions: The first principles simulation

    Directory of Open Access Journals (Sweden)

    Genghong Zhang

    2016-06-01

    Full Text Available Piezoelectricity is closely related with the performance and application of piezoelectric devices. It is a crucial issue to understand its detailed fundamental for designing functional devices with more peculiar performances. Basing on the first principles simulations, the ZnO piezoelectric tunnel junction is taken as an example to systematically investigate its piezoelectricity (including the piezopotential energy, piezoelectric field, piezoelectric polarization and piezocharge and explore their correlation. The comprehensive picture of the piezoelectricity in the ZnO tunnel junction is revealed at atomic scale and it is verified to be the intrinsic characteristic of ZnO barrier, independent of its terminated surface but dependent on its c axis orientation and the applied strain. In the case of the ZnO c axis pointing from right to left, an in-plane compressive strain will induce piezocharges (and a piezopotential energy drop with positive and negative signs (negative and positive signs emerging respectively at the left and right terminated surfaces of the ZnO barrier. Meanwhile a piezoelectric polarization (and a piezoelectric field pointing from right to left (from left to right are also induced throughout the ZnO barrier. All these piezoelectric physical quantities would reverse when the applied strain switches from compressive to tensile. This study provides an atomic level insight into the fundamental behavior of the piezoelectricity of the piezoelectric tunnel junction and should have very useful information for future designs of piezoelectric devices.

  6. Influence of SiO{sub 2} buffer layer on the crystalline quality and photoluminescence of ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Xu, L H; Chen, Y L; Xu, F [College of Math and Physics, Nanjing University of Information Science and Technology, Nanjing, 210044 (China); Li, X Y [Department of Applied Physics, Nanjing University of Science and Technology, Nanjing, 210094 (China); Hua, S, E-mail: congyu3256@sina.com [Institute of Electronic Engineering and Photoelectric Technology, Nanjing University of Science and Technology, Nanjing, 210094 (China)

    2011-02-01

    In this work, a SiO{sub 2} buffer layer was first grown on Si substrate by thermal oxidation, and then ZnO thin films were deposited on SiO{sub 2} buffer layer and Si substrate by electron beam evaporation and sol-gel method. The influence of SiO{sub 2} buffer layer on the crystalline quality and photoluminescence of the films was investigated. The analyses of X-ray diffraction (XRD) showed that all the ZnO thin films had a hexagonal wurtzite structure and were preferentially oriented along the c-axis perpendicular to the substrate surface. The SiO{sub 2} buffer layer improved the crystalline quality and decreased the stress in ZnO thin films. The surface morphology analyses of the samples indicated that ZnO thin films deposited on SiO{sub 2} buffer layers had densely packed grains which obviously increased compared with those grown on bare Si substrate. The photoluminescence spectra of the samples showed that the ZnO thin films deposited on SiO{sub 2} buffer layers had stronger ultraviolet emission performance. The results suggest that SiO{sub 2} buffer layer can improve the crystalline quality and ultraviolet emission of ZnO thin films.

  7. Effect of Ga doping on micro/structural, electrical and optical properties of pulsed laser deposited ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Shinde, S.D. [Centre for Advanced Studies in Materials Science and Condensed Matter Physics, Department of Physics, University of Pune, Pune 411 007 (India); Deshmukh, A.V. [Centre for Advanced Studies in Materials Science and Condensed Matter Physics, Department of Physics, University of Pune, Pune 411 007 (India); Department of Physics, College of Engineering, Pune 411 005 (India); Date, S.K. [Centre for Advanced Studies in Materials Science and Condensed Matter Physics, Department of Physics, University of Pune, Pune 411 007 (India); Sathe, V.G. [UGC-DAE Consortium for Scientific Research, University Campus, Indore-452 017 (India); Adhi, K.P., E-mail: kpa@physics.unipune.ac.in [Centre for Advanced Studies in Materials Science and Condensed Matter Physics, Department of Physics, University of Pune, Pune 411 007 (India)

    2011-12-01

    Undoped and Ga doped ZnO thin films (1% GZO, 3% GZO and 5% GZO) were grown on c-Al{sub 2}O{sub 3} substrates using the 1, 3 and 5 at. wt.% Ga doped ZnO targets by pulsed laser deposition. X-ray diffraction studies revealed that highly c-axis oriented, single phase, undoped and Ga doped ZnO thin films with wurtzite structure were deposited. Micro-Raman scattering analysis showed that Ga doping introduces defects in the host lattice. The E{sub 2}{sup High} mode of ZnO in Ga doped ZnO thin film was observed to shift to higher wavenumber indicating the presence of residual compressive stress. Appearance of the normally Raman inactive B{sub 1} modes (B{sub 1}{sup Low}, 2B{sub 1}{sup Low} and B{sub 1}{sup High}) due to breaking of local translational symmetry, also indicated that defects were introduced into the host lattice due to Ga incorporation. Band gap of the Ga doped ZnO thin films was observed to shift to higher energy with the increase in doping concentration and is explicated by the Burstein-Moss effect. Electrical resistivity measurements of the undoped and GZO thin films in the temperature range 50 to 300 K revealed the metal to semiconductor transition for 3 and 5% GZO thin films.

  8. Structural, electrical, and dielectric properties of Cr doped ZnO thin films: Role of Cr concentration

    Energy Technology Data Exchange (ETDEWEB)

    Gürbüz, Osman, E-mail: osgurbuz@yildiz.edu.tr; Okutan, Mustafa

    2016-11-30

    Highlights: • Magnetic material of Cr and semiconductor material of ZnO were grown by the magnetron sputtering co-sputter technique. • Perfect single crystalline structures were grown. • DC and AC conductivity with dielectric properties as a function of frequency (f = 5Hz–13 MHz) at room temperature were measured and compared. • Cr doped ZnO can be used in microwave, sensor and optoelectronic devices as the electrical conductivity increases while dielectric constant decreases with the Cr content. - Abstract: An undoped zinc oxide (ZnO) and different concentrations of chromium (Cr) doped ZnO Cr{sub x}ZnO{sub 1−x} (x = 3.74, 5.67, 8.10, 11.88, and 15.96) thin films were prepared using a magnetron sputtering technique at room temperature. These films were characterized by X-ray diffraction (XRD), High resolution scanning electron microscope (HR-SEM), and Energy dispersive X-ray spectrometry (EDS). XRD patterns of all the films showed that the films possess crystalline structure with preferred orientation along the (100) crystal plane. The average crystallite size obtained was found to be between 95 and 83 nm which was beneficial in high intensity recording peak. Both crystal quality and crystallite sizes decrease with increasing Cr concentration. The crystal and grain sizes of the all film were investigated using SEM analysis. The surface morphology that is grain size changes with increase Cr concentration and small grains coalesce together to form larger grains for the Cr{sub 11.88}ZnO and Cr{sub 15.96}ZnO samples. Impedance spectroscopy studies were carried out in the frequencies ranging from 5 Hz to 13 MHz at room temperature. The undoped ZnO film had the highest dielectric value, while dielectric values of other films decreased as doping concentrations increased. Besides, the dielectric constants decreased whereas the loss tangents increased with increasing Cr content. This was considered to be related to the reduction of grain size as Cr content in ZnO

  9. Fabrication of needle-like ZnO nanorods arrays by a low-temperature seed-layer growth approach in solution

    Science.gov (United States)

    Zhang, Haimin; Quan, Xie; Chen, Shuo; Zhao, Huimin

    2007-11-01

    Uniform, large-scale, and well-aligned needle-like ZnO nanorods with good photoluminescence and photocatalysis properties on Zn substrates, have been successfully fabricated using a simple low-temperature seed-layer growth approach in solution (50 °C). The formation of ZnO seed-layer by the anodic oxidation technique (AOT) plays an important role in the subsequent growth of highly oriented ZnO nanorods arrays. Temperature also proved to be a significant factor in the growth of ZnO nanorods and had a great effect on their optical properties. X-ray diffraction (XRD) analysis, selected-area electron diffraction (SAED) pattern and high-resolution TEM (HRTEM) indicated that the needle-like ZnO nanorods were single crystal in nature and that they had grown up preferentially along the [0001] direction. The well-aligned ZnO nanorods arrays on Zn substrates exhibited strong UV emission at around 380 nm at room temperature. To investigate their potential as photocatalysts, degradation of pentachlorophenol (PCP) in aqueous solution was carried out using photocatalytic processes, with comparison to direct photolysis. After 1 h, the degradation efficiencies of PCP by direct photolysis and photocatalytic processes achieved 57% and 76% under given experimental conditions, respectively. This improved degradation efficiency of PCP illustrates that ZnO nanorods arrays on Zn substrates have good photocatalytic activity. This simple low-temperature seed-layer growth approach in solution resulted in the development of an effective and low-cost fabrication process for high-quality ZnO nanorods arrays with good optical and photocatalytic properties that can be applicable in many fields such as photocatalysis, photovoltaic cells, luminescent sensors, and photoconductive sensors.

  10. Fast production of ZnO nanorods by arc discharge in de-ionized water and applications in dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Sönmezoğlu, S., E-mail: svssonmezoglu@kmu.edu.tr [Department of Materials Science and Engineering, Karamanoğlu Mehmetbey University, Karaman (Turkey); Eskizeybek, V. [Department of Materials Science and Engineering, Çanakkale Onsekiz Mart University, Çanakkale (Turkey); Toumiat, A. [Department of Physics, Constantine Ceramics Lab., Mentouri University (Algeria); Avcı, A. [Department of Mechanical Engineering, Selçuk University, Konya (Turkey)

    2014-02-15

    Highlights: • Fast production of ZnO nanorods was synthesized by bottom up approach using arc discharge in de-ionized water method. • A dye-sensitized solar cell based on ZnO nanorod displayed the most efficient solar to electricity conversion efficiency of the N719 dyes with a maximum η value of 6.96%. • We focused on the morphology, photocatalytical and optical properties of the ZnO nanorods. -- Abstract: Fast production of the ZnO nanorods by bottom up approach using arc discharge method in de-ionized water was carried out. Structural analysis showed that the obtained ZnO powder exhibits crystallize in the hexagonal wurtzite structure with (1 0 1) preferential orientation. Furthermore, transmission electron microscopy observations showed that rod-like structure is the abundant form with a bimodial grain size distribution around 10 and 30 nm. Optical characterization of the as-synthesized ZnO nanorods revealed the existence of the two absorption and photoluminescence (PL) bands both located at UV spectral region attributed to the two grain size distributions. In addition, the two additional visible bands PL spectrum located at 430 and 492 nm are attributed the interstitial zinc and oxygen vacancies; respectively. Dye sensitized solar cells (DSSCs) were successfully produced via different ruthenium based dyes and ferrocene liquid electrolyte by using of as synthesized ZnO nanorods modified photoanodes. It has been found that DSSCs made with N719 dye is the most efficient with photoconversion of approximately 7% compared to the other dyes. Such nanorod form of the ZnO nanostructures with ruthenium dyes resulted in significant improvements of the device performance in terms of electron transportation and UV light absorption. This work would explore feasible routes to synthesize efficient metal-oxide nanostructures for opto-electronic or other related applications.

  11. Electrowetting on ZnO nanowires

    Science.gov (United States)

    Wu, Jun; Xia, Jun; Lei, Wei; Wang, Bao-Ping

    2010-06-01

    In this paper, we study the electrowetting character on ZnO nanowires. We grow the ZnO nanowires on indium tin oxide (ITO) by a hydrothermal method, and the ZnO nanowires surface is further hydrophobized by spin-coating Teflon. Such a prepared surface shows superhydrophobic properties with an initial contact angle 165°. When the applied external voltage between the ITO and the sessile droplet is less than 50 V, the contact angle continuously changed from 165° to 120°, and exhibits instant reversibility. For a slightly higher voltage, a mutation of the contact angle changing to 100° was observed and the contact angle was not reversible after removing the applied voltage, which indicates a transition from non-wetting state to wetting state. Further increasing of the applied voltage, the apparent contact angle decreased to an invariable value 70°, and electrical breakdown emerged synchronously.

  12. Orienteering Club

    CERN Multimedia

    Club d'orientation

    2013-01-01

    Courses d’orientation Une bonne dizaine de clubs étaient représentés samedi dernier à La Faucille pour participer à la  2e manche de la coupe genevoise organisée par le club du CERN. Les 120 coureurs ont pu découvrir des parcours classés "technique". Ceux du Haut-Jura familiarisés à ce type de terrain ont pu sortir leur épingle du jeu et se sont octroyé la victoire sur 4 des 5 circuits. Samedi 21 septembre, la montagne du Haut-Jura était encore plébiscitée puisque les coureurs étaient attendus à Saint Cergue sur la carte des Pralies. Pour les résultats complets de La Faucille et les informations sur la prochaine étape, consultez le site du club http://cern.ch/club-orientation.

  13. Photoluminescence properties of Co-doped ZnO nanocrystals

    DEFF Research Database (Denmark)

    Lommens, P.; Smet, P.F.; De Mello Donega, C.

    2006-01-01

    We performed photoluminescence experiments on colloidal, Co -doped ZnO nanocrystals in order to study the electronic properties of Co in a ZnO host. Room temperature measurements showed, next to the ZnO exciton and trap emission, an additional emission related to the Co dopant. The spectral...... position and width of this emission does not depend on particle size or Co concentration. At 8 K, a series of ZnO bulk phonon replicas appear on the Co-emission band. We conclude that Co ions are strongly localized in the ZnO host, making the formation of a Co d-band unlikely. Magnetic measurements...

  14. Singularities in primate orientation maps.

    Science.gov (United States)

    Obermayer, K; Blasdel, G G

    1997-04-01

    We report the results of an analysis of orientation maps in primate striate cortex with focus on singularities and their distribution. Data were obtained from squirrel monkeys and macaque monkeys of different ages. We find the approximately 80% of singularities that are nearest neighbors have the opposite sign and that the spatial distribution of singularities differs significantly from a random distribution of points. We do not find evidence for consistent geometric patterns that singularities may form across the cortex. Except for a different overall alignment of orientation bands and different periods of repetition, maps obtained from different animals and different ages are found similar with respect to the measures used. Orientation maps are then compared with two different pattern models that are currently discussed in the literature: bandpass-filtered white noise, which accounts very well for the overall map structure, and the field analogy model, which specifies the orientation map by the location of singularities and their properties. The bandpass-filtered noise approach to orientation patterns correctly predicts the sign correlations between singularities and accounts for the deviations in the spatial distribution of singularities away from a random dot pattern. The field analogy model can account for the structure of certain local patches of the orientation map but not for the whole map. Neither of the models is completely satisfactory, and the structure of the orientation map remains to be fully explained.

  15. Orientation Club

    CERN Multimedia

    Club d'orientation

    2014-01-01

    COURSE ORIENTATION Résultats de samedi 10 mai    C’est sur une carte entièrement réactualisée dans les bois de Versoix, que plus de 100 coureurs sont venus participer à la course d’orientation, type longue distance, préparée par des membres du club du CERN. Le terrain plutôt plat nécessitait une orientation à grande vitesse, ce qui a donné les podiums suivants :  Technique long avec 17 postes : 1er Jurg Niggli, O’Jura en 52:48, 2e Beat Muller, COLJ Lausanne-Jorat en 58:02, 3e Christophe Vuitton, CO CERN en 58:19 Technique moyen avec 13 postes : 1er Jean-Bernard Zosso, CO CERN, en 46:05 ; 2e Yves Rousselot, Balise 25 Besançon, en 55:11 ; 3e Laurent Merat, O'Jura, en 55:13 Technique court avec 13 postes : 1er Julien Vuitton, CO CERN en 40:59, 2e Marc Baumgartner, CO CERN en 43:18, 3e Yaelle Mathieu en 51:42 Su...

  16. Orienteering Club

    CERN Multimedia

    Club d'orientation

    2013-01-01

    Courses d’orientation ce printemps Le Club d’orientation du CERN vous invite à venir découvrir la course d’orientation et vous propose, en partenariat avec d’autres clubs de la région, une dizaine de courses populaires. Celles-ci ont lieu les samedis après-midi, elles sont ouvertes à tous, quel que soit le niveau, du débutant au sportif confirmé, en famille ou en individuel, en promenade ou en course. Si vous êtes débutant vous pouvez profiter d’une petite initiation offerte par l’organisateur avant de vous lancer sur un parcours. Divers types de parcours sont à votre choix lors de chaque épreuve : facile court (2-3 km), facile moyen (3-5 km), technique court (3-4 km), technique moyen (4-5 km) et technique long (5-7 km). Les dates à retenir sont les suivantes : Samedi 23 mars: Pully (Vd) Samedi 13 avril: Pougny...

  17. Soft and Hard Tissue Changes around Tissue-Oriented Tulip-Design Implant Abutments: A 1-Year Randomized Prospective Clinical Trial.

    Science.gov (United States)

    Gutmacher, Zvi; Levi, Guy; Blumenfeld, Israel; Machtei, Eli E

    2015-10-01

    The advantages of platform switching using narrower abutments remain controversial. Many researchers suggest that platform switching can yield enhanced clinical results, while others remain skeptical. We hypothesize that the effectiveness of platform switching might be associated with the degree of reduction in size of the abutment. To radiographically and clinically examine a new abutment design created to move the implant-abutment interface farther medially. This was a prospective, randomized controlled clinical trial that included 27 patients (41 MIS Lance Plus® implants; MIS Implant Technologies, Karmiel, Israel). The patients' age ranged from 39 to 75 years. At the second stage of the surgery, the implants were randomly assigned to either the new platform switch Tulip abutment (TA) design or to the standard platform abutment (SA). Implant probing depth (IPD) and bleeding on probing (BOP) were recorded at baseline and after 12 months. Standardized periapical radiographs were taken (at baseline and at 12 months) and the marginal bone height measured. All implants were successfully integrated. The mean IPD at 1 year post-op was 2.91 mm for the SA group and 2.69 mm for the TA group (p > .05). Similarly, the BOP at 1 year was almost identical in both groups. The mean values of bone resorption at baseline were 0.98 ± 0.37 mm and 0.69 ± 0.20 for the TA and SA groups, respectively (p > .05). Bone loss (baseline to 12 months) was significantly greater in the SA group compared with the TA group. Use of the new TA, with its significantly downsized diameter, resulted in reduced bone loss at 1 year. Further research will be required to assess the long-term effect of this abutment on peri-implant health. © 2014 Wiley Periodicals, Inc.

  18. ZnO nanofluids: Green synthesis, characterization, and antibacterial activity

    Energy Technology Data Exchange (ETDEWEB)

    Jalal, Razieh [Dept. of Chemistry, Ferdowsi University of Mashhad, Mashhad 91779 Mashhad (Iran, Islamic Republic of); Goharshadi, Elaheh K., E-mail: gohari@ferdowsi.um.ac.ir [Dept. of Chemistry, Ferdowsi University of Mashhad, Mashhad 91779 Mashhad (Iran, Islamic Republic of); Center of Nano Research, Ferdowsi University of Mashhad (Iran, Islamic Republic of); Abareshi, Maryam [Dept. of Chemistry, Ferdowsi University of Mashhad, Mashhad 91779 Mashhad (Iran, Islamic Republic of); Moosavi, Majid [Dept. of Chemistry, Faculty of Sciences, University of Isfahan, Isfahan 81746-73441 (Iran, Islamic Republic of); Yousefi, Abbas [Pare-Tavous Research Institute, Mashhad (Iran, Islamic Republic of); Nancarrow, Paul [QUILL Research Centre and School of Chemistry and Chemical Engineering, Queen' s University Belfast (United Kingdom)

    2010-05-15

    Zinc oxide nanoparticles have been synthesized by microwave decomposition of zinc acetate precursor using an ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide, [bmim][NTf{sub 2}] as a green solvent. The structure and morphology of ZnO nanoparticles have been characterized using X-ray diffraction and transmission electron microscopy. The ZnO nanofluids have been prepared by dispersing ZnO nanoparticles in glycerol as a base fluid in the presence of ammonium citrate as a dispersant. The antibacterial activity of suspensions of ZnO nanofluids against (E. coli) has been evaluated by estimating the reduction ratio of the bacteria treated with ZnO. Survival ratio of bacteria decreases with increasing the concentrations of ZnO nanofluids and time. The results show that an increase in the concentrations of ZnO nanofluids produces strong antibacterial activity toward E. coli.

  19. Control of conductivity type in undoped ZnO thin films grown by metalorganic vapor phase epitaxy

    Science.gov (United States)

    Ma, Y.; Du, G. T.; Yang, S. R.; Li, Z. T.; Zhao, B. J.; Yang, X. T.; Yang, T. P.; Zhang, Y. T.; Liu, D. L.

    2004-06-01

    The properties of the ZnO thin films prepared by metalorganic vapor phase epitaxy under various oxygen partial pressures were thoroughly studied. It was found that the conduction type in undoped ZnO epilayers could be controlled by adjusting the family VI precursor, oxygen partial pressure during growth. The films were characteristic of n-type conductivity under oxygen partial pressure lower than 45 Pa. With the increase of oxygen content, the crystallinity of the ZnO thin films was degraded to polycrystalline with additional (10-12) orientation and the intrinsic p-type ZnO was produced as the oxygen partial pressure was larger than 55 Pa. The hole concentration and mobility could reach to 1.59×1016 cm-3 and 9.23 cm2 V-1 s-1, and the resistivity was 42.7 Ω cm. The near-band-edge emission and the deep level emission in photoluminescence (PL) spectra at room temperature were influenced strongly by the oxygen partial pressure. Temperature-dependent PL spectra in n-type ZnO films showed a dominant neutral-donor bound exciton emission, while p-ZnO was dominated by neutral-acceptor bound exciton emission. Both peaks increased in intensity with the decrease of the temperature and shifted to the short-wavelength side. The band that originated from zinc vacancies emerged at a temperature lower than 155 K only in the p-type films. The origin of intrinsic p-type conductivity in ZnO thin films might be related to zinc vacancy.

  20. Nanocrystalline ZnO film deposited by ultrasonic spray on textured silicon substrate as an anti-reflection coating layer

    Energy Technology Data Exchange (ETDEWEB)

    Sali, S., E-mail: samira_sali@yahoo.fr [Silicon Technology Development Unit (UDTS), 02 Bd, Frantz FANON, B.P. 140, Algiers (Algeria); Houari Boumediene University (USTHB), Faculty of Physics, Algiers (Algeria); Boumaour, M. [Silicon Technology Development Unit (UDTS), 02 Bd, Frantz FANON, B.P. 140, Algiers (Algeria); Kechouane, M. [Houari Boumediene University (USTHB), Faculty of Physics, Algiers (Algeria); Kermadi, S.; Aitamar, F. [Silicon Technology Development Unit (UDTS), 02 Bd, Frantz FANON, B.P. 140, Algiers (Algeria)

    2012-07-01

    A ZnO thin film was successfully synthesized on glass, flat surface and textured silicon substrates by chemical spray deposition. The textured silicon substrate was carried out using two solutions (NaOH/IPA and Na{sub 2}CO{sub 3}). Textured with Na{sub 2}CO{sub 3} solution, the sample surface exhibits uniform pyramids with an average height of 5 {mu}m. The properties and morphology of ZnO films were investigated. X-ray diffraction (XRD) spectra revealed a preferred orientation of the ZnO nanocrystalline film along the c-axis where the low value of the tensile strain 0.26% was obtained. SEM images show that all films display a granular, polycrystalline morphology. The morphology of the ZnO layers depends dramatically on the substrate used and follows the contours of the pyramids on the substrate surface. The average reflectance of the textured surface was found to be around 13% and it decreases dramatically to 2.57% after deposition of a ZnO antireflection coating. FT-IR peaks arising from the bonding between Zn-O are clearly represented using a silicon textured surface. A very intense photoluminescence (PL) emission peak is observed for ZnO/textured Si, revealing the good quality of the layer. The PL peak at 380.5 nm (UV emission) and the high-intensity PL peak at 427.5 nm are observed and a high luminescence occurs when using a textured Si substrate.

  1. Effect of Al and Fe doping in ZnO on magnetic and magneto-transport properties

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Santosh, E-mail: skphysics@yahoo.co.in [Department of Physics, College of Commerce, Arts & Science, Patna 800020, Bihar (India); Deepika [Department of Physics, College of Commerce, Arts & Science, Patna 800020, Bihar (India); Tripathi, Malvika [UGC DAE, Consortium for scientific research, Indore 452001, Madhya Pradesh (India); Vaibhav, Pratyush [Jaypee University of Engineering and Technology, Guna 473226, Madhya Pradesh (India); Kumar, Aman [Indian Institute of Technology, Roorkee (India); Kumar, Ritesh [Department of Physics, College of Commerce, Arts & Science, Patna 800020, Bihar (India); Choudhary, R.J., E-mail: ram@csr.res.in [UGC DAE, Consortium for scientific research, Indore 452001, Madhya Pradesh (India); Phase, D.M. [UGC DAE, Consortium for scientific research, Indore 452001, Madhya Pradesh (India)

    2016-12-01

    The structural, magnetic and magneto-transport of undoped ZnO, Zn{sub 0.97}Al{sub 0.03}O, Zn{sub 0.95}Fe{sub 0.05}O and Zn{sub 0.92}Al{sub 0.03}Fe{sub 0.05}O thin films grown on Si(100) substrate using pulsed laser deposition were investigated. The single phase nature of the films is confirmed by X-ray diffraction and Raman spectroscopy measurements. The possibility of Fe metal cluster in Fe doped/co-doped films is ruled out by Fe 2p core level photoelectron spectra. From O 1s core level spectra it is observed that oxygen vacancy is present in all the films. The undoped ZnO film shows magnetic ordering below ∼175 K, whereas Fe doped/codoped samples show magnetic ordering even at 300 K. The Al doped sample reveals paramagnetic behavior. The magneto-transport measurements suggest that the mobile carriers undergo exchange interaction with local magnetic moments. - Highlights: • Al, Fe, Al–Fe co-doped and undoped films of ZnO are deposited on Si by PLD. • Single phase (002) oriented Wurtzite ZnO phase is formed for all films. • Fe doped and Fe–Al co-doped ZnO films reveal magnetic hysteresis at 300 K. • Negative magnetoresistance is observed in undoped and Fe–Al co-doped ZnO film. • It is apparent that charge carriers are coupled with the local magnetic moment.

  2. Growth of novel ZnO nanohelices modified by SiO{sub 2}-sheathed ZnO discs

    Energy Technology Data Exchange (ETDEWEB)

    Gao, H [Department of Physics, Harbin Institute of Technology, PO Box 3025, Harbin 150080 (China); Zhang, X T [Department of Physics, Chinese University of Hong Kong, Shatin, NT, Hong Kong (China); Zhou, M Y [Department of Physics, Harbin Normal University, Harbin 150080 (China); Zhang, Z G [Department of Physics, Harbin Institute of Technology, PO Box 3025, Harbin 150080 (China); Wang, X Z [Department of Physics, Harbin Normal University, Harbin 150080 (China)

    2007-02-14

    Disc-modified nanohelices (DNHs) of ZnO were synthesized by thermal evaporation. The ZnO DNHs are constructed by nanowires which are regularly attached with discs. The axis of the DNH structure is along the ZnO[0001] direction. The pitch distance, the mean diameter, and the thickness of the nanowires are uniform for each ZnO DNH. Within one period there are 12 discs symmetrically attached on the surfaces of the nanowires. The discs are composed of nanometre-sized ZnO crystal cores and amorphous SiO{sub 2} shells. The mechanism of formation of the nanostructures is also discussed.

  3. Cr-N co-doped ZnO nanoparticles: synthesis, characterization and ...

    African Journals Online (AJOL)

    Modified photocatalysts were synthesized by the incipient wetness impregnation method (chromium-doped ZnO) and by solid state reactions using ZnO and urea as precursors (nitrogen-doped ZnO). Chromium-nitrogen co-doped ZnO nanomaterials were prepared from the already prepared N-doped ZnO nanomaterials via ...

  4. H2O2 sensing using HRP modified catalyst-free ZnO nanorods synthesized by RF sputtering

    Science.gov (United States)

    Srivastava, Amit; Kumar, Naresh; Singh, Priti; Singh, Sunil Kumar

    2017-06-01

    Catalyst-free ( 00 l) oriented ZnO nanorods (NRs) -based biosensor for the H2O2 sensing has been reported. The (002) oriented ZnO NRs as confirmed by X-ray diffraction were successfully grown on indium tin oxide (ITO) coated glass substrate by radio frequency (RF) sputtering technique without using any catalyst. Horseradish peroxidase (HRP) enzyme was immobilized on ZnO NRs by physical adsorption technique to prepare the biosensor. In this HRP/ZnO NR/ITO bioelectrode, nafion solution was added to form a tight membrane on surface. The prepared bioelectrode has been used for biosensing measurements by electrochemical analyzer. The electrochemical studies reveal that the prepared HRP/ZnO NR/ITO biosensor is highly sensitive to the detection of H2O2 over a linear range of 0.250-10 μM. The ZnO NR-based biosensor showed lower value of detection limit (0.125 μM) and higher sensitivity (13.40 µA/µM cm2) towards H2O2. The observed value of higher sensitivity attributed to larger surface area of ZnO nanostructure for effective loading of HRP besides its high electron communication capability. In addition, the biosensor also shows lower value of enzyme's kinetic parameter (Michaelis-Menten constant, K m) of 0.262 μM which indicates enhanced enzyme affinity of HRP to H2O2. The reported biosensor may be useful for various applications in biosensing, clinical, food, and beverage industry.

  5. Fabrication and characterization of ZnO and Li doped ZnO by a sol-gel method

    Science.gov (United States)

    Fadillah, L.; Soegijono, B.; Budiawanti, S.; Mudzakir, I.

    2017-07-01

    The substitution of group-I and or group V elements on Zn-site and O-site respectively are challenge that needs to be overcome for the realization of the most ZnO based application materials. The process of fabrication to obtain high quality crystal samples in various structures should be handled carefully with precaution. ZnO and Li doped ZnO have been fabricated via sol-gel method. The samples have been observed by means of X-ray diffractometer, Thermal gravimetry analyzer (TGA), and FTIR. The characterization results show similar to commercial powder for undoped ZnO while Li doped ZnO show a shifting in crystallographic properties. It concludes that fabrication of high quality ZnO and Li doped ZnO was accomplished.

  6. Experimental and theoretical investigation of silver-coated ZnO nanorod arrays as antennas for the visible and near-IR spectral range

    Science.gov (United States)

    Kaidashev, E. M.; Lyanguzov, N. V.; Lerer, A. M.; Raspopova, E. A.

    2014-04-01

    A new design of optical antennas consisting of zinc oxide (ZnO) nanorods covered by a thin metal film is proposed. Arrays of highly oriented ZnO nanorods perpendicular to a substrate and covered by a thin silver film have been obtained using methods of carbothermal synthesis and magnetron sputtering. The problems of electromagnetic wave diffraction on a single metal/dielectric nanovibrator (situated at the interface of dielectrics) and on a two-dimensional periodic array of these nanovibrators have been solved. The results of calculations of the electrodynamic characteristics of optical antennas with various lengths have been compared to experimental data.

  7. Orienteering Club

    CERN Multimedia

    Le Club d’orientation du CERN

    2017-01-01

    Calendrier des courses de la Coupe Genevoise – printemps 2017 Club d'orientation - Julien,  jeune membre du club. Le Club d’orientation du CERN, en partenariat avec d’autres clubs de la région, vous propose une série de courses populaires, qui se dérouleront des deux côtés de la frontière franco-suisse, à savoir : Samedi 1 avril : Pougny/Challex (01) Samedi 8 avril: Ballens (VD) Samedi 22 avril: Apples (VD) Samedi 29 avril: Mont Mussy (01) Samedi 6 mai: Prémanon (39) Samedi 13 mai: Mont Mourex (01) Samedi 20 mai: Prévondavaux (VD) Samedi 10 juin: Chancy/Valleiry (74) Samedi 17 juin: Trélex - Finale (VD) Ces courses sont ouvertes à tous, quel que soit le niveau, du débutant au sportif confirmé, en famille ou en individuel. Les inscriptions sur un des 5 parcours proposés se font sur place le jour de l...

  8. COURSE ORIENTATION

    CERN Multimedia

    Club d'orientation du CERN

    2015-01-01

      Les coureurs d’orientation de la région se sont donné rendez-vous samedi dernier dans les bois de Pougny/Challex lors de l’épreuve organisée par le club d’orientation du CERN. La carte proposée pour les 5 circuits offrait aussi bien un coté très technique avec un relief pentu qu’un coté avec de grandes zones plates à forêt claire. Le parcours technique long comportant 20 postes a été remporté par Beat Muller du COLJ Lausanne en 56:26 devançant Denis Komarov, CO CERN en 57:30 et Yvan Balliot, ASO Annecy en 57:46. Pour les autres circuits les résultats sont les suivants: Technique moyen (13 postes): 1er Joël Mathieu en 52:32 à une seconde du 2e Vladimir Kuznetsov, COLJ Lausanne-Jorat, 3e Jean-Bernard Zosso, CO CERN, en 54:01 Technique court (12 postes): 1er Lennart Jirden, ...

  9. Orienteering Club

    CERN Multimedia

    Club d'orientation

    2010-01-01

    COURSE D’ORIENTATION La finale de la coupe de printemps Après avoir remporté le challenge club, samedi 29 juin lors du relais inter-club à Lausanne, le Club d’orientation du CERN organisait la dernière étape de la coupe genevoise de printemps samedi 5 juin à Saint-Cergue dans les bois de Monteret (Canton de Vaud). Plus de 100 participants se sont déplacés pour venir participer à la finale et découvrir une toute nouvelle carte dans une forêt vallonnée. Les résultats pour chaque circuit de cette étape sont : Technique long : 1. Jurg Niggli du club O’Jura, 2. Clément Poncet, 3. Oystein Midttun. Technique moyen : 1. Zoltan Trocsanyi CO CERN, 2. Christophe Ingold, 3. Christina Falga. Technique court : 1. Pierre-Andre Baum, CARE Vevey, 2. Emese Szunyog, 3. Solène Balay. Facile moyen : 1. Elisa P...

  10. Orienteering Club

    CERN Multimedia

    Le Club d’orientation du CERN

    2017-01-01

    COURSE ORIENTATION Finale de la coupe d’automne Le club d’orientation du CERN (COC Genève) a organisé sa dernière course populaire de la saison samedi 4 novembre au lieu-dit Les Terrasses de Genève (74). Cette 9e épreuve qui se courait sous la forme d’un One-Man-Relay, clôturait ainsi la coupe genevoise d’automne dont les lauréats sont : Circuit technique long : 1. Julien Vuitton (COC Genève), 2. Berni Wehrle (COC Genève), 3. Christophe Vuitton (COC Genève). Circuit technique moyen : 1. Vladimir Kuznetsov (Lausanne-Jorat), 2. J.-Bernard Zosso (COC Genève), 3. Laurent Merat (O’Jura). Circuit technique court : 1. Thibault Rouiller (COC Genève), 2. exæquo Lennart Jirden (COC Genève) et Katya Kuznetsova (Lausanne-Jorat). Circuit facile moyen : 1. Tituan Barge ...

  11. Orienteering Club

    CERN Multimedia

    Le Club d’orientation du CERN

    2017-01-01

    COURSE ORIENTATION Finale de la coupe d’automne Le club d’orientation du CERN (COC Genève) a organisé sa dernière course populaire de la saison samedi 4 novembre au lieu-dit Les Terrasses de Genève (74). Cette 9e épreuve qui se courait sous la forme d’un One-Man-Relay, clôturait ainsi la coupe genevoise d’automne dont les lauréats sont : Circuit technique long : 1. Julien Vuitton (COC Genève), 2. Berni Wehrle (COC Genève), 3. Christophe Vuitton (COC Genève). Circuit technique moyen : 1. Vladimir Kuznetsov (Lausanne-Jorat), 2. J.-Bernard Zosso (COC Genève), 3. Laurent Merat (O’Jura). Circuit technique court : 1. Thibault Rouiller (COC Genève), 2. exæquo Lennart Jirden (COC Genève) et Katya Kuznetsova (Lausanne-Jorat). Circuit facile moyen : 1. Tituan Barge...

  12. Club Orientation

    CERN Multimedia

    Club d'orientation

    2014-01-01

      COURSE ORIENTATION   Pas moins de 100 concurrents sont venus s’affronter sur les parcours proposés par le club d’orientation du CERN ce samedi 26 avril lors de la 4e étape de la coupe genevoise de printemps. Les podiums ont été attribués à :  Technique long avec 19 postes : 1er Yvan Balliot, ASO Annecy en 1:01:39 ; 2e Dominique Fleurent, ASO Annecy, en 1:05:12 ; 3e Rémi Fournier, SOS Sallanches, en 1:05:40. Technique moyen avec 14 postes : 1er Jean-Bernard Zosso, CO CERN, en 46:42 ; 2e Céline Zosso, CO CERN, en 50:51 ; 3e Clément Poncet, O’Jura Prémanon, en 51:27. Technique court avec 13 postes : 1er Jaakko Murtomaki, YKV Seinaejoki, en 36:04 ; 2e Marc Baumgartner en 41:27 ; 3e Natalia Niggli, O’Jura Prémanon, en 52:43. Sur les parcours facile moyen et facile court, victoire respectivement de Stéphanie...

  13. Orienteering club

    CERN Multimedia

    Club d'orientation

    2010-01-01

    Course d’orientation : Coupe Genevoise de printemps 2010 Et c’est reparti pour une nouvelle saison! Pour cette coupe de printemps 2010, le Club d’Orientation du CERN, en partenariat avec d’autres clubs de la région, vous propose le calendrier suivant: – samedi 20 mars : Cossonay (Vd) – samedi 10 avril : Echallens (Vd) – samedi 17 avril : Trélex (Vd) – samedi 24 avril : Genolier (Vd) – samedi 1 mai : Vulbens/Valleiry (74) – samedi 8 mai : Bois de la Rippe (Vd) – samedi 29 mai : Sauvabellin (Vd) : relais – samedi 5 juin: St Cergue (Vd) : grande finale Les courses populaires ont lieu en général le samedi après-midi, elles sont ouvertes à tous, quel que soit le niveau, du débutant au sportif confirmé, en famille ou en individuel, en promenade ou en course. Pour cela, divers types de parcours sont &agr...

  14. Orienteering club

    CERN Multimedia

    Club d'orientation

    2013-01-01

    Courses d’orientation Le soleil enfin de retour a incité nombre de sportifs et promeneurs à nous rejoindre dans la belle forêt de Challex /Pougny pour la deuxième étape de notre coupe de printemps 2013. Certains sont revenus crottés et fourbus alors que d’autres avaient les joues bien roses après un grand bol d’air frais. Mais tous avaient passé un agréable moment dans la nature. Nous rappelons que nos activités sont ouvertes à tous, jeunes, moins jeunes, sportifs, familles, du CERN ou d’ailleurs, et que le seul inconvénient est que si vous goûtez à la course d’orientation, il vous sera difficile de ne pas y revenir ! Samedi 20 avril 2013, nous serons sur le Mont Mourex (entre Gex et Divonne) pour notre prochaine épreuve et vous y serez les bienvenus. Les inscriptions et les départ...

  15. Orienteering club

    CERN Multimedia

    Orienteering Club

    2016-01-01

    Course d'orientation Calendrier des courses d’orientation Coupe genevoise d’automne 2016 Samedi 3 septembre : La Faucille (01) Samedi 10 septembre : Prémanon (39) Samedi 17 septembre : Saint-Cergue (VD) Samedi 24 septembre : Jorat / Corcelles (VD) Samedi 1 octobre: Bière - Ballens (VD) -relais Vendredi 14 octobre : Parc Mon Repos (GE) - nocturne Samedi 15 octobre : Terrasse de Genève (74) Samedi 29 octobre : Bonmont (VD) Samedi 5 novembre : Pomier (74) – one-man-relay - Finale   Courses ouvertes à toutes et à tous, sportifs, familles, débutants ou confirmés, du CERN ou d’ailleurs. Cinq circuits disponibles, ceci va du facile court (2 km) adapté aux débutants et aux enfants jusqu’au parcours technique long de 6 km pour les chevronnés en passant par les parcours facile moyen (4&am...

  16. Orienteering Club

    CERN Multimedia

    Le Club d’orientation du CERN

    2017-01-01

    Course orientation Les courses d’orientation comptant pour la coupe genevoise de printemps s’enchainent dans la région franco-suisse. Samedi dernier, une bonne centaine de coureurs se sont retrouvés au Mont Mourex où le club du CERN avait préparé la sixième épreuve. A l’issue de la course, les participants confirmaient l’exigence des circuits, à savoir la condition physique et le côté technique du traçage. Le parcours technique long comportant 20 postes a été remporté par Darrell High du Care Vevey en 1:22:38 devançant Beat Muller du COLJ Lausanne-Jorat en 1:25:25 et Alison High également du Care Vevey en 1:28:51. Le circuit technique moyen a été remporté par Christophe Vuitton du CO CERN et le circuit technique court par Claire-Lise Rouiller, CO CERN. Les trois pr...

  17. Orienteering club

    CERN Multimedia

    Club d’Orientation du CERN

    2015-01-01

    Courses d’orientation Nouvelle saison nouveau programme Le Club d’orientation du CERN, en partenariat avec d’autres clubs de la région, vous propose une dizaine de courses populaires comptant pour la coupe Genevoise de printemps: samedi 28 mars: Vernand Dessus samedi 18 avril: Pougny/Challex samedi 25 avril: Chancy/Valleiry samedi 2 mai: Mauvernay samedi 9 mai: Longchaumois samedi 16 mai: Genolier samedi 30 mai: Prevondavaux samedi 6 juin: Biere-Ballens samedi 13 juin: Haut-Jura samedi 20 juin: Bonmont - Finale Ces courses sont ouvertes à tous, quel que soit le niveau, du débutant au sportif confirmé, en famille ou en individuel, en promenade ou en course. Les inscriptions se font sur place le jour de l’épreuve. Si vous êtes débutant, vous pouvez profiter d’une initiation offerte par l’organisateur avant de vous lancer sur un parcours. Le club propose aussi...

  18. Orienteering Club

    CERN Multimedia

    Club d'Orientation

    2015-01-01

    Course orientation C’est au pied du Salève, proche du Golf de Bosset, que le club d’orientation du CERN (CO CERN) a organisé samedi 19 septembre une nouvelle épreuve comptant pour la Coupe Genevoise d’automne. La zone « des Terrasses de Genève » avait été cartographiée et mise en service l’année dernière. Les participants ont pu apprécier un terrain ludique avec beaucoup de microreliefs, de points d’eau et de gros rochers, le tout au milieu d’une forêt assez claire et agréable à courir. Sur le parcours technique long, le résultat a été très serré puisque Pierrick Merino du club d’Annecy a gagné avec seulement 9 secondes d’avance sur Gaëtan Vuitton (CO CERN) qui confiait avoir perdu beaucoup du te...

  19. Orienteering Club

    CERN Multimedia

    Club d'Orientation

    2012-01-01

     Course d’orientation C’est sous un magnifique soleil que s’est tenue la 7e épreuve de la coupe genevoise organisée par le club d’orientation du CERN. Les organisateurs avaient concocté des parcours assez techniques sur le site de La Faucille. Sur le parcours technique long, beau podium avec la victoire de Domenico Lepori (double médaillés aux championnats du monde en 2010 en vétéran) du club Care Vevey en 1:00:23, juste devant Jürg Niggli du club O’Jura en 1:00:56 puis Beat Mueller du club Lausanne-Jorat en 1:04:28. Sur le parcours technique moyen, Franck Longchampt s’est octroyé la première place, sur le parcours technique court, le jeune Julien Vuitton, qui n’a pas tout à fait 11 ans, a remporté son circuit. Coté parcours facile moyen, Victor Kuznetsov a une fois de plus gagn&eacut...

  20. Photoluminescence of nanocoral ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Borysiewicz, M.A., E-mail: mbory@ite.waw.pl [Institute of Electron Technology, Al. Lotników 32/46, Warsaw 02-668 (Poland); Wzorek, M. [Institute of Electron Technology, Al. Lotników 32/46, Warsaw 02-668 (Poland); Wojciechowski, T.; Wojtowicz, T. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, Warsaw 02-668 (Poland); Kamińska, E.; Piotrowska, A. [Institute of Electron Technology, Al. Lotników 32/46, Warsaw 02-668 (Poland)

    2014-03-15

    Photoluminescence studies of nanocoral ZnO nanostructures, fabricated using magnetron sputter deposition of porous Zn films with subsequent oxidation by RTP annealing at 400–800 °C is presented. Structural characterization of the films performed using electron microscopy techniques show the nanocoral morphology of the films with individual coral branches constituting of bunched single crystal ZnO grains of 30–100 nm in dimensions. High resolution images confirm the high quality of individual grains. The features in the photoluminescence spectra are identified using temperature-dependent and power-dependent measurements, with rich features observed in the excitonic region at 5 K, as well as zinc vacancy lines and surface-state recombination lines being present. It is found, that the spectra significantly depend on the annealing temperatures of the samples, with the spectra acquired for the sample annealed at 800 °C exhibiting stronger excitonic emission by 2 orders of magnitude than any other features, thus proving the highest structural quality of the nanostructures. -- Highlights: • Photoluminescence (PL) of nanocoral ZnO nanostructures is studied. • Nanocoral ZnO fabricated by sputtering with post deposition oxidation at 400–800 °C. • PL spectra taken at 300 K and 5 K exhibit excitonic and intrinsic defect lines. • Rich excitonic features identified in temperature- /power-dependent spectra. • Structures fabricated at 800 °C show significantly dominating excitonic emission.

  1. Different etching evolution from initial to etched ZnO nanorods on substrates of dissimilar geometries

    Science.gov (United States)

    Jing, Weixuan; Shi, Jiafan; Xu, Zhipeng; Jiang, Zhuangde; Wei, Zhengying; Zhou, Fan; Gao, Weizhuo

    2017-08-01

    In this paper the influencing factors and their effects on the etching evolution from initial to etched ZnO nanorods (ZnONRs) were identified and investigated. Batches of ZnO nanorods were hydrothermally synthesized on planar, convex, and concave substrates, and then were etched in NaOH solution. It was found that not only the synthesizing and etching parameters but also the geometries of the substrates influence significantly the diameters, density, and orientation of both initial and etched ZnONRs. The larger the diameters of ZnONRs are, the more the oxygen vacancies on (001) crystal planes. It is at these oxygen vacancies that the etching process starts. Due to larger average diameters, initial ZnONRs on convex substrates are more readily etched than that on planar and concave ones. Thus uniform ZnO nanotubes (ZnONTs) appear quickest and most easily on convex substrates. The results can benefit the batch preparation, the performance improvement, and the process standardization of related ZnONR- and ZnONT-based devices and sensors.

  2. Au cluster growth on ZnO thin films by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Gyoergy, E. [Consejo Superior de Investigaciones Cientificas, Instituto de Ciencia de Materiales de Barcelona, Campus UAB, 08193 Bellaterra (Spain)]. E-mail: egyorgy@icmab.es; Santiso, J. [Consejo Superior de Investigaciones Cientificas, Instituto de Ciencia de Materiales de Barcelona, Campus UAB, 08193 Bellaterra (Spain); Figueras, A. [Consejo Superior de Investigaciones Cientificas, Instituto de Ciencia de Materiales de Barcelona, Campus UAB, 08193 Bellaterra (Spain); Giannoudakos, A. [National Hellenic Research Foundation, Theoretical and Physical Chemistry Institute, Vasileos Konstantinou Avenue 48, 11635 Athens (Greece); Kompitsas, M. [National Hellenic Research Foundation, Theoretical and Physical Chemistry Institute, Vasileos Konstantinou Avenue 48, 11635 Athens (Greece); Mihailescu, I.N. [Institute of Atomic Physics, P.O. Box MG 36, 77125 Bucharest (Romania); Ducu, C. [University of Pitesti, Targul din Vale 1, 110040 Pitesti (Romania)

    2006-04-30

    Nanostructures formed by Au nanoparticles on ZnO thin film surface are of interest for applications which include medical implants, gas-sensors, and catalytic systems. A frequency tripled Nd:YAG laser ({lambda} = 355 nm, {tau} {sub FWHM} {approx} 10 ns) was used for the successive irradiation of the Zn and Au targets. The ZnO films were synthesized in 20 Pa oxygen pressure while the subsequent Au coverage was grown in vacuum. The obtained structures surface morphology, crystalline quality, and chemical composition depth profile were investigated by acoustic (dynamic) mode atomic force microscopy, X-ray diffraction, and wavelength dispersive X-ray spectroscopy. The surface is characterized by a granular morphology, with average grain diameters of a few tens of nanometers. The surface roughness decreases with the increase of the number of laser pulses applied for the irradiation of the Au target. The Au coverage reveals a predominant (1 1 1) texture, whereas the underlying ZnO films are c-axis oriented. A linear dependence was established between the thickness of the Au coverage and the number of laser pulses applied for the irradiation of the Au target.

  3. Design and Fabrication of a Novel T-Shaped Piezoelectric ZnO Cantilever Sensor

    Directory of Open Access Journals (Sweden)

    Kai Yang

    2012-01-01

    Full Text Available A novel T-shaped piezoelectric ZnO cantilever sensor for chem/bio-detection is designed and fabricated with MEMS technology. By using Rayleigh-Ritz method, the fundamental resonant frequency formula of T-shaped cantilevers is deduced for the first time and is validated by simulation results and experimental results. From this formula, we can easily find the superiority of adopting T-shape for the cantilevers. The complete process of the cantilever sensor is then successfully developed. The cantilever sensor is actuated by a layer of high-quality ZnO film with preferred (002 orientation, which is evaluated by SEM and XRD. The key step of the process is protecting the ZnO film from KOH etching by a novel and effective method, which has rarely appeared in the literature. Finally, this cantilever sensor is measured by a network analyzer, and it has a fundamental resonant frequency of 24.60 kHz. The cantilever sensor developed in this study illustrates the feasibility and potential for many miniaturized sensor applications.

  4. Optical properties of p-type Al and N co-doped ZnO films

    Science.gov (United States)

    Zhang, Li; Yu, Wei; Zhang, Zicai; Zhang, Jinchuan; Fu, Guangsheng

    2008-11-01

    Effect of Al-N codoping ratio on the conducting and optical properties of ZnO films deposited by helicon wave plasma assisted radio frequency magnetron sputtering under various N2 gas flow is investigated. Hall measurements show that p-type ZnO thin films have been achieved with proper N2 flow rate. X-ray diffraction patterns indicate that all the films are highly c-axis oriented. Room temperature photoluminescence spectra show a strong near-band-edge emission. With increasing N doping, the intensity of the emission behaves an increased and then decreased trend while the full width at half maximum is narrowed and then widened. In addition, photoluminescence spectrum at 77 K in the p-type ZnO film with the highest hole concentration show a much stronger peak near 3.32 eV (due to N related neutral acceptor bound excitons), than at 3.36 eV (neutral donor bound excitons), and the acceptor energy level is estimated to be 186 meV.

  5. ZnO THIN FILMS PREPARED BY SPRAY-PYROLYSIS TECHNIQUE FROM ORGANO-METALLIC PRECURSOR

    Directory of Open Access Journals (Sweden)

    Martin Mikulics

    2012-07-01

    Full Text Available Presented experiments utilize methanolic solution of zinc acetyl-acetonate as a precursor and sapphire (001 as a substrate for deposition of thin films of ZnO. The X-ray diffraction analysis revealed polycrystalline character of prepared films with preferential growth orientation along c-axis. The roughness of prepared films was assessed by AFM microscopy and represented by roughness root mean square (RMS value in range of 1.8 - 433 nm. The surface morphology was mapped by scanning electron microscopy showing periodical structure with several local defects. The optical transmittance spectrum of ZnO films was measured in wavelength range of 200-1000 nm. Prepared films are transparent in visible range with sharp ultra-violet cut-off at approximately 370 nm. Raman spectroscopy confirmed wurtzite structure and the presence of compressive stress within its structure as well as the occurrence of oxygen vacancies. The four-point Van der Pauw method was used to study the transport prosperities. The resistivity of presented ZnO films was found 8 × 10–2 Ω cm with carrier density of 1.3 × 1018 cm–3 and electron mobility of 40 cm2 V–1 s–1.

  6. Growth of transparent conducting nanocrystalline Al doped ZnO thin films by pulsed laser deposition

    Science.gov (United States)

    Shukla, R. K.; Srivastava, Anchal; Srivastava, Atul; Dubey, K. C.

    2006-09-01

    Nanocrystalline thin films of Al doped ZnO (Al:0-5 at%) with low electrical resistivity and high optical transparency have been grown by pulsed laser deposition. X-ray diffraction patterns showed the presence of hexagonal wurtzite ZnO phase with strong c-axis orientation in all the cases. The c-axis lattice parameter was found to increase with increase in Al doping. The average grain size in the film decreases from ˜38 to ˜25 nm with increasing Al concentration from 0 to 5 at%. For a critical doping of 2 at%, the resistivity of the AZO film is minimum (6×10 -4 Ω-cm) and the average optical transparency is nearly 85%. The band gap increases with increase in doping which is in accordance to Burstein-Moss shift. A blue shift in the absorption edge of ZnO with increasing Al concentration in the film is noteworthy as it leads to increase in the width of the transmission window.

  7. Synthesis and characterization of hydrothermally grown zinc oxide (ZnO) nanorods for optical waveguide application

    Science.gov (United States)

    Pandey, Chandan A.; Rahim, Rafis; Manjunath, S.; Hornyak, Gabor L.; Mohammed, Waleed S.

    2015-07-01

    We report a simple method to synthesize Zinc oxide nanorods, grown without using catalysis with less complicity. This was done by hydrothermal treatment of zinc nitrate and hexamine at 90°C and various times (5- 20h) and also we find that the nanorod size and shape depends on heating rate, temperature and heating time. ZnO nanorods have been investigated for their light guiding ability and their effective index of refraction for use in near air index optical systems by developing a ridge waveguide structure. ZnO nanorod waveguides (100 μm w x 2.5 μm h x 1mm l) were grown on a seeded glass substrate template using hydrothermal process at 90°C. Modification of the substrate surface in order to obtain dense perpendicularly-oriented ordered nanorods induced selective growth. These structures were characterized by SEM, EDX, and XRD. The guiding property, i.e. locally excited photoluminescence propagation along the length of the waveguide, was analyzed with imageprocessing program in MATLAB. Following application of a fiber optic white light source on the ZnO nanostructure, we found that light propagation occurred within the glass substrate. No such propagation occurred if light was applied on uncoated areas of the glass. Modeling of waveguide behavior to determine the number propagating modes was exercised using waveguide mode solver in COMSOL.

  8. Microscopic characteristics of the Ag(111)/ZnO(0001) interface present in optical coatings

    Science.gov (United States)

    Lin, Zheshuai; Bristowe, Paul D.

    2007-05-01

    A first-principles computational method is used to investigate the microscopic properties of the Ag(111)/ZnO(0001) interface that is often present in optical coatings designed for solar-control windows. The mechanical stability of the interface is important and therefore the ideal work of separation has been calculated for several structural variants of the interface which have different lattice mismatches and in-plane orientations. The process by which silver atoms are deposited, cluster, and form layers on the ZnO(0001) surface has also been studied. It is found that interfaces with the O-terminated ZnO surface are stronger than those with the Zn-terminated surface. In addition, incoherent interfaces with small lattice mismatch and minimal strain are preferred. In particular, the large period (9×8) Ag/ZnO coincidence superstructure (0.1% mismatch) is found to have a significantly higher work of separation than the coherent (1×1) interface (11% mismatch). A rotated variant of the interface (2×√3) R30 (2.6% mismatch) has a work of separation that is comparable with the coincidence superstructure. Both the (9×8) and (2×√3) R30 Ag/ZnO interfaces have been observed in deposition experiments and which one is seen depends on the ambient conditions and strain state of the interface. The calculated works of separation are consistent with measured works of adhesion obtained from cantilever beam experiments.

  9. Photoelectrocatrocatalytic hydrolysis of starch by using sprayed ZnO thin films

    Science.gov (United States)

    Sapkal, R. T.; Shinde, S. S.; Rajpure, K. Y.; Bhosale, C. H.

    2013-05-01

    Thin films of zinc oxide have been deposited onto glass/FTO substrates at optimized 400 °C by using a chemical spray pyrolysis technique. Deposited films are character photocatalytic activity by using XRD, an SEM, a UV-vis spectrophotometer, and a PEC single-cell reactor. Films are polycrystalline and have a hexagonal (wurtzite) crystal structure with c-axis (002) orientation growth perpendicular to the substrate surface. The observed direct band gap is about 3.22 eV for typical films prepared at 400 °C. The photocatalytic activity of starch with a ZnO photocatalyst has been studied by using a novel photoelectrocatalytic process.

  10. Hybrid ZnO/phthalocyanine photovoltaic device with highly resistive ZnO intermediate layer.

    Science.gov (United States)

    Izaki, Masanobu; Chizaki, Ryo; Saito, Takamasa; Murata, Kazufumi; Sasano, Junji; Shinagawa, Tsutomu

    2013-10-09

    We report a hybrid photovoltaic device composed of a 3.3 eV bandgap zinc oxide (ZnO) semiconductor and metal-free phthalocyanine layers and the effects of the insertion of the highly resistive ZnO buffer layer on the electrical characteristics of the rectification feature and photovoltaic performance. The hybrid photovoltaic devices have been constructed by electrodeposition of the 300 nm thick ZnO layer in a simple zinc nitrate aqueous solution followed by vacuum evaporation of 50-400 nm thick-phthalocyanine layers. The ZnO layers with the resistivity of 1.8 × 10(3) and 1 × 10(8) Ω cm were prepared by adjusting the cathodic current density and were installed into the hybrid photovoltaic devices as the n-type and buffer layer, respectively. The phthalocyanine layers with the characteristic monoclinic lattice showed a characteristic optical absorption feature regardless of the thickness, but the preferred orientation changed depending on the thickness. The ZnO buffer-free hybrid 50 nm thick phthalocyanine/n-ZnO photovoltaic device showed a rectification feature but possessed a poor photovoltaic performance with a conversion efficiency of 7.5 × 10(-7) %, open circuit voltage of 0.041 V, and short circuit current density of 8.0 × 10(-5) mA cm(-2). The insertion of the ZnO buffer layer between the n-ZnO and phthalocyanine layers induced improvements in both the rectification feature and photovoltaic performance. The excellent rectification feature with a rectification ratio of 3188 and ideally factor of 1.29 was obtained for the hybrid 200 nm thick phthalocyanine/ZnO buffer/n-ZnO photovoltaic device, and the hybrid photovoltaic device possessed an improved photovoltaic performance with the conversion efficiency of 0.0016%, open circuit voltage of 0.31 V, and short circuit current density of 0.015 mA cm(-2).

  11. Effect of N2O-doped buffer layer on the optical properties of ZnO films grown on glass substrates using high-energy H2O generated by catalytic reaction

    Science.gov (United States)

    Kanauchi, Shingo; Ohashi, Yuki; Ohishi, Koichiro; Katagiri, Hironori; Tamayama, Yasuhiro; Kato, Takahiro; Yasui, Kanji

    2016-02-01

    Improvement in the optical properties of ZnO films grown on glass substrates was investigated using a N2O-doped buffer layer inserted between the glass substrate and a ZnO film deposited by chemical vapor deposition (CVD). ZnO films were grown at 773 K using dimethylzinc (DMZn) and high-temperature H2O generated by catalytic reaction as zinc and oxygen sources, respectively. Crystal growth was enhanced for the ZnO film grown on the N2O-doped buffer layer, and the fluctuation in crystal orientation along the c-axis became less than that for a film grown directly on the glass substrate by CVD. The optical transmittance of the film in the wavelength range of 375-700 nm also increased with insertion of the buffer layer.

  12. Synthesis of ZnO Hexagonal Micro Discs on Glass Substrates Using the Spray Pyrolysis Technique

    Science.gov (United States)

    Ikhmayies, Shadia J.; Zbib, Mohamad B.

    2017-07-01

    Zinc oxide (ZnO) is an important transparent conducting oxide of potential use in solar cells, electronics, photoelectronics, and sensors. In this work ZnO micro discs were synthesized in thin film form on glass substrates using the low cost spray pyrolysis method. The films were prepared from a precursor solution of ZnCl2 in distilled water at a substrate temperature of 300 ± 5°C. The as-synthesized samples were analyzed with x-ray diffraction, scanning electron microscopy, and x-ray energy dispersive spectroscopy (EDS). The morphology of the films showed randomly distributed micro discs of hexagonal shape. The EDS reports showed that the films contained Cl and Fe. Size analysis was performed using ImageJ software, where the average diameter was found to be 4.8 ± 0.9 μm, and the average thickness was found to be 254 ± 43 nm.

  13. Reducing ZnO nanoparticles toxicity through silica coating.

    Science.gov (United States)

    Chia, Sing Ling; Leong, David Tai

    2016-10-01

    ZnO NPs have good antimicrobial activity that can be utilized as agents to prevent harmful microorganism growth in food. However, the use of ZnO NPs as food additive is limited by the perceived high toxicity of ZnO NPs in many earlier toxicity studies. In this study, surface modification by silica coating was used to reduce the toxicity of ZnO NPs by significantly reducing the dissolution of the core ZnO NPs. To more accurately recapitulate the scenario of ingested ZnO NPs, we tested our as synthesized ZnO NPs in ingestion fluids (synthetic saliva and synthetic gastric juice) to determine the possible forms of ZnO NPs in digestive system before exposing the products to colorectal cell lines. The results showed that silica coating is highly effective in reducing toxicity of ZnO NPs through prevention of the dissociation of ZnO NPs to zinc ions in both neutral and acidic condition. The silica coating however did not alter the desired antimicrobial activity of ZnO NPs to E. coli and S. aureus. Thus, silica coating offered a potential solution to improve the biocompatibility of ZnO NPs for applications such as antimicrobial agent in foods or food related products like food packaging. Nevertheless, caution remains that high concentration of silica coated ZnO NPs can still induce undesirable cytotoxicity to mammalian gut cells. This study indicated that upstream safer-by-design philosophy in nanotechnology can be very helpful in a product development.

  14. Reducing ZnO nanoparticles toxicity through silica coating

    Directory of Open Access Journals (Sweden)

    Sing Ling Chia

    2016-10-01

    Full Text Available ZnO NPs have good antimicrobial activity that can be utilized as agents to prevent harmful microorganism growth in food. However, the use of ZnO NPs as food additive is limited by the perceived high toxicity of ZnO NPs in many earlier toxicity studies. In this study, surface modification by silica coating was used to reduce the toxicity of ZnO NPs by significantly reducing the dissolution of the core ZnO NPs. To more accurately recapitulate the scenario of ingested ZnO NPs, we tested our as synthesized ZnO NPs in ingestion fluids (synthetic saliva and synthetic gastric juice to determine the possible forms of ZnO NPs in digestive system before exposing the products to colorectal cell lines. The results showed that silica coating is highly effective in reducing toxicity of ZnO NPs through prevention of the dissociation of ZnO NPs to zinc ions in both neutral and acidic condition. The silica coating however did not alter the desired antimicrobial activity of ZnO NPs to E. coli and S. aureus. Thus, silica coating offered a potential solution to improve the biocompatibility of ZnO NPs for applications such as antimicrobial agent in foods or food related products like food packaging. Nevertheless, caution remains that high concentration of silica coated ZnO NPs can still induce undesirable cytotoxicity to mammalian gut cells. This study indicated that upstream safer-by-design philosophy in nanotechnology can be very helpful in a product development.

  15. ALD grown nanostructured ZnO thin films: Effect of substrate temperature on thickness and energy band gap

    Directory of Open Access Journals (Sweden)

    Javed Iqbal

    2016-10-01

    Full Text Available Nanostructured ZnO thin films with high transparency have been grown on glass substrate by atomic layer deposition at various temperatures ranging from 100 °C to 300 °C. Efforts have been made to observe the effect of substrate temperature on the thickness of the deposited thin films and its consequences on the energy band gap. A remarkably high growth rate of 0.56 nm per cycle at a substrate temperature of 200 °C for ZnO thin films have been achieved. This is the maximum growth rate for ALD deposited ZnO thin films ever reported so far to the best of our knowledge. The studies of field emission scanning electron microscopy and X-ray diffractometry patterns confirm the deposition of uniform and high quality nanosturtured ZnO thin films which have a polycrystalline nature with preferential orientation along (100 plane. The thickness of the films deposited at different substrate temperatures was measured by ellipsometry and surface profiling system while the UV–visible and photoluminescence spectroscopy studies have been used to evaluate the optical properties of the respective thin films. It has been observed that the thickness of the thin film depends on the substrate temperatures which ultimately affect the optical and structural parameters of the thin films.

  16. Large-scale uniform ZnO tetrapods on catalyst free glass substrate by thermal evaporation method

    Energy Technology Data Exchange (ETDEWEB)

    Alsultany, Forat H., E-mail: foratusm@gmail.com [School of Physics, USM, 11800 Penang (Malaysia); Hassan, Z. [Institute of Nano-Optoelectronics Research and Technology Laboratory (INOR), USM, 11800 Penang (Malaysia); Ahmed, Naser M. [School of Physics, USM, 11800 Penang (Malaysia)

    2016-07-15

    Highlights: • Investigate the growth of ZnO-Ts on glass substrate by thermal evaporation method. • Glass substrate without any catalyst or a seed layer. • The morphology was controlled by adjusting the temperature of the material and the substrate. • Glass substrate was placed vertically in the quartz tube. - Abstract: Here, we report for the first time the catalyst-free growth of large-scale uniform shape and size ZnO tetrapods on a glass substrate via thermal evaporation method. Three-dimensional networks of ZnO tetrapods have needle–wire junctions, an average leg length of 2.1–2.6 μm, and a diameter of 35–240 nm. The morphology and structure of ZnO tetrapods were investigated by controlling the preparation temperature of each of the Zn powder and the glass substrate under O{sub 2} and Ar gases. Studies were carried out on ZnO tetrapods using X-ray diffraction, field emission scanning electron microscopy, UV–vis spectrophotometer, and a photoluminescence. The results showed that the sample grow in the hexagonal wurtzite structure with preferentially oriented along (002) direction, good crystallinity and high transmittance. The band gap value is about 3.27 eV. Photoluminescence spectrum exhibits a very sharp peak at 378 nm and a weak broad green emission.

  17. Effect of growth time on Ti-doped ZnO nanorods prepared by low-temperature chemical bath deposition

    Science.gov (United States)

    Bidier, Shaker A.; Hashim, M. R.; Al-Diabat, Ahmad M.; Bououdina, M.

    2017-04-01

    Ti-doped ZnO nanorod arrays were grown onto Si substrate using chemical bath deposition (CBD) method at 93 °C. To investigate the effect of time deposition on the morphological, and structural properties, four Ti-doped ZnO samples were prepared at various deposition periods of time (2, 3.5, 5, and 6.5 h). FESEM images displayed high-quality and uniform nanorods with a mean length strongly dependent upon deposition time; i.e. it increases for prolonged growth time. Additionally, EFTEM images reveal a strong erosion on the lateral side for the sample prepared for 6.5 h as compared to 5 h. This might be attributed to the dissolution reaction of ZnO with for prolonged growth time. XRD analysis confirms the formation of a hexagonal wurtzite-type structure for all samples with a preferred growth orientation along the c-axis direction. The (100) peak intensity was enhanced and then quenched, which might be the result of an erosion on the lateral side of nanorods as seen in EFTEM. This study confirms the important role of growth time on the morphological features of Ti-doped ZnO nanorods prepared using CBD.

  18. Effect of ZnO core electrodeposition conditions on electrochemical and photocatalytic properties of polypyrrole-graphene oxide shelled nanoarrays

    Science.gov (United States)

    Pruna, A.; Shao, Q.; Kamruzzaman, M.; Li, Y. Y.; Zapien, J. A.; Pullini, D.; Busquets Mataix, D.; Ruotolo, A.

    2017-01-01

    Novel hybrid core-shell nanoarchitectures were fabricated by a simple two-step electrochemical approach: first ZnO nanorod core was electrodeposited from Zn(NO3)2 solution; further, the core nanoarray was coated with a shell based on polypyrrole hybridized with graphene oxide by electropolymerization. The properties of the core/shell nanoarchitectures were studied as a function of the core properties induced by electrodeposition parameters. The ZnO nanostructures showed improved crystallinity and c-axis preferred orientation with increasing cathodic deposition potential while the increased deposition duration resulted in a morphology transition from nanorod to pyramidal shape. The electrochemical activity of the core/shell arrays was found to increase with the deposition potential of ZnO core but decreased when morphology changed from nanorod to pyramid shape. The photocatalytic results showed improved activity for the core/hybrid shell nanoarrays with respect to ZnO and ZnO/PPy ones. The degradation rate for methylene blue decreased with prolonged deposition duration of the core. The obtained results highlight the importance of electrochemical tuning of ZnO-based core/shell nanoarrays for improved performance in electrochemical and photocatalytic applications.

  19. The characterization of Cu-doped ZnO thin films prepared by using radio-frequency reactive magnetron sputtering

    Science.gov (United States)

    Cai, Chaoqun; Zhang, Hongqiang; Xie, Jun; Ma, Ligang

    2017-05-01

    Textured zinc-oxide (ZnO) thin films and Cu-doped ZnO (ZnO:Cu) thin films are deposited on glass substrates by using radio-frequency reactive magnetron sputtering. The effect of Cu-doping concentration on the crystallization behavior, surface morphology, transmission spectrum, and luminescence properties of the ZnO thin films are systematically investigated by using X-ray diffraction, scanning probe microscopy and photoluminescence spectra. The results indicate that the crystallization quality, morphology, transmission, and luminescence of the ZnO films is affected by Cu-element doping. A stronger preferred orientation toward the c-axis is obtained after Cu doping at an appropriate concentration (3%). The transmittance rate gradually decreases with increasing Cu doping concentration. In the photoluminescence spectra of the samples measured at room temperature, four main emission peaks are observed: a violet peak located at about 390 nm, two blue peaks, one located at about 445 nm and the other at about 485 nm, and a green peak located at about 527 nm. The origins of these emissions are discussed in detail.

  20. Fabrication of Ag/ZnO heterostructure and the role of surface coverage of ZnO microrods by Ag nanoparticles on the photophysical and photocatalytic properties of the metal-semiconductor system

    Energy Technology Data Exchange (ETDEWEB)

    Sarma, Bikash; Sarma, Bimal K., E-mail: sarmabimal@gmail.com

    2017-07-15

    Highlights: • Fabrication of Ag/ZnO heterostructure by facile chemical processes. • Decoration of plasmonic Ag nanoparticles on ZnO microrods through direct attachment. • Quenching of photoluminescence is observed in Ag/ZnO heterostructure. • Extent of surface coverage governs photophysical and photochemical properties. - Abstract: This report presents findings on microstructural, photophysical, and photocatalytic properties of Ag/ZnO heterostructure grown on flexible and silicon substrates. ZnO microrods are prepared by thermal decomposition method for different solute concentrations and Ag/ZnO heterostructure are fabricated by photo-deposition of Ag nanoparticles on ZnO microrods. X-ray diffraction and electron microscopy studies confirm that ZnO microrods belong to the hexagonal wurtzite structure and grown along [001] direction with random alignment showing that majority microrods are aligned with (100) face parallel to the sample surface. Plasmonic Ag nanoparticles are attached to different faces of ZnO. In the optical reflection spectra of Ag/ZnO heterostructure, the surface plasmon resonance peak due to Ag nanoparticles appears at 445 nm. Due to the oxygen vacancies the band gaps of ZnO microrods turn out to be narrower compared to that of bulk ZnO. The presence of Ag nanoparticles decreases the photoluminescence intensity which might be attributed to the non-radiative energy and direct electron transfer in the plasmon–exciton system. The quenching of photoluminescence in Ag/ZnO heterostructure at different growth conditions depend on the extent of surface coverage of ZnO by plasmonic Ag nanoparticles. Photocatalytic degradation efficiency of Ag/ZnO heterostructure is higher than that of ZnO microrods. The extent of surface coverage of ZnO microrods by Ag nanoparticles is crucial for the observed changes in photophysical and photochemical properties.

  1. Orienteering club

    CERN Multimedia

    Club d'orientation

    2011-01-01

    Reprise fin août Le Club d’orientation, en partenariat avec d’autres clubs de la région, vous propose une nouvelle série de courses pour cet automne. Le calendrier à retenir est le suivant : Samedi 27 août : Granges Malval (GE) – type classique Samedi 10 septembre : Lamoura (39) – type classique Samedi 17 septembre : La Dôle (F/VD) – type classique Samedi 24 septembre : Monteret (VD) – relais Samedi 8 octobre : Saint Cergue (VD) – type classique Vendredi 14 octobre : Les Evaux (GE) – nocturne Samedi 15 octobre : Grand Jorat (VD) – type classique Samedi 22 octobre : Pomier (74) – type classique Samedi 5 novembre : Echallens (VD) – type classique Samedi 12 novembre : CERN (GE) - sprint - Finale Généralement cinq circuits sont disponibles : ceci va du facile court (2 km) adapt&eacu...

  2. Orienting hypnosis.

    Science.gov (United States)

    Hope, Anna E; Sugarman, Laurence I

    2015-01-01

    This article presents a new frame for understanding hypnosis and its clinical applications. Despite great potential to transform health and care, hypnosis research and clinical integration is impaired in part by centuries of misrepresentation and ignorance about its demonstrated efficacy. The authors contend that advances in the field are primarily encumbered by the lack of distinct boundaries and definitions. Here, hypnosis, trance, and mind are all redefined and grounded in biological, neurological, and psychological phenomena. Solutions are proposed for boundary and language problems associated with hypnosis. The biological role of novelty stimulating an orienting response that, in turn, potentiates systemic plasticity forms the basis for trance. Hypnosis is merely the skill set that perpetuates and influences trance. This formulation meshes with many aspects of Milton Erickson's legacy and Ernest Rossi's recent theory of mind and health. Implications of this hypothesis for clinical skills, professional training, and research are discussed.

  3. Orientation games in kindergarten

    OpenAIRE

    Pišek, Anja

    2012-01-01

    The thesis presents the area of general orientation and orientation of the child. The focus is placed on orientation games for preschool children. The first part outlines different definitions of orientation, types of orientation, accessories for orientation and major errors in orientation. It also presents the development of spatial orientation of preschool children, the development of the concept of space according to the level of cognitive development in line with the theory by Piaget,...

  4. Development of Room Temperature Excitonic Lasing From ZnO and MgZnO Thin Film Based Metal-Semiconductor-Metal Devices

    Science.gov (United States)

    Suja, Mohammad Zahir Uddin

    Room temperature excitonic lasing is demonstrated and developed by utilizing metal-semiconductor-metal devices based on ZnO and MgZnO materials. At first, Cu-doped p-type ZnO films are grown on c-sapphire substrates by plasma-assisted molecular beam epitaxy. Photoluminescence (PL) experiments reveal a shallow acceptor state at 0.15 eV above the valence band edge. Hall effect results indicate that a growth condition window is found for the formation of p-type ZnO thin films and the best conductivity is achieved with a high hole concentration of 1.54x1018 cm-3, a low resistivity of 0.6 O cm and a moderate mobility of 6.65 cm2 V -1 s-1 at room temperature. Metal oxide semiconductor (MOS) capacitor devices have been fabricated on the Cu-doped ZnO films and the characteristics of capacitance-voltage measurements demonstrate that the Cu-doped ZnO thin films under proper growth conditions are p-type. Seebeck measurements on these Cu-doped ZnO samples lead to positive Seebeck coefficients and further confirm the p-type conductivity. Other measurements such as XRD, XPS, Raman and absorption are also performed to elucidate the structural and optical characteristics of the Cu-doped p-type ZnO films. The p-type conductivity is explained to originate from Cu substitution of Zn with a valency of +1 state. However, all p-type samples are converted to n-type over time, which is mostly due to the carrier compensation from extrinsic defects of ZnO. To overcome the stability issue of p-type ZnO film, alternate devices other than p-n junction has been developed. Electrically driven plasmon-exciton coupled random lasing is demonstrated by incorporating Ag nanoparticles on Cu-doped ZnO metal-semiconductor-metal (MSM) devices. Both photoluminescence and electroluminescence studies show that emission efficiencies have been enhanced significantly due to coupling between ZnO excitons and Ag surface plasmons. With the incorporation of Ag nanoparticles on ZnO MSM structures, internal quantum

  5. EDITORIAL: Optical orientation Optical orientation

    Science.gov (United States)

    SAME ADDRESS *, Yuri; Landwehr, Gottfried

    2008-11-01

    priority of the discovery in the literature, which was partly caused by the existence of the Iron Curtain. I had already enjoyed contact with Boris in the 1980s when the two volumes of Landau Level Spectroscopy were being prepared [2]. He was one of the pioneers of magneto-optics in semiconductors. In the 1950s the band structure of germanium and silicon was investigated by magneto-optical methods, mainly in the United States. No excitonic effects were observed and the band structure parameters were determined without taking account of excitons. However, working with cuprous oxide, which is a direct semiconductor with a relative large energy gap, Zakharchenya and his co-worker Seysan showed that in order to obtain correct band structure parameters, it is necessary to take excitons into account [3]. About 1970 Boris started work on optical orientation. Early work by Hanle in Germany in the 1920s on the depolarization of luminescence in mercury vapour by a transverse magnetic field was not appreciated for a long time. Only in the late 1940s did Kastler and co-workers in Paris begin a systematic study of optical pumping, which led to the award of a Nobel prize. The ideas of optical pumping were first applied by Georges Lampel to solid state physics in 1968. He demonstrated optical orientation of free carriers in silicon. The detection method was nuclear magnetic resonance; optically oriented free electrons dynamically polarized the 29Si nuclei of the host lattice. The first optical detection of spin orientation was demonstrated by with the III-V semiconductor GaSb by Parsons. Due to the various interaction mechanisms of spins with their environment, the effects occurring in semiconductors are naturally more complex than those in atoms. Optical detection is now the preferred method to detect spin alignment in semiconductors. The orientation of spins in crystals pumped with circularly polarized light is deduced from the degree of circular polarization of the recombination

  6. Growth of a Novel Nanostructured ZnO Urchin: Control of Cytotoxicity and Dissolution of the ZnO Urchin.

    Science.gov (United States)

    Imani, Roghayeh; Drašler, Barbara; Kononenko, Veno; Romih, Tea; Eleršič, Kristina; Jelenc, Janez; Junkar, Ita; Remškar, Maja; Drobne, Damjana; Kralj-Iglič, Veronika; Iglič, Aleš

    2015-12-01

    The applications of zinc oxide (ZnO) nanowires (NWs) in implantable wireless devices, such as diagnostic nanobiosensors and nanobiogenerators, have recently attracted enormous attention due to their unique properties. However, for these implantable nanodevices, the biocompatibility and the ability to control the behaviour of cells in contact with ZnO NWs are demanded for the success of these implantable devices, but to date, only a few contrasting results from their biocompatibility can be found. There is a need for more research about the biocompatibility of ZnO nanostructures and the adhesion and viability of cells on the surface of ZnO nanostructures. Here, we introduce synthesis of a new nature-inspired nanostructured ZnO urchin, with the dimensions of the ZnO urchin's acicula being controllable. To examine the biocompatibility and behaviour of cells in contact with the ZnO urchin, the Madin-Darby canine kidney (MDCK) epithelial cell line was chosen as an in vitro experimental model. The results of the viability assay indicated that, compared to control, the number of viable cells attached to the surface of the ZnO urchin and its surrounding area were reduced. The measurements of the Zn contents of cell media confirmed ZnO dissolution, which suggests that the ZnO dissolution in cell culture medium could lead to cytotoxicity. A purposeful reduction of ZnO cytotoxicity was achieved by surface coating of the ZnO urchin with poly(vinylidene fluorid-co-hexafluoropropylene) (PVDF-HFP), which changed the material matrix to slow the Zn ion release and consequently reduce the cytotoxicity of the ZnO urchin without reducing its functionality.

  7. Heteroepitaxial Patterned Growth of Vertically Aligned and Periodically Distributed ZnO Nanowires on GaN Using Laser Interference Ablation

    KAUST Repository

    Yuan, Dajun

    2010-08-23

    A simple two-step method of fabricating vertically aligned and periodically distributed ZnO nanowires on gallium nitride (GaN) substrates is described. The method combines laser interference ablation (LIA) and low temperature hydrothermal decomposition. The ZnO nanowires grow heteroepitaxially on unablated regions of GaN over areas spanning 1 cm2, with a high degree of control over size, orientation, uniformity, and periodicity. High resolution transmission electron microscopy and scanning electron microscopy are utilized to study the structural characteristics of the LIA-patterned GaN substrate in detail. These studies reveal the possible mechanism for the preferential, site-selective growth of the ZnO nanowires. The method demonstrates high application potential for wafer-scale integration into sensor arrays, piezoelectric devices, and optoelectronic devices. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. High Temperature Thermoelectric Properties of ZnO Based Materials

    DEFF Research Database (Denmark)

    Han, Li

    This thesis investigated the high temperature thermoelectric properties of ZnO based materials. The investigation first focused on the doping mechanisms of Al-doped ZnO, and then the influence of spark plasma sintering conditions on the thermoelectric properties of Al, Ga-dually doped ZnO....... Following that, the nanostructuring effect for Al-doped ZnO was systematically investigated using samples with different microstructure morphologies. At last, the newly developed ZnCdO materials with superior thermoelectric properties and thermal stability were introduced as promising substitutions...... for conventional ZnO materials. For Al-doped ZnO, α- and γ-Al2O3 were selectively used as dopants in order to understand the doping mechanism of each phase and their effects on the thermoelectric properties. The samples were prepared by the spark plasma sintering technique from precursors calcined at various...

  9. Strain effects on valence bands of wurtzite ZnO

    Science.gov (United States)

    Qiao, LiPing; Chai, ChangChun; Jin, Zhao; Yang, YinTang; Ma, ZhenYang

    2013-09-01

    Based on the k.p theory of Luttinger-Kohn and Bir-Pikus, analytical E-k solutions for the valence band of strained wurtzite ZnO materials are obtained. Strain effects on valence band edges and hole effective masses in strained wurtzite ZnO materials are also discussed. In comparison with unstrained ZnO materials, apparent movement of valence band edges such as "light hole band", "heavy hole band" and "crystal splitting band" at Γ point is found in strained wurtzite ZnO materials. Moreover, effective masses of "light hole band", "heavy hole band" and "crystal splitting band" for strained wurtzite ZnO materials as the function of stress are given. The analytical results can provide a theoretical foundation for the understanding of physics of strained ZnO materials and its applications with the framework for an effective mass theory.

  10. Optical, electrical and structural properties of nano-pyramidal ZnO films grown on glass substrate by spray pyrolysis technique

    Science.gov (United States)

    Bedia, A.; Bedia, F. Z.; Aillerie, M.; Maloufi, N.; Ould Saad Hamady, S.; Perroud, O.; Benyoucef, B.

    2014-05-01

    Optical, electrical and structural properties of ZnO nano-pyramidal films, synthesized by chemical spray pyrolysis technique on glass substrates were investigated. A complete set of structural, optical and electrical parameters is proposed in this contribution. ZnO films possess polycrystalline wurtzite structure showing a preferential orientation along the c-axis as confirmed by XRD measurements. The structure has been investigated by using Raman spectroscopy, at 532 nm excitation source and the morphology is characterized by scanning electron microscopy (SEM). Link to the specific growing parameters, the morphology of the so-obtained films is rarely observed in nanostructures family with a diameter of ZnO hexagonal nano-pyramids in the range of 50-150 nm smaller than this usually obtained by spray pyrolysis. The strong peaks of the E2 Raman mode at 99.3 cm-1 (low) and 439.4 cm-1 (high), indicate a good crystal quality of the ZnO nano-pyramids. The existence of a compressive stress in the ZnO structure was pointed out by Raman scattering and estimated by XRD measurements. High optical transmittance value of the film above 90% in the visible region was observed and the optical band gap was found to be 3.273 eV at room temperature. The photoluminescence (PL) spectrum of ZnO hexagonal pyramid shows an intensity ratio of the UV emission to the visible band more than 20. By electrical characterizations of the ZnO films, we obtained the values of the resistivity and Hall mobility equal to 17 Ω cm and 8.49 cm2 V-1 s-1, respectively.

  11. ZnO dense nanowire array on a film structure in a single crystal domain texture for optical and photoelectrochemical applications

    Science.gov (United States)

    Zhong, Miao; Sato, Yukio; Kurniawan, Mario; Apostoluk, Aleksandra; Masenelli, Bruno; Maeda, Etsuo; Ikuhara, Yuichi; Delaunay, Jean-Jacques

    2012-12-01

    A single crystal domain texture quality (a unique in-plane and out-of-plane crystalline orientation over a large area) ZnO nanostructure of a dense nanowire array on a thick film has been homogeneously synthesized on a-plane sapphire substrates over large areas through a one-step chemical vapor deposition (CVD) process. The growth mechanism is clarified: a single crystal [0\\bar {2}1] oriented ZnAl2O4 buffer layer was formed at the ZnO film and the a-plane sapphire substrate interface via a diffusion reaction process during the CVD process, providing improved epitaxial conditions that enable the synthesis of the high crystalline quality ZnO nanowire array on a film structure. The high optoelectronic quality of the ZnO nanowire array on a film sample is evidenced by the free exitonic emissions in the low-temperature photoluminescence spectroscopy. A carrier density of ˜1017 cm-3 with an n-type conductivity of the ZnO nanowire array on a film sample is obtained by electrochemical impedance analysis. Finally, the ZnO nanowire array on a film sample is demonstrated to be an ideal template for a further synthesis of a single crystal quality ZnO-ZnGa2O4 core-shell nanowire array on a film structure. The fabricated ZnO-ZnGa2O4 sample revealed an enhanced anticorrosive ability and photoelectrochemical performance when used as a photoanode in a photoelectrochemical water splitting application.

  12. Synthesis and Optical Properties of ZnO Nanostructures

    OpenAIRE

    Li-li YANG

    2008-01-01

    One-dimensional ZnO nanostructures have great potential applications in the fields of optoelectronic and sensor devices. Therefore, it is really important to realize the controllable growth of one-dimensional ZnO nanostructures and investigate their properties. The main points for this thesis are not only to successfully realize the controllable growth of ZnO nonawires, nanorods and quantum dots (QDs), and also investigate the structure and optical properties in detail by the methods of scan ...

  13. Orienteering club

    CERN Multimedia

    Club d'orientation

    2013-01-01

    Courses d’orientation Samedi 20 avril, les organisateurs du Club de CO du CERN ont accueilli au Mont Mourex 70 participants qui n’ont pas hésité à venir malgré la forte bise. Berni Wehrle du CO CERN s’est octroyé la première place en 1:04:49 sur le parcours technique long devant Pyry Kettunen du Saynso Juankoski en 1:06:52, la 3e place revenant à Bruno Barge, CO CERN, à 7 secondes. Les autres parcours ont été remportés par : Technique moyen : 1er Jacques Moisset, Chamonix (47:44), 2e Yves Rousselot, Balise 25 Besançon (57:16), 3e Jean-Bernard Zosso, CO CERN (59:28). Technique court : 1er Victor Kuznetsov, COLJ (51:53), 2e Pierrick Collet, CO CERN (1:12:52), 3e Dominique Balay, CO CERN (1:16:04). Pour les parcours facile moyen et facile court, Ralf Nardini et Léa Nicolas, tous deux du CO CERN, terminaient respectivement premier. Voi...

  14. Orienteering Club

    CERN Multimedia

    Club d'Orientation

    2012-01-01

    Relais inter-club/Challenge Carlo Milan Samedi dernier, lors de l’épreuve de course d’orientation organisée par le club du O’Jura, le moteur de la discipline était l’esprit d’équipe, puisqu’il était question d’un relais inter-club avec le Challenge Carlo Milan. Les clubs avaient aligné leurs coureurs soit sur le relais technique (trois participants) soit sur le relais facile (deux participants). Côté O’Jura, il fallait noter la participation de François Gonon, champion du monde 2011, côté club du CERN, Marie et Gaëtan Vuitton, jeunes espoirs du club, devaient préparer la piste pour lancer le dernier relayeur. Côté Lausanne-Jorat, il fallait compter sur le très jeune Viktor Kuznetsov. Les 31 équipes engagées n’ont pas m&ea...

  15. Orienteering Club

    CERN Multimedia

    Club d'Orientation

    2012-01-01

     Finale de la coupe de printemps   La dernière course d’orientation comptant pour la Coupe de printemps a eu lieu samedi dernier dans le village des Rousses et vers le Fort. Il s’agissait d’un sprint organisé par le club O’Jura. Les temps de course ont avoisiné les 20 minutes que ce soit pour le parcours technique moyen ou technique long. Tous les habitués étaient au rendez-vous pour venir consolider ou améliorer leur place au classement. A l’issue de cette course, le classement général de la Coupe de printemps prenant en compte les 6 meilleurs résultats des 9 courses était établi et les lauréats de chaque catégorie sont les suivants: Circuit technique long : 1er Berni Wehrle, 2e Bruno Barge, 3e Edvins Reisons. Circuit technique moyen : 1er Jean-Bernard Zosso, 2e Cédric Wehrl&...

  16. Orienteering club

    CERN Multimedia

    Club d'orientation

    2013-01-01

    Course d'orientation Vers les dernières courses de printemps Une centaine de coureurs se sont déplacés sur le site de la Roche Fendue prés de Morez pour gouter à un des 5 parcours proposés par le club du O’Jura. Le terrain était gras mais que peut-on trouver d’autre avec cette météo! Les vainqueurs de chaque circuit sont : Alina Niggli (O’Jura) facile court, Natalja Niggli (O’Jura) facile moyen, Victor Kuznetsov (COLJ) technique court, Yves Rousselot (Balise 25) technique moyen et pour finir François Gonon (O’Jura) avec une victoire haut la main sur le technique long. Il ne reste plus que deux épreuves pour la coupe genevoise de printemps : à savoir samedi 8 juin, course de type longue distance organisée par le club de Lausanne Jorat (COLJ) dans le bois de Seyte sur Mutrux/Concise, inscription de 12h &...

  17. Orienteering Club

    CERN Multimedia

    Club d'orientation

    2013-01-01

    Finale de la coupe d’automne La dernière épreuve de la coupe d’automne organisée par le club d’orientation du CERN s’est déroulée ce samedi 2 novembre avec une course au score dans le bois Tollot (GE). Les concurrents disposaient d’un temps imparti pour poinçonner le maximum de balises différemment placées selon le circuit choisi. Juerg Niggli (club O’Jura) a remporté le parcours technique long. A l’issue de cette course, le classement général de la coupe d’automne, basé sur les 6 meilleurs résultats de la saison, est le suivant : Circuit technique long : 1er Juerg Niggli (O’Jura), 2e Bruno Barge, 3e Beat Mueller. Circuit technique moyen : 1er Laurent Merat (O’Jura), 2e Jirden Lennart, 3e Daria Niggli. Circuit technique court : 1er Victor Kuznetsov (COLJ), 2e N...

  18. Orienteering club

    CERN Multimedia

    Club d'orientation

    2014-01-01

    Course d'orientation Finale de la coupe d’automne La dernière épreuve de la coupe d’automne organisée par le club s’est déroulée ce samedi 1er novembre avec une course type «one-man-relay» dans la forêt de Trelex (Vd). Les concurrents des circuits techniques devaient parcourir trois boucles et ceux des circuits «faciles» deux boucles, avec changements de carte. Le parcours technique long a été remporté par un membre du club, Berni Wehrle. A l’issue de cette course, le Président du club, L. Jirden annonçait le classement général de la coupe d’automne, basé sur les 6 meilleurs résultats de la saison : Circuit technique long : 1er Juerg Niggli (O’Jura), 2e Berni Wehrle, 3e Beat Mueller. Circuit technique moyen : 1er Laurent Merat (O&r...

  19. Orienteering club

    CERN Multimedia

    Club d'orientation

    2013-01-01

    Course d'orientation Finale de la coupe genevoise Rapide et méthodique, voilà les qualités dont il fallait faire preuve pour remporter la dernière étape de la coupe organisée par le club du CERN dans les bois de Monteret. Il s’agissait d’une course au score où chaque concurrent disposait d’un temps imparti pour poinçonner le maximum de balises. Le parcours technique a été remporté par Tomas Shellman et le parcours facile par Victor Dannecker. Cette dernière étape était aussi décisive pour la désignation des lauréats de la coupe genevoise de printemps. Les résultats officiels étaient donnés par le président du club, L. Jirden : Circuit Technique Long : Berni Wehrle, Bruno Barge, Edvins Reisons Circuit Technique Moyen : J.-Bernard Zosso, ...

  20. Orienteering club

    CERN Multimedia

    Club d'orientation

    2010-01-01

    COURSE D’ORIENTATION  De La Rippe à Sauvabellin, la coupe genevoise continue ! Le rendez-vous était donné samedi 8 mai aux amateurs de course d’orientation dans les bois de La Rippe (Canton de Vaud). Cette 6e épreuve était organisée par le Club Satus Grutli de Genève. Il est dommage que les participants n’aient pas été aussi nombreux que lors des dernières courses, les Championnats de France des clubs à Dijon ayant certainement retenus plus d’un compétiteur. La première place est revenue à : – Technique long : Berni Wehrle – Technique moyen : Jean-Bernard Zosso – Technique court : Berni Wehrle – Facile moyen : Peter Troscanyi – Facile court : Claire Droz. Il ne restera plus que deux épreuves ...

  1. Orienteering Club

    CERN Multimedia

    Club d'orientation

    2012-01-01

    Finale de la coupe d’automne   La coupe d’automne organisée par le club d’orientation du CERN s’est terminée ce samedi 10 novembre avec une course sprint à Prévessins. C’était la 12e épreuve de la saison. En stage dans la région, Tanya Ryabkina, championne d’Europe en titre et médaillée de bronze en moyenne distance lors des championnats du monde à La Givrine cet été, a fait l’honneur de sa présence et termine 2e à 8 secondes de Trygve Buanes, norvégien du club de Bergen. A l’issue de cette dernière épreuve, le classement général de la coupe d’automne, basé sur les 8 meilleurs résultats de la saison, est ainsi le suivant : Circuit technique long : 1er Jurg Niggli (O&rsqu...

  2. Orienteering Club

    CERN Multimedia

    Club d'Orientation

    2012-01-01

    Course d'orientation Ces deux dernières semaines, le club a organisé la troisième puis la quatrième étape de la coupe de printemps, une dans la forêt de Collogny/Moissey près de Vulbens, l’autre vers le parcours vita de Trélex. Les résultats sont: Facile court Vulbens : 1er Léo Lonchampt, O’Jura (16:04), 2e Timothée Bazin (23:07), 3e Francesco Pieri (26:57) Trélex : 1er Noora Maurent (23:11), 2e Sarah Stuber, COLJ (26:51), 3e T. Bazin (28:17) Facile moyen Vulbens : 1er Victor Kuznetsov, CO CERN (25:36), 2e Didier Descourvières (28:03), 3e Konstantinos Haider, CO CERN (36:53) Trélex : 1er V. Kuznetsov, COLJ (38:01), 2e K. Haider, CO CERN (43:15), 3e ex aequo Olivia Nguyen et Sven Vietmeier (58:11) Technique court Vulbens : 1er Benoit Bazin (41:21), 2e Colas Gintzburger (55:12), 3e Nathan Freydoz (55:48) Trélex : 1...

  3. Orienteering club

    CERN Multimedia

    Club d'orientation

    2014-01-01

    Course d'orientation C’est sous un beau soleil samedi 4 octobre que s’est déroulée la 6e étape de la Coupe genevoise d’automne organisée par le club. Plus d’une centaine de concurrents provenant de 7 clubs de CO avaient fait le déplacement pour courir sur un des cinq parcours proposés dans les bois de Trélex-Génolier (VD). Le podium est le suivant : Technique long (5,9 km, 19 postes) : 1er Jurg Niggli, O’Jura (1:00:02); 2e Berni Wehrle, CO CERN (1:06:44); 3e Konrad Ehrbar, COLJ (1:07:08) Technique moyen (4,8 km, 18 postes) : 1er Christophe Vuitton, CO CERN (54:25); 2e J.B. Zosso, CO CERN (1:01:19); 3e Jeremy Wichoud, COLJ (1:06:21) Technique court (3,8 km, 14 postes) : 1er Julien Vuitton, CO CERN (36:19); 2e Vladimir Kuznetsov, COLJ (48:47); 3e Natalia Niggli, O’Jura (50:38) Facile moyen (3,2 km, 11 postes) : 1ère Alina Niggli, O&...

  4. Orienteering Club

    CERN Multimedia

    Club d'Orientation

    2015-01-01

    Course orientation Finale de la coupe genevoise La série des courses de printemps s’est achevée samedi dernier dans les bois de Bonmont (Vaud) avec une épreuve «one-man-relay» organisée par le club. Le vainqueur du parcours technique  long, Yann Locatelli (Club de Chambéry Savoie) a réalisé les deux boucles comportant 24 balises avec presque 6 minutes d’avance sur le second concurrent Domenico Lepori (Club CARE Vevey). Cette dernière étape était aussi décisive pour la désignation des lauréats de la coupe genevoise de printemps, en comptabilisant les 6 meilleurs résultats sur les 10 épreuves. Le podium officiel était donné par le président du club, L. Jirden, qui profitait de l’occasion pour remercier tous les participants et également tous les...

  5. Orienteering Club

    CERN Multimedia

    Club d'orientation

    2013-01-01

    De jour comme de nuit Les amateurs de course d’orientation ont pu s’en donner à cœur joie ce week-end puisqu’ils avaient la possibilité de courir sur deux épreuves en moins de 24 heures. En effet, le club du CERN organisait une course de nuit aux Evaux et la 7e étape de la coupe genevoise se tenait samedi après-midi dans les bois du Grand Jorat à Savigny. Les vainqueurs pour chaque course sont : Technique long CO de nuit: Julien Charlemagne, SOS Sallanches CO samedi: Philipp Khlebnikov, ANCO   Technique moyen CO de nuit: Céline Zosso, CO CERN CO samedi: Pavel Khlebnikov, ANCO Technique court CO de nuit: Colas Ginztburger, SOS Sallanches CO samedi: Victor Kuznetsov, COLJ Lausannne Facile moyen CO de nuit: Gaëtan Rickenbacher, CO CERN CO samedi: Tamas Szoke   Facile court CO de nuit:Oriane Rickenbacher, CO CERN CO samedi: Katya Kuznetsov...

  6. Orienteering Club

    CERN Document Server

    CLUB D'ORIENTATION

    2013-01-01

    Calendrier de la coupe d’automne Le Club d’orientation du CERN, en partenariat avec d’autres clubs de la région, vous propose, pour cette nouvelle coupe d’automne genevoise, une série de 10 courses. Le club du O’Jura donnera le coup d’envoi le samedi 31 août. Les courses s’enchaîneront selon le calendrier suivant : Samedi 31 août : Prémanon (39) - longue distance Samedi 14 septembre : La Faucille (01) - longue distance Samedi 21 septembre : Saint Cergue (VD) - longue distance Samedi 28 septembre : Ballens (VD) - relais Samedi 5 octobre : La Pile (VD) - longue distance Vendredi 11 octobre : Les Evaux (GE) - nocturne Samedi 12 octobre : Grand Jorat, Savigny (VD) - longue distance Samedi 19 octobre : Terrasses de Genève (74) - longue distance Samedi 26 octobre : Prémanon (39) - longue distance Samedi 2 novembre : Bois Tollot (GE) - score - Finale Les &a...

  7. Orienteering Club

    CERN Multimedia

    Club d'Orientation

    2011-01-01

    Course d'orientation Avec la CO en nocturne organisée par le club du CERN vendredi 14 octobre au stade des Eveaux (Ge), et la CO à Savigny (Vd) proposée par le club de Lausanne-Jorat le lendemain, les étapes de la coupe genevoise d’automne s’enchainent rapidement. Il ne reste plus que 3 rendez-vous pour boucler la saison. Les premières places devraient certainement se jouer entre des membres du club du CERN, du O’Jura ou de Lausanne-Jorat. La prochaine course du club est programmée pour samedi 22 octobre à Pomier, près de Cruseilles. L’accueil se fera à partir de 12h30 et les départs s’échelonneront de 13h à 15h. * * * * * * * Nouvelle belle victoire samedi 8 octobre à Saint Cergue du jeune finlandais Ville Keskisaari (COLJ) en 50:56 devant Jürg Niggli (O’Jura) en 1:03:32, et Alexandre...

  8. Orienteering Club

    CERN Document Server

    Club d'orientation

    2013-01-01

    Course d'orientation Le coup d’envoi de la coupe genevoise a été donné samedi 31 août dans les bois de Combe Froide à Prémanon. Plus de 150 coureurs avaient fait le déplacement. Les parcours facile court, facile moyen et technique court ont été remportés par des coureurs du club O’Jura - Ulysse Dannecker, Léo Lonchampt, Franck Lonchampt, le technique moyen par Pekka Marti du club Ol Biel Seeland et le technique long par Térence Risse du CA Rosé – également membre de l’équipe nationale suisse des moins de 20 ans. Pour le club du CERN, les meilleures résultats ont été obtenus pas Emese Szunyog sur technique court et Marie Vuitton sur technique moyen avec une 4e place. La prochaine course aura lieu samedi 14 septembre à La Faucille. Le club propose aussi...

  9. Indium-doped ZnO nanorods grown on Si (1 1 1) using a hybrid ALD-solvothermal method

    Science.gov (United States)

    Cervantes-López, J. L.; Rangel, R.; García-Méndez, M.; Tiznado, H.; Contreras, O.; Quintana, P.; Bartolo-Pérez, P.; Alvarado-Gil, J. J.

    2017-07-01

    Atomic layer deposition (ALD) followed by microwave hydrothermal processing was successfully employed for producing doped and vertically aligned ZnO nanorod arrays with different aspect ratio. Firstly, a textured ZnO layer with preferential orientation normal to the c-axis was formed on substrate (1 1 1) silicon single crystals by means of the ALD technique. This was achieved through the decomposition of diethylzinc at 190 °C and 3.289  ×  10-4 atm, which provided an adequate template with nucleation sites, favoring further growth of vertical nanorods. Subsequently, nanorod array growth was produced on the same surfaces through solvothermal synthesis using as promoter a solution of Zn(NO3)2. In addition, growth of indium-doped ZnoO nanorods over the substrates was produced by using In(CH3COO)3 as a doping agent. The method presented allows good quality ZnO and Zn1-x In x O thin films to be obtained. Photoluminiscence spectra show clear evidence of the inclusion of indium in the ZnO matrix. The higher intensity ratio Zn0.96In0.4O/ZnO was increased 40-fold, demonstrating such an effect.

  10. Effect of Zn/O contents ratio on the structural, optical and electrical properties of MBE grown ZnO

    Science.gov (United States)

    Asghar, M.; Mahmood, K.; Malik, F.; Rabia, S.; M, Samaa B.; Hasan, M. A.

    2014-06-01

    In this study, the strong dependence of structural, optical and electrical properties of ZnO on the concentration of Zn/O has been observed. Four samples of ZnO with Zn/O-ratio of 1.08, 1.12, 1.17 and 1.22 were grown by molecular beam epitaxy. The x-ray diffraction (XRD) pattern demonstrates that intensity of (002) peak and crystallite size decreases as the Zn/O ratio increases in the samples, suggesting that the crystallinity of the samples degraded. In Raman spectra the Ehigh2 mode shifts towards higher frequency with increasing the concentration of Zn in films. According to electrical measurements, the VO-Zni act as donor defects in ZnO because the carrier concentration increases and resistivity decreases with increasing the Zn/O ratio in the samples.

  11. Fabrication of ZnO nanoparticles by laser ablation of sintered ZnO in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Kawabata, Keisuke; Nanai, Yasushi; Okuno, Tsuyoshi [University of Electro-Communications, Department of Applied Physics and Chemistry, Chofu, Tokyo (Japan); Kimura, Seiji [University of Electro-Communications, The Center for Instrumental Analysis, Chofu, Tokyo (Japan)

    2012-04-15

    Fabrication of ZnO nanoparticles by laser ablation in liquid medium is reported. The possibility of using a sintered ZnO target for the ablation as well as a Zn plate is demonstrated. The appropriate aqueous solution of sodium dodecyl sulfate is found to be 1 mM for ZnO growing. The shape of ZnO nanoparticles is sphere and its diameter is 30{proportional_to}60 nm. Fourier transform infrared spectra, Raman scattering spectra, and photoluminescence spectra reveal the optical properties of ZnO nanoparticles. Nanoparticles obtained by using ZnO targets show a smaller defect density compared with those by using Zn targets. (orig.)

  12. Optical Properties of ZnO Nanoparticles Capped with Polymers

    Directory of Open Access Journals (Sweden)

    Atsushi Noguchi

    2011-06-01

    Full Text Available Optical properties of ZnO nanoparticles capped with polymers were investigated. Polyethylene glycol (PEG and polyvinyl pyrrolidone (PVP were used as capping reagents. ZnO nanoparticles were synthesized by the sol-gel method. Fluorescence and absorption spectra were measured. When we varied the timing of the addition of the polymer to the ZnO nanoparticle solution, the optical properties were drastically changed. When PEG was added to the solution before the synthesis of ZnO nanoparticles, the fluorescence intensity increased. At the same time, the total particle size increased, which indicated that PEG molecules had capped the ZnO nanoparticles. The capping led to surface passivation, which increased fluorescence intensity. However, when PEG was added to the solution after the synthesis of ZnO nanoparticles, the fluorescence and particle size did not change. When PVP was added to the solution before the synthesis of ZnO nanoparticles, aggregation of nanoparticles occurred. When PVP was added to the solution after the synthesis of ZnO nanoparticles, fluorescence and particle size increased. This improvement of optical properties is advantageous to the practical usage of ZnO nanoparticles, such as bioimaging

  13. An organometallic route to chiroptically active ZnO nanocrystals.

    Science.gov (United States)

    Chwojnowska, Elżbieta; Wolska-Pietkiewicz, Małgorzata; Grzonka, Justyna; Lewiński, Janusz

    2017-10-12

    The unique optical properties of zinc oxide nanocrystals (ZnO NCs) are strongly dependent on both the properties and the composition of the inorganic core-organic ligand interface. Developing a novel organometallic self-supporting approach, we report on the synthesis and characterization of ZnO nanocrystals coated by chiral monoanionic aminoalcoholate ligands. The resulting ZnO NCs are both chiroptically active and possess size dependent optical properties. The size and in consequence the emission color of the ZnO NCs could be simply adjusted by the characteristic of the aminoalcohol used.

  14. Resistive switching behaviors of ZnO nanorod layers

    Science.gov (United States)

    Chang, Wen-Yuan; Lin, Chin-An; He-Hau, Jr.; Wu, Tai-Bor

    2010-06-01

    We have fabricated vertically aligned ZnO nanorod layers (NRLs) on indium tin oxide (ITO) electrodes using a hydrothermal process. The Pt/ZnO NRL/ITO capacitor exhibits bipolar resistive switching behavior. The resistive switching behavior may be related to the oxygen vacancies and/or zinc interstitials confined on the surface of the ZnO NRs, giving rise to the formation of straight and extensible conducting filaments along each vertically aligned ZnO NR. Superior stability in resistive switching characteristics was also observed, demonstrating that ZnO NRLs have the potential for next-generation nonvolatile memory applications.

  15. Hydrothermal growth of ZnO nanostructures - revew article

    Directory of Open Access Journals (Sweden)

    Sunandan Baruah and Joydeep Dutta

    2009-01-01

    Full Text Available One-dimensional nanostructures exhibit interesting electronic and optical properties due to their low dimensionality leading to quantum confinement effects. ZnO has received lot of attention as a nanostructured material because of unique properties rendering it suitable for various applications. Amongst the different methods of synthesis of ZnO nanostructures, the hydrothermal method is attractive for its simplicity and environment friendly conditions. This review summarizes the conditions leading to the growth of different ZnO nanostructures using hydrothermal technique. Doping of ZnO nanostructures through hydrothermal method are also highlighted.

  16. Synthesis, characterization and photocatalytic activity of PVP stabilized ZnO and modified ZnO nanostructures

    Science.gov (United States)

    Bandekar, Gauri; Rajurkar, N. S.; Mulla, I. S.; Mulik, U. P.; Amalnerkar, D. P.; Adhyapak, P. V.

    2013-01-01

    In the present study, ZnO nanostructures have been successfully synthesized by hydrothermal, sonochemical and precipitation methods using polyvinyl pyrrolidone (PVP) as the capping agent. The ZnO nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), UV-Visible spectroscopy and photoluminescence (PL) techniques. The XRD results revealed the hexagonal wurtzite structure of the ZnO nanostructures for all the samples. Furthermore, the morphology of the ZnO particles was obtained from FESEM micrographs. Particles prepared by hydrothermal method were found to be rice grain shaped and that prepared by precipitation and sonochemical methods were spherical shaped. Sunlight driven photocatalytic degradation of methylene blue (MB) was studied for ZnO nanostructures synthesized by various methods. The ZnO nanostructures were further decorated with Ag nanoparticles to enhance its dye degradation efficiency. The Ag decorated ZnO nanoparticles exhibited a higher degradation rate as compared to pure ZnO nanoparticles which was independent of pH. Since this process of dye degradation relies on the degradation of dye due to oxidation by highly reactive hydroxyl radicals, there are many factors which affect the efficiency of this process. Hence a study was conducted on the effect of various parameters on ZnO viz amount of catalyst, reaction pH and concentration of MB dye.

  17. Dependence of the deposition conditions on ZnO surface morphology

    Energy Technology Data Exchange (ETDEWEB)

    Moenkemoeller, Viola; Luekermann, Florian; Sacher, Marc; Brechling, Armin; Heinzmann, Ulrich [Molecular and Surface Physics, Bielefeld University (Germany); Kurz, Henning; Hamelmann, Frank; Stiebig, Helmut [Malibu GmbH, Bielefeld (Germany)

    2009-07-01

    Boron doped ZnO films deposited by Low Pressure Chemical Vapour Deposition are used as transparent conductive oxide (TCO) for thin film solar cells. The films show an interesting surface morphology composed of pyramidal grains, which are formed due to a pronounced orientation of the [11 anti 20] crystallographic axis perpendicular to the surface. We performed AFM measurements on ZnO films to investigate the change in surface morphology with respect to the depostion conditions such as deposition time, temperature and the boron doping concentration. We found that the thicker the films, the larger the pyramids and in contrast the higher the boron doping, the smaller the pyramids. For a varied depostion temperature we observed a change in crystallographic orientation by XRD measurements around 160 C from a pronounced [0002] to a [11 anti 20] axis growth. This change was also detected by AFM measurements due to a drastic change in surface morphology. Films below 160 C show a nearly flat surface whereas films above that temperature show a rough surface of pyramidal structures.

  18. Role of indium in highly crystalline ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Anil; Chaudhary, Sujeet; Pandya, Dinesh K. [Thin Film Laboratory, Physics Department, Indian Institute of Technology Delhi, New Delhi 110016 (India)

    2013-02-05

    Zinc oxide and indium doped zinc oxide (ZnO:In) transparent conducting thin films were deposited on glass substrates by pulsed DC magnetron sputtering using separate Zn and In targets. The independent control of the In content in ZnO has helped us to explore the role of indium in influencing the oriented (002) growth, crystallinity, conductivity and mobility of the doped films. The lowest resistivity of ZnO:In thin film is 2.73 Multiplication-Sign 10{sup -3} ohm-cm. At the optimal condition of high (002) orientation, ZnO:In films with electrical resistivity of 7.63 Multiplication-Sign 10{sup -3} ohm.cm and mobility of 126.4 cm{sup 2}/V.s are achieved.

  19. Photoinduced orientation in natural rubber

    Science.gov (United States)

    de Souza, Nara C.; Cavalheri, Adriana S.; Brito, Jackeline B.; Job, Aldo E.; Oliveira, Osvaldo N.; Giacometti, José A.; Silva, Josmary R.

    2012-04-01

    Azobenzene molecules and their derivatives have been widely investigated for their potential applications in optical and electrooptical devices. We have prepared a new guest-host system from natural rubber (NR) impregnated with azobenzene derivative Sudan Red B (SRB). The effects of stretching and immersion time on photoinduced orientation were investigated by birefringence signal measurements. We have found that the molecular orientation increase when the samples are stretched and decrease with the increase of immersion time. The first behavior was explained by using the random coil model and the latter was attributed to increase of the aggregation of SRB into NR matrix.

  20. Weak localization of light in ZnO nanorods in space and time

    Energy Technology Data Exchange (ETDEWEB)

    Mascheck, Manfred; Schmidt, Slawa; Silies, Martin; Lienau, Christoph [Carl von Ossietzky Universitaet, Oldenburg (Germany); Leipold, David; Runge, Erich [Technische Universitaet, Ilmenau (Germany); Yatsui, Takashi; Kitamura, Kokoro; Ohtsu, Motoichi [University of Tokyo (Japan)

    2011-07-01

    An array of ZnO nanorods is used to directly visualize the weak localization of light in both space and time. Ultrashort laser pulses from a Ti:Sapphire oscillator with a pulse duration of 6 fs are focused to their diffraction-limit of 1 {mu}m{sup 2} onto the ZnO nanorod array using an all-reflective Cassegrain objective. The generated SH emission is collected in reflection geometry and detected as a function of the lateral position of the laser focus. Pronounced intensity fluctuations on a sub-{mu}m scale due to the multiple random scattering inside the nanoneedle array are taken as the spatial hallmark of weak the localization of light. By varying the delay between the phase-stabilized pair of laser pulses from a dispersion-balanced Michelson interferometer, interferometric frequency-resolved autocorrelation (IFRAC) traces are measured. By analyzing these traces in the frequency domain, the dephasing time and therewith the temporal evolution of the electric field within the ZnO array could be deduced.

  1. Adsorption of xylenol orange dye on nano ZnO: Kinetics, thermodynamics and isotherm study

    Science.gov (United States)

    Priyadarshini, B.; Behera, S. S.; Rath, P. P.; Sahoo, T. R.; Parhi, P. K.

    2017-05-01

    Study on removal of Xylenol Orange (XO) from aqueous solution was investigated using synthesized ZnO nano particle on batch adsorption process. The effectiveness of the microwave combustion route in producing cubic ZnO with fluorite structure was checked by the X-ray powder diffraction pattern and surface morphology of ZnO was investigated by Field Emission Scanning Electron Microscopy (FESEM) micrographs shows irregular nanoparticles with an average size of 18 nm. Effect of operating adsorption factors that influence on the adsorption process such as contact time (1-300 min), initial dye concentration (5-30ppm), solution pH (4.4-7.4), adsorbent dose (100-400mg/L) and temperature (293-333K) were studied. Equilibrium data were analysed by both Langmuir isotherm and Freundlich adsorption isotherm. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° was calculated and the negative value of ΔH° (-0.115 kJ mol-1) corresponds to an exothermic nature of the adsorption process and the positive values of ΔS° (0.053Jmol-1K-1) reveals the increased randomness of the dye during adsorption process. Kinetics result revealed that the adsorption of XO is of pseudo second-order and chemisorptions type.

  2. Physical properties of annealed ZnO nanowire/CuSCN heterojunctions for self-powered UV photodetectors.

    Science.gov (United States)

    Garnier, Jérôme; Parize, Romain; Appert, Estelle; Chaix-Pluchery, Odette; Kaminski-Cachopo, Anne; Consonni, Vincent

    2015-03-18

    The low-cost fabrication of ZnO nanowire/CuSCN heterojunctions is demonstrated by combining chemical bath deposition with impregnation techniques. The ZnO nanowire arrays are completely filled by the CuSCN layer from their bottoms to their tops. The CuSCN layer is formed of columnar grains that are strongly oriented along the [003] direction owing to the polymeric form of the β-rhombohedral crystalline phase. Importantly, an annealing step is found essential in a fairly narrow range of low temperatures, not only for outgassing the solvent from the CuSCN layer, but also for reducing the density of interfacial defects. The resulting electrical properties of annealed ZnO nanowire/CuSCN heterojunctions are strongly improved: a maximum rectification ratio of 2644 at ±2 V is achieved following annealing at 150 °C under air atmosphere, which is related to a strong decrease in the reverse current density. Interestingly, the corresponding self-powered UV photodetectors exhibit a responsivity of 0.02 A/W at zero bias and at 370 nm with a UV-to-visible (370-500 nm) rejection ratio of 100 under an irradiance of 100 mW/cm(2). The UV selectivity at 370 nm can also be readily modulated by tuning the length of ZnO nanowires. Eventually, a significant photovoltaic effect is revealed for this type of heterojunctions, leading to an open circuit voltage of 37 mV and a short circuit current density of 51 μA/cm(2), which may be useful for the self-powering of the complete device. These findings show the underlying physical mechanisms at work in ZnO nanowire/CuSCN heterojunctions and reveal their high potential as self-powered UV photodetectors.

  3. Homoepitaxial growth of ZnO; Homoepitaxie von ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Neumann, C.

    2006-08-15

    This thesis deals with the homoepitaxial growth of ZnO epitaxial thin-films. It starts with a theoretical consideration of this material system and shows how to establish a successful epitaxy. Then, the thesis shows the development of a CVD process with metallic zinc precursor and nitrogen dioxide as oxygen precursor. Finally, the physical properties of the realized epitaxial thin films are shown. Besides excellent crystalline and optical properties one finds the dependence of incorporation of atoms of the gaseous phase from the polarity of the ZnO growth polarity. (orig.)

  4. Root uptake and phytotoxicity of ZnO nanoparticles.

    Science.gov (United States)

    Lin, Daohui; Xing, Baoshan

    2008-08-01

    Increasing application of nanotechnology highlights the need to clarify nanotoxicity. However, few researches have focused on phytotoxicity of nanomaterials; it is unknown whether plants can uptake and transport nanoparticles. This study was to examine cell internalization and upward translocation of ZnO nanoparticles by Lolium perenne (ryegrass). The dissolution of ZnO nanoparticles and its contribution to the toxicity on ryegrass were also investigated. Zn2+ ions were used to compare and verify the root uptake and phytotoxicity of ZnO nanoparticles in a hydroponic culture system. The root uptake and phytotoxicity were visualized by light scanning electron, and transmission electron microscopies. In the presence of ZnO nanoparticles, ryegrass biomass significantly reduced, root tips shrank, and root epidermal and cortical cells highly vacuolated or collapsed. Zn2+ ion concentrations in bulk nutrient solutions with ZnO nanoparticles were lower than the toxicity threshold of Zn2+ to the ryegrass; shoot Zn contents under ZnO nanoparticle treatments were much lower than that under Zn2+ treatments. Therefore, the phytotoxicity of ZnO nanoparticles was not directly from their limited dissolution in the bulk nutrient solution or rhizosphere. ZnO nanoparticles greatly adhered on to the rootsurface. Individual ZnO nanoparticles were observed present in apoplast and protoplast of the root endodermis and stele. However, translocation factors of Zn from root to shoot remained very low under ZnO nanoparticle treatments, and were much lower than that under Zn2+ treatments, implying that little (if any) ZnO nanoparticles could translocate up in the ryegrass in this study.

  5. Effect of copper doping sol-gel ZnO thin films: physical properties and sensitivity to ethanol vapor

    Science.gov (United States)

    Boukaous, Chahra; Benhaoua, Boubaker; Telia, Azzedine; Ghanem, Salah

    2017-10-01

    In the present paper, the effect of copper doping ZnO thin films, deposited using a sol-gel dip-coating technique, on the structural, optical and ethanol vapor-sensing properties, was investigated. The range of the doping content is 0 wt. %–5 wt. % Cu/Zn and the films’ properties were studied using x-ray diffraction, scanning electron microscopy and a UV–vis spectrophotometer. The obtained results indicated that undoped and copper-doped zinc oxide thin films have polycrystalline wurtzite structure with (1 0 1) preferred orientation. All samples have a smooth and dense structure free of pinholes. A decrease in the band gap with Cu concentration in the ZnO network was observed. The influence of the dopant on ethanol vapor-sensing properties shows an increase in the film sensitivity to the ethanol vapor within the Cu concentration.

  6. Properties of ZnO thin films grown at room temperature by using ionized cluster beam deposition

    CERN Document Server

    Whangbo, S W; Kim, S G; Cho, M H; Jeong, K H; Whang, C N

    2000-01-01

    ZnO films with a thickness of 120 nm were deposited on Si(100) at room temperature by using the reactive-ionized cluster beam deposition technique. The effects of the acceleration voltage (V sub a) on the properties, such as the crystallinity, the induced film strain, the surface roughness, and the electrical and the optical properties of the films, were investigated. The ZnO films had only a (002) crystalline orientation and uniformly composed through the whole thickness. As the V sub a increased, more strain was induced in the film, and the packing density caused by the structural imperfection was lowered. The films prepared under the optimum condition (V sub a = 3 kV) on a glass substrate showed good optical transmittance, and the band-gap of the film was evaluated to be 3.32 eV.

  7. Formation of Three-Dimensional ZnO Microflowers from Self-Assembled ZnO Microdiscs

    Science.gov (United States)

    Ikhmayies, Shadia J.

    2017-08-01

    Three-dimensional zinc oxide (ZnO) microflowers of average diameter 1.1 ± 0.25 µm were produced in this work by the spray pyrolysis (SP) method in thin film form on glass substrates at a substrate temperature of 350 ± 5 °C. X-ray diffraction revealed that the films are hexagonal (wurtzite) with high crystallinity and preferred (002) orientation. Scanning electron microscope (SEM) images revealed the morphology of the films, which consists of hexagonal microdiscs, and these microdiscs self-assembled into three-dimensional microflowers. The hexagonal microdiscs have noticeable thickness and average size of 500 ± 130 nm. The microflowers have hexagonal shapes, and some of them are linked together to form larger three-dimensional structures. Assembling of the microdiscs and formation of the three-dimensional hexagonal flowers occurred during the deposition process without the aid of any surfactant. X-ray energy dispersive spectroscopy (EDX) showed that the films are non-stoichiometric, and they contain chlorine besides Zn and O. These three-dimensional flowers are of potential use in several technological applications such as gas sensors, electronic devices, and solar cells.

  8. UV protective zinc oxide coating for biaxially oriented polypropylene packaging film by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lahtinen, Kimmo, E-mail: kimmo.lahtinen@lut.fi [ASTRaL, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland); Kääriäinen, Tommi, E-mail: tommi.kaariainen@colorado.edu [ASTRaL, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland); Johansson, Petri, E-mail: petri.johansson@tut.fi [Paper Converting and Packaging Technology, Tampere University of Technology, P.O.Box 589, FI-33101 Tampere (Finland); Kotkamo, Sami, E-mail: sami.kotkamo@tut.fi [Paper Converting and Packaging Technology, Tampere University of Technology, P.O.Box 589, FI-33101 Tampere (Finland); Maydannik, Philipp, E-mail: philipp.maydannik@lut.fi [ASTRaL, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland); Seppänen, Tarja, E-mail: tarja.seppanen@lut.fi [ASTRaL, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland); Kuusipalo, Jurkka, E-mail: jurkka.kuusipalo@tut.fi [Paper Converting and Packaging Technology, Tampere University of Technology, P.O.Box 589, FI-33101 Tampere (Finland); Cameron, David C., E-mail: david.cameron@miktech.fi [ASTRaL, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland)

    2014-11-03

    Biaxially oriented polypropylene (BOPP) packaging film was coated with zinc oxide (ZnO) coatings by atomic layer deposition (ALD) in order to protect the film from UV degradation. The coatings were made at a process temperature of 100 °C using diethylzinc and water as zinc and oxygen precursors, respectively. The UV protective properties of the coatings were tested by using UV–VIS and infrared spectrometry, differential scanning calorimetry (DSC) and a mechanical strength tester, which characterised the tensile and elastic properties of the film. The results obtained with 36 and 67 nm ZnO coatings showed that the ZnO UV protective layer is able to provide a significant decrease in photodegradation of the BOPP film under UV exposure. While the uncoated BOPP film suffered a complete degradation after a 4-week UV exposure, the 67 nm ZnO coated BOPP film was able to preserve half of its original tensile strength and 1/3 of its elongation at break after a 6-week exposure period. The infrared analysis and DSC measurements further proved the UV protection of the ZnO coatings. The results show that a nanometre scale ZnO coating deposited by ALD is a promising option when a transparent UV protection layer is sought for polymer substrates. - Highlights: • Atomic layer deposited zinc oxide coatings were used as UV protection layers. • Biaxially oriented polypropylene (BOPP) film was well protected against UV light. • Formation of UV degradation products in BOPP was significantly reduced. • Mechanical properties of the UV exposed BOPP film were significantly improved.

  9. [Structure and luminescence properties of ZnO films prepared by RF magnetron sputtering].

    Science.gov (United States)

    Xu, Xiao-li; Ma, Shu-yi; Chen, Yan; Zhang, Guo-heng; Sun, Xiao-jing; Wei, Jin-jun

    2008-09-01

    ZnO thin films with c-axis preferred orientation were prepared on glass substrates by radio frequency co-reactive magnetron sputtering technique, and the effect of the substrate temperature on the microstructure and the luminescence properties of the ZnO thin films was studied by X-ray diffractometry (XRD), scanning probe microscopy(SPM)and fluorescence spectrophotometer. The XRD patterns of the four ZnO samples prepared at different substrate temperatures were measured by XRD. figure which embodied the relation of full wave at half maximum (FWHM) and grain size of the four samples as a function of substrate temperatures was given out, too. It was concluded that the crystallization of the samples was promoted by appropriate substrate temperatures, the results consist with the AFM microscopic photos of the two samples. In addition, the photoluminescence (PL) spectra of the four samples were measured at room temperature. Violet peak located at about 400 nm, blue peak located at 446 nm and green peak located at about 502 nm were observed from the PL spectra of the four samples. With the rise of the growth temperature, the intensity of the violet peak and the blue peak increased sharply, and the intensity of green peak increased at the same time. It was concluded that the violet peak may correspond to the exciton emission, the blue peak was mainly attributed to the interstitial Zinc (Zn(i)) and the green emission peak must be related to the deep level defects of oxygen (Vo) in the crystal of ZnO films. Absorption property of the samples were researched by UV spectrophotometer, and the absorption spectrum of the film deposited at 150 degrees C and the (alpha h nu)2 versus h nu of the ZnO thin film were given. From the absorption spectrum, it could be observed that the spectroscopic data in UV region showed split peak and shoulder peak. With analysis of the absorption spectrum of the sample deposited at 150 degrees C, it was proved that our analysis of the

  10. Microstructural, chemical and textural characterization of ZnO nanorods synthesized by aerosol assisted chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Sáenz-Trevizo, A.; Amézaga-Madrid, P.; Fuentes-Cobas, L.; Pizá-Ruiz, P.; Antúnez-Flores, W.; Ornelas-Gutiérrez, C. [Centro de Investigación en Materiales Avanzados, S.C., Chihuahua, Chihuahua 31109 (Mexico); Pérez-García, S.A. [Centro de Investigación en Materiales Avanzados, S.C., Unidad Monterrey, Apodaca, Nuevo León 66600 (Mexico); Miki-Yoshida, M., E-mail: mario.miki@cimav.edu.mx [Centro de Investigación en Materiales Avanzados, S.C., Chihuahua, Chihuahua 31109 (Mexico)

    2014-12-15

    ZnO nanorods were synthesized by aerosol assisted chemical vapor deposition onto TiO{sub 2} covered borosilicate glass substrates. Deposition parameters were optimized and kept constant. Solely the effect of different nozzle velocities on the growth of ZnO nanorods was evaluated in order to develop a dense and uniform structure. The crystalline structure was characterized by conventional X-ray diffraction in grazing incidence and Bragg–Brentano configurations. In addition, two-dimensional grazing incidence synchrotron radiation diffraction was employed to determine the preferred growth direction of the nanorods. Morphology and growth characteristics analyzed by electron microscopy were correlated with diffraction outcomes. Chemical composition was established by X-ray photoelectron spectroscopy. X-ray diffraction results and X-ray photoelectron spectroscopy showed the presence of wurtzite ZnO and anatase TiO{sub 2} phases. Morphological changes noticed when the deposition velocity was lowered to the minimum, indicated the formation of relatively vertically oriented nanorods evenly distributed onto the TiO{sub 2} buffer film. By coupling two-dimensional X-ray diffraction and computational modeling with ANAELU it was proved that a successful texture determination was achieved and confirmed by scanning electron microscopy analysis. Texture analysis led to the conclusion of a preferred growth direction in [001] having a distribution width Ω = 20° ± 2°. - Highlights: • Uniform and pure single-crystal ZnO nanorods were obtained by AACVD technique. • Longitudinal and transversal axis parallel to the [001] and [110] directions, respectively. • Texture was determined by 2D synchrotron diffraction and electron microscopy analysis. • Nanorods have its [001] direction distributed close to the normal of the substrate. • Angular spread about the preferred orientation is 20° ± 2°.

  11. Fabrication of Ag/ZnO heterostructure and the role of surface coverage of ZnO microrods by Ag nanoparticles on the photophysical and photocatalytic properties of the metal-semiconductor system

    Science.gov (United States)

    Sarma, Bikash; Sarma, Bimal K.

    2017-07-01

    This report presents findings on microstructural, photophysical, and photocatalytic properties of Ag/ZnO heterostructure grown on flexible and silicon substrates. ZnO microrods are prepared by thermal decomposition method for different solute concentrations and Ag/ZnO heterostructure are fabricated by photo-deposition of Ag nanoparticles on ZnO microrods. X-ray diffraction and electron microscopy studies confirm that ZnO microrods belong to the hexagonal wurtzite structure and grown along [001] direction with random alignment showing that majority microrods are aligned with (100) face parallel to the sample surface. Plasmonic Ag nanoparticles are attached to different faces of ZnO. In the optical reflection spectra of Ag/ZnO heterostructure, the surface plasmon resonance peak due to Ag nanoparticles appears at 445 nm. Due to the oxygen vacancies the band gaps of ZnO microrods turn out to be narrower compared to that of bulk ZnO. The presence of Ag nanoparticles decreases the photoluminescence intensity which might be attributed to the non-radiative energy and direct electron transfer in the plasmon-exciton system. The quenching of photoluminescence in Ag/ZnO heterostructure at different growth conditions depend on the extent of surface coverage of ZnO by plasmonic Ag nanoparticles. Photocatalytic degradation efficiency of Ag/ZnO heterostructure is higher than that of ZnO microrods. The extent of surface coverage of ZnO microrods by Ag nanoparticles is crucial for the observed changes in photophysical and photochemical properties.

  12. Role of ZnO thin film in the vertically aligned growth of ZnO nanorods by chemical bath deposition

    Science.gov (United States)

    Son, Nguyen Thanh; Noh, Jin-Seo; Park, Sungho

    2016-08-01

    The effect of ZnO thin film on the growth of ZnO nanorods was investigated. ZnO thin films were sputter-deposited on Si substrate with varying the thickness. ZnO nanorods were grown on the thin film using a chemical bath deposition (CBD) method at 90 °C. The ZnO thin films showed granular structure and vertical roughness on the surface, which facilitated the vertical growth of ZnO nanorods. The average grain size and the surface roughness of ZnO film increased with an increase in film thickness, and this led to the increase in both the average diameter and the average length of vertically grown ZnO nanorods. In particular, it was found that the average diameter of ZnO nanorods was very close to the average grain size of ZnO thin film, confirming the role of ZnO film as a seed layer for the vertical growth of ZnO nanorods. The CBD growth on ZnO seed layers may provide a facile route to engineering vertically aligned ZnO nanorod arrays.

  13. Comparison between ZnO films grown by plasma-assisted atomic layer deposition using H{sub 2}O plasma and O{sub 2} plasma as oxidant

    Energy Technology Data Exchange (ETDEWEB)

    Kawamura, Yumi; Hattori, Nozomu; Miyatake, Naomasa; Uraoka, Yukiharu [Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192 (Japan); Mitsui Engineering and shipbuilding Co., Ltd., 3-16-1 Tamahara, Tamano, Okayama 706-0014 (Japan); Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192 (Japan) and CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan)

    2013-01-15

    Zinc oxide (ZnO) thin films have attracted significant attention for application in thin film transistors (TFTs) due to their specific characteristics, such as high mobility and transparency. In this paper, the authors fabricated TFTs with ZnO thin films as channel layers deposited by plasma-assisted atomic layer deposition (PAALD) at 100 Degree-Sign C using two different plasma sources, water (H{sub 2}O-plasma) and oxygen gas (O{sub 2}-plasma), as oxidants, and investigated the effects of the plasma sources on TFT performances. The TFT with ZnO channel layer deposited with H{sub 2}O-plasma indicated higher performances such as a field effect mobility ({mu}) of 1.1 cm{sup 2}/Vs. Analysis of the ZnO films revealed that the residual carbon in the film deposited with H{sub 2}O-plasma was lower than that of O{sub 2}-plasma. In addition, the c-axis preferred orientation was obtained in the case of the ZnO film deposited with H{sub 2}O-plasma. These results suggest that it is possible to fabricate high-performance ZnO TFTs at low temperatures by PAALD with H{sub 2}O-plasma.

  14. A simple route to vertical array of quasi-1D ZnO nanofilms on FTO surfaces: 1D-crystal growth of nanoseeds under ammonia-assisted hydrolysis process

    Directory of Open Access Journals (Sweden)

    Abd Rahman Mohd Yusri

    2011-01-01

    Full Text Available Abstract A simple method for the synthesis of ZnO nanofilms composed of vertical array of quasi-1D ZnO nanostructures (quasi-NRs on the surface was demonstrated via a 1D crystal growth of the attached nanoseeds under a rapid hydrolysis process of zinc salts in the presence of ammonia at room temperature. In a typical procedure, by simply controlling the concentration of zinc acetate and ammonia in the reaction, a high density of vertically oriented nanorod-like morphology could be successfully obtained in a relatively short growth period (approximately 4 to 5 min and at a room-temperature process. The average diameter and the length of the nanostructures are approximately 30 and 110 nm, respectively. The as-prepared quasi-NRs products were pure ZnO phase in nature without the presence of any zinc complexes as confirmed by the XRD characterisation. Room-temperature optical absorption spectroscopy exhibits the presence of two separate excitonic characters inferring that the as-prepared ZnO quasi-NRs are high-crystallinity properties in nature. The mechanism of growth for the ZnO quasi-NRs will be proposed. Due to their simplicity, the method should become a potential alternative for a rapid and cost-effective preparation of high-quality ZnO quasi-NRs nanofilms for use in photovoltaic or photocatalytics applications. PACS: 81.07.Bc; 81.16.-c; 81.07.Gf.

  15. ZnO nanostructured microspheres and grown structures by thermal ...

    Indian Academy of Sciences (India)

    Wintec

    Abstract. Synthesis of flower-shaped ZnO nanostructures composed of ZnO nanosticks was achieved by the solution process using zinc acetate dihydrate, sodium hydroxide and polyethylene glycol-20000 (PEG-20000) at 180°C for 4 h. The diameter of individual nanosticks was about 100 nm. Detailed structure ...

  16. Synthesis and characterization of thermally oxidized ZnO films

    Indian Academy of Sciences (India)

    Administrator

    The main goal of this paper is to establish some corre- lations between the oxidation conditions and optical, electrical and gas sensing properties of ZnO thin films. 2. Experimental. The preparation method of ZnO thin films consists of two steps: (a) deposition of zinc metallic films by thermal evaporation under vacuum and (b) ...

  17. Adsorption property of volatile molecules on ZnO nanowires ...

    Indian Academy of Sciences (India)

    2018-02-02

    Feb 2, 2018 ... Abstract. ZnO nanowires (NWs) were deposited on a glass substrate by the successive ionic layer adsorption and reaction method (SILAR). Sensing response of ZnO NWs towards reducing vapours was tested at ambient temperature (∼32◦. C) by the chemiresistor method. The vapour response was found ...

  18. Synthesis and optical characteristics of ZnO nanocrystals

    Indian Academy of Sciences (India)

    Administrator

    (Johnson et al 2001; Zhang et al 2002). Compared to other semiconductors, ZnO has wide bandgap of 3⋅37 eV and other large excitation binding energy, which makes excitation stable even at room temperature. There are various methods in order to synthesize ZnO nanomaterials viz. solvothermal synthesis, sol–gel (Li ...

  19. Photochemical events during photosensitization of colloidal ZnO ...

    Indian Academy of Sciences (India)

    The photosensitization of colloidal ZnO nanoparticles with riboflavin (RF) was investigated using absorption, fluorescence spectroscopic measurements and time resolved fluorescence measurements. Riboflavin adsorbed strongly on the surface of ZnO nanoparticles. Apparent association constant was obtained from the ...

  20. Screen printed nanosized ZnO thick film

    Indian Academy of Sciences (India)

    Nanosized ZnO was prepared by polyol synthesis. Fluorescence spectrum of the ZnO colloid at varying pump intensities was studied. The powder was extracted and characterized by XRD and BET. The extracted powder was screen printed on glass substrates using ethyl cellulose as binder and turpinol as solvent.

  1. Optical Properties of Indium Doeped ZnO Nanowires

    Directory of Open Access Journals (Sweden)

    Tsung-Shine Ko

    2015-01-01

    Full Text Available We report the synthesis of the ZnO nanowires (NWs with different indium concentrations by using the thermal evaporation method. The gold nanoparticles were used as the catalyst and were dispersed on the silicon wafer to facilitate the growth of the ZnO NWs. High resolution transmission electron microscopy confirms that the ZnO NWs growth relied on vapor-liquid-solid mechanism and energy dispersion spectrum detects the atomic percentages of indium in ZnO NWs. Scanning electron microscopy shows that the diameters of pure ZnO NWs range from 20 to 30 nm and the diameters of ZnO:In were increased to 50–80 nm with increasing indium doping level. X-ray diffraction results point out that the crystal quality of the ZnO NWs was worse with doping higher indium concentration. Photoluminescence (PL study of the ZnO NWs exhibited main photoemission at 380 nm due to the recombination of excitons in near-band-edge (NBE. In addition, PL results also indicate the slightly blue shift and PL intensity decreasing of NBE emission from the ZnO NWs with higher indium concentrations could be attributed to more donor-induced trap center generations.

  2. Next-generation hydrothermal ZnO crystals

    Science.gov (United States)

    Ehrentraut, Dirk; Maeda, Katsumi; Kano, Masataka; Fujii, Katsushi; Fukuda, Tsuguo

    2011-04-01

    Zinc oxide (ZnO) crystals were grown by the hydrothermal method under significantly improved conditions. Careful adjustment of critical growth conditions led the way towards ZnO crystals with extremely low (indium and lithium yields high-quality crystals.

  3. Magnetism in dopant-free ZnO nanoplates.

    Science.gov (United States)

    Hong, Jung-Il; Choi, Jiil; Jang, Seung Soon; Gu, Jiyeong; Chang, Yangling; Wortman, Gregory; Snyder, Robert L; Wang, Zhong Lin

    2012-02-08

    It is known that bulk ZnO is a nonmagnetic material. However, the electronic band structure of ZnO is severely distorted when the ZnO is in the shape of a very thin plate with its dimension along the c-axis reduced to a few nanometers while keeping the bulk scale sizes in the other two dimensions. We found that the chemically synthesized ZnO nanoplates exhibit magnetism even at room temperature. First-principles calculations show a growing asymmetry in the spin distribution within the distorted bands formed from Zn (3d) and O (2p) orbitals with the reduction of thickness of the ZnO nanoplates, which is suggested to be responsible for the observed magnetism. In contrast, reducing the dimension along the a- or b-axes of a ZnO crystal does not yield any magnetism for ZnO nanowires that grow along c-axis, suggesting that the internal electric field produced by the large {0001} polar surfaces of the nanoplates may be responsible for the distorted electronic band structures of thin ZnO nanoplates. © 2012 American Chemical Society

  4. Manufacturing of patterned ZnO films with application for ...

    Indian Academy of Sciences (India)

    Patterned thin films, ZnO, are successfully prepared on glass substrates by the sol–gel method using dip-coating technique. The films, formed of ZnO nanocrystallites with hexagonal crystal structure, are characterized by means of scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction.

  5. Photoluminescent ZnO Nanoparticles and Their Biological Applications

    Science.gov (United States)

    Zhang, Zheng-Yong; Xiong, Huan-Ming

    2015-01-01

    During the past decades, numerous achievements concerning luminescent zinc oxide nanoparticles (ZnO NPs) have been reported due to their improved luminescence and good biocompatibility. The photoluminescence of ZnO NPs usually contains two parts, the exciton-related ultraviolet (UV) emission and the defect-related visible emission. With respect to the visible emission, many routes have been developed to synthesize and functionalize ZnO NPs for the applications in detecting metal ions and biomolecules, biological fluorescence imaging, nonlinear multiphoton imaging, and fluorescence lifetime imaging. As the biological applications of ZnO NPs develop rapidly, the toxicity of ZnO NPs has attracted more and more attention because ZnO can produce the reactive oxygen species (ROS) and release Zn2+ ions. Just as a coin has two sides, both the drug delivery and the antibacterial effects of ZnO NPs become attractive at the same time. Hence, in this review, we will focus on the progress in the synthetic methods, luminescent properties, and biological applications of ZnO NPs.

  6. Photoluminescent ZnO Nanoparticles and Their Biological Applications

    Directory of Open Access Journals (Sweden)

    Zheng-Yong Zhang

    2015-05-01

    Full Text Available During the past decades, numerous achievements concerning luminescent zinc oxide nanoparticles (ZnO NPs have been reported due to their improved luminescence and good biocompatibility. The photoluminescence of ZnO NPs usually contains two parts, the exciton-related ultraviolet (UV emission and the defect-related visible emission. With respect to the visible emission, many routes have been developed to synthesize and functionalize ZnO NPs for the applications in detecting metal ions and biomolecules, biological fluorescence imaging, nonlinear multiphoton imaging, and fluorescence lifetime imaging. As the biological applications of ZnO NPs develop rapidly, the toxicity of ZnO NPs has attracted more and more attention because ZnO can produce the reactive oxygen species (ROS and release Zn2+ ions. Just as a coin has two sides, both the drug delivery and the antibacterial effects of ZnO NPs become attractive at the same time. Hence, in this review, we will focus on the progress in the synthetic methods, luminescent properties, and biological applications of ZnO NPs.

  7. Photoluminescent hierarchical Zno micro-flower and its surface wettability

    Energy Technology Data Exchange (ETDEWEB)

    Ji, X.B.; Lu, W.C.; Ma, H.P. [College of Sciences, Shanghai University, Shanghai 200444 (China)

    2012-10-15

    The flower-like ZnO with micro-nano hierarchical structure is successfully obtained by a simple hydrothermal synthesis, using sodium dodecyl benzene sulfonate (SDBS) as a structure direct agent. The resulted ZnO micro-flowers are very uniform in morphology with particle sizes around 1 {mu}m. A number of techniques, including X-ray diffraction (XRD), field emission scan electron microscopy (FESEM), energy-dispersive spectroscopy (EDS), fourier transform infrared (FTIR) spectra and thermogravimetry analysis (TGA), are used to characterize the obtained ZnO. The self-assemble of ZnO nano-sheets under the direction of SDBS leads to the formation of ZnO micro-flowers. The room temperature photoluminescence property of the obtained flower-like ZnO exhibits a broad visible light emission. The surface of as-made ZnO shows a very hydrophilic property, while the special micro-nano hierarchical structure enables the ZnO micro-flower a superhydrophobic surface after modification of fluoroalkylsilane. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Adsorption property of volatile molecules on ZnO nanowires ...

    Indian Academy of Sciences (India)

    7

    energy of the ZnO nanowire and adsorbed ZnO nanowire system, an increase in the total energy was observed after ... This means that conductivity increased when the film surface was exposed to the reducing molecules. .... reality, there will be plenty of vapor molecules which will interact over the entire sensing element ...

  9. ZnO nanowire arrays with and without cavity tops

    Energy Technology Data Exchange (ETDEWEB)

    Li Hongyu; Quan Baogang; Tang Haoying; Guo Chuanfei [National Center for Nanoscience and Technology, Beijing 100190 (China); Jiang Peng, E-mail: pjiang@nanoctr.cn [National Center for Nanoscience and Technology, Beijing 100190 (China); Yu Aifang [National Center for Nanoscience and Technology, Beijing 100190 (China); Xie Sishen, E-mail: ssxie@aphy.iphy.ac.cn [Institute of Physics, Chinese Academy of Sciences (CAS), Beijing 100190 (China); Wang Zhonglin, E-mail: zhong.wang@mse.gatech.edu [National Center for Nanoscience and Technology, Beijing 100190 (China); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States)

    2011-10-03

    Highlights: {yields} ZnO NW array structure was formed on a ZnO-seed-layer-patterned Si substrate. {yields} Both e-beam lithography and a wet chemical method were employed. {yields} A bubble-assisted method was used for constructing ZnO nanowire arrays with cavity tops. {yields} ZnO NW array structures with different morphologies exhibited different photoluminescence properties. - Abstract: We report a new bubble-assisted growing and etching method for constructing ZnO nanowire (NW) arrays with cavity tops. Firstly, a ZnO NW array structure was formed on a ZnO-seed-layer-patterned Si substrate by combining e-beam lithography and a wet chemical method. Secondly, a new kind of ZnO NW array with cavity tops could be formed by a subsequent bubble-assisted growing and etching. These ZnO NW array structures with different morphologies exhibited different photoluminescence properties, showing their potential applications in lasing cavities, stimulated emitters, nanogenerator, photocatalysis and light-emitting diodes. The bubble-assisted etching method will open a new door for morphology design of ZnO and other semiconductor nanowire arrays at special sites.

  10. Shape tunable synthesis of Eu- and Sm-doped ZnO microstructures ...

    Indian Academy of Sciences (India)

    microstructures and vibration properties of ZnO. 3. Results and discussion. Three typical samples and related morphological, structural, compositional and vibrational properties have been inves- tigated in this work: namely ZO (ZnO microdisks), EZO. (Eu-doped ZnO microspheres) and SZO (Sm-doped ZnO microplates).

  11. Photocatalysis and Bandgap Engineering Using ZnO Nanocomposites

    Directory of Open Access Journals (Sweden)

    Muhammad Ali Johar

    2015-01-01

    Full Text Available Nanocomposites have a great potential to work as efficient, multifunctional materials for energy conversion and photoelectrochemical reactions. Nanocomposites may reveal more improved photocatalysis by implying the improvements of their electronic and structural properties than pure photocatalyst. This paper presents the recent work carried out on photoelectrochemical reactions using the composite materials of ZnO with CdS, ZnO with SnO2, ZnO with TiO2, ZnO with Ag2S, and ZnO with graphene and graphene oxide. The photocatalytic efficiency mainly depends upon the light harvesting span of a material, lifetime of photogenerated electron-hole pair, and reactive sites available in the photocatalyst. We reviewed the UV-Vis absorption spectrum of nanocomposite and photodegradation reported by the same material and how photodegradation depends upon the factors described above. Finally the improvement in the absorption band edge of nanocomposite material is discussed.

  12. Resonant exciton-phonon coupling in ZnO nanorods at room temperature

    Directory of Open Access Journals (Sweden)

    Soumee Chakraborty

    2011-09-01

    Full Text Available Vibronic and optoelectronic properties, along with detailed studies of exciton-phonon coupling at room temperature (RT for random and aligned ZnO nanorods are reported. Excitation energy dependent Raman studies are performed for detailed analysis of multi-phonon processes in the nanorods. We report here the origin of coupling between free exciton and its associated phonon replicas, including its higher order modes, in the photoluminescence spectra at RT. Resonance of excitonic electron and resonating first order zone center LO phonon, invoked strongly by Frolich interaction, are made responsible for the observed phenomenon.

  13. Hydrothermal epitaxial growth of ZnO films on sapphire substrates presenting epitaxial ZnAl{sub 2}O{sub 4} buffer layers

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hou-Guang, E-mail: houguang@isu.edu.tw; Wang, Chi-Wei; Tu, Zhi-Fan

    2014-03-01

    This article describes our investigation of the hydrothermal epitaxial growth of c-plane ZnO films on Al{sub 2}O{sub 3} substrates presenting ZnAl{sub 2}O{sub 4} buffer layers. We obtained (111) ZnAl{sub 2}O{sub 4} epitaxial layers on a-plane Al{sub 2}O{sub 3} substrates readily through solid phase epitaxy. Although the ZnAl{sub 2}O{sub 4} buffer layers grew epitaxially with a (111) out-of-plane orientation and comprised two coexisting equivalent azimuthal variants with relative 180° in-plane rotation, the ZnO epitaxial films grown upon them exhibited a c-plane orientation with unitary in-plane epitaxial orientation of <11{sup ¯}00>{sub ZnO}∥<11{sup ¯}0>{sub ZnAl{sub 2O{sub 4}}} on the two different ZnAl{sub 2}O{sub 4} variants. Taking the coincidence of the site lattices between the (0001) plane of ZnO and the (111) plane of ZnAl{sub 2}O{sub 4} into account, a reduction in lattice misfit was achieved through a 30° rotation between the lattices of the ZnO and the ZnAl{sub 2}O{sub 4}. We used X-ray diffraction and transmission electron microscopy to obtain detailed microstructural views of the hydrothermally grown ZnO epitaxial films on the ZnAl{sub 2}O{sub 4} buffer layers. - Highlights: • The c-plane ZnO films were epitaxially grown on Al{sub 2}O{sub 3} substrates presenting ZnAl{sub 2}O{sub 4} buffer layers. • We obtained (111) ZnAl{sub 2}O{sub 4} epitaxial layers on a-plane Al{sub 2}O{sub 3} substrates through solid phase epitaxy. • The ZnAl{sub 2}O{sub 4} layers comprised two equivalent azimuthal variants with relative 180° in-plane rotation. • The c-plane ZnO epitaxial films grown on ZnAl{sub 2}O{sub 4} layers with an in-plane relationship of <11{sup ¯}00>{sub ZnO}∥<11{sup ¯}0>{sub ZnAl{sub 2O{sub 4}}}.

  14. Analysis of Li-related defects in ZnO thin films influenced by ...

    Indian Academy of Sciences (India)

    ZnO annealed under O2 ambient and an amount of Lii(o) defect had existed in ZnO annealed under Ar ambient. First-principle calculations were performed to calculate formation energies of Li-doped ZnO in order to explain the formation mechanism of Li-related defects in ZnO. Keywords. ZnO; thin films; radio frequency ...

  15. Solution growth of ZnO microwires and grass architectures

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, Nitin, E-mail: nchopra@eng.ua.edu; Wu, Junchi; Shi, Wenwu

    2013-06-20

    Highlights: • Au nanoparticles with different shapes and sizes were produced. • Au nanoparticles resulted in uniformly dispersed and standing ZnO microwires. • Au nanoparticles serve as heterogeneous nucleation sites for the ZnO microwires. • Au nanoparticles also resulted in ZnO grass architectures. -- Abstract: In spite of extensive research in gold (Au) nanoparticles, it remains a challenge to synthesize structurally homogeneous sample-set with controlled morphologies. The latter critically affect the role of Au nanoparticles as a seed/catalyst for the growth of other nanostructures. Here, we systematically studied and quantified the growth of Au nanoparticles in a single-step chemical synthesis approach and observed the effects of growth temperature and duration, metal salt and surfactant concentration, and surfactant type. These parameters strongly influenced morphological evolution, distribution, and heterogeneities in the as-synthesized Au nanoparticles. Next, the synthesized Au nanoparticles were utilized for the growth of zinc oxide (ZnO) microwires in a solution growth approach. It was observed that Au nanoparticles on the substrate did not catalyze the growth of ZnO microwires but facilitated uniform dispersion of standing microwires. Supported by microscopic analysis, the proposed growth mechanism is heterogeneous nucleation of ZnO on the loosely bound Au nanoparticles on the substrates, favored by lattice match between the ZnO and Au. Based on this mechanism, Au nanoparticles only assisted in the initial stages of ZnO microwire growth. For longer growth duration (∼10 h), over-deposition of ZnO from the solution on already grown wires led to their micron scale diameters as well as grass architectures and making the growth process independent of size and shape of the Au nanoparticles. The formation of ZnO grass architecture is due to attachment of Au nanoparticles on the growing microwire surface, which further served as a heterogeneous

  16. Piezo and photoelectric coupled nanogenerator using CdSe quantum dots incorporated ZnO nanowires in ITO/ZnO NW/Si structure

    Energy Technology Data Exchange (ETDEWEB)

    Kathalingam, A.; Valanarasu, S.; Senthilkumar, V. [Millimeter-wave INnovation Technology Research Center (MINT), Dongguk University, Seoul 100-715 (Korea, Republic of); Rhee, Jin-Koo, E-mail: jkrhee@dongguk.edu [Millimeter-wave INnovation Technology Research Center (MINT), Dongguk University, Seoul 100-715 (Korea, Republic of)

    2013-02-15

    We report the fabrication of ITO/n-ZnO NW/p-Si sandwiched structure and its photoelectric and piezoelectric conversion properties. This hybrid cell was designed to harvest simultaneously both solar and mechanical energies. ZnO nanowires used in the work were grown on p-type Si substrates employing seed mediated low-temperature aqueous solution method. The synthesized ZnO nanowires were characterized by XRD, SEM and EDX characterization for their structural and morphological evaluation. The as-grown ZnO nanowires showed good crystallinity with c-axis preferable orientation. Free ZnO nanowires and CdSe quantum dots were also incorporated with the vertically grown nanowires and their response in harvesting optical and mechanical energies were investigated. The piezoelectric and photoelectric coupled effects of a ZnO nanowire device in the simultaneous conversion of both optical and mechanical energies have been studied for the first time with the goal of designing piezoelectric and photoelectric hybrid nanogenerator. This presented ITO/n-ZnO NW/p-Si heterojunction architecture is envisaged as a potentially valuable candidate for the next generation energy harvesting devices. Graphene-coated ITO was also used and its response was studied. - Highlights: ► Fabricated an unique sandwich type ITO/n-ZnO NW/p-Si nanogenerator. ► Simultaneous harvesting of both light and mechanical energy achieved. ► CdSe incorporation with ZnO nanowires increased the performance of the device. ► First report integrated both nanogenerator and solar cell in a same surface. ► Incorporating nanoantenna this structure can harvest light, heat and sound.

  17. Growth and electro-optical properties of Ga-doped ZnO films prepared by aerosol assisted chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shuqun [School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); Carraro, Giorgio [Department of Chemistry and INSTM, Padova University, Padova 35131 (Italy); Barreca, Davide [CNR-IENI and INSTM, Department of Chemistry, Padova University, Padova 35131 (Italy); Binions, Russell [School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom)

    2015-06-01

    Transparent conductive Ga-doped ZnO thin films were deposited onto glass substrates by a low-cost aerosol assisted chemical vapour deposition technique and the effect of gallium content on the ZnO film growth behaviour and opto-electronic properties was systematically investigated. It is found that, upon increasing Ga addition, the ZnO film crystallinity exhibits a continuous reduction in quality associated with the preferential orientation transformed from (002) to (102). The (002) oriented samples had a microstructure of parallel columnar grains while the (102) oriented coating was thickened by overlapping particles. The ZnO:Ga coatings exhibit high carrier concentration (up to 4.1 × 10{sup 20} cm{sup −3}) but low carrier mobility (up to 0.8 cm{sup 2} V{sup −1} s{sup −1}), resulting in a minimum resistivity value of 2.3 × 10{sup −2} Ω cm. The inferior carrier mobility performance could result from a profound ionized and neutral impurity scattering effect. Good visible transmittance (≈ 70–80%) is observed in these ZnO:Ga films and samples with higher carrier density present better infrared reflection performance (up to 37.2% at 2500 nm). - Highlights: • Aerosol assisted chemical vapour deposition of doped zinc oxide thin films • Gallium doping and opto-electronic properties systemically investigated • Growth mechanism changed by % gallium incorporation.

  18. Polarized Raman scattering of single ZnO nanorod

    Energy Technology Data Exchange (ETDEWEB)

    Yu, J. L., E-mail: jlyu@semi.ac.cn; Lai, Y. F., E-mail: laiyunfeng@gmail.com; Wang, Y. Z.; Cheng, S. Y. [Institute of Micro/Nano Devices and Solar Cells, School of Physics and Information Engineering, Fuzhou University, Fuzhou (China); Chen, Y. H. [Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China)

    2014-01-21

    Polarized Raman scattering measurement on single wurtzite c-plane (001) ZnO nanorod grown by hydrothermal method has been performed at room temperature. The polarization dependence of the intensity of the Raman scattering for the phonon modes A{sub 1}(TO), E{sub 1}(TO), and E{sub 2}{sup high} in the ZnO nanorod are obtained. The deviations of polarization-dependent Raman spectroscopy from the prediction of Raman selection rules are observed, which can be attributed to the structure defects in the ZnO nanorod as confirmed by the comparison of the transmission electron microscopy, photoluminescence spectra as well as the polarization dependent Raman signal of the annealed and unannealed ZnO nanorod. The Raman tensor elements of A{sub 1}(TO) and E{sub 1}(TO) phonon modes normalized to that of the E{sub 2}{sup high} phonon mode are |a/d|=0.32±0.01, |b/d|=0.49±0.02, and |c/d|=0.23±0.01 for the unannealed ZnO nanorod, and |a/d|=0.33±0.01, |b/d|=0.45±0.01, and |c/d|=0.20±0.01 for the annealed ZnO nanorod, which shows strong anisotropy compared to that of bulk ZnO epilayer.

  19. Superhydrophobic ZnO networks with high water adhesion.

    Science.gov (United States)

    Florica, Camelia; Preda, Nicoleta; Enculescu, Monica; Zgura, Irina; Socol, Marcela; Enculescu, Ionut

    2014-01-01

    ZnO structures were deposited using a simple chemical bath deposition technique onto interdigitated electrodes fabricated by a conventional photolithography method on SiO2/Si substrates. The X-ray diffraction studies show that the ZnO samples have a hexagonal wurtzite crystalline structure. The scanning electron microscopy observations prove that the substrates are uniformly covered by ZnO networks formed by monodisperse rods. The ZnO rod average diameter and length were tuned by controlling reactants' concentration and reaction time. Optical spectroscopy measurements demonstrate that all the samples display bandgap values and emission bands typical for ZnO. The electrical measurements reveal percolating networks which are highly sensitive when the samples are exposed to ammonia vapors, a variation in their resistance with the exposure time being evidenced. Other important characteristics are that the ZnO rod networks exhibit superhydrophobicity, with water contact angles exceeding 150° and a high water droplet adhesion. Reproducible, easily scalable, and low-cost chemical bath deposition and photolithography techniques could provide a facile approach to fabricate such ZnO networks and devices based on them for a wide range of applications where multifunctionality, i.e., sensing and superhydrophobicity, properties are required. 81.07.-b; 81.05.Dz; 68.08.Bc.

  20. Fabrication and characterization of pristine and annealed Ga doped ZnO thin films using sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Abhisek, E-mail: abhisekmishra153@gmail.com; Gouda, Himanshu Sekhar, E-mail: himanshugouda@yahoo.in [School of Applied Sciences, KIIT University, Campus-3, Patia, Bhubaneswar, Odisha-751024 (India); Mohapatra, Saswat, E-mail: saswat44@gmail.com [Department of Applied Physics, Indian School of Mines, Dhanbad, Jharkhand-826004 (India); Singh, Udai P. [School of Electronics Engineering, KIIT University, Campus-3, Patia, Bhubaneswar, Odisha-751024 (India)

    2016-05-06

    ZnO is a wide-band gap, transparent, polar semiconductor with unparalleled optoelectronic, piezoelectric, thermal and transport properties, which make it the material of choice for a wide range of applications such as blue/UV optoelectronics, energy conversion, transparent electronics, spintronic, plasmonic and sensor devices. We report, three sets of Ga doped Zinc Oxide (GZO) were fabricated in different sputtering power (100 watt, 200 watt and 300 watt). Thereafter films were annealed in nitrogen ambient for 30 minutes at 400° C. From the optical absorption spectroscopy it was found that pristine films are showing a 75% transmittance in the visible region of light and it increases after the annealing. However, for 300 W grown sample opposite trend has been achieved for the post annealed sample. X-ray diffraction pattern of all the pristine and annealed films showed a preferable growth orientation at (002) phase. Some other weak peaks were also appeared in different angle which indicates that films are polycrystalline in nature. XRD data also reveals that crystallite size increases with sputtering power up to 200 W and thereafter it decreases with the deposition power. It also noted that the crystallite size of the annealed film increases with compare to the non annealed films. At room temperature an enhancement in electrical properties of Ga doped ZnO thin films was noted for the annealed ZnO films except for the film deposited at 300 watt. More significantly, it was found that annealed thin films showed the resistivity in the range of 10{sup −3} ∼ 10{sup −4} ohm-cm. Such a high optical transmittance and conducting zinc-oxide thin film can be used as a window layer in solar cell.

  1. Comparative Study About the Structural Properties of ZnO Films Grown on Si, GaAs, And Al2O3 Substrates and a GaN Template

    Directory of Open Access Journals (Sweden)

    Jang T.S.

    2016-01-01

    Full Text Available We report on the structural properties of ZnO films grown on (001 Si, (001 GaAs, (0001 Al2O3 substrates and a (0001 GaN template by RF-sputtering. It is observed that all the ZnO films have textured structures with a preferred orientation of the c-axis, irrespective growth conditions, in terms of atomic-force microscope and wide-range X-ray diffractometer. However, it is found that the ZnO films in the ZnO-on-Si and ZnO-on-GaAs are consisted of various domains with different orientations, while the ZnO films in the ZnO-on-Al2O3 and ZnO-on-GaN are consisted of a single domain with the same orientation in terms of the φ-scan of X-ray diffractometer. Moreover, it is found that the ZnO-on-GaN has smaller edge dislocation density and screw dislocation density than the ZnO-on-Al2O3, which seriously depends on substrate temperature, in terms of the ω-scan of X-ray diffractometer.

  2. ZnO Nanowire Array-Based Optoelectronic Devices

    OpenAIRE

    Wang, Guoping

    2011-01-01

    ZnO nanowire array-based optoelectronic devices are discussed in this dissertation. ZnO has a wide band gap of 3.37 eV and a large exciton binding energy of 60 meV at room temperature, which make it a promising candidate for optoelectronic devices such as blue-light emitting diodes, ultraviolet laser diodes and photodiodes. Recently, there have been tremendous interests in ZnO nanowire arrays. It is well known that one of the biggest challenges toward good ZnO-based optoelectronic devices is ...

  3. High pressure and high temperature behaviour of ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Thakar, Nilesh A. [K. K. Shah Jarodwala Maninagar Science College, Rambaug, Maninagar, Ahmedabad-380008 (India); Bhatt, Apoorva D. [Department of Physics, Gujarat University, Ahmedabad-380009 (India); Pandya, Tushar C., E-mail: pandyatc@gmail.com [St. Xavier' s College, Navrangpura, Ahmedabad-380009 (India)

    2014-04-24

    The thermodynamic properties with the wurtzite (B4) and rocksalt (B1) phases of ZnO under high pressures and high temperatures have been investigated using Tait's Equation of state (EOS). The effects of pressures and temperatures on thermodynamic properties such as bulk modulus, thermal expansivity and thermal pressure are explored for both two structures. It is found that ZnO material gradually softens with increase of temperature while it hardens with the increment of the pressure. Our predicted results of thermodynamics properties for both the phases of ZnO are in overall agreement with the available data in the literature.

  4. Hierarchical structures of ZnO spherical particles synthesized solvothermally

    Directory of Open Access Journals (Sweden)

    Noriko Saito and Hajime Haneda

    2011-01-01

    Full Text Available We review the solvothermal synthesis, using a mixture of ethylene glycol (EG and water as the solvent, of zinc oxide (ZnO particles having spherical and flower-like shapes and hierarchical nanostructures. The preparation conditions of the ZnO particles and the microscopic characterization of the morphology are summarized. We found the following three effects of the ratio of EG to water on the formation of hierarchical structures: (i EG restricts the growth of ZnO microcrystals, (ii EG promotes the self-assembly of small crystallites into spheroidal particles and (iii the high water content of EG results in hollow spheres.

  5. ZnO materials and surface tailoring for biosensing.

    Science.gov (United States)

    Yakimova, Rositza; Selegard, Linnea; Khranovskyy, Volodymyr; Pearce, Ruth; Spetz, Anita Lloyd; Uvdal, Kajsa

    2012-01-01

    ZnO nanostructured materials, such as films and nanoparticles, could provide a suitable platform for development of high performance biosensors due to their unique fundamental material properties. This paper reviews different preparation techniques of ZnO nanocrystals and material issues like wettability, biocompatibility and toxicity, which have an important relevance to biosensor functionality. Efforts are made to summarize and analyze existing results regarding surface modification and molecular attachments for successful biofunctionalization and understanding of the mechanisms involved. A section is devoted to implementations of tailored surfaces in biosensors. We end with conclusions on the feasibility of using ZnO nanocrystals for biosensing.

  6. Ultrahydrophobicity of ZnO modified CVD diamond films

    Science.gov (United States)

    Yang, YiZhou; Wang, ChuanXi; Li, HongDong; Lin, Quan

    2013-04-01

    Chemical vapor deposited (CVD) polycrystalline diamond films with an ultrahydrophobic surface were fabricated by constructing a hierarchical structure through sputtering a ZnO layer on diamond grains, with a growth step feature. Under optimized conditions, the combined original diamond with a step structure of the ZnO can achieve a water contact angle (WCA) of as high as 141° ± 1°. It is proved that WCA decreases as the roughness of ZnO/PDF reduced. It can be concluded that the step structure of diamond grains and ZnO nuclei size have a great influence on the variation of WCA.

  7. Oxygen Defects Mediated Magnetism of Ni Doped ZnO

    Directory of Open Access Journals (Sweden)

    W. J. Liu

    2013-01-01

    Full Text Available Ni doped ZnO nanoparticles were synthesized by a solution route and annealed in O2, air, and Ar, respectively. X-ray diffraction and X-ray photoelectron spectroscopy measurements show that the samples possess typical wurtzite structure and have no other impurity phases. Magnetization loops for ZnO samples were measured and clearly show typical ferromagnetic saturation behavior. With the defect analysis based on photoluminescence spectroscopy, the effect of defects on the nature and origin of ferromagnetism was investigated. The results suggest that oxygen vacancies, especially single ionized oxygen vacancies, play a crucial role in mediating ferromagnetism in the Ni doped ZnO.

  8. Preparation, characterization and properties of ZnO nanomaterials

    Science.gov (United States)

    Luo, Jiaolian; Zhang, Xiaoming; Chen, Ruxue; Wang, Xiaohui; Zhu, Ji; Wang, Xiaomin

    2017-06-01

    In this paper, using the hydrothermal synthesis method, NaOH, Zn(NO3)2, anhydrous ethanol, deionized water as raw material to prepare ZnO nanomaterial, and by X ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence spectroscopy (PL) on the synthesis of nano materials, surface morphology and phase luminescence characterization. The results show that the nano materials synthesized for single-phase ZnO, belonging to the six wurtzite structure; material surface shaped, arranged evenly distributed, and were the top six party structure; ZnO nano materials synthesized with strong emission spectra, emission peak is located at 394nm.

  9. Simulation, fabrication and characterization of ZnO based thin film transistors grown by radio frequency magnetron sputtering.

    Science.gov (United States)

    Singh, Shaivalini; Chakrabarti, P

    2012-03-01

    We report the performance of the thin film transistors (TFTs) using ZnO as an active channel layer grown by radio frequency (RF) magnetron sputtering technique. The bottom gate type TFT, consists of a conventional thermally grown SiO2 as gate insulator onto p-type Si substrates. The X-ray diffraction patterns reveal that the ZnO films are preferentially orientated in the (002) plane, with the c-axis perpendicular to the substrate. A typical ZnO TFT fabricated by this method exhibits saturation field effect mobility of about 0.6134 cm2/V s, an on to off ratio of 102, an off current of 2.0 x 10(-7) A, and a threshold voltage of 3.1 V at room temperature. Simulation of this TFT is also carried out by using the commercial software modeling tool ATLAS from Silvaco-International. The simulated global characteristics of the device were compared and contrasted with those measured experimentally. The experimental results are in fairly good agreement with those obtained from simulation.

  10. Effect of Post-Deposition Annealing on RF-Sputtered Catalyst-Free Grown ZnO Nanostructures

    Science.gov (United States)

    Srivastava, Amit; Kumar, Naresh

    2017-08-01

    Catalyst-free zinc oxide (ZnO) nano-structures were synthesized on silicon (100) substrate by radio frequency sputtering. The as-deposited films were post-annealed at 200°C, 400°C, 600°C, and 800°C. The effects of annealing temperature on the structural, morphological and optical properties of these nanostructures were investigated using x-ray diffraction (XRD), atomic force microscopy (AFM) and spectroscopic ellipsometry. XRD showed c-axis-oriented growth with the increase in crystallinity at the higher annealing temperature of these ZnO nanostructures. The crystallite size calculated using Scherrer's formula in the XRD data was found to increase with the annealing temperature. AFM images confirmed the growth of grains at higher annealing temperatures. Optical band gaps of these ZnO nanostructures were calculated using reflectance spectra in the ultraviolet-visible region and found to decrease from 3.19 eV to 3.09 eV as the annealing temperature increased from 200°C to 800°C. The decrease in band gap may be attributed to the decrease in oxygen vacancies at higher annealing temperatures and may be useful for different applications.

  11. Controlling of ZnO nanostructures by solute concentration and its effect on growth, structural and optical properties

    Science.gov (United States)

    Kumar, Yogendra; Rana, Amit Kumar; Bhojane, Prateek; Pusty, Manojit; Bagwe, Vivas; Sen, Somaditya; Shirage, Parasharam M.

    2015-10-01

    ZnO nanostructured films were prepared by a chemical bath deposition method on glass substrates without any assistance of either microwave or high pressure autoclaves. The effect of solute concentration on the pure wurtzite ZnO nanostructure morphologies is studied. The control of the solute concentration helps to control the nanostructure to form nano-needles, and -rods. X-ray diffraction (XRD) studies revealed highly c-axis oriented thin films. Scanning electron microscopy (SEM) confirms the modification of the nanostructure dependent on the concentration. Transmission electron microscopy (TEM) results show the single crystalline electron diffraction pattern, indicating high quality nano-material. UV-vis results show the variation in the band gap from 3.20 eV to 3.14 eV with increasing concentration as the nanostructures change from needle- to rod-like. Photoluminescence (PL) data indicate the existence of defects in the nanomaterials emitting light in the yellow-green region, with broad UV and visible spectra. A sharp and strong peak is observed at ˜438 cm-1 by Raman spectroscopy, assigned to the {{{{E}}}2}{{high}} optical mode of ZnO, the characteristic peak for the highly-crystalline wurtzite hexagonal phase. The solute concentration significantly affects the formation of defect states in the nanostructured films, and as a result, it alters the structural and optical properties. Current-voltage characteristics alter with the measurement environment, indicating potential sensor applications.

  12. Structural, optical and electrical properties of Al-doped ZnO microrods prepared by spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Bacaksiz, Emin [Department of Physics, Karadeniz Technical University, 61080 Trabzon (Turkey); Aksu, Serdar, E-mail: saksu@solopower.co [SoloPower, Inc. 5981 Optical Ct., San Jose, CA 95138 (United States); Yilmaz, Salih [Department of Physics, Karadeniz Technical University, 61080 Trabzon (Turkey); Parlak, Mehmet [Department of Physics, Middle East Technical University, 06531, Ankara (Turkey); Altunbas, Mustafa [Department of Physics, Karadeniz Technical University, 61080 Trabzon (Turkey)

    2010-05-31

    Al-doped ZnO thin films were obtained on glass substrates by spray pyrolysis in air atmosphere. The molar ratio of Al in the spray solution was changed in the range of 0-20 at.% in steps of 5 at.%. X-ray diffraction patterns of the films showed that the undoped and Al-doped ZnO films exhibited hexagonal wurtzite crystal structure with a preferred orientation along (002) direction. Surface morphology of the films obtained by scanning electron microscopy revealed that pure ZnO film grew as quasi-aligned hexagonal shaped microrods with diameters varying between 0.7 and 1.3 {mu}m. However, Al doping resulted in pronounced changes in the morphology of the films such as the reduction in the rod diameter and deterioration in the surface quality of the rods. Nevertheless, the morphology of Al-doped samples still remained rod-like with a hexagonal cross-section. Flower-like structures in the films were observed due to rods slanting to each other when spray solution contained 20 at.% Al. Optical studies indicated that films had a low transmittance and the band gap decreased from 3.15 to 3.10 eV with the increasing Al molar ratio in the spray solution from 0 to 20 at.%.

  13. A Grazing-Incidence Small-Angle X-Ray Scattering View of Vertically Aligned ZnO Nanowires

    Directory of Open Access Journals (Sweden)

    M. Lučić Lavčević

    2013-01-01

    Full Text Available We report a grazing-incidence small-angle X-ray scattering study of ZnO films with vertically aligned and randomly distributed nanowires, grown through a hydrothermal growth process on nanostructured ZnO seeding coatings and deposited by electron beam evaporation on silicon and glass, respectively. The comparison of the scattering patterns of seeding coatings and nanowires showed that the scattering of vertically aligned nanowires exhibited a specific feature: the dominant characteristic of their scattering patterns is the appearance of fine structure effects around the specular peak. These effects were clarified by the combined reflection and scattering phenomena, suggested for the aligned nanowires-substrate system. Furthermore, they enabled the calculation of the average gyration radius of nanowires in horizontal direction. The calculated value was in good agreement with the radii of nanowires estimated by surface electron microscopy. Therefore, the observed feature in the scattering pattern can serve as evidence of the aligned growth of nanowires.

  14. Market orientation in the hospital industry.

    Science.gov (United States)

    Bhuian, S N; Abdul-Gader, A

    1997-01-01

    Using the more recent methodological developments in the assessment of the unidemensionality, reliability, and validity, the authors developed and examined a scale of market orientation for the hospital industry. The scale is based on a clear definition of the content of the construct of market orientation in the hospital industry. To this end, a national random sample of 237 hospital administrators was used. In addition to the support for the reliability and validity, the scale promises parsimony, pragmatism, and wide-ranging applicability.

  15. Growth and characterization of thin ZnO films deposited on glass substrates by electrodeposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Mouet, T., E-mail: Toufik_mouet@yahoo.fr [Institut PRISME, Universite d' Orleans, LESI-IUT de Chartres, EA 1715, 21 rue Loigny la Bataille, 28000 Chartres (France); Laboratoire de Micro-systeme et Instrumentation, departement d' electronique, faculte des sciences de l' ingenieur, Universite Mentouri de Constantine, Route de Ain el-Bey, 25000 Constantine (Algeria); Devers, T. [Institut PRISME, Universite d' Orleans, LESI-IUT de Chartres, EA 1715, 21 rue Loigny la Bataille, 28000 Chartres (France); Telia, A. [Laboratoire de Micro-systeme et Instrumentation, departement d' electronique, faculte des sciences de l' ingenieur, Universite Mentouri de Constantine, Route de Ain el-Bey, 25000 Constantine (Algeria); Messai, Z.; Harel, V. [Institut PRISME, Universite d' Orleans, LESI-IUT de Chartres, EA 1715, 21 rue Loigny la Bataille, 28000 Chartres (France); Konstantinov, K. [University of Wollongong, Engineering Faculty, Institute for Superconducting and Electronic Materials, 2522 Wollongong (Australia); Kante, I. [Laboratoire de Microscopies et d' Etude de Nanostructures, UFR Sciences, B.P. 1039, 51687 Reims Cedex (France); Ta, M.T. [Institut PRISME, Universite d' Orleans, LESI-IUT de Chartres, EA 1715, 21 rue Loigny la Bataille, 28000 Chartres (France)

    2010-04-15

    Electrodeposition technique was used in order to produce nanometric zinc oxide films on glass insulating substrates. The effect of electrolyte concentration and applied current density on the formation and growth of electrodeposited Zn thin films in aqueous solutions of ZnSO{sub 4} were studied. After a thermal oxidation, a characterization of the structural morphology of the films deposited was carried out by optical microscopy (OM), atomic force microscopy (AFM), scanning electron microscopy (SEM) and by grazing incidence X-rays diffraction (GIXD). These characterization techniques show that the grains size of the films after oxidation at temperature 450 deg. C is between 5 and 15 nm, as well as the structure is polycrystalline nature with several orientations. UV/vis spectrophotometry confirms that it is possible to obtain transparent good ZnO films with an average transmittance of approximately 80% within the visible wavelength region, as well as the optical gap of obtained ZnO films is 3.17 eV.

  16. Growth process optimization of ZnO thin film using atomic layer deposition

    Science.gov (United States)

    Weng, Binbin; Wang, Jingyu; Larson, Preston; Liu, Yingtao

    2016-12-01

    The work reports experimental studies of ZnO thin films grown on Si(100) wafers using a customized thermal atomic layer deposition. The impact of growth parameters including H2O/DiethylZinc (DEZn) dose ratio, background pressure, and temperature are investigated. The imaging results of scanning electron microscopy and atomic force microscopy reveal that the dose ratio is critical to the surface morphology. To achieve high uniformity, the H2O dose amount needs to be at least twice that of DEZn per each cycle. If the background pressure drops below 400 mTorr, a large amount of nanoflower-like ZnO grains would emerge and increase surface roughness significantly. In addition, the growth temperature range between 200 °C and 250 °C is found to be the optimal growth window. And the crystal structures and orientations are also strongly correlated to the temperature as proved by electron back-scattering diffraction and x-ray diffraction results.

  17. Facile synthesis of one dimensional ZnO nanostructures for DSSC applications

    Energy Technology Data Exchange (ETDEWEB)

    Marimuthu, T.; Anandhan, N., E-mail: anandhan-kn@rediffmail.com [Advanced Materials and Thin Film Physics Lab, School of Physics, Alagappa University, Karaikudi – 630 003, India. (India)

    2016-05-06

    Development of zinc oxide (ZnO) nanostructure based third generation dye sensitized solar cell is interesting compared to conventional silicon solar cells. ZnO nanostructured thin films were electrochemically deposited onto fluorine doped tin oxide (FTO) glass substrate. The effect of ethylene-diamine-tetra-acetic acid (EDTA) on structural, morphological and optical properties is investigated using X-ray diffraction (XRD) meter, field emission scanning electron microscope (FE-SEM) and micro Raman spectroscopy. XRD patterns reveal that the prepared nanostructures are hexagonal wutrzite structures with (101) plane orientation, the nanostructure prepared using EDTA exhibits better crystallinity. FE-SEM images illustrate that the morphological changes are observed from nanorod structure to cauliflower like structure as EDTA is added. Micro Raman spectra predict that cauliflower like structure possesses a higher crystalline nature with less atomic defects compared to nanorod structures. Dye sensitized solar cell (DSSC) is constructed for the optimized cauliflower structure, and open circuit voltage, short circuit density, fill factor and efficiency are estimated from the J-V curve.

  18. Structural and optical characteristics of spin-coated ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, M. [' Al. I. Cuza' University, Physics Department, 11 Carol I Blvd, Iasi 700506 (Romania); Baban, C., E-mail: baban@uaic.ro [' Al. I. Cuza' University, Physics Department, 11 Carol I Blvd, Iasi 700506 (Romania); Rusu, G.I. [' Al. I. Cuza' University, Physics Department, 11 Carol I Blvd, Iasi 700506 (Romania)

    2010-02-01

    Zinc oxide (ZnO) thin films were deposited onto glass substrates by spin-coating method, from a precursor solution containing zinc acetate, ethanol and ammonium hydroxide. After deposition, the films were heated at a temperature of 100 deg. C in order to remove unwanted materials. Finally, the films were annealed at 500 deg. C for complete oxidation. X-ray diffraction showed that ZnO films were polycrystalline and have a hexagonal (wurtzite) structure. The crystallites are preferentially oriented with (0 0 2) planes parallel to the substrate surface. The films have a high transparency (more than 75%) in the spectral range from 450 nm to 1300 nm. The analysis of absorption spectra shows the direct nature of band-to-band transitions. The optical bandgap energy ranges between 3.15 eV and 3.25 eV. Some correlations between the processing parameters (spinning speed, temperature of post deposition heat treatment) and structure and optical characteristics of the respective thin films were established.

  19. Investigation of structural and optical properties in Cobalt–Chromium co-doped ZnO thin films within the Lattice Compatibility Theory scope

    Energy Technology Data Exchange (ETDEWEB)

    Mimouni, R.; Boubaker, K., E-mail: mmbb11112000@yahoo.fr; Amlouk, M.

    2015-03-05

    Highlights: • Co/Cr co-doped ZnO thin films were synthesized by a low-cost spray technique. • Optical and morphological properties of the Co/Cr co-doped ZnO system were described. • Lattice Compatibility Theory explains Co preferential incorporation in ZnO lattice. - Abstract: (Co,Cr)-codoped zinc oxide thin films (ZnO:Cr:Co) at different percentages (0%, 1–1%, 1–2%, 2–1%) were deposited on glass substrates using a chemical low-cost spray technique. The effect of Cr and Co concentration on the structural, morphological and optical properties of the ZnO:Cr:Co thin films were investigated by means of X-ray diffraction, optical measurement, contact Atomic Force Microscopy (AFM), and Photoluminescence spectroscopy. The results revealed that all films consist of single phase ZnO and were well crystallized in würtzite phase with the crystallites preferentially oriented towards (0 0 2) direction parallel to c-axis. Also, the co-doping has effective role in the enhancement of the crystallinity and leads to an improvement of roughness of the ZnO films. Doping by chrome and cobalt resulted in a slight decrease in the optical band gap energy of the films. The optical band gap of these films is calculated. The optical absorption spectra show that the absorption mechanism is a direct transition. The UV peak positions for ZnO:Cr:Co samples slightly red shift to the longer wavelength in comparison with the pure ZnO which can be attributed to the change in the acceptor level induced by the substitutional Co{sup 2+} and Cr{sup 3+} and the band-gap narrowing of ZnO with the Cr and Co dopants. The Lattice Compatibility Theory analyses have been applied in order to give original, plausible and founded explanation to the recorded preferential incorporation of cobalt ions within ZnO lattice over chromium.

  20. Comparative study of quaternary Mg and Group III element co-doped ZnO thin films with transparent conductive characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Kim, In Young [Department of Materials Science and Engineering, Chonnam National University, 300 Yongbong-Dong, Puk-Gu, Gwangju 500-757 (Korea, Republic of); Shin, Seung Wook [Department of Materials Science and Engineering, KAIST, IBS 291 Daehak-ro Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Center for Nanomaterials and Chemical Reactions, Institute for Basic Science, Daejeon 305-701 (Korea, Republic of); Gang, Myeng Gil; Lee, Seung Hyoun; Gurav, K.V. [Department of Materials Science and Engineering, Chonnam National University, 300 Yongbong-Dong, Puk-Gu, Gwangju 500-757 (Korea, Republic of); Patil, P.S. [Thin Film Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (India); Yun, Jae Ho [Photovoltaic Research Group, Korea Institute of Energy Research, 71-2 Jang-Dong Yuseong-Gu, Daejeon 305-343 (Korea, Republic of); Lee, Jeong Yong [Department of Materials Science and Engineering, KAIST, IBS 291 Daehak-ro Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Center for Nanomaterials and Chemical Reactions, Institute for Basic Science, Daejeon 305-701 (Korea, Republic of); Kim, Jin Hyeok, E-mail: jinhyeok@chonnam.ac.kr [Department of Materials Science and Engineering, Chonnam National University, 300 Yongbong-Dong, Puk-Gu, Gwangju 500-757 (Korea, Republic of)

    2014-11-03

    Mg and Ga co-doped ZnO (Mg{sub x}Ga{sub y}Zn{sub z}O, x + y + z = 1, x = 0.05, y = 0.02 and z = 0.93, MGZO), Mg and Al co-doped ZnO (Mg{sub x}Al{sub y}Zn{sub z}O, x + y + z = 1, x = 0.05, y = 0.02 and z = 0.93, MAZO), Mg and In co-doped ZnO (Mg{sub x}In{sub y}Zn{sub z}O, x + y + z = 1, x = 0.05, y = 0.02 and z = 0.93, MIZO), Mg doped ZnO (Mg{sub x}Zn{sub y}O, x + y = 1, x = 0.05 and y = 0.95, MZO) and pure ZnO thin films have been prepared on the glass substrates by RF magnetron sputtering. Their structural, morphological, compositional, electrical, and optical properties were characterized. The X-ray diffraction patterns showed that all the thin films were grown as a hexagonal wurtzite phase with c-axis preferred orientation without secondary phase. The (0002) peak positions of MGZO, MAZO and MIZO thin films were not significantly changed. The cross-section field emission scanning electron microscopy images of MGZO, MAZO and MIZO thin films showed that all the thin films have a columnar structure with dense morphology. The MGZO thin film showed the best electrical characteristics in terms of the carrier concentration (3.7 × 10{sup 20}/cm{sup 3}), charge carrier mobility (8.39 cm{sup 2}/Vs), and a lower resistivity (1.85 × 10{sup −3} Ω cm). UV–visible spectroscopy studies showed that the MGZO, MAZO and MIZO thin films exhibit high transmittance over 85% in the visible region. The MGZO thin films showed wider optical band gap energy of 3.75 eV. - Highlights: • Mg and Group III Co-doped ZnO thin films were prepared by RF sputtering technique. • The Co-doped ZnO thin films showed better properties than those of un-doped. • The Mg and Ga Co-doped ZnO (MGZO) thin film showed the best properties. • The MGZO thin films showed the band gap of 3.75 eV and resistivity of 1.83 × 10{sup −3} Ω cm.

  1. Entrepreneurial orientation, market orientation, and competitive environment

    DEFF Research Database (Denmark)

    Sørensen, Hans Eibe; Cadogan, John W.

    This study sheds light on the role that the competitive environment plays in determining how elements of market orientation and elements of entrepreneurial orientation interact to influence business success. We develop a model in which we postulate that market orientation, entrepreneurial...... orientation, and competitive environment shape business performance via a three-way interaction. We test the model using primary data from the CEOs of 270 CEO of manufacturing firms, together with secondary data on these firms' profit performance. An assessment of the results indicates that customer...... orientations. Also, these moderating effects are stronger for firms operating in highly competitive environments. For the innovativeness component of entrepreneurship, however, the positive relationship between innovativeness and ROA decreases as the competitive environment becomes more hostile....

  2. Spontaneous orientation-tuning driven by the strain variation in self-assembled ZnO-SrRuO{sub 3} heteroepitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Yuanmin; Liu, Ruirui; Zhan, Qian, E-mail: qzhan@mater.ustb.edu.cn [Department of Material Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Chang, Wei Sea [School of Engineering, Monash University Malaysia, Bandar Sunway, Selangor 47500 (Malaysia); Yu, Rong [National Center for Electron Microscopy in Beijing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Wei, Tzu-Chiao [Institute of Photonics and Optoelectronics and Department of Electrical Engineering, National Taiwan University, Taipei 10617, Taiwan (China); He, Jr-Hau [Electrical Engineering Program, King Abdullah University of Science & Technology (Saudi Arabia); Chu, Ying-Hao [Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Institute of Physics, Academia Sinica, Taipei 105, Taiwan (China)

    2015-11-09

    Heteroepitaxial ZnO and SrRuO{sub 3} were grown on SrTiO{sub 3} (111) substrates and formed a self-assembled wurtzite-perovskite nanostructure. Spontaneous orientation-tuning of the SrRuO{sub 3} pillars was observed, with the growth direction changing from [111]{sub SRO} to [011]{sub SRO} as the film thickness increased, which is attributed to a misfit strain transition from the biaxial strain imposed by the SrTiO{sub 3} substrate to the vertical strain provided by the ZnO matrix. The [011]-SrRuO{sub 3} and [0001]-ZnO combination presents a favorable matching in the nanocomposite films, resulting in higher charge carrier mobility. This vertically integrated configuration and regulation on the crystallographic orientations are expected to be employed in designing multi-functional nanocomposite systems for applications in electronic devices.

  3. Spontaneous orientation-tuning driven by the strain variation in self-assembled ZnO-SrRuO3 heteroepitaxy

    KAUST Repository

    Zhu, Yuanmin

    2015-11-09

    Heteroepitaxial ZnO and SrRuO3 were grown on SrTiO3 (111) substrates and formed a self-assembled wurtzite-perovskite nanostructure. Spontaneous orientation-tuning of the SrRuO3 pillars was observed, with the growth direction changing from [111]SRO to [011]SRO as the film thickness increased, which is attributed to a misfit strain transition from the biaxial strain imposed by the SrTiO3 substrate to the vertical strain provided by the ZnO matrix. The [011]-SrRuO3 and [0001]-ZnO combination presents a favorable matching in the nanocomposite films, resulting in higher charge carrier mobility. This vertically integrated configuration and regulation on the crystallographic orientations are expected to be employed in designing multi-functional nanocomposite systems for applications in electronic devices.

  4. Synthesis of 1-D ZnO nanorods and polypyrrole/1-D ZnO ...

    Indian Academy of Sciences (India)

    [51] Patil D R 2007 Studies on ZnO based gas sensors Ph.D Thesis. [52] Velmurugan R and Swaminathan M 2011 Sol. Energ. Mat. Sol. C 95 942. [53] Senthilkumaar S and Porkodi K 2005 J. Colloid. Interf. Sci. 288 184. [54] Chougule M A, Dalvi D S, Mali S, Patil P S, Moholkar A V,. Agawane G L et al 2012 Measurement 45 ...

  5. Effect of O2/Ar Gas Flow Ratios on Properties of Cathodic Vacuum Arc Deposited ZnO Thin Films on Polyethylene Terephthalate Substrate

    Directory of Open Access Journals (Sweden)

    Chien-Wei Huang

    2016-01-01

    Full Text Available Cathodic vacuum arc deposition (CVAD can obtain a good quality thin film with a low growth temperature and a high deposition rate, thus matching the requirement of film deposition on flexible electronics. This paper reported the room-temperature deposition of zinc oxide (ZnO thin films deposited by CVAD on polyethylene terephthalate (PET substrate. Microstructure, optical, and electrical measurements of the deposited ZnO thin films were investigated with various O2/Ar gas flow ratios from 6 : 1 to 10 : 1. The films showed hexagonal wurtzite crystal structure. With increasing the O2/Ar gas flow ratios, the c-axis (002 oriented intensity decreased. The crystal sizes were around 16.03 nm to 23.42 nm. The average transmittance values in the visible range of all deposited ZnO films were higher than 83% and the calculated band gaps from the absorption data were found to be around 3.1 to 3.2 eV. The resistivity had a minimum value in the 3.65 × 10−3 Ω·cm under the O2/Ar gas flow ratio of 8 : 1. The luminescence mechanisms of the deposited film were also investigated to understand the defect types of room-temperature grown ZnO films.

  6. Novel chemical vapor deposition process of ZnO films using nonequilibrium N2 plasma generated near atmospheric pressure with small amount of O2 below 1%

    Science.gov (United States)

    Nose, Yukinori; Yoshimura, Takeshi; Ashida, Atsushi; Uehara, Tsuyoshi; Fujimura, Norifumi

    2016-05-01

    We propose a novel chemical vapor deposition (CVD) process of ZnO films involving a nonequilibrium N2 plasma generated near atmospheric pressure with small O2 concentration (O2%) below 1%. In the optical emission (OE) spectra of the plasma, OE lines corresponding to the NO-γ system ( A 2 Σ + → X 2 Πγ + ) were observed, despite the only introduced gases being N2 and O2; these vanish at an O2% of more than 1%. ZnO films were grown on a glass substrate placed in the plasma at a growth temperature of as low as 200 °C and at an O2% of below 1% in the presence of the NO-γ system. This plasma yielded almost the same growth rate for ZnO films as O2 plasma including atomic O radicals that are often observed in low-pressure O2 plasma, suggesting that some highly reactive oxidant was sufficiently generated in such a small O2%. ZnO films synthesized using this plasma exhibited excellent ( 0001 ) preferred orientation without other diffractions such as 10 1 ¯ 1 diffraction, and with an optical bandgap of 3.30 eV. Based on the analyses of the plasma and the exhaust gases, the coexistence state of NO-γ and O3 should be essential and useful for the decomposition and oxidation of Zn source material in the proposed CVD process.

  7. Low-temperature growth and physical investigations of undoped and (In, Co) doped ZnO thin films sprayed on PEI flexible substrate

    Science.gov (United States)

    Ben Ameur, S.; Barhoumi, A.; Mimouni, R.; Amlouk, M.; Guermazi, H.

    2015-08-01

    ZnO thin films were deposited on polymer substrate Polyethyerimide (PEI) at 250 °C by spray pyrolysis technique. The effects of different doping elements (Co and In) on physical properties of ZnO thin films were investigated. Thin film characterizations were carried out using X-ray diffraction technique, UV-Vis-NIR spectroscopy, Photoluminescence (PL) spectroscopy and the contact angle measurement method. XRD measurement showed a successful growth of crystalline films on polymer substrate at low temperature by the spray pyrolysis process. XRD patterns revealed that all films consist of single ZnO phase and were well crystallized with preferential orientation towards (1 0 1) direction. Doping by cobalt has effective role in the enhancement of the crystalline quality, increases in the band gap according to Burstein Moss effect. Doping with indium leads rather to the decrease of both crystallinity and optical band gap energy value. Photoluminescence of the films showed UV emission (NBE) and visible emission related to defects. The contact angles were measured to study the effect of various doping elements on the hydrophobicity of the film depending on surface roughness. Results showed strong dependence on the doping element. In fact, doping with cobalt element increases the roughness of ZnO films and reinforces the surface from hydrophilic to hydrophobic (θ > 90°).

  8. Epitaxial growth of Sc-doped ZnO films on Si by sol-gel route

    Science.gov (United States)

    Sharma, Ruchika; Sehrawat, Kiran; Wakahara, Akihiro; Mehra, R. M.

    2009-03-01

    The epitaxial growth of doped ZnO films is of great technological importance. Present paper reports a detailed investigation of Sc-doped ZnO films grown on (1 0 0) silicon p-type substrates. The films were deposited by sol-gel technique using zinc acetate dihydrate as precursor, 2-methoxyethanol as solvent and monoethanolamine (MEA) as a stabilizer. Scandium was introduced as dopant in the solution by taking 0.5 wt% of scandium nitrate hexahydrate. The effect of annealing on structural and photoluminescence properties of nano-textured Sc-doped films was investigated in the temperature range of 300-550 °C. Structural investigations were carried out using X-ray diffraction, scanning electron microscopy and atomic force microscopy. X-ray diffraction study revealed that highly c-axis oriented films with full-width half maximum of 0.21° are obtained at an annealing temperature of 400 °C. The SEM images of ZnO:Sc films have revealed that coalescence of ZnO grains occurs due to annealing. Ostwald ripening was found to be the dominant mass transport mechanism in the coalescence process. A surface roughness of 4.7 nm and packing density of 0.93 were observed for the films annealed at 400 °C. Room temperature photoluminescence (PL) measurements of ZnO:Sc films annealed at 400 °C showed ultraviolet peak at about (382 nm) with FWHM of 141 meV, which are comparable to those found in high-quality ZnO films. The films annealed below or above 400 °C exhibited green emission as well. The presence of green emission has been correlated with the structural changes due to annealing. Reflection high energy electron diffraction pattern confirmed the nearly epitaxial growth of the films. Ruchika Sharma, P. K. Shishodia, A. Wakahara and R. M. Mehra, Materials Science-Poland 27 (2009) Ist issue.

  9. The frequency-dependent AC photoresistance behavior of ZnO thin films grown on different sapphire substrates.

    Science.gov (United States)

    Cholula-Díaz, Jorge L; Barzola-Quiquia, José; Videa, Marcelo; Yin, Chunhai; Esquinazi, Pablo

    2017-09-13

    Zinc oxide (ZnO) thin films were grown by pulsed layer deposition under an N 2 atmosphere at low pressures on a- and r-plane sapphire substrates. Structural studies using X-ray diffraction confirmed that all films had a wurtzite phase. ZnO thin films on a- and r-plane sapphire have grown with orientations along the [0002] and [112[combining macron]0] directions, respectively. Room temperature photoluminescence measurements indicate that the presence of native point defects (interstitial zinc, oxygen vacancies, oxygen antisites and zinc vacancies) is more preponderant for ZnO thin films grown on the r-plane sapphire substrate than the sample grown on the a-plane sapphire substrate. Room temperature impedance spectroscopy measurements were performed in an alternating current frequency range from 40 to 10 5 Hz in the dark and under normal light. An unusual positive photoresistance effect is observed at frequencies above 100 kHz, which we suggest to be due to intrinsic defects present in the ZnO thin films. Furthermore, an analysis of the optical time response revealed that the film grown on the r-plane sapphire substrate responds faster (characteristic relaxation times for τ 1 , τ 2 and τ 3 of 0.05, 0.26 and 6.00 min, respectively) than the film grown on the a-plane sapphire substrate (characteristic relaxation times for τ 1 , τ 2 and τ 3 of 0.10, 0.73 and 4.02 min, respectively).

  10. Effect of growth solution concentration on the performance of gallium doped ZnO nanostructures dye sensitized solar cells (DSSCs)

    Science.gov (United States)

    Iwantono, I.; Tugirin, S.; Anggelina, F.; Awitdrus, Taer, Erman; Roza, L.; Umar, A. A.

    2016-02-01

    This paper reports the synthesis of gallium doped ZnO nanostructures via seed mediated growth hydrothermal technique and their application as photo-anode in DSSC. ZnO nanostructures have been grown on Flourin Tin Oxide (FTO). The precursor used in this research was zinc-nitrate-hexahydrate (Zn (NO3)2.6H2O) and hexa-metylene-tetramine (HMT) was chosen as surfactant. The growth process was carried out at various precursor solution concentrations, 0.1, 0.2, 0.3 and 0.4 M at 90°C for 8 hours. The growth solution was then doped with 1% wt gallium nitrate hydrate. The grown ZnO nanostructures were characterized by X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-Ray (EDX) and UV-Vis Spectroscopy. The samples were crystalline with wurtzite-hexagonal and their crystal orientation was (100), (002), (101), and (110). The morphological shape of the samples changed with the concentration of the precursor. The optical absorption decreased as the concentration increased. As can be seen from SEM images that the diameter of the particles ranged from 95 to 500 nm and the thickness ranged from 1540 to 3640 nm (1.54-3.64 µm). The best performance of DSSC was obtained from the sample utilizing the ZnO nanostructures prepared at 0.1 M precursor, with their photovoltaic parameters were the Jsc of 2.190 mA cm-2, FF of 0.39, and η of 0.41%, respectively.

  11. Improvement of antimony sulfide photo absorber performance by interface modification in Sb2S3-ZnO hybrid nanostructures

    Science.gov (United States)

    Ali, Asad; Hasanain, Syed Khurshid; Ali, Tahir; Sultan, Muhammad

    2017-03-01

    Metal-oxide chalcogenide nanostructures as part of hybrid systems are very important for photovoltaic and optoelectronic applications. It is however known that the various interfaces within the hybrid structures play a crucial role in limiting the efficiency of these devices. Here we report on the improvement of Sb2S3 structure through modification of interface between Zn-oxide nanostructures and chalcogenides. ZnO nanorods were grown on fluorine doped tin oxide (FTO) substrate by chemical bath deposition (CBD) method. X-ray diffraction (XRD) and SEM analysis confirmed the single phase wurtzite structure and c-axis orientation of the ZnO nanorod arrays. Antimony tri-sulfide (Sb2S3) was deposited on ZnO nanords by CBD and subsequently annealed at 300 °C in argon environment for 30 min. XRD and the XPS analysis of ZnO-Sb2S3 system showed the dominant presence of Sb2O3 rather than Sb2S3. Since oxidation of Sb2S3 is understood to proceed mainly from the ZnO-Sb2S3 interface, a ZnS interlayer was introduced between ZnO nanorods and Sb2S3 by chemical route. The subsequent structural and optical properties of the ZnO-ZnS-Sb2S3 system are analyzed in detail. The introduction of sulfide interlayer prevents the oxidation of Sb2S3 which is evident from reduced oxide phase in Sb2S3. Significant improvement in the structural and optical properties of Sb2S3 are reported as compared to the parent ZnO-Sb2S3 system. This gain in the optical properties of hybrid ZnO-ZnS-Sb2S3 nanostructures is explained as being related to successful prevention of Sb2O3 formation at the Sb-ZnO interface and stabilization of the desired Sb2S3.

  12. EPD-deposited ZnO thin films: a review

    Energy Technology Data Exchange (ETDEWEB)

    Verde, M.

    2014-07-01

    ZnO-based materials and specifically ZnO films with tailored morphology have been subjected to extensive research in the past few years due to their high potential for multiple prospective applications, mainly in electronics. Electrophoretic Deposition (EPD) constitutes an economical, eco friendly, low energy consuming and easily scalable alternative to the high energy consuming evaporative techniques which are commonly used for the obtaining of these ZnO films. For its application, however, the use of stable, well dispersed suspensions is a necessary requirement, and thus a thorough study of their colloidal chemistry is essential. In this work the main contributions to the study of colloidal chemistry of ZnO nanoparticle suspensions and their shaping into ZnO films by EPD are summarized. (Author)

  13. Photochemical events during photosensitization of colloidal ZnO ...

    Indian Academy of Sciences (India)

    ) was investigated using absorption, fluorescence spectroscopic measurements and time resolved fluorescence measurements. Riboflavin adsorbed strongly on the surface of ZnO nanoparticles. Apparent association constant was obtained ...

  14. Enhanced Photoluminescence in Acetylene-Treated ZnO Nanorods

    National Research Council Canada - National Science Library

    Jäppinen, Luke; Jalkanen, Tero; Sieber, Brigitte; Addad, Ahmed; Heinonen, Markku; Kukk, Edwin; Radevici, Ivan; Paturi, Petriina; Peurla, Markus; Shahbazi, Mohammad-Ali; Santos, Hélder A; Boukherroub, Rabah; Santos, Hellen; Lastusaari, Mika; Salonen, Jarno

    2016-01-01

    Zinc oxide (ZnO) nanorods were manufactured using the aqueous chemical growth (ACG) method, and the effect of thermal acetylene treatment on their morphology, chemical composition, and optical properties was investigated...

  15. Nanogenerator made of ZnO nanosheet networks

    Science.gov (United States)

    Zhang, Renyun; Hummelgård, Magnus; Olsen, Martin; Örtegren, Jonas; Olin, Håkan

    2017-05-01

    The piezoelectricity of nanomaterials attracts a great deal of attention due to its broad application, including the harvesting of ambient mechanical energy to power small electronics devices. We report here a simple method to fabricate piezoelectric nanogenerators consisting of networks of ZnO nanosheets grown on aluminum (Al) foils, where the Al acts as both a substrate for growth and as an electrode contacting the ZnO network. A second, top electrode was tapped, rolled, or rubbed against the ZnO to generate piezoelectricity. This second electrode was either a copper foil or fluorine doped tin oxide (FTO) glass. A piezo voltage of up to 0.924 V was detected during rolling and 6 μA was the highest current observed when rubbing the ZnO film with a FTO glass. Due to its simplicity, this nanogenerator fabrication method has the potential to be scaled up for the industrial production of piezoelectric energy harvesting devices.

  16. Direct observation of voltage barriers in ZnO varistors

    Science.gov (United States)

    Krivanek, O. L.; Williams, P.; Lin, Y.-C.

    1979-01-01

    Voltage barriers in a ZnO varistor have been imaged by voltage-contrast scanning electron microscopy. They are due to grain boundaries and are capable of supporting voltage differences of up to about 4 V.

  17. ZnO Nanowire Application in Chemoresistive Sensing: A Review

    Directory of Open Access Journals (Sweden)

    Simas Rackauskas

    2017-11-01

    Full Text Available This article provides an overview of the recent development of ZnO nanowires (NWs for chemoresistive sensing. Working mechanisms of chemoresistive sensors are unified for gas, ultraviolet (UV and bio sensor types: single nanowire and nanowire junction sensors are described, giving the overview for a simple sensor manufacture by multiple nanowire junctions. ZnO NW surface functionalization is discussed, and how this effects the sensing is explained. Further, novel approaches for sensing, using ZnO NW functionalization with other materials such as metal nanoparticles or heterojunctions, are explained, and limiting factors and possible improvements are discussed. The review concludes with the insights and recommendations for the future improvement of the ZnO NW chemoresistive sensing.

  18. Sonochemical effects on ZnO particles

    Directory of Open Access Journals (Sweden)

    Bruna C. Costa

    2014-01-01

    Full Text Available La variedad de aplicaciones tecnológicas relacionadas a los dispositivos basados en óxidos semiconductores nanoestructurados ha despertado un gran interés en la comunidad científica, haciendo con que los estudios relacionados a estos materiales han aumentado en los últimos años. Entre estos materiales, se encuentra el óxido de zinc (ZnO, que presenta aplicaciones en las más diversas áreas, desde diodos emisores de luz (LEDs a los dispositivos fotovoltaicos en células solares. Con el conocimiento de que las propiedades químicas y físicas que confieren a estos materiales las posibilidades de aplicación en dispositivos tecnológicos son fuertemente dependientes de las rutas de síntesis empleadas para la obtención de los mismos, presentamos en este trabajo una investigación con respecto de las modificaciones morfológicas ocurridas en partículas de ZnO, cuando el mismo es expuesto a un tratamiento sonoquímico, además de las influencias de los parámetros relacionados a éste método de síntesis en la obtención de este material. Para analizar los parámetros presentados anteriormente, tres muestras fueron preparadas, dos de ellas manteniendo la amplitud y variando el tiempo de sonicación y otra manteniendo el tiempo y variando la amplitud de sonicación, durante el tratamiento sonoquímico. El análisis de los resultados obtenidos indica que el tratamiento sonoquímico conduce a modificaciones morfológicas superficiales en las partículas de ZnO, además estas modificaciones se presentaron más evidentes cuando una mayor amplitud y un mayor tiempo de sonicación fueron utilizados en la síntesis de las muestras.

  19. Photoluminescence of sequential infiltration synthesized ZnO nanostructures

    Science.gov (United States)

    Ocola, Leonidas E.; Gosztola, David J.; Yanguas-Gil, Angel; Suh, Hyo-Seon; Connolly, Aine

    2016-02-01

    For the past several years there have been ongoing efforts to incorporate zinc oxide (ZnO) inside polymethyl methacrylate (PMMA), in the form of nanoparticles or quantum dots, to combine their optical properties for multiple applications. We have investigated a variation of atomic layer deposition (ALD), called sequential infiltration synthesis (SiS), as an alternate method to incorporate ZnO and other oxides inside the polymer. PMMA is a well-known ebeam resist. We can expose and develop patterns useful for photonics or sensing applications first, and then convert them afterwards into a hybrid oxide material with enhanced photonic, or sensing, properties. This is much easier than micromachining films of ZnO or other similar oxides because they are difficult to etch. The amount of ZnO formed inside the polymer film is magnitudes higher than equivalent amount deposited on a flat 2D surface, and the intensity of the photoemission suggests there is an enhancement created by the polymer-ZnO interaction. Photoemission from thin films exhibit photoemission similar to intrinsic ZnO with oxygen vacancies. These vacancies can be removed by annealing the sample at 500°C in an oxygen rich environment. SiS ZnO exhibits unusual photoemission properties for thick polymer films, emitting at excitations wavelengths not found in bulk or standard ZnO. Finally we have shown that patterning the polymer and then doing SiS ZnO treatment afterwards allows modifying or manipulating the photoemission spectra. This opens the doors to novel photonic applications.

  20. Measurement of the Euler Angles of Wurtzitic ZnO by Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    Wu Liu

    2017-01-01

    Full Text Available A Raman spectroscopy-based step-by-step measuring method of Euler angles φ,θ,and  ψ was presented for the wurtzitic crystal orientation on a microscopic scale. Based on the polarization selection rule and coordinate transformation theory, a series of analytic expressions for the Euler angle measurement using Raman spectroscopy were derived. Specific experimental measurement processes were presented, and the measurement of Raman tensor elements and Euler angles of the ZnO crystal were implemented. It is deduced that there is a trigonometric functional relationship between the intensity of each Raman bands of wurtzite crystal and Euler angle ψ, the polarization direction of incident light under different polarization configurations, which can be used to measure the Euler angles. The experimental results show that the proposed method can realize the measurement of Euler angles for wurtzite crystal effectively.

  1. Enhanced photoconductivity of ZnO films Co-doped with nitrogen and tellurium

    Science.gov (United States)

    Porter, H. L.; Cai, A. L.; Muth, J. F.; Narayan, J.

    2005-05-01

    Zinc oxide films are typically found to be n type, and conductive under most growth conditions and growth methods. Co-doping with multiple elements is one strategy for improving the electrical and optical properties of zinc oxide materials for optoelectronic device applications. Using pulsed-laser deposition, thin ZnO films were grown on c-axis oriented sapphire. The films were co-doped with nitrogen and tellurium. Depending on the relative concentrations of the dopants, the resistivity of the films was observed to increase by several orders of magnitude, significantly improving the photoconductive response. The enhancement of the photosensitivity reached a maximum at a tellurium concentration of around 1020cm-3.

  2. Structural and spectroscopic ellipsometry characterization for electrodeposited ZnO growth at different hydrogen peroxide concentration

    Energy Technology Data Exchange (ETDEWEB)

    El Hichou, A., E-mail: elhichou@fstg-marrakech.ac.m [Laboratoire de la Matiere Condensee et Nanostructures (LMCN), Faculte des Sciences et Techniques, BP 549, 40000 Marrakech (Morocco); Stein, N.; Boulanger, C. [Institut Jean Lamour, Laboratoire d' Electrochimie des Materiaux, UPV-M, CNRS, 1 bd Arago CP 87811, 57078 Metz cedex 3 (France); Johann, L. [Laboratoire de Physique des Milieux denses, UPV-M, 1 bd Arago CP 87811, 57078 Metz cedex 3 (France)

    2010-05-31

    This work deals with textural and optical characterization of zinc oxide (ZnO) layers obtained by potentiostatic electroplating at various hydrogen peroxide concentrations (from 0 up to 5 mM). The electrodeposition process was studied by cyclic voltametry and chronoamperometry. The [002] preferred growth orientation of hexagonal phase is obtained for the lowest hydrogen peroxide concentration (1 mM), while additionally X-ray diffraction peaks are observed for hydrogen peroxide concentration ranging from 3 to 5 mM. The optical constants and the thickness of films were determined by spectroscopic ellipsometry measurements. The refractive index of all thin films shows normal dispersion behavior. It was also found that refractive index values decrease with increasing hydrogen peroxide concentration. Further, it was revealed that the changes in the optical properties are correlated to the changes in the surface structure.

  3. Enhanced photoluminescence and heterojunction characteristics of pulsed laser deposited ZnO nanostructures

    Science.gov (United States)

    Mannam, Ramanjaneyulu; Kumar, E. Senthil; Priyadarshini, D. M.; Bellarmine, F.; DasGupta, Nandita; Ramachandra Rao, M. S.

    2017-10-01

    We report on the growth of ZnO nanostructures in different gas ambient (Ar and N2) using pulsed laser deposition technique. Despite the similar growth temperature, use of N2 ambient gas resulted in well-aligned nanorods with flat surface at the tip, whereas, nanorods grown with Ar ambient exhibited tapered tips. The Nanorods grown under N2 ambient exhibited additional Raman modes corresponding to N induced zinc interstitials. The nanorods are c-axis oriented and highly epitaxial in nature. Photoluminescence spectroscopy reveals that the UV emission can be significantly enhanced by 10 times for the nanorods grown under Ar ambient. The enhanced UV emission is attributed to the reduction in polarization electric field along the c-axis. n-ZnO nanorods/p-Si heterojunction showed rectifying I-V characteristics with a turn of voltage of 3.4 V.

  4. First-principles study of CO adsorption on ZnO surfaces

    CERN Document Server

    Meyer, B

    2003-01-01

    Using density-functional theory we have calculated the equilibrium geometries and binding energies of a CO monolayer adsorbed on the nonpolar (1010) and the polar (0001)-Zn and (0001)-O surfaces of ZnO. Different adsorption sites and CO orientations were considered, and for the polar surfaces the influence of a hydrogen coverage upon CO adsorption was studied. For the clean surfaces we find that CO exclusively binds to Zn ions with a binding energy of 0.24 and 0.37 eV for the nonpolar (1010) and the polar (0001)-Zn surface, respectively. A purely repulsive interaction of CO with surface oxygen ions is obtained. On the other hand, if the polar surfaces are hydrogen saturated, we predict a weak chemisorption of CO to the OH-terminated (0001) surface with a binding energy of 0.20 eV but no CO adsorption for the ZnH-terminated (0001) face. (letter to the editor)

  5. Influence of Te and Se doping on ZnO films growth by SILAR method

    Energy Technology Data Exchange (ETDEWEB)

    Güney, Harun, E-mail: harunguney25@hotmail.com [Department of Electric and Energy, Vocation High School, Ağrı İbrahim Çeçen University (Turkey); Duman, Çağlar, E-mail: caglarduman@erzurum.edu.tr [Department of Electrical and Electronic Engineering, Faculty of Engineering, Erzurum Technical University (Turkey)

    2016-04-18

    The AIP Successive ionic layer adsorption and reaction (SILAR) is an economic and simple method to growth thin films. In this study, SILAR method is used to growth Selenium (Se) and Tellurium (Te) doped zinc oxide (ZnO) thin films with different doping rates. For characterization of the films X-ray diffraction (XRD), absorbance and scanning electron microscopy (SEM) are used. XRD results are showed well-defined strongly (002) oriented crystal structure for all samples. Also, absorbance measurements show, Te and Se concentration are proportional and inversely proportional with band gap energy, respectively. SEM measurements show that the surface morphology and thickness of the material varied with Se and/or Te and varying concentrations.

  6. Electronic properties of a grain boundary in Sb-doped ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Carlsson, J.M.; Hellsing, B. [Experimental Physics, Chalmers and Goeteborg University, Gothenburg (Sweden); Domingos, H.S.; Bristowe, P.D. [Department of Materials Science and Metallurgy, University of Cambridge, Cambridge (United Kingdom)]. E-mail: pdb1000@cus.cam.ac.uk

    2001-11-05

    The electronic properties of a {sigma}=13 32.2 deg. [0001] tilt grain boundary in ZnO have been investigated using first-principles calculations. Two atomic models for the boundary have been considered, one of which contains structural units that are consistent with those observed for this orientation using electron microscopy. Doping both the grain boundary models with antimony reveals a strong driving force for segregation. Analysis of the electronic densities of states, bond populations and Mulliken charges shows that antimony creates a localized impurity state in the grain boundary and acts as a donor dopant. The resulting charge accumulation at the grain boundary together with the presence of local bonds that are metallic in character, will influence the mechanism for charge transport across the interface and this is discussed in relation to varistor applications. (author)

  7. Electronic properties of a grain boundary in Sb-doped ZnO

    Science.gov (United States)

    Carlsson, J. M.; Hellsing, B.; Domingos, H. S.; Bristowe, P. D.

    2001-11-01

    The electronic properties of a Σ = 13 32.2° [0001] tilt grain boundary in ZnO have been investigated using first-principles calculations. Two atomic models for the boundary have been considered, one of which contains structural units that are consistent with those observed for this orientation using electron microscopy. Doping both the grain boundary models with antimony reveals a strong driving force for segregation. Analysis of the electronic densities of states, bond populations and Mulliken charges shows that antimony creates a localized impurity state in the grain boundary and acts as a donor dopant. The resulting charge accumulation at the grain boundary together with the presence of local bonds that are metallic in character, will influence the mechanism for charge transport across the interface and this is discussed in relation to varistor applications.

  8. ZnO Nanostructures for Tissue Engineering Applications.

    Science.gov (United States)

    Laurenti, Marco; Cauda, Valentina

    2017-11-06

    This review focuses on the most recent applications of zinc oxide (ZnO) nanostructures for tissue engineering. ZnO is one of the most investigated metal oxides, thanks to its multifunctional properties coupled with the ease of preparing various morphologies, such as nanowires, nanorods, and nanoparticles. Most ZnO applications are based on its semiconducting, catalytic and piezoelectric properties. However, several works have highlighted that ZnO nanostructures may successfully promote the growth, proliferation and differentiation of several cell lines, in combination with the rise of promising antibacterial activities. In particular, osteogenesis and angiogenesis have been effectively demonstrated in numerous cases. Such peculiarities have been observed both for pure nanostructured ZnO scaffolds as well as for three-dimensional ZnO-based hybrid composite scaffolds, fabricated by additive manufacturing technologies. Therefore, all these findings suggest that ZnO nanostructures represent a powerful tool in promoting the acceleration of diverse biological processes, finally leading to the formation of new living tissue useful for organ repair.

  9. ZnO Tetrapods: Synthesis and Applications in Solar Cells

    Directory of Open Access Journals (Sweden)

    Luting Yan

    2015-06-01

    Full Text Available Zinc oxide (ZnO tetrapods have received much interest due to their unique morphology, that is, four arms con‐ nected to one centre. Tetrapod networks possess the excellent electronic properties of the ZnO semiconductor, which is attractive for photoelectrode materials in energy- conversion devices because of their advantages in electron extraction and transportation. In this review, we have discussed recent advancements in the field of ZnO tetrapod synthesis, including vapour transport synthesis and the wet chemical method, together with their advantages and disadvantages in terms of morphology control and yield regulation. The developments and improvements in the applications of ZnO nanotetrapods in photovoltaics, including dye-sensitized solar cells and polymer solar cells, are also described. Our aim is to give readers a compre‐ hensive and critical overview of this unique morphology of ZnO, including synthesis control and growth mechanism, and to understand the role of this particular morphology in the development of solar cells. The future research directions in ZnO tetrapods-based solar cell are also discussed.

  10. Cytotoxicity of ZnO Nanowire Arrays on Excitable Cells

    Directory of Open Access Journals (Sweden)

    Yongchen Wang

    2017-04-01

    Full Text Available Zinc oxide (ZnO nanowires have been widely studied for their applications in electronics, optics, and catalysts. Their semiconducting, piezoelectric, fluorescent, and antibacterial properties have also attracted broad interest in their biomedical applications. Thus, it is imperative to evaluate the biosafety of ZnO nanowires and their biological effects. In this study, the cellular level biological effects of ZnO nanowire arrays are specifically tested on three types of excitable cells, including NG108-15 neuronal cell line, HL-1 cardiac muscle cell line, and neonatal rat cardiomyocytes. Vertically aligned and densely packed ZnO nanowire arrays are synthesized using a solution-based method and used as a substrate for cell culture. The metabolism levels of all three types of cells cultured on ZnO nanowire arrays are studied using the 3-(4,5-dimethyl-2-thiazolyl-2,5-diphenyl-2H-tetrazolium bromide (MTT assays of a full factorial design. Under the studied settings, the results show statistically significant inhibitory effects of ZnO nanowire arrays on the metabolism of NG108-15 and HL-1 cells in comparison to gold, glass, and polystyrene substrates, and on the metabolism of cardiomyocytes in comparison to gold substrate.

  11. ZnO Nanostructures for Tissue Engineering Applications

    Directory of Open Access Journals (Sweden)

    Marco Laurenti

    2017-11-01

    Full Text Available This review focuses on the most recent applications of zinc oxide (ZnO nanostructures for tissue engineering. ZnO is one of the most investigated metal oxides, thanks to its multifunctional properties coupled with the ease of preparing various morphologies, such as nanowires, nanorods, and nanoparticles. Most ZnO applications are based on its semiconducting, catalytic and piezoelectric properties. However, several works have highlighted that ZnO nanostructures may successfully promote the growth, proliferation and differentiation of several cell lines, in combination with the rise of promising antibacterial activities. In particular, osteogenesis and angiogenesis have been effectively demonstrated in numerous cases. Such peculiarities have been observed both for pure nanostructured ZnO scaffolds as well as for three-dimensional ZnO-based hybrid composite scaffolds, fabricated by additive manufacturing technologies. Therefore, all these findings suggest that ZnO nanostructures represent a powerful tool in promoting the acceleration of diverse biological processes, finally leading to the formation of new living tissue useful for organ repair.

  12. Synthesis, characteristics and antimicrobial activity of ZnO nanoparticles

    Science.gov (United States)

    Janaki, A. Chinnammal; Sailatha, E.; Gunasekaran, S.

    2015-06-01

    The utilization of various plant resources for the bio synthesis of metallic nano particles is called green technology and it does not utilize any harmful protocols. Present study focuses on the green synthesis of ZnO nano particles by Zinc Carbonate and utilizing the bio-components of powder extract of dry ginger rhizome (Zingiber officinale). The ZnO nano crystallites of average size range of 23-26 nm have been synthesized by rapid, simple and eco friendly method. Zinc oxide nano particles were characterized by using X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive X-ray spectroscopy (EDX). FTIR spectra confirmed the adsorption of surfactant molecules at the surface of ZnO nanoparticles and the presence of ZnO bonding. Antimicrobial activity of ZnO nano particles was done by well diffusion method against pathogenic organisms like Klebsiella pneumonia, Staphylococcus aureus and Candida albicans and Penicillium notatum. It is observed that the ZnO synthesized in the process has the efficient antimicrobial activity.

  13. Localized modes in orientation-disordered uniaxial medium

    Energy Technology Data Exchange (ETDEWEB)

    Wan Zhenzhu; Han Yanling [School of Mathematics and Physics, China University of Geosciences, Wuhan 430074 (China); Wang Hong, E-mail: wanghong745@sohu.com, E-mail: w_pearl2008@163.com [Center of Information and Laboratory, China University of Geosciences, Wuhan 430074 (China)

    2011-02-01

    Using a 4x4 transfer matrix method, localized modes in orientation-disordered uniaxial medium have been investigated. We confirm that localized modes origin from the randomness of spatial orientation of optical axes. The misalignment of the optical axe provides the opportunity for a rearrangement of the localized modes. The number of localize mode also closely relative to the spatial orientation of optical axis. Numerical results indicate that it is possible to adjust the localized modes through altering the relative orientation of the optical axes of scatterers. This study is an importance for well understanding of localization of light wave and lasing action in anisotropic random media.

  14. Entrepreneurial Orientation and Internationalisation

    DEFF Research Database (Denmark)

    Decker, Arnim; Rollnik-Sadowska, Ewa; Servais, Per

    orientation as an attitude held by principals we investigate how entrepreneurial orientation affected the behaviour of these firms, specifically in terms of their internationalisation. Despite the fact that all firms have identical roots we find that entrepreneurial orientation held by their principals affect...

  15. Synthesis, Characterization and renal toxicity of ZnO and polyethylene glycol Coated ZnO nanoparticles

    Directory of Open Access Journals (Sweden)

    Banafsheh Raisi Dehkourdi

    2017-01-01

    Full Text Available Objective(s: The wide scale use of Zinc oxide nanoparticles (ZnO NPs in the consumer market world makes human beings more prone to the exposure to ZnO nanoparticles and its adverse effects. Therefore, the aim of the present study is to assess renal toxicity potential of ZnO and Polyethylene glycol Coated ZnO Nanoparticles in rat.Materials and Methods: Co-precipitation chemical method was used in order to synthesize ZnO nanoparticles. The synthesized nanoparticles were coated with PEG (Polyethylene glycol and the coating interactions were investigated by FTIR (Fourier Transform Infrared Spectroscopy. Structural properties of ZnO NPs were evaluated by TEM (Transmission Electron Microscope and XRD (X Ray Diffraction. Toxicity assessment of ZnO and PEG coated ZnO nanoparticles were studied in rat by intra peritoneal injections during a one-month. Renal factors (Creatinine, Uric acid and Blood Urea Nitrogen were measured 15 and 30 days post injection.Results: The synthesized nanoparticles were single phase and have spinel structure. Their size distribution was around 18 nm. Some kidney factors were changed due to the injection of both uncoated and coated nanoparticles (especially in groups received concentrations of more than 100 mg per kg of body weight. Renal factors changes were more considerable in groups received ZnO NPs in comparison with those received PEG coated ZnO NPs. Chemical toxicity studies showed that there was no irreversible effect in the groups received  concentrations less than 200 mg/kg (mg per kg of body weight.Conclusion: The results indicated that renal factors were changed during 15 days post injection, especially in groups received high doses (200 mg/kg. The results of measurements 30 days post injection showed less change in comparison with the control and this indicates that there was no irreversible effect on kidney. Moreover, PEG coated nanoparticles were less toxic in comparison with Uncoated ZnO NPs.

  16. Comparative toxicity of nano ZnO and bulk ZnO towards marine algae Tetraselmis suecica and Phaeodactylum tricornutum.

    Science.gov (United States)

    Li, Jiji; Schiavo, Simona; Rametta, Gabriella; Miglietta, Maria Lucia; La Ferrara, Vera; Wu, Changwen; Manzo, Sonia

    2017-03-01

    The wide use of ZnO nanoparticles in a number of products implies an increasing release into the marine environment, resulting in the need to evaluate the potential effects upon organisms, and particularly phytoplankton, being at the base of the throphic chain. To this aim, dose-response curves for the green alga Tetraselmis suecica and the diatom Phaeodactylum tricornutum derived from the exposure to nano ZnO (100 nm) were evaluated and compared with those obtained for bulk ZnO (200 nm) and ionic zinc. The toxic effects to both algae species were reported as no observable effect concentration (NOEC) of growth inhibition and as 1, 10, and 50% effect concentrations (EC1, EC10, and EC50). The toxicity decreased in the order nano ZnO > Zn 2+ > bulk ZnO. EC50 values for nano ZnO were 3.91 [3.66-4.14] mg Zn/L towards the green microalgae and 1.09 [0.96-1.57] mg Zn/L towards the diatom, indicating a higher sensitivity of P. tricornutum. The observed diverse effects can be ascribed to the interaction occurring between different algae and ZnO particles. Due to algae motility, ZnO particles were intercepted in different phases of aggregation and sedimentation processes, while algae morphology and size can influence the level of entrapment by NP aggregates.This underlines the need to take into account the peculiarity of the biological system in the assessment of NP toxicity.

  17. Chemical manipulation of oxygen vacancy and antibacterial activity in ZnO.

    Science.gov (United States)

    V, Lakshmi Prasanna; Vijayaraghavan, Rajagopalan

    2017-08-01

    Pure and doped ZnO (cation and anion doping) compositions have been designed in order to manipulate oxygen vacancy and antibacterial activity of ZnO. In this connection, we have synthesized and characterized micron sized ZnO, N doped micron sized ZnO, nano ZnO, nano Na and La doped ZnO. The intrinsic vacancies in pure ZnO and the vacancies created by N and Na doping in ZnO have been confirmed by X-ray Photoelectron Spectroscopy(XPS) and Photoluminiscence Spectroscopy(PL). Reactive oxygen species (ROS) such as hydroxyl radicals, superoxide radicals and H2O2 responsible for antibacterial activity have been estimated by PL, UV-Vis spectroscopy and KMnO4 titrations respectively. It was found that nano Na doped ZnO releases highest amount of ROS followed by nano ZnO, micron N doped ZnO while micron ZnO releases the least amount of ROS. The concentration of vacancies follows the same sequence. This illustrates directly the correlation between ROS and oxygen vacancy in well designed pure and doped ZnO. For the first time, material design in terms of cation doping and anion doping to tune oxygen vacancies has been carried out. Interaction energy (Eg), between the bacteria and nanoparticles has been calculated based on Extended Derjaguin-Landau-Verwey-Overbeek (EDLVO) theory and is correlated with antibacterial activity. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Microwave synthesis and photocatalytic activities of ZnO bipods with different aspect ratios

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Fazhe; Zhao, Zengdian [Analysis and Testing Center, Shandong University of Technology, Zibo 255100 (China); Qiao, Xueliang, E-mail: xuelqiao@163.com [State Key Laboratory of Plastic Forming Simulation and Die and Mould Technology, Huazhong University of Science and Technology, Wuhan 430074, Hubei (China); Tan, Fatang; Wang, Wei [State Key Laboratory of Plastic Forming Simulation and Die and Mould Technology, Huazhong University of Science and Technology, Wuhan 430074, Hubei (China)

    2016-02-15

    Highlights: • We synthesized linked ZnO nanorods by a facile microwave method. • The effect of reaction parameters on ZnO was investigated. • ZnO bipods with different aspect ratios were prepared. • The photocatalytic performance of ZnO bipods was evaluated. - Abstract: Linked ZnO nanorods have been successfully prepared via a facile microwave method without any post-synthesis treatment. The X-ray diffraction (XRD) patterns indicated the precursor had completely transformed into the pure ZnO crystal. The images of field emitting scanning electron microscope (FESEM) and transmission electron microscope (TEM) showed that linked ZnO nanorods consisted predominantly of ZnO bipods. The formation process of the ZnO bipods was clearly discussed. ZnO bipods with different aspect ratios have been obtained by tuning the concentrations of reagents and microwave power. Moreover, the photocatalytic performance of ZnO bipods with different aspect ratios for degradation of methylene blue was systematically evaluated. The results of photocatalytic experiments showed that the photocatalytic activity increased with the aspect ratios of ZnO bipods increased. The reason is that ZnO bipods with larger aspect ratio have higher surface area, which can absorb more MB molecules to react with ·OH radicals.

  19. Influence of film thickness and oxygen partial pressure on cation-defect-induced intrinsic ferromagnetic behavior in luminescent p-type Na-doped ZnO thin films.

    Science.gov (United States)

    Ghosh, S; Khan, Gobinda Gopal; Varma, Shikha; Mandal, K

    2013-04-10

    In this article, we have investigated the effect of oxygen partial pressure (PO2) and film thickness on defect-induced room-temperature (RT) ferromagnetism (FM) of highly c-axis orientated p-type Na-doped ZnO thin films fabricated by pulse laser deposition (PLD) technique. We have found that the substitution of Na at Zn site (NaZn) can be effective to stabilize intrinsic ferromagnetic (FM) ordering in ZnO thin films with Curie temperature (TC) as high as 509 K. The saturation magnetization (MS) is found to decrease gradually with the increase in thickness of the films, whereas an increase in "MS" is observed with the increase in PO2 of the PLD chamber. The enhancement of ferromagnetic signature with increasing PO2 excludes the possibility of oxygen vacancy (VO) defects for the magnetic origin in Na-doped ZnO films. On the other hand, remarkable enhancement in the green emission (IG) are observed in the photoluminescence (PL) spectroscopic measurements due to Na-doping and that indicates the stabilization of considerable amount of Zn vacancy (VZn)-type defects in Na-doped ZnO films. Correlating the results of PL and X-ray photoelectron spectroscopy (XPS) studies with magnetic measurements we have found that VZn and Na substitutional (NaZn) defects are responsible for the hole-mediated FM in Na-doped ZnO films, which might be an effective candidate for modern spintronic technology.

  20. Characterization of ZnO thin film grown on c-plane substrates by MO-CVD: Effect of substrate annealing temperature, vicinal-cut angle and miscut direction

    Science.gov (United States)

    Boukadhaba, M. A.; Fouzri, A.; Sallet, V.; Hassani, S. S.; Amiri, G.; Lusson, A.; Oumezzine, M.

    2015-09-01

    The annealing effects of c-plane sapphire (α-Al2O3) substrate with a nominally vicinal-cut angle α (α ZnO films grown by metal organic chemical vapor deposition (MO-CVD) were studied. The atomic steps formed on sapphire substrate surface by annealing at high temperature were analyzed by atomic force microscopy (AFM). The annealing and the miscut direction of sapphire substrate on the microstructural and optical properties for ZnO films were examined by high resolution X-ray diffraction (HR-XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and photoluminescence spectroscopy (PL). Experimental results indicate that the film quality is strongly affected by annealing treatment and miscut direction of the sapphire substrate. X-ray diffraction study revealed that all films exhibit a wurtzite phase and have a c-axis orientation. ZnO films deposited on sapphire substrate (α ZnO layer deposited on annealed sapphire substrate with increase the annealing substrate temperature for all samples. AFM image show significant differences between morphologies of samples depending on annealing treatment and miscut direction of substrates but no significant differences on surface roughness have been found. Sapphire annealing at 1100 °C with a nominally vicinal-cut angle α = 0.25° toward the m-plane (1 0 1 bar 0), provides the best optical quality of ZnO film.

  1. Enhancement of UV emission in ZnO nanorods by growing additional ZnO layers on the surface

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yongseon; Kang, Shinhoo, E-mail: yskim01@snu.ac.kr, E-mail: shinkang@snu.ac.kr [Department of Materials Science and Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of)

    2011-07-08

    Ultraviolet (UV) photoluminescence emission from ZnO nanorod arrays was greatly enhanced by growing additional thin ZnO layers on the surface after thermal reduction of the nanorods. Appropriate selection of additives based on the shape of the original ZnO samples was found to be an important factor in designing the solution composition for growing the additional ZnO layers. This is because the additives modify the growth rates with respect to crystallographic planes. Adding ethylene glycol to the solution was effective for rod-shaped ZnO nanorods in enhancing the UV emission, whereas adding polyethylenimine was better for plate-like particles. These results can be explained by the presence of non-luminescent regions near the surface, where UV emission is thought to be suppressed by non-radiative surface centers. Growing additional layers on side planes increases the volume of the optically active region of ZnO nanorods, with a lower transmittance loss; thus, it effectively enhances the UV emission intensity.

  2. Preparation of ZnO film on p-Si and I-V characteristics of p-Si/n-ZnO

    Directory of Open Access Journals (Sweden)

    Shampa Mondal

    2013-02-01

    Full Text Available Zinc oxide (ZnO thin films were deposited on p-silicon (Si substrate from ammonium zincate bath following a chemical dipping technique called SILAR. Films in the thickness range 0.5-4.5 µm could be prepared by varying the number of dipping for a fixed concentration (0.125 M of zincate bath and fixed pH (11.00-11.10. Higher values of dipping produced nonadherent and poor quality films. Structural characterization by X-ray diffraction (XRD indicates the formation of polycrystalline single phase ZnO with strong c-axis orientation. The structural characteristics of the films were found to be a sensitive function of film thickness. The degree of orientation was found to be a function of film thickness and a maximum was found at around 2.2 µm. Scanning electron microscopy (SEM reveals the formation of sub-micrometer crystallites on silicon substrate. The coverage of crystallites (grains on substrate surface increases with number of dipping. Dense film containing grains distributed throughout the surface is obtained at large thicknesses. The ohmic nature of silver (Ag on ZnO and Aluminum (Al on p-Si was confirmed by I-V measurements. I-V characteristic of the p-Si/n-ZnO heterojunction was studied and rectification was observed. The maximum value of forward to reverse current ratio was ~15 at 3.0 V.

  3. Understanding political market orientation

    DEFF Research Database (Denmark)

    Ormrod, Robert P.; Henneberg, Stephan C.

    This article develops a conceptual framework and measurement model of political market orientation that consists of attitudinal and behavioural constructs. The article reports on perceived relationships among different behavioral aspects of political market orientation and the attitudinal...... influences of such behavior. The study includes structural equation modeling to investigate several propositions. While the results show that political parties need to focus on several different aspects of market-oriented behavior, especially using an internal and external orientation as cultural antecedents......, a more surprising result is the inconclusive effect of a voter orientation on market-oriented behaviours. The article discusses the findings in the context of the existing literature in political marketing and commercial market orientation....

  4. Summary Time Oriented Record (STOR)

    Science.gov (United States)

    O'Keefe, Q.E. Whiting; Simborg, Donald W.

    1980-01-01

    STOR is a computerized three component, time-oriented, summary, medical record designed to partially replace the traditional paper chart in the outpatient clinics at the University of California San Francisco. Information from at least four distributed databases functioning independently is brought together in a single paper document. Informationally, STOR is prioritized, displays inter-problem and chronological relationships, provides a high degree of physician control over the display and provides a great deal of information with little manual physician effort. Besides the usual issues of cost, impact, and acceptance, the evaluation will address the question of the informational competence of STOR in two single blind randomized controlled trials.

  5. Optical and Sensing Properties of Cu Doped ZnO Nanocrystalline Thin Films

    National Research Council Canada - National Science Library

    Shukla, R. K; Srivastava, Anchal; Kumar, Nishant; Pandey, Akhilesh; Pandey, Mamta

    2015-01-01

    Undoped and Cu doped ZnO films of two different molarities deposited by spray pyrolysis using zinc nitrate and cupric chloride as precursors show polycrystalline nature and hexagonal wurtzite structure of ZnO...

  6. Luminance behavior of lithium-doped ZnO nanowires with p-type conduction characteristics.

    Science.gov (United States)

    Ko, Won Bae; Lee, Jun Seok; Lee, Sang Hyo; Cha, Seung Nam; Sohn, Jung Inn; Kim, Jong Min; Park, Young Jun; Kim, Hyun Jung; Hong, Jin Pyo

    2013-09-01

    The present study describes the room-temperature cathodeluminescence (CL) and temperature-dependent photoluminescence (PL) properties of p-type lithium (Li)-doped zinc oxide (ZnO) nanowires (NWs) grown by hydrothermal doping and post-annealing processes. A ZnO thin film was used as a seed layer in NW growth. The emission wavelengths and intensities of undoped ZnO NWs and p-type Li-doped ZnO NWs were analyzed for comparison. CL and PL observations of post-annealed p-type Li-doped ZnO NWs clearly exhibited a dominant sharp band-edge emission. Finally, a n-type ZnO thin film/p-type annealed Li-doped ZnO NW homojunction diode was prepared to confirm the p-type conduction of annealed Li-doped ZnO NWs as well as the structural properties measured by transmission electron microscopy.

  7. Fabrication and photovoltaic properties of ZnO nanorods/perovskite solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Shirahata, Yasuhiro; Tanaike, Kohei; Akiyama, Tsuyoshi; Fujimoto, Kazuya; Suzuki, Atsushi; Balachandran, Jeyadevan; Oku, Takeo, E-mail: oku@mat.usp.ac.jp [Department of Materials Science, The University of Shiga Prefecture, 2500 Hassaka, Hikone, Shiga 522-8533 (Japan)

    2016-02-01

    ZnO nanorods/perovskite solar cells with different lengths of ZnO nanorods were fabricated. The ZnO nanorods were prepared by chemical bath deposition and directly confirmed to be hexagon-shaped nanorods. The lengths of the ZnO nanorads were controlled by deposition condition of ZnO seed layer. Photovoltaic properties of the ZnO nanorods/CH{sub 3}NH{sub 3}PbI{sub 3} solar cells were investigated by measuring current density-voltage characteristics and incident photon to current conversion efficiency. The highest conversion efficiency was obtained in ZnO nanorods/CH{sub 3}NH{sub 3}PbI{sub 3} with the longest ZnO nanorods.

  8. Electrochemical Sensing, Photocatalytic and Biological Activities of ZnO Nanoparticles: Synthesis via Green Chemistry Route

    Science.gov (United States)

    Yadav, L. S. Reddy; Archana, B.; Lingaraju, K.; Kavitha, C.; Suresh, D.; Nagabhushana, H.; Nagaraju, G.

    2016-05-01

    In this paper, we have successfully synthesized ZnO nanoparticles (Nps) via solution combustion method using sugarcane juice as the novel fuel. The structure and morphology of the synthesized ZnO Nps have been analyzed using various analytical tools. The synthesized ZnO Nps exhibit excellent photocatalytic activity for the degradation of methylene blue dye, indicating that the ZnO Nps are potential photocatalytic semiconductor materials. The synthesized ZnO Nps also show good electrochemical sensing of dopamine. ZnO Nps exhibit significant bactericidal activity against Klebsiella aerogenes, Pseudomonas aeruginosa, Eschesichia coli and Staphylococcus aureus using agar well diffusion method. Furthermore, the ZnO Nps show good antioxidant activity by potentially scavenging 1-diphenyl-2-picrylhydrazyl (DPPH) radicals. The above studies clearly demonstrate versatile applications of ZnO synthesized by simple eco-friendly route.

  9. Recent Progress in Ohmic/Schottky-Contacted ZnO Nanowire Sensors

    National Research Council Canada - National Science Library

    Zhao, Xiaoli; Zhou, Ranran; Hua, Qilin; Dong, Lin; Yu, Ruomeng; Pan, Caofeng

    2015-01-01

      We review the recent progress of zinc oxide (ZnO) nanowire sensors with ohmic-contacted and Schottky-contacted configurations and the enhancement of the performances of Schottky-contacted ZnO NW sensors (SCZNSs...

  10. Fabrication and photovoltaic properties of ZnO nanorods/perovskite solar cells

    Science.gov (United States)

    Shirahata, Yasuhiro; Tanaike, Kohei; Akiyama, Tsuyoshi; Fujimoto, Kazuya; Suzuki, Atsushi; Balachandran, Jeyadevan; Oku, Takeo

    2016-02-01

    ZnO nanorods/perovskite solar cells with different lengths of ZnO nanorods were fabricated. The ZnO nanorods were prepared by chemical bath deposition and directly confirmed to be hexagon-shaped nanorods. The lengths of the ZnO nanorads were controlled by deposition condition of ZnO seed layer. Photovoltaic properties of the ZnO nanorods/CH3NH3PbI3 solar cells were investigated by measuring current density-voltage characteristics and incident photon to current conversion efficiency. The highest conversion efficiency was obtained in ZnO nanorods/CH3NH3PbI3 with the longest ZnO nanorods.

  11. Enhanced field emission of ZnO nanoneedle arrays via solution etching at room temperature

    DEFF Research Database (Denmark)

    Ma, Huanming; Qin, Zhiwei; Wang, Zaide

    2017-01-01

    ZnO nanoneedle arrays (ZnO nns) were synthesized by a facile two-step solution-phase method based on the etching of pre-synthesized ZnO nanowire arrays (ZnO nws) with flat ends at room temperature. Field emission measurement results showed that the turn-on electronic fields of ZnO nns and nws wer...... 2.7 and 5.3 V μm−1 at a current density of 10 μA cm−2, and the field enhancement factors were 4939.3 for ZnO nns and 1423.6 for ZnO nws. The enhanced field emission properties in ZnO nns were ascribed to the sharp tip geometry....

  12. The effect of cation doping on the morphology, optical and structural properties of highly oriented wurtzite ZnO-nanorod arrays grown by a hydrothermal method

    Science.gov (United States)

    Hassanpour, A.; Guo, P.; Shen, S.; Bianucci, P.

    2017-10-01

    Undoped and C-doped (C: Mg2+, Ni2+, Mn2+, Co2+, Cu2+, Cr3+) ZnO nanorods were synthesized by a hydrothermal method at temperatures as low as 60 °C. The effect of doping on the morphology of the ZnO nanorods was visualized by taking their cross section and top SEM images. The results show that the size of nanorods was increased in both height and diameter by cation doping. The crystallinity change of the ZnO nanorods due to each doping element was thoroughly investigated by an x-ray diffraction (XRD). The XRD patterns show that the wurtzite crystal structure of ZnO nanorods was maintained after cation addition. The optical Raman-active modes of undoped and cation-doped nanorods were measured with a micro-Raman setup at room temperature. The surface chemistry of samples was investigated by x-ray photoelectron spectroscopy and energy-dispersive x-ray spectroscopy. Finally, the effect of each cation dopant on band-gap shift of the ZnO nanorods was investigated by a photoluminescence setup at room temperature. Although the amount of dopants (Mg2+, Ni2+, and Co2+) was smaller than the amount of Mn2+, Cu2+, and Cr3+ in the nanorods, their effect on the band structure of the ZnO nanorods was profound. The highest band-gap shift was achieved for a Co-doped sample, and the best crystal orientation was for Mn-doped ZnO nanorods. Our results can be used as a comprehensive reference for engineering of the morphological, structural and optical properties of cation-doped ZnO nanorods by using a low-temperature synthesis as an economical mass-production approach.

  13. A high speed PE-ALD ZnO Schottky diode rectifier with low interface-state density

    Science.gov (United States)

    Jin, Jidong; Zhang, Jiawei; Shaw, Andrew; Kudina, Valeriya N.; Mitrovic, Ivona Z.; Wrench, Jacqueline S.; Chalker, Paul R.; Balocco, Claudio; Song, Aimin; Hall, Steve

    2018-02-01

    Zinc oxide (ZnO) has recently attracted attention for its potential application to high speed electronics. In this work, a high speed Schottky diode rectifier was fabricated based on a ZnO thin film deposited by plasma-enhanced atomic layer deposition and a PtOx Schottky contact deposited by reactive radio-frequency sputtering. The rectifier shows an ideality factor of 1.31, an effective barrier height of 0.79 eV, a rectification ratio of 1.17  ×  107, and cut-off frequency as high as 550 MHz. Low frequency noise measurements reveal that the rectifier has a low interface-state density of 5.13  ×  1012 cm‑2 eV‑1, and the noise is dominated by the mechanism of a random walk of electrons at the PtO x /ZnO interface. The work shows that the rectifier can be used for both noise sensitive and high frequency electronics applications.

  14. Highly transparent and reproducible nanocrystalline ZnO and AZO thin films grown by room temperature pulsed-laser deposition on flexible Zeonor plastic substrates

    Science.gov (United States)

    Inguva, Saikumar; Vijayaraghavan, Rajani K.; McGlynn, Enda; Mosnier, Jean-Paul

    2015-09-01

    Zeonor plastics are highly versatile due to exceptional optical and mechanical properties which make them the choice material in many novel applications. For potential use in flexible transparent optoelectronic applications, we have investigated Zeonor plastics as flexible substrates for the deposition of highly transparent ZnO and AZO thin films. Films were prepared by pulsed laser deposition at room temperature in oxygen ambient pressures of 75, 150 and 300 mTorr. The growth rate, surface morphology, hydrophobicity and the structural, optical and electrical properties of as-grown films with thicknesses ˜65-420 nm were recorded for the three oxygen pressures. The growth rates were found to be highly linear both as a function of film thickness and oxygen pressure, indicating high reproducibility. All the films were optically smooth, hydrophobic and nanostructured with lateral grain shapes of ˜150 nm wide. This was found compatible with the deposition of condensed nanoclusters, formed in the ablation plume, on a cold and amorphous substrate. Films were nanocrystalline (wurtzite structure), c-axis oriented, with average crystallite size ˜22 nm for ZnO and ˜16 nm for AZO. In-plane compressive stress values of 2-3 GPa for ZnO films and 0.5 GPa for AZO films were found. Films also displayed high transmission greater than 95% in some cases, in the 400-800 nm wavelength range. The low temperature photoluminescence spectra of all the ZnO and AZO films showed intense near band edge emission. A considerable spread from semi-insulating to n-type conductive was observed for the films, with resistivity ˜103 Ω cm and Hall mobility in 4-14 cm2 V-1 s-1 range, showing marked dependences on film thickness and oxygen pressure. Applications in the fields of microfluidic devices and flexible electronics for these ZnO and AZO films are suggested.

  15. Role of hydrogen addition in the plasma phase in determining the structural and chemical properties of RF sputtered ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Gottardi, Gloria, E-mail: ggottard@fbk.eu [Fondazione Bruno Kessler, Center for Materials and Microsystems, PAM Unit, via Sommarive 18, I - 38123 Povo, Trento (Italy); Bartali, Ruben; Micheli, Victor; Laidani, Nadhira [Fondazione Bruno Kessler, Center for Materials and Microsystems, PAM Unit, via Sommarive 18, I - 38123 Povo, Trento (Italy); Avi, Damiano [University of Trento, Physics Department, Atomic and Molecular Physics Lab., Via Sommarive 14, I - 38123 Povo, Trento (Italy)

    2011-05-16

    Research highlights: {yields} Effects of H in corporation on ZnO thin films growth and properties. {yields} Modification of the sputtering mechanism according to H{sub 2} percentage in the plasma. {yields} Structural changes turns up with variations of the surface and bulk oxide chemistry. {yields} Development of an hydroxide component due to atomic H incorporation. - Abstract: In the present work, ZnO thin films were RF sputtered from a pure ZnO target, without external heating, in H{sub 2}:Ar plasma at different H{sub 2} concentrations (0-50%). Aim of the study was the identification of the effects of H incorporation on the film growth and properties. During the deposition experiments, optical emission (OES) spectra were recorded to monitor any variation in the plasma chemical species relative to different process or gas mixture settings. X-ray photoelectron spectroscopy (XPS) and attenuated total reflection Fourier-transformed infrared spectroscopy (ATR-FTIR) were used to study the bulk and surface chemical composition of the films, while X-ray diffraction (XRD) analysis allowed lattice structure and grain size determination. The introduction of hydrogen in the plasma phase appears to strongly affect the structural and chemical properties of ZnO films. Both FTIR spectra and X-ray diffraction patterns showed that all the films crystallized in the hexagonal wuertzite form. Nevertheless, while samples deposited in pure Ar plasma are highly textured, presenting just one dominant preferred orientation along the [0 0 2] axis, films sputtered in H{sub 2}:Ar atmosphere exhibit multiple growth directions with crystallites of noticeably reduced dimensions. Such a structural modification turns up together with clear variations in the films surface chemical state which appears to deviate from the pure oxide (Zn-O). By combining XPS, ATR-FTIR and OES data we could correlate such variations with the process induced H incorporation in the crystal structure in the form of

  16. High electron mobility and low carrier concentration of hydrothermally grown ZnO thin films on seeded a-plane sapphire at low temperature

    Science.gov (United States)

    Jayah, Nurul Azzyaty; Yahaya, Hafizal; Mahmood, Mohamad Rusop; Terasako, Tomoaki; Yasui, Kanji; Hashim, Abdul Manaf

    2015-01-01

    Hydrothermal zinc oxide (ZnO) thick films were successfully grown on the chemical vapor deposition (CVD)-grown thick ZnO seed layers on a-plane sapphire substrates using the aqueous solution of zinc nitrate dehydrate (Zn(NO3)2). The use of the CVD ZnO seed layers with the flat surfaces seems to be a key technique for obtaining thick films instead of vertically aligned nanostructures as reported in many literatures. All the hydrothermal ZnO layers showed the large grains with hexagonal end facets and were highly oriented towards the c-axis direction. Photoluminescence (PL) spectra of the hydrothermal layers were composed of the ultraviolet (UV) emission (370 to 380 nm) and the visible emission (481 to 491 nm), and the intensity ratio of the former emission ( I UV) to the latter emission ( I VIS) changed, depending on both the molarity of the solution and temperature. It is surprising that all the Hall mobilities for the hydrothermal ZnO layers were significantly larger than those for their corresponding CVD seed films. It was also found that, for the hy