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Sample records for based zno film

  1. Comparative study of ZnO nanorods and thin films for chemical and biosensing applications and the development of ZnO nanorods based potentiometric strontium ion sensor

    Science.gov (United States)

    Khun, K.; Ibupoto, Z. H.; Chey, C. O.; Lu, Jun.; Nur, O.; Willander, M.

    2013-03-01

    In this study, the comparative study of ZnO nanorods and ZnO thin films were performed regarding the chemical and biosensing properties and also ZnO nanorods based strontium ion sensor is proposed. ZnO nanorods were grown on gold coated glass substrates by the hydrothermal growth method and the ZnO thin films were deposited by electro deposition technique. ZnO nanorods and thin films were characterised by field emission electron microscopy [FESEM] and X-ray diffraction [XRD] techniques and this study has shown that the grown nanostructures are highly dense, uniform and exhibited good crystal quality. Moreover, transmission electron microscopy [TEM] was used to investigate the quality of ZnO thin film and we observed that ZnO thin film was comprised of nano clusters. ZnO nanorods and thin films were functionalised with selective strontium ionophore salicylaldehyde thiosemicarbazone [ST] membrane, galactose oxidase, and lactate oxidase for the detection of strontium ion, galactose and L-lactic acid, respectively. The electrochemical response of both ZnO nanorods and thin films sensor devices was measured by using the potentiometric method. The strontium ion sensor has exhibited good characteristics with a sensitivity of 28.65 ± 0.52 mV/decade, for a wide range of concentrations from 1.00 × 10-6 to 5.00 × 10-2 M, selectivity, reproducibility, stability and fast response time of 10.00 s. The proposed strontium ion sensor was used as indicator electrode in the potentiometric titration of strontium ion versus ethylenediamine tetra acetic acid [EDTA]. This comparative study has shown that ZnO nanorods possessed better performance with high sensitivity and low limit of detection due to high surface area to volume ratio as compared to the flat surface of ZnO thin films.

  2. ZnO based transparent conductive oxide films with controlled type of conduction

    Energy Technology Data Exchange (ETDEWEB)

    Zaharescu, M., E-mail: mzaharescu@icf.ro [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Mihaiu, S., E-mail: smihaiu@icf.ro [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Toader, A. [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Atkinson, I., E-mail: irinaatkinson@yahoo.com [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Calderon-Moreno, J.; Anastasescu, M.; Nicolescu, M.; Duta, M.; Gartner, M. [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Vojisavljevic, K.; Malic, B. [Institute Jožef Stefan, Ljubljana (Slovenia); Ivanov, V.A.; Zaretskaya, E.P. [State Scientific and Production Association “Scientific-Practical Materials Research Center of the National Academy of Science Belarus, P. Brovska str.19, 220072, Minsk (Belarus)

    2014-11-28

    The transparent conductive oxide films with controlled type of conduction are of great importance and their preparation is intensively studied. In our work, the preparation of such films based on doped ZnO was realized in order to achieve controlled type of conduction and high concentration of the charge carriers. Sol–gel method was used for films preparation and several dopants were tested (Sn, Li, Ni). Multilayer deposition was performed on several substrates: SiO{sub 2}/Si wafers, silica-soda-lime and/or silica glasses. The structural and morphological characterization of the obtained films were done by scanning electron microscopy, X-ray diffraction, X-ray fluorescence, X-ray photoelectron spectroscopy and atomic force microscopy respectively, while spectroscopic ellipsometry and transmittance measurements were done for determination of optical properties. The selected samples with the best structural, morphological and optical properties were subjected to electrical measurement (Hall and Seebeck effect). In all studied cases, samples with good adherence and homogeneous morphology as well as monophasic wurtzite type structure were obtained. The optical constants (refractive index and extinction coefficient) were calculated from spectroscopic ellipsometry data using Cauchy model. Films with n- or p-type conduction were obtained depending on the composition, number of deposition and thermal treatment temperature. - Highlights: • Transparent conductive ZnO based thin films were prepared by the sol–gel method. • Controlled type of conduction is obtained in (Sn, Li) doped and Li-Ni co-doped ZnO films. • Hall and Seebeck measurements proved the p-type conductivity for Li-Ni co-doped ZnO films. • The p-type conductivity was maintained even after 4-months of storage. • Influence of dopant- and substrate-type on the ZnO films properties was established.

  3. Third generation biosensing matrix based on Fe-implanted ZnO thin film

    International Nuclear Information System (INIS)

    Saha, Shibu; Gupta, Vinay; Sreenivas, K.; Tan, H. H.; Jagadish, C.

    2010-01-01

    Third generation biosensor based on Fe-implanted ZnO (Fe-ZnO) thin film has been demonstrated. Implantation of Fe in rf-sputtered ZnO thin film introduces redox center along with shallow donor level and thereby enhance its electron transfer property. Glucose oxidase (GOx), chosen as model enzyme, has been immobilized on the surface of the matrix. Cyclic voltammetry and photometric assay show that the prepared bioelectrode, GOx/Fe-ZnO/ITO/Glass is sensitive to the glucose concentration with enhanced response of 0.326 μA mM -1 cm -2 and low Km of 2.76 mM. The results show promising application of Fe-implanted ZnO thin film as an attractive matrix for third generation biosensing.

  4. Third generation biosensing matrix based on Fe-implanted ZnO thin film

    Science.gov (United States)

    Saha, Shibu; Gupta, Vinay; Sreenivas, K.; Tan, H. H.; Jagadish, C.

    2010-09-01

    Third generation biosensor based on Fe-implanted ZnO (Fe-ZnO) thin film has been demonstrated. Implantation of Fe in rf-sputtered ZnO thin film introduces redox center along with shallow donor level and thereby enhance its electron transfer property. Glucose oxidase (GOx), chosen as model enzyme, has been immobilized on the surface of the matrix. Cyclic voltammetry and photometric assay show that the prepared bioelectrode, GOx/Fe-ZnO/ITO/Glass is sensitive to the glucose concentration with enhanced response of 0.326 μA mM-1 cm-2 and low Km of 2.76 mM. The results show promising application of Fe-implanted ZnO thin film as an attractive matrix for third generation biosensing.

  5. 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.

  6. Disposable urea biosensor based on nanoporous ZnO film fabricated from omissible polymeric substrate

    International Nuclear Information System (INIS)

    Rahmanian, Reza; Mozaffari, Sayed Ahmad; Abedi, Mohammad

    2015-01-01

    In the present study, a facile and simple fabrication method of a semiconductor based urea biosensor was reported via three steps: (i) producing a ZnO–PVA composite film by means of a polymer assisted electrodeposition of zinc oxide (ZnO) on the F-doped SnO 2 conducting glass (FTO) using water soluble polyvinyl alcohol (PVA), (ii) obtaining a nanoporous ZnO film by PVA omission via a subsequent post-treatment by annealing of the ZnO–PVA film, and (iii) preparation of a FTO/ZnO/Urs biosensor by exploiting a nanoporous ZnO film as an efficient and excellent platform area for electrostatic immobilization of urease enzyme (Urs) which was forced by the difference in their isoelectric point (IEP). The characterization techniques focused on the analysis of the ZnO–PVA film surfaces before and after annealing, which had a prominent effect on the porosity of the prepared ZnO film. The surface characterization of the nanostructured ZnO film by a field emission-scanning electron microscopy (FE–SEM), exhibited a film surface area as an effective bio-sensing matrix for enzyme immobilization. The structural characterization and monitoring of the biosensor fabrication was performed using UV–Vis, Fourier Transform Infrared (FT-IR), Raman Spectroscopy, Thermogravimetric Analysis (TGA), Cyclic Voltammetry (CV), and Electrochemical Impedance Spectroscopy (EIS) techniques. The impedimetric results of the FTO/ZnO/Urs biosensor showed a high sensitivity for urea detection within 8.0–110.0 mg dL −1 with the limit of detection as 5.0 mg dL −1 . - Highlights: • Novel disposable impedimetric urea biosensor fabrication based on ZnO–nanoporous transducer • Exploiting omissible PVA polymer as a simple strategy for ZnO–nanoporous film preparation • ZnO–nanoporous film as a good pore framework with large surface area/volume for enzyme immobilization • Application of impedimetric measurement for urea monitoring due to its rapidity, sensitivity, and repeatability

  7. Disposable urea biosensor based on nanoporous ZnO film fabricated from omissible polymeric substrate

    Energy Technology Data Exchange (ETDEWEB)

    Rahmanian, Reza; Mozaffari, Sayed Ahmad, E-mail: mozaffari@irost.ir; Abedi, Mohammad

    2015-12-01

    In the present study, a facile and simple fabrication method of a semiconductor based urea biosensor was reported via three steps: (i) producing a ZnO–PVA composite film by means of a polymer assisted electrodeposition of zinc oxide (ZnO) on the F-doped SnO{sub 2} conducting glass (FTO) using water soluble polyvinyl alcohol (PVA), (ii) obtaining a nanoporous ZnO film by PVA omission via a subsequent post-treatment by annealing of the ZnO–PVA film, and (iii) preparation of a FTO/ZnO/Urs biosensor by exploiting a nanoporous ZnO film as an efficient and excellent platform area for electrostatic immobilization of urease enzyme (Urs) which was forced by the difference in their isoelectric point (IEP). The characterization techniques focused on the analysis of the ZnO–PVA film surfaces before and after annealing, which had a prominent effect on the porosity of the prepared ZnO film. The surface characterization of the nanostructured ZnO film by a field emission-scanning electron microscopy (FE–SEM), exhibited a film surface area as an effective bio-sensing matrix for enzyme immobilization. The structural characterization and monitoring of the biosensor fabrication was performed using UV–Vis, Fourier Transform Infrared (FT-IR), Raman Spectroscopy, Thermogravimetric Analysis (TGA), Cyclic Voltammetry (CV), and Electrochemical Impedance Spectroscopy (EIS) techniques. The impedimetric results of the FTO/ZnO/Urs biosensor showed a high sensitivity for urea detection within 8.0–110.0 mg dL{sup −1} with the limit of detection as 5.0 mg dL{sup −1}. - Highlights: • Novel disposable impedimetric urea biosensor fabrication based on ZnO–nanoporous transducer • Exploiting omissible PVA polymer as a simple strategy for ZnO–nanoporous film preparation • ZnO–nanoporous film as a good pore framework with large surface area/volume for enzyme immobilization • Application of impedimetric measurement for urea monitoring due to its rapidity, sensitivity, and

  8. Physical deoxygenation of graphene oxide paper surface and facile in situ synthesis of graphene based ZnO films

    International Nuclear Information System (INIS)

    Ding, Jijun; Wang, Minqiang; Zhang, Xiangyu; Ran, Chenxin; Shao, Jinyou; Ding, Yucheng

    2014-01-01

    In-situ sputtering ZnO films on graphene oxide (GO) paper are used to fabricate graphene based ZnO films. Crystal structure and surface chemical states are investigated. Results indicated that GO paper can be effectively deoxygenated by in-situ sputtering ZnO on them without adding any reducing agent. Based on the principle of radio frequency magnetron sputtering, we propose that during magnetron sputtering process, plasma streams contain large numbers of electrons. These electrons not only collide with argon atoms to produce secondary electrons but also they are accelerated to bombard the substrates (GO paper) resulting in effective deoxygenation of oxygen-containing functional groups. In-situ sputtering ZnO films on GO paper provide an approach to design graphene-semiconductor nanocomposites

  9. 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.

  10. A vacuum pressure sensor based on ZnO nanobelt film

    International Nuclear Information System (INIS)

    Zheng, X J; Cao, X C; Sun, J; Yuan, B; Zhu, Z; Zhang, Y; Li, Q H

    2011-01-01

    A vacuum pressure sensor was fabricated by assembling ZnO nanobelt film on the interdigital electrodes, and the current-voltage characteristics were measured with an Agilent semiconductor parameter tester. Under different pressures of 1.0 x 10 3 , 6.7 x 10 -3 , 8.2 x 10 -4 and 9.5 x 10 -5 mbar, the currents are 8.71, 28.1, 46.1 and 89.6 nA, and the pressure sensitive resistances are 1150, 356, 217 and 112 MΩ, respectively. In the range of 10 -5 -10 3 mbar the smaller the pressure is, the higher the current is. The pressure sensitive resistance of the vacuum pressure sensor increases linearly with the logarithmic pressure, and the measurement range is at least one order of magnitude wider than that of the previous sensors. Under the final pressure, the vacuum pressure sensor has maximum sensitivity (9.29) and power consumption of 0.9 μW. The sensitivity is larger than that of the previous sensor based on a ZnO single nanowire at that pressure, and the power consumption is much lower than that for the sensor based on a ZnO nanowire array. The pressure sensitive mechanism is reasonably explained by using oxygen chemisorption and energy band theory.

  11. Ultrasonic vibration imposed on nanoparticle-based ZnO film improves the performance of the ensuing perovskite solar cell

    Science.gov (United States)

    Miao, Yihe; Du, Peng; Wang, Zhiyu; Chen, Qianli; Eslamian, Morteza

    2018-02-01

    This work focuses on the development of nearly annealing-free ZnO-based perovskite solar cells (PSCs), suitable for low-cost manufacturing of PSCs on flexible substrates. To this end, thin film of ZnO nanoparticles is employed as the electron transporting layer (ETL), because of its low-temperature solution-processability and high electron mobility. In order to remove the structural and surface defects, ultrasonic vibration is imposed on the substrate of the as-spun wet ZnO films for a short duration of 3 min. It is shown that the ultrasonic excitation bridges the ZnO nanoparticles (cold sintering), and brings about significant improvement in the ZnO film nanostructure and functionality. In addition, ethyl acetate (EA), as an emerging volatile anti-solvent, is employed to deposit the methylammonium (MA) lead halide perovskite thin film atop the ZnO ETL, in order to prepare perovskite layers that only need an annealing time of 30 s. The ZnO-based PSCs, with a simple structure and free of additional treatments, except for the ultrasonic vibration, exhibit a promising performance with a power conversion efficiency (PCE) of over 11%, 40% higher than that of the control device. The ultrasonic vibration treatment is facile, low-cost, environmentally friendly, and compatible with the scalable coating and printing techniques, such as spray and blade coating.

  12. The preparation of ZnO based gas-sensing thin films by ink-jet printing method

    International Nuclear Information System (INIS)

    Shen Wenfeng; Zhao Yan; Zhang Caibei

    2005-01-01

    An ink-jet printing technique was applied to prepare ZnO based gas-sensing thin films. ZnO inks with appropriate viscosity and surface tension were prepared by sol-gel techniques, and printed onto substrates using a commercial printer. After the drying and heating treatment processes, continuous ZnO films were formed and studied by scanning electron microscopy, X-ray diffraction and by a home-made gas sensitivity measuring system. It was found that the morphology and electrical properties of the films changed significantly with the thickness of the films, which can be adjusted simply by printing on the film with increasing frequency. Highest resistance and sensitivity to acetone vapor were obtained when the film was prepared by printing only once on it. Different dopants with certain concentrations could be added into the films by printing with different dopant inks and printing frequency. All Pd, Ag, and ZrO 2 dopants increased both the resistivity and the sensitivity of the films (180 ppm acetone). This work showed that the ink-jet printing technique was a convenient and low cost method to prepare films with controlled film thickness and dopant concentration

  13. Nano-structural properties of ZnO films for Si based heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Breivik, T.H. [University of Oslo, Department of Physics, P.O. Box 1048, Blindern, NO-0316, Oslo (Norway)], E-mail: t.h.breivik@fys.uio.no; Diplas, S. [University of Oslo, Department of Physics, P.O. Box 1048, Blindern, NO-0316, Oslo (Norway); University of Oslo, Center for Material Science and Nanotechnology, P.O. Box 1126, Blindern, NO-0318 Oslo (Norway); Ulyashin, A.G. [Section for Renewable Energy, Institute for Energy Technology, P.O. Box 40, NO-2027 Kjeller (Norway); Gunnaes, A.E. [University of Oslo, Department of Physics, P.O. Box 1048, Blindern, NO-0316, Oslo (Norway); Olaisen, B.R.; Wright, D.N.; Holt, A. [Section for Renewable Energy, Institute for Energy Technology, P.O. Box 40, NO-2027 Kjeller (Norway); Olsen, A. [University of Oslo, Department of Physics, P.O. Box 1048, Blindern, NO-0316, Oslo (Norway)

    2007-10-15

    Properties and structure of ZnO and ZnO:Al films deposited on c-Si, a-Si:H/Si and glass substrates are studied by various methods. The transmittance of the ZnO:Al was found to be higher when compared to ZnO, and the refractive index lower. X-ray photoelectron spectroscopy (XPS) shows that the screening efficiency in the presence of core holes is enhanced in the Al doped ZnO. The roughness of the ZnO:Al surfaces is strongly substrate dependent. With transmission electron microscopy (TEM) a 2-3 nm thick amorphous interfacial layer was observed independently of substrate and doping. Deposition of ZnO on a-Si:H substrate results in crystallization of the a-Si:H layer independently of Al doping.

  14. Nano-structural properties of ZnO films for Si based heterojunction solar cells

    International Nuclear Information System (INIS)

    Breivik, T.H.; Diplas, S.; Ulyashin, A.G.; Gunnaes, A.E.; Olaisen, B.R.; Wright, D.N.; Holt, A.; Olsen, A.

    2007-01-01

    Properties and structure of ZnO and ZnO:Al films deposited on c-Si, a-Si:H/Si and glass substrates are studied by various methods. The transmittance of the ZnO:Al was found to be higher when compared to ZnO, and the refractive index lower. X-ray photoelectron spectroscopy (XPS) shows that the screening efficiency in the presence of core holes is enhanced in the Al doped ZnO. The roughness of the ZnO:Al surfaces is strongly substrate dependent. With transmission electron microscopy (TEM) a 2-3 nm thick amorphous interfacial layer was observed independently of substrate and doping. Deposition of ZnO on a-Si:H substrate results in crystallization of the a-Si:H layer independently of Al doping

  15. Development of Antibacterial Composite Films Based on Isotactic Polypropylene and Coated ZnO Particles for Active Food Packaging

    Directory of Open Access Journals (Sweden)

    Clara Silvestre

    2016-01-01

    Full Text Available This study was aimed at developing new films based on isotactic polypropylene (iPP for food packaging applications using zinc oxide (ZnO with submicron dimension particles obtained by spray pyrolysis. To improve compatibility with iPP, the ZnO particles were coated with stearic acid (ZnOc. Composites based on iPP with 2 wt % and 5 wt % of ZnOc were prepared in a twin-screw extruder and then filmed by a calender. The effect of ZnOc on the properties of iPP were assessed and compared with those obtained in previous study on iPP/ZnO and iPP/iPPgMA/ZnO. For all composites, a homogeneous distribution and dispersion of ZnOc was obtained indicating that the coating with stearic acid of the ZnO particles reduces the surface polarity mismatch between iPP and ZnO. The iPP/ZnOc composite films have relevant zinc oxide with respect to E. coli, higher thermal stability and improved mechanical and impact properties than the pure polymer and the composites iPP/ZnO and iPP/iPPgMA/ZnO. This study demonstrated that iPP/ZnOc films are suitable materials for potential application in the active packaging field.

  16. Fabrication and study of sol-gel ZnO films for use in Si-based heterojunction photovoltaic devices

    Directory of Open Access Journals (Sweden)

    Daniya Mukhamedshina

    2017-12-01

    Full Text Available This paper considers the use of zinc oxide thin films prepared via the sol-gel route as an n-type layer in heterojunction ZnO/Si solar cells. The ZnO films were prepared via a simple spin-coating technique using zinc acetate dihydrate as a zinc precursor, isopropanol as a solvent and monoethanolamine as a stabilizing agent. Optical, structural and morphological properties of ZnO were investigated for thin films grown from sol-gel solutions with different concentrations both on glass and silicon substrates. As such, a distribution of crystallite sizes and surface topology parameters corresponding to various zinc acetate dihydrate concentrations were obtained to elucidate optimal film deposition conditions. Correlation between thin film morphology and structural characteristics of ZnO thin films was made based on atomic-force microscopy studies. Finally, our results on fabrication, characterization and simulation of ZnO/Si heterojunctions for use as photovoltaic devices are presented. Although noticeable rectifying and photovoltaic properties were observed for Al/Si/ZnO/Ti/Au devices, there appears to exist a considerable room for device improvement with simulation studies suggesting that efficiencies of the order of 24% may be obtained for devices with optimal silicon wafer passivation, i.e. with lifetimes of the order of 1000 μs.

  17. Blue electroluminescence nanodevice prototype based on vertical ZnO nanowire/polymer film on silicon substrate

    International Nuclear Information System (INIS)

    He Ying; Wang Junan; Chen Xiaoban; Zhang Wenfei; Zeng Xuyu; Gu Qiuwen

    2010-01-01

    We present a polymer-complexing soft template technique to construct the ZnO-nanowire/polymer light emitting device prototype that exhibits blue electrically driven emission with a relatively low-threshold voltage at room temperature in ambient atmosphere, and the ZnO-nanowire-based LED's emission wavelength is easily tuned by controlling the applied-excitation voltage. The nearly vertically aligned ZnO-nanowires with polymer film were used as emissive layers in the devices. The method uses polymer as binder in the LED device and dispersion medium in the luminescence layer, which stabilizes the quasi-arrays of ZnO nanowires embedding in a thin polymer film on silicon substrate and passivates the surface of ZnO nanocrystals, to prevent the quenching of luminescence. Additionally, the measurements of electrical properties showed that ZnO-nanowire/polymer film could significantly improve the conductivity of the film, which could be attributed to an increase in both Hall mobility and carrier concentration. The results indicated that the novel technique is a low-cost process for ZnO-based UV or blue light emission and reduces the requirement for achieving robust p-doping of ZnO film. It suggests that such ZnO-nanowire/polymer-based LEDs will be suitable for the electro-optical application.

  18. doped ZnO thick film resistors

    Indian Academy of Sciences (India)

    The characterization and ethanol gas sensing properties of pure and doped ZnO thick films were investigated. Thick films of pure zinc oxide were prepared by the screen printing technique. Pure zinc oxide was almost insensitive to ethanol. Thick films of Al2O3 (1 wt%) doped ZnO were observed to be highly sensitive to ...

  19. Inverter Circuits Using ZnO Nanoparticle Based Thin-Film Transistors for Flexible Electronic Applications.

    Science.gov (United States)

    Vidor, Fábio F; Meyers, Thorsten; Hilleringmann, Ulrich

    2016-08-23

    Innovative systems exploring the flexibility and the transparency of modern semiconducting materials are being widely researched by the scientific community and by several companies. For a low-cost production and large surface area applications, thin-film transistors (TFTs) are the key elements driving the system currents. In order to maintain a cost efficient integration process, solution based materials are used as they show an outstanding tradeoff between cost and system complexity. In this paper, we discuss the integration process of ZnO nanoparticle TFTs using a high- k resin as gate dielectric. The performance in dependence on the transistor structure has been investigated, and inverted staggered setups depict an improved performance over the coplanar device increasing both the field-effect mobility and the I ON / I OFF ratio. Aiming at the evaluation of the TFT characteristics for digital circuit applications, inverter circuits using a load TFT in the pull-up network and an active TFT in the pull-down network were integrated. The inverters show reasonable switching characteristics and V / V gains. Conjointly, the influence of the geometry ratio and the supply voltage on the devices have been analyzed. Moreover, as all integration steps are suitable to polymeric templates, the fabrication process is fully compatible to flexible substrates.

  20. Inverter Circuits Using ZnO Nanoparticle Based Thin-Film Transistors for Flexible Electronic Applications

    Directory of Open Access Journals (Sweden)

    Fábio F. Vidor

    2016-08-01

    Full Text Available Innovative systems exploring the flexibility and the transparency of modern semiconducting materials are being widely researched by the scientific community and by several companies. For a low-cost production and large surface area applications, thin-film transistors (TFTs are the key elements driving the system currents. In order to maintain a cost efficient integration process, solution based materials are used as they show an outstanding tradeoff between cost and system complexity. In this paper, we discuss the integration process of ZnO nanoparticle TFTs using a high-k resin as gate dielectric. The performance in dependence on the transistor structure has been investigated, and inverted staggered setups depict an improved performance over the coplanar device increasing both the field-effect mobility and the ION/IOFF ratio. Aiming at the evaluation of the TFT characteristics for digital circuit applications, inverter circuits using a load TFT in the pull-up network and an active TFT in the pull-down network were integrated. The inverters show reasonable switching characteristics and V/V gains. Conjointly, the influence of the geometry ratio and the supply voltage on the devices have been analyzed. Moreover, as all integration steps are suitable to polymeric templates, the fabrication process is fully compatible to flexible substrates.

  1. Nanostructured porous ZnO film with enhanced photocatalytic activity

    International Nuclear Information System (INIS)

    Wang Lina; Zheng Yingying; Li Xiaoyun; Dong Wenjun; Tang Weihua; Chen Benyong; Li Chaorong; Li Xiao; Zhang Tierui

    2011-01-01

    Well-defined ZnO nanostructured films have been fabricated directly on Zn foil via hydrothermal synthesis. During the fabrication of the ZnO nanostructured films, the Zn foil serves as the Zn source and also the substrate. Porous nanosheet-based, nanotube-based and nanoflower-based ZnO films can all be easily prepared by adjusting the alkali type, reaction time and reaction temperature. The composition, morphology and structure of ZnO films are characterized by X-ray diffraction, scanning electron microscope and high-resolution transmission electron microscope. The porous ZnO nanosheet-based film exhibits enhanced photocatalytic activity in the degradation of Rhodamine B under UV light irradiation. This can be attributed to the high surface area of the ZnO nanosheet and the large percentage of the exposed [001] facet. Moreover, the self-supporting, recyclable and stable ZnO photocatalytic film can be readily recovered and potentially applied for pollution disposal.

  2. Enzymatic glucose sensor based on Au nanoparticle and plant-like ZnO film modified electrode

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Kun [Nanostructured Materials Research Laboratory, Department of Materials Science and Engineering, University of Utah, Salt Lake City, UT 84112 (United States); Alex, Saji [Nanostructured Materials Research Laboratory, Department of Materials Science and Engineering, University of Utah, Salt Lake City, UT 84112 (United States); Department of Chemistry, Government College for Women, Thiruvananthapuram, Kerala 695014 (India); Siegel, Gene [Nanostructured Materials Research Laboratory, Department of Materials Science and Engineering, University of Utah, Salt Lake City, UT 84112 (United States); Tiwari, Ashutosh, E-mail: tiwari@eng.utah.edu [Nanostructured Materials Research Laboratory, Department of Materials Science and Engineering, University of Utah, Salt Lake City, UT 84112 (United States)

    2015-01-01

    A novel electrochemical glucose sensor was developed by employing a composite film of plant-like Zinc oxide (ZnO) and chitosan stabilized spherical gold nanoparticles (AuNPs) on which Glucose oxidaze (GOx) was immobilized. The ZnO was deposited on an indium tin oxide (ITO) coated glass and the AuNPs of average diameter of 23 nm were loaded on ZnO as the second layer. The prepared ITO/ZnO/AuNPs/GOx bioelectrode exhibited a low value of Michaelis–Menten constant of 1.70 mM indicating a good bio-matrix for GOx. The studies of electrochemical properties of the electrode using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) showed that, the presence of AuNPs provides significant enhancement of the electron transfer rate during redox reactions. The linear sweep voltammetry (LSV) shows that the ITO/ZnO/AuNPs/GOx based sensor has a high sensitivity of 3.12 μA·mM{sup −1}·cm{sup −2} in the range of 50 mg/dL to 400 mg/dL glucose concentration. The results show promising application of the gold nanoparticle modified plant-like ZnO composite bioelectrode for electrochemical sensing of glucose.

  3. Resistive Switching Characteristics in Electrochemically Synthesized ZnO Films

    Directory of Open Access Journals (Sweden)

    Shuhan Jing

    2015-04-01

    Full Text Available The semiconductor industry has long been seeking a new kind of non-volatile memory technology with high-density, high-speed, and low-power consumption. This study demonstrated the electrochemical synthesis of ZnO films without adding any soft or hard templates. The effect of deposition temperatures on crystal structure, surface morphology and resistive switching characteristics were investigated. Our findings reveal that the crystallinity, surface morphology and resistive switching characteristics of ZnO thin films can be well tuned by controlling deposition temperature. A conducting filament based model is proposed to explain the switching mechanism in ZnO thin films.

  4. Effect of initialization time on application potentiality of a ZnO thin film based LPG sensor

    Directory of Open Access Journals (Sweden)

    Parta Mitra

    2009-09-01

    Full Text Available A prototype electronic LPG (Liquid Petroleum Gas sensor based on zinc oxide (ZnO film has been fabricated. The objective of the present work was to investigate the importance of initialization time (also called warm-up time on the application potentiality of the ZnO based alarm. The role of sensor geometry on initialization time is presented. The electronic circuitry of the prototype LPG device alarm is discussed. It is shown that that the initialization time depends on the switch off time (or the time for which the sensor was kept idle. The resistive mode sensors can be fixed at 40% LEL (Lower Explosive Limit of LPG for safe operation.

  5. Random laser based on Rhodamine 6G (Rh6G doped poly(methyl methacrylate (PMMA films coating on ZnO nanorods synthesized by hydrothermal oxidation

    Directory of Open Access Journals (Sweden)

    Hua Zhang

    Full Text Available Random laser based on Rh6G doped PMMA thin films coating on ZnO nanorods synthesized by a simple hydrothermal oxidation method has been demonstrated. This kind of random laser medium is based on waveguide structure consisting of ZnO nanorods, Rh6G doped PMMA film and air. By controlling the time of hydrothermal oxidation reaction, wheat-like and hexagonal prism ZnO nanorods have been successfully fabricated. The emission spectra of these gain mediums based on different ZnO nanorods are different. The one based on wheat-like ZnO nanorods mainly exhibits amplified spontaneous emission, and the other one based on hexagonal prism ZnO nanorods shows random laser emission. The threshold of the random laser medium is about 73.8 μJ/pulse, and the full width at half maximum (FWHM is around 2.1 nm. The emission spectra measured at different detecting angles reveal that the output direction is strongly confined in ±30° by the waveguide effect. Our experiments demonstrate a promising method to achieve organic random laser medium. Keywords: Random laser, ZnO nanorods, Hydrothermal oxidation, Rhodamine 6G (Rh6G, Poly(methyl methacrylate (PMMA

  6. Enhanced ultraviolet photo-response in Dy doped ZnO thin film

    Science.gov (United States)

    Kumar, Pawan; Singh, Ranveer; Pandey, Praveen C.

    2018-02-01

    In the present work, a Dy doped ZnO thin film deposited by the spin coating method has been studied for its potential application in a ZnO based UV detector. The investigations on the structural property and surface morphology of the thin film ensure that the prepared samples are crystalline and exhibit a hexagonal crystal structure of ZnO. A small change in crystallite size has been observed due to Dy doping in ZnO. AFM analysis ascertains the grain growth and smooth surface of the thin films. The Dy doped ZnO thin film exhibits a significant enhancement in UV region absorption as compared to the pure ZnO thin film, which suggests that Dy doped ZnO can be used as a UV detector. Under UV irradiation of wavelength 325 nm, the photocurrent value of Dy doped ZnO is 105.54 μA at 4.5 V, which is 31 times greater than that of the un-doped ZnO thin film (3.39 μA). The calculated value of responsivity is found to increase significantly due to the incorporation of Dy in the ZnO lattice. The observed higher value of photocurrent and responsivity could be attributed to the substitution of Dy in the ZnO lattice, which enhances the conductivity, electron mobility, and defects in ZnO and benefits the UV sensing property.

  7. Electrical characteristics and density of states of thin-film transistors based on sol-gel derived ZnO channel layers with different annealing temperatures

    Science.gov (United States)

    Wang, S.; Mirkhani, V.; Yapabandara, K.; Cheng, R.; Hernandez, G.; Khanal, M. P.; Sultan, M. S.; Uprety, S.; Shen, L.; Zou, S.; Xu, P.; Ellis, C. D.; Sellers, J. A.; Hamilton, M. C.; Niu, G.; Sk, M. H.; Park, M.

    2018-04-01

    We report on the fabrication and electrical characterization of bottom gate thin-film transistors (TFTs) based on a sol-gel derived ZnO channel layer. The effect of annealing of ZnO active channel layers on the electrical characteristics of the ZnO TFTs was systematically investigated. Photoluminescence (PL) spectra indicate that the crystal quality of the ZnO improves with increasing annealing temperature. Both the device turn-on voltage (Von) and threshold voltage (VT) shift to a positive voltage with increasing annealing temperature. As the annealing temperature is increased, both the subthreshold slope and the interfacial defect density (Dit) decrease. The field effect mobility (μFET) increases with annealing temperature, peaking at 800 °C and decreases upon further temperature increase. An improvement in transfer and output characteristics was observed with increasing annealing temperature. However, when the annealing temperature reaches 900 °C, the TFTs demonstrate a large degradation in both transfer and output characteristics, which is possibly produced by non-continuous coverage of the film. By using the temperature-dependent field effect measurements, the localized sub-gap density of states (DOSs) for ZnO TFTs with different annealing temperatures were determined. The DOSs for the subthreshold regime decrease with increasing annealing temperature from 600 °C to 800 °C and no substantial change was observed with further temperature increase to 900 °C.

  8. A novel fiber-optic temperature sensor based on high temperature-dependent optical properties of ZnO film on sapphire fiber-ending

    International Nuclear Information System (INIS)

    Cai Pinggen; Zhen Dong; Xu Xiaojun; Liu Yulin; Chen Naibo; Wei Gaorao; Sui Chenghua

    2010-01-01

    We report the growth of high-quality thin films of ZnO via an electron-beam evaporation technique. Studies of the transmittance spectra have revealed a sharp optical absorption edge and a significant redshift. After annealing at 673 K, the ZnO films again demonstrated a sharp absorption edge in a manner similar to the as-deposited samples. This illustrates the excellent thermal stability of the thin films and, as such, demonstrates their potential as fiber-optic temperature sensors. Utilizing the influence of optical absorption spectra at different temperatures, a novel fiber-optic temperature sensor based on this material has been designed and tested. This technique could offer a simple, robust and cost-effective method to be used in high temperature sensing applications.

  9. Nanostructured hybrid ZnO thin films for energy conversion

    Directory of Open Access Journals (Sweden)

    Samantilleke Anura

    2011-01-01

    Full Text Available Abstract We report on hybrid films based on ZnO/organic dye prepared by electrodeposition using tetrasulfonated copper phthalocyanines (TS-CuPc and Eosin-Y (EoY. Both the morphology and porosity of hybrid ZnO films are highly dependent on the type of dyes used in the synthesis. High photosensitivity was observed for ZnO/EoY films, while a very weak photoresponse was obtained for ZnO/TS-CuPc films. Despite a higher absorption coefficient of TS-CuPc than EoY, in ZnO/EoY hybrid films, the excited photoelectrons between the EoY levels can be extracted through ZnO, and the porosity of ZnO/EoY can also be controlled.

  10. ZnO film deposition on Al film and effects of deposition temperature on ZnO film growth characteristics

    International Nuclear Information System (INIS)

    Yoon, Giwan; Yim, Munhyuk; Kim, Donghyun; Linh, Mai; Chai, Dongkyu

    2004-01-01

    The effects of the deposition temperature on the growth characteristics of the ZnO films were studied for film bulk acoustic wave resonator (FBAR) device applications. All films were deposited using a radio frequency magnetron sputtering technique. It was found that the growth characteristics of ZnO films have a strong dependence on the deposition temperature from 25 to 350 deg. C. ZnO films deposited below 200 deg. C exhibited reasonably good columnar grain structures with highly preferred c-axis orientation while those above 200 deg. C showed very poor columnar grain structures with mixed-axis orientation. This study seems very useful for future FBAR device applications

  11. ZnO Thin Film Electronics for More than Displays

    Science.gov (United States)

    Ramirez, Jose Israel

    Zinc oxide thin film transistors (TFTs) are investigated in this work for large-area electronic applications outside of display technology. A constant pressure, constant flow, showerhead, plasma-enhanced atomic layer deposition (PEALD) process has been developed to fabricate high mobility TFTs and circuits on rigid and flexible substrates at 200 °C. ZnO films and resulting devices prepared by PEALD and pulsed laser deposition (PLD) have been compared. Both PEALD and PLD ZnO films result in densely packed, polycrystalline ZnO thin films that were used to make high performance devices. PEALD ZnO TFTs deposited at 300 °C have a field-effect mobility of ˜ 40 cm2/V-s (and > 20 cm2/V-S deposited at 200 °C). PLD ZnO TFTs, annealed at 400 °C, have a field-effect mobility of > 60 cm2/V-s (and up to 100 cm2/V-s). Devices, prepared by either technique, show high gamma-ray radiation tolerance of up to 100 Mrad(SiO2) with only a small radiation-induced threshold voltage shift (VT ˜ -1.5 V). Electrical biasing during irradiation showed no enhanced radiation-induced effects. The study of the radiation effects as a function of material stack thicknesses revealed the majority of the radiation-induced charge collection happens at the semiconductor-passivation interface. A simple sheet-charge model at that interface can describe the radiation-induced charge in ZnO TFTs. By taking advantage of the substrate-agnostic process provided by PEALD, due to its low-temperature and excellent conformal coatings, ZnO electronics were monolithically integrated with thin-film complex oxides. Application-based examples where ZnO electronics provide added functionality to complex oxide-based devices are presented. In particular, the integration of arrayed lead zirconate titanate (Pb(Zr, Ti)O3 or PZT) thin films with ZnO electronics for microelectromechanical systems (MEMs) and deformable mirrors is demonstrated. ZnO switches can provide voltage to PZT capacitors with fast charging and slow

  12. Oxidant-Dependent Thermoelectric Properties of Undoped ZnO Films by Atomic Layer Deposition

    KAUST Repository

    Kim, Hyunho

    2017-02-27

    Extraordinary oxidant-dependent changes in the thermoelectric properties of undoped ZnO thin films deposited by atomic layer deposition (ALD) have been observed. Specifically, deionized water and ozone oxidants are used in the growth of ZnO by ALD using diethylzinc as a zinc precursor. No substitutional atoms have been added to the ZnO films. By using ozone as an oxidant instead of water, a thermoelectric power factor (σS) of 5.76 × 10 W m K is obtained at 705 K for undoped ZnO films. In contrast, the maximum power factor for the water-based ZnO film is only 2.89 × 10 W m K at 746 K. Materials analysis results indicate that the oxygen vacancy levels in the water- and ozone-grown ZnO films are essentially the same, but the difference comes from Zn-related defects present in the ZnO films. The data suggest that the strong oxidant effect on thermoelectric performance can be explained by a mechanism involving point defect-induced differences in carrier concentration between these two oxides and a self-compensation effect in water-based ZnO due to the competitive formations of both oxygen and zinc vacancies. This strong oxidant effect on the thermoelectric properties of undoped ZnO films provides a pathway to improve the thermoelectric performance of this important material.

  13. Oxidant-Dependent Thermoelectric Properties of Undoped ZnO Films by Atomic Layer Deposition

    KAUST Repository

    Kim, Hyunho; Wang, Zhenwei; Hedhili, Mohamed N.; Wehbe, Nimer; Alshareef, Husam N.

    2017-01-01

    , the maximum power factor for the water-based ZnO film is only 2.89 × 10 W m K at 746 K. Materials analysis results indicate that the oxygen vacancy levels in the water- and ozone-grown ZnO films are essentially the same, but the difference comes from Zn

  14. Admittance spectroscopy of spray-pyrolyzed ZnO film

    International Nuclear Information System (INIS)

    Kavasoglu, Nese; Kavasoglu, A. Sertap

    2008-01-01

    A ZnO film was deposited using the spray pyrolysis method. The admittance spectroscopy method was used to establish the contributions to electrical behavior from grains, grain boundaries, and electrodes of film. Proper equivalent electrical circuit of a ZnO film composed of a single parallel resistor, capacitor, and inductor network connected with a series resistance was proposed. Moreover, we displayed metal-semiconductor transition (MST) in the ZnO film via admittance spectroscopy

  15. 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.

  16. Visible tunable lighting system based on polymer composites embedding ZnO and metallic clusters: from colloids to thin films

    Science.gov (United States)

    Truong, Thai Giang; Dierre, Benjamin; Grasset, Fabien; Saito, Noriko; Saito, Norio; Nguyen, Thi Kim Ngan; Takahashi, Kohsei; Uchikoshi, Tetsuo; Amela-Cortes, Marian; Molard, Yann; Cordier, Stéphane; Ohashi, Naoki

    2016-01-01

    The development of phosphor devices free of heavy metal or rare earth elements is an important issue for environmental reasons and energy efficiency. Different mixtures of ZnO nanocrystals with Cs2Mo6I8(OOC2F5)6 cluster compound (CMIF) dispersed into polyvinylpyrrolidone matrix have been prepared by very simple and low cost solution chemistry. The resulting solutions have been used to fabricate highly transparent and luminescent films by dip coating free of heavy metal or rare earth elements. The luminescence properties of solution and dip-coated films were investigated. The luminescence of such a system is strongly dependent on the ratios between ZnO and CMIF amounts, the excitation wavelength and the nature of the system. By varying these two parameters (ratio and wavelength), a large variety of colors, from blue to red as well as white, can be achieved. In addition, differences in the luminescence properties have been observed between solutions and thin films as well as changes of CMIF emission band maximum wavelength. This may suggest some possible interactions between the different luminophore centers, such as energy transfer or ligands exchange on the Mo6 clusters.

  17. Visible tunable lighting system based on polymer composites embedding ZnO and metallic clusters: from colloids to thin films

    OpenAIRE

    Truong, Thai Giang; Dierre, Benjamin; Grasset, Fabien; Saito, Noriko; Saito, Norio; Nguyen, Thi Kim Ngan; Takahashi, Kohsei; Uchikoshi, Tetsuo; Amela-Cortes, Marian; Molard, Yann; Cordier, St?phane; Ohashi, Naoki

    2016-01-01

    Abstract The development of phosphor devices free of heavy metal or rare earth elements is an important issue for environmental reasons and energy efficiency. Different mixtures of ZnO nanocrystals with Cs2Mo6I8(OOC2F5)6 cluster compound (CMIF) dispersed into polyvinylpyrrolidone matrix have been prepared by very simple and low cost solution chemistry. The resulting solutions have been used to fabricate highly transparent and luminescent films by dip coating free of heavy metal or rare earth ...

  18. Effect of Mg doping in ZnO buffer layer on ZnO thin film devices for electronic applications

    Science.gov (United States)

    Giri, Pushpa; Chakrabarti, P.

    2016-05-01

    Zinc Oxide (ZnO) thin films have been grown on p-silicon (Si) substrate using magnesium doped ZnO (Mg: ZnO) buffer layer by radio-frequency (RF) sputtering method. In this paper, we have optimized the concentration of Mg (0-5 atomic percent (at. %)) ZnO buffer layer to examine its effect on ZnO thin film based devices for electronic and optoelectronic applications. The crystalline nature, morphology and topography of the surface of the thin film have been characterized. The optical as well as electrical properties of the active ZnO film can be tailored by varying the concentration of Mg in the buffer layer. The crystallite size in the active ZnO thin film was found to increase with the Mg concentration in the buffer layer in the range of 0-3 at. % and subsequently decrease with increasing Mg atom concentration in the ZnO. The same was verified by the surface morphology and topography studies carried out with scanning electron microscope (SEM) and atomic electron microscopy (AFM) respectively. The reflectance in the visible region was measured to be less than 80% and found to decrease with increase in Mg concentration from 0 to 3 at. % in the buffer region. The optical bandgap was initially found to increase from 3.02 eV to 3.74 eV by increasing the Mg content from 0 to 3 at. % but subsequently decreases and drops down to 3.43 eV for a concentration of 5 at. %. The study of an Au:Pd/ZnO Schottky diode reveals that for optimum doping of the buffer layer the device exhibits superior rectifying behavior. The barrier height, ideality factor, rectification ratio, reverse saturation current and series resistance of the Schottky diode were extracted from the measured current voltage (I-V) characteristics.

  19. Optoelectronic properties of doped hydrothermal ZnO thin films

    KAUST Repository

    Mughal, Asad J.; Carberry, Benjamin; Oh, Sang Ho; Myzaferi, Anisa; Speck, James S.; Nakamura, Shuji; DenBaars, Steven P.

    2017-01-01

    , or In were evaluated for their optoelectronic properties. Inductively coupled plasma atomic emission spectroscopy was used to determine the concentration of dopants within the ZnO films. While Al and Ga-doped films showed linear incorporation rates

  20. Variable range hopping in ZnO films

    Science.gov (United States)

    Ali, Nasir; Ghosh, Subhasis

    2018-04-01

    We report the variable range hopping in ZnO films grown by RF magnetron sputtering in different argon and oxygen partial pressure. It has been found that Mott variable range hopping dominant over Efros variable range hopping in all ZnO films. It also has been found that hopping distance and energy increases with increasing oxygen partial pressure.

  1. Influence of Dopants in ZnO Films on Defects

    Science.gov (United States)

    Peng, Cheng-Xiao; Weng, Hui-Min; Zhang, Yang; Ma, Xing-Ping; Ye, Bang-Jiao

    2008-12-01

    The influence of dopants in ZnO films on defects is investigated by slow positron annihilation technique. The results show S that parameters meet SAl > Sun > SAg for Al-doped ZnO films, undoped and Ag-doped ZnO films. Zinc vacancies are found in all ZnO films with different dopants. According to S parameter and the same defect type, it can be induced that the zinc vacancy concentration is the highest in the Al-doped ZnO film, and it is the least in the Ag-doped ZnO film. When Al atoms are doped in the ZnO films grown on silicon substrates, Zn vacancies increase as compared to the undoped and Ag-doped ZnO films. The dopant concentration could determine the position of Fermi level in materials, while defect formation energy of zinc vacancy strongly depends on the position of Fermi level, so its concentration varies with dopant element and dopant concentration.

  2. 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.

  3. Significant room-temperature ferromagnetism in porous ZnO films: The role of oxygen vacancies

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Xue; Liu, Huiyuan [College of Physics Science & Information Engineering, Hebei Normal University, Shijiazhuang 050024 (China); Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050024 (China); Sun, Huiyuan, E-mail: huiyuansun@126.com [College of Physics Science & Information Engineering, Hebei Normal University, Shijiazhuang 050024 (China); Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050024 (China); Liu, Lihu; Jia, Xiaoxuan [College of Physics Science & Information Engineering, Hebei Normal University, Shijiazhuang 050024 (China); Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050024 (China)

    2015-10-15

    Graphical abstract: - Highlights: • Porous ZnO films were deposited on porous anodic alumina substrates. • Significant ferromagnetism (FM) has been observed in porous ZnO films (110 emu/cm{sup 3}). • The strong magnetic anisotropy was observed in the porous ZnO films. • The origin of FM is attributed to the oxygen vacancy with a local magnetic moment. - Abstract: Pure porous ZnO films were prepared by direct current reactive magnetron sputtering on porous anodic alumina substrates. Remarkably large room-temperature ferromagnetism was observed in the films. The highest saturation moment along the out-of-plane direction was about 110 emu/cm{sup 3}. Experimental and theoretical results suggested that the oxygen vacancies and the unique porous structure of the films are responsible for the large ferromagnetism. There are two modes of coupling between oxygen vacancies in the porous ZnO films: (i) exchange interactions directly between the oxygen vacancies and (ii) with the mediation of conduction electrons. In addition, it was found that the magnetic moment of ZnO films can be changed by tuning the concentration of oxygen vacancies. These observations may be useful in the development of ZnO-based spintronics devices.

  4. Photosensitivity of nanocrystalline ZnO films grown by PLD

    International Nuclear Information System (INIS)

    Ayouchi, R.; Bentes, L.; Casteleiro, C.; Conde, O.; Marques, C.P.; Alves, E.; Moutinho, A.M.C.; Marques, H.P.; Teodoro, O.; Schwarz, R.

    2009-01-01

    We have studied the properties of ZnO thin films grown by laser ablation of ZnO targets on (0 0 0 1) sapphire (Al 2 O 3 ), under substrate temperatures around 400 deg. C. The films were characterized by different methods including X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and atomic force microscopy (AFM). XPS analysis revealed that the films are oxygen deficient, and XRD analysis with θ-2θ scans and rocking curves indicate that the ZnO thin films are highly c-axis oriented. All the films are ultraviolet (UV) sensitive. Sensitivity is maximum for the films deposited at lower temperature. The films deposited at higher temperatures show crystallite sizes of typically 500 nm, a high dark current and minimum photoresponse. In all films we observe persistent photoconductivity decay. More densely packed crystallites and a faster decay in photocurrent is observed for films deposited at lower temperature

  5. Wound Healing Bionanocomposites Based on Castor Oil Polymeric Films Reinforced with Chitosan-Modified ZnO Nanoparticles.

    Science.gov (United States)

    Díez-Pascual, Ana M; Díez-Vicente, Angel L

    2015-09-14

    Castor oil (CO), which is a readily available, relatively inexpensive, and environmentally benign nonedible oil, has been successfully used as matrix material to prepare biocompatible and biodegradable nanocomposite films filled with chitosan (CS)-modified ZnO nanoparticles. The biocomposites were synthesized via a simple and versatile solution mixing and casting method. The morphology, structure, thermal stability, water absorption, biodegradability, cytocompatibility, barrier, mechanical, viscoelastic, antibacterial, and wound healing properties of the films have been analyzed. FT-IR spectra were used to obtain information about the nanoparticle-matrix interactions. The thermal stability, hydrophilicity, degree of porosity, water absorption, water vapor transmission rate (WVTR), oxygen permeability (Dk), and biodegradability of the films increased with the CS-ZnO loading. The WVTR and Dk data obtained are within the range of values reported for commercial wound dressings. Tensile tests demonstrated that the nanocomposites displayed a good balance between elasticity, strength, and flexibility under both dry and simulated body fluid (SBF) environments. The flexibility increased in a moist atmosphere due to the plasticization effect of absorbed water. The nanocomposites also exhibited significantly enhanced dynamic mechanical performance (storage modulus and glass transition temperature) than neat CO under different humidity conditions. The antibacterial activity of the films against Escherichia coli, Staphylococcus aureus, and Micrococcus luteus bacteria was investigated in the presence and the absence of UV light. The biocide effect increased progressively with the CS-ZnO content and was systematically stronger against Gram-positive cells. Composites with nanoparticle loading ≤5.0 wt % exhibited very good in vitro cytocompatibility and enabled a faster wound healing than neat CO and control gauze, hence showing great potential to be applied as antibacterial

  6. Preparation of Aligned ZnO Nanorod Arrays on Sn-Doped ZnO Thin Films by Sonicated Sol-Gel Immersion Fabricated for Dye-Sensitized Solar Cell

    Directory of Open Access Journals (Sweden)

    I. Saurdi

    2014-01-01

    Full Text Available Aligned ZnO Nanorod arrays are deposited on the Sn-doped ZnO thin film via sonicated sol-gel immersion method. The structural, optical, and electrical properties of the Sn-doped ZnO thin films were investigated. Results show that the Sn-doped ZnO thin films with small grain size (~20 nm, high average transmittance (96% in visible region, and good resistivity 7.7 × 102 Ω·cm are obtained for 2 at.% Sn doping concentration. The aligned ZnO nanorod arrays with large surface area were also obtained for 2 at.% Sn-doped ZnO thin film. They were grown on sol-gel derived Sn-doped ZnO thin film, which acts as a seed layer, via sonicated sol-gel immersion method. The grown aligned ZnO nanorod arrays show high transmittance at visible region. The fabricated dye-sensitised solar cell based on the 2.0 at.% Sn-doped ZnO thin film with aligned ZnO nanorod arrays exhibits improved current density, open-circuit voltage, fill factor, and conversion efficiency compared with the undoped ZnO and 1 at.% Sn-doped ZnO thin films.

  7. Catalyst growth of single crystal aligned ZnO nanorods on ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Dongxu; Andreazza, Caroline; Andreazza, Pascal [Centre de Recherche sur la Matiere Divisee, CNRS-Universite d' Orleans, 1b rue de la Ferollerie, 45071 Orleans cedex 2 (France)

    2005-02-01

    One dimensional ZnO nanorods were successfully fabricated on Si substrates via a simple physical vapor-phase transport method at 950 C. A ZnO shell covered Au/Zn alloy is assumed as the nucleation site, then ZnO nanorods grow following a vapor-solid (VS) process. In order to guide the nanorod growth a c-axis oriented ZnO thin film and Au catalyst were first deposited on Si (100) surface. SEM images show nanorods grown on this substrate are vertical to the substrate surface. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Synthesis, characterization and electrochemical behavior of Sb-doped ZnO microsphere film

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qian [Department of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou, 310027 (China); Cheng, Kui, E-mail: chengkui@zju.edu.cn [Department of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou, 310027 (China); Weng, Wenjian, E-mail: wengwj@zju.edu.cn [Department of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou, 310027 (China); The Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai, 200050 (China); Du, Piyi; Han, Gaorong [Department of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou, 310027 (China)

    2013-10-01

    Sb-doped ZnO microsphere film was fabricated by a carboxylate ion assisted hydrothermal route coupled with a post-calcination process. The structure, chemical composition and optical band gap of the Sb-doped ZnO microsphere film were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, inductively couple plasma optical emission spectroscopy and UV–visible spectrophotometry, and compared with the un-doped ZnO microsphere film. The results suggest that the formation of zinc–antimony tartrate complex species during hydrothermal growth is the key to realize Sb-doped ZnO microstructures, and the present hydrothermal method with post-calcination is an effective way to dope Sb into ZnO. Furthermore, the Sb-doped ZnO microsphere film based electrochemical biosensor exhibits a good sensing performance for the detection of hydrogen peroxide, with a sensitivity of 271 μA mM{sup −1} cm{sup −2} which is more than three times higher than that of the un-doped ZnO biosensor. - Highlights: • Sb-doped ZnO microsphere (SZM) films were grown by hydrothermal deposition. • Carboxylate ions were used to form complex during hydrothermal growth. • The formation of Zn–Sb tartrate complex is the key to realize SZM. • The biosensors based on SZM film are feasible and sensitive to detect H{sub 2}O{sub 2}. • The Sb doping could improve the electrochemical property of ZnO.

  9. Roughness-based monitoring of transparency and conductivity in boron-doped ZnO thin films prepared by spray pyrolysis

    International Nuclear Information System (INIS)

    Gaikwad, Rajendra S.; Bhande, Sambhaji S.; Mane, Rajaram S.; Pawar, Bhagwat N.; Gaikwad, Sanjay L.; Han, Sung-Hwan; Joo, Oh-Shim

    2012-01-01

    Graphical abstract: Display Omitted Highlights: ► We report surface roughness dependent transparency and conductivity in ZnO films. ► The surface roughness with respected to boron doping concentrations is studied. ► Boron doped and pristine Zinc oxide thin films have showed ≥95% transmittance. ► Increased carrier concentration of 9.21 × 10 21 cm −3 revealed from Hall measurement. -- Abstract: Sprayed polycrystalline ZnO and boron-doped ZnO thin films composed of spherical grains of 25–32 nm in diameters are used in roughness measurement and further correlated with the transparency and the conductivity characteristics. The surface roughness is increased up to Zn 0.98 B 0.02 O and then declined at higher boron concentrations. The sprayed ZnO films revealed ≥95% transmittance in the visible wavelength range, 1.956 × 10 −4 Ω cm electrical resistivity, 46 cm 2 /V s Hall mobility and 9.21 × 10 21 cm −3 charge carrier concentration. The X-ray photoelectron spectroscopy study has confirmed 0.15 eV binding energy change for Zn 2p 3/2 when 2 at% boron content is mixed without altering electro-optical properties substantially. Finally, using soft modeling importance of these textured ZnO over non-textured films for enhancing the solar cells performance is explored.

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

    International Nuclear Information System (INIS)

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

    2012-01-01

    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: ► This review highlights various approaches to synthesize ZnO nanostructures and thin films. ► Article highlights the importance of ZnO nanostructures as biosensor matrix. ► Article highlights the advances in various biosensors based on ZnO nanostructures. ► 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 nanostructures suitable candidate for future small integrated biosensor devices. This review

  11. 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

  12. Hydrogen absorption in thin ZnO films prepared by pulsed laser deposition

    International Nuclear Information System (INIS)

    Melikhova, O.; Čížek, J.; Lukáč, F.; Vlček, M.; Novotný, M.; Bulíř, J.; Lančok, J.; Anwand, W.; Brauer, G.; Connolly, J.; McCarthy, E.; Krishnamurthy, S.; Mosnier, J.-P.

    2013-01-01

    Highlights: ► Thin ZnO films and high quality ZnO crystal were electrochemically doped with hydrogen. ► Hydrogen absorbed in ZnO causes plastic deformation both in ZnO crystal and thin films. ► In ZnO crystal a sub-surface region with very high density of defects was formed. ► Moreover, plastic deformation causes specific surface modification of ZnO crystal. ► In ZnO films hydrogen-induced plastic deformation introduced defects in the whole film. -- Abstract: ZnO films with thickness of ∼80 nm were grown by pulsed laser deposition (PLD) on MgO (1 0 0) single crystal and amorphous fused silica (FS) substrates. Structural studies of ZnO films and a high quality reference ZnO single crystal were performed by slow positron implantation spectroscopy (SPIS). It was found that ZnO films exhibit significantly higher density of defects than the reference ZnO crystal. Moreover, the ZnO film deposited on MgO substrate exhibits higher concentration of defects than the film deposited on amorphous FS substrate most probably due to a dense network of misfit dislocations. The ZnO films and the reference ZnO crystal were subsequently loaded with hydrogen by electrochemical cathodic charging. SPIS characterizations revealed that absorbed hydrogen introduces new defects into ZnO

  13. Hydrogen absorption in thin ZnO films prepared by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Melikhova, O., E-mail: oksivmel@yahoo.com [Charles University in Prague, Faculty of Mathematics and Physics, V Holesovickach 2, CZ-180 00 Praha 8 (Czech Republic); Čížek, J.; Lukáč, F.; Vlček, M. [Charles University in Prague, Faculty of Mathematics and Physics, V Holesovickach 2, CZ-180 00 Praha 8 (Czech Republic); Novotný, M.; Bulíř, J.; Lančok, J. [Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague (Czech Republic); Anwand, W.; Brauer, G. [Institut für Strahlenphysik, Helmholtz-Zentrum Dresden-Rossendorf, PO Box 510 119, D-01314 Dresden (Germany); Connolly, J.; McCarthy, E.; Krishnamurthy, S.; Mosnier, J.-P. [National Centre for Plasma Science and Technology, School of Physical Sciences, Glasnevin, Dublin 9 (Ireland)

    2013-12-15

    Highlights: ► Thin ZnO films and high quality ZnO crystal were electrochemically doped with hydrogen. ► Hydrogen absorbed in ZnO causes plastic deformation both in ZnO crystal and thin films. ► In ZnO crystal a sub-surface region with very high density of defects was formed. ► Moreover, plastic deformation causes specific surface modification of ZnO crystal. ► In ZnO films hydrogen-induced plastic deformation introduced defects in the whole film. -- Abstract: ZnO films with thickness of ∼80 nm were grown by pulsed laser deposition (PLD) on MgO (1 0 0) single crystal and amorphous fused silica (FS) substrates. Structural studies of ZnO films and a high quality reference ZnO single crystal were performed by slow positron implantation spectroscopy (SPIS). It was found that ZnO films exhibit significantly higher density of defects than the reference ZnO crystal. Moreover, the ZnO film deposited on MgO substrate exhibits higher concentration of defects than the film deposited on amorphous FS substrate most probably due to a dense network of misfit dislocations. The ZnO films and the reference ZnO crystal were subsequently loaded with hydrogen by electrochemical cathodic charging. SPIS characterizations revealed that absorbed hydrogen introduces new defects into ZnO.

  14. A hydroxylamine electrochemical sensor based on electrodeposition of porous ZnO nanofilms onto carbon nanotubes films modified electrode

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Cuihong; Wang Guangfeng; Liu Min; Feng Yuehua; Zhang Zhidan [College of Chemistry and Materials Science, Anhui Key Laboratory of Chem-Biosensing, Beijing East Road No. 1, Anhui Normal University, Anhui, Wuhu 241000 (China); Fang Bin, E-mail: binfang_47@yahoo.com.c [College of Chemistry and Materials Science, Anhui Key Laboratory of Chem-Biosensing, Beijing East Road No. 1, Anhui Normal University, Anhui, Wuhu 241000 (China)

    2010-03-01

    A novel route (electrodeposition) for the fabrication of porous ZnO nanofilms attached multi-walled carbon nanotubes (MWCNTs) modified glassy carbon electrodes (GCEs) was proposed. The morphological characterization of ZnO/MWCNT films was examined by scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). The performances of the ZnO/MWCNTs/GCE were characterized with cyclic voltammetry (CV), Nyquist plot (EIS) and typical amperometric response (i-t). The potential utility of electrodes constructed was demonstrated by applying them to the analytical determination of hydroxylamine concentration. An optimized limit of detection of 0.12 muM was obtained at a signal-to-noise ratio of 3 and with a fast response time (within 3 s). Additionally, the ZnO/MWCNTs/GCE exhibited a wide linear range from 0.4 to 1.9 x 10{sup 4} muM and higher sensitivity. The ease of fabrication, high stability, and low cost of the modified electrode are the promising features of the proposed sensor.

  15. Superhydrophobic Ag decorated ZnO nanostructured thin film as effective surface enhanced Raman scattering substrates

    Science.gov (United States)

    Jayram, Naidu Dhanpal; Sonia, S.; Poongodi, S.; Kumar, P. Suresh; Masuda, Yoshitake; Mangalaraj, D.; Ponpandian, N.; Viswanathan, C.

    2015-11-01

    The present work is an attempt to overcome the challenges in the fabrication of super hydrophobic silver decorated zinc oxide (ZnO) nanostructure thin films via thermal evaporation process. The ZnO nanowire thin films are prepared without any surface modification and show super hydrophobic nature with a contact angle of 163°. Silver is further deposited onto the ZnO nanowire to obtain nanoworm morphology. Silver decorated ZnO (Ag@ZnO) thin films are used as substrates for surface enhanced Raman spectroscopy (SERS) studies. The formation of randomly arranged nanowire and silver decorated nanoworm structure is confirmed using FESEM, HR-TEM and AFM analysis. Crystallinity and existence of Ag on ZnO are confirmed using XRD and XPS studies. A detailed growth mechanism is discussed for the formation of the nanowires from nanobeads based on various deposition times. The prepared SERS substrate reveals a reproducible enhancement of 3.082 × 107 M for Rhodamine 6G dye (R6G) for 10-10 molar concentration per liter. A higher order of SERS spectra is obtained for a contact angle of 155°. Thus the obtained thin films show the superhydrophobic nature with a highly enhanced Raman spectrum and act as SERS substrates. The present nanoworm morphology shows a new pathway for the construction of semiconductor thin films for plasmonic studies and challenges the orderly arranged ZnO nanorods, wires and other nano structure substrates used in SERS studies.

  16. 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

  17. Laser nanostructuring of ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Nedyalkov, N., E-mail: nned@ie.bas.bg [Department of Electronics and Electrical Engineering, Keio University, 3-14-1 Hiyoshi Kohoku-ku, Yokohama-shi, Kanagawa-ken 223-8522 (Japan); Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko shousse 72, Sofia 1784 (Bulgaria); Koleva, M.; Nikov, R.; Atanasov, P. [Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko shousse 72, Sofia 1784 (Bulgaria); Nakajima, Y.; Takami, A.; Shibata, A.; Terakawa, M. [Department of Electronics and Electrical Engineering, Keio University, 3-14-1 Hiyoshi Kohoku-ku, Yokohama-shi, Kanagawa-ken 223-8522 (Japan)

    2016-06-30

    Highlights: • Nanosecond laser pulse nanostructuring of ZnO thin films on metal substrate is demonstrated. • Two regimes of the thin film modification are observed depending on the applied laser fluence. • At high fluence regime the ZnO film is homogeneously decomposed into nanosized particles. • The characteristic size of the formed nanostructures corresponds to the domain size of the thin film. - Abstract: In this work, results on laser processing of thin zinc oxide films deposited on metal substrate are presented. ZnO films are obtained by classical nanosecond pulsed laser deposition method in oxygen atmosphere on tantalum substrate. The produced films are then processed by nanosecond laser pulses at wavelength of 355 nm. The laser processing parameters and the film thickness are varied and their influence on the fabricated structures is estimated. The film morphology after the laser treatment is found to depend strongly on the laser fluence as two regimes are defined. It is shown that at certain conditions (high fluence regime) the laser treatment of the film leads to formation of a discrete nanostructure, composed of spherical like nanoparticles with narrow size distribution. The dynamics of the melt film on the substrate and fast cooling are found to be the main mechanisms for fabrication of the observed structures. The demonstrated method is an alternative way for direct fabrication of ZnO nanostructures on metal which can be easy implemented in applications as resistive sensor devices, electroluminescent elements, solar cell technology.

  18. Preparation and characterization of ALD deposited ZnO thin films studied for gas sensors

    Energy Technology Data Exchange (ETDEWEB)

    Boyadjiev, S.I., E-mail: boiajiev@gmail.com [MTA-BME Technical Analytical Chemistry Research Group, Szent Gellért tér 4, Budapest, H-1111 (Hungary); Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia (Bulgaria); Georgieva, V. [Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia (Bulgaria); Yordanov, R. [Department of Microelectronics, Technical University of Sofia, 8 Kliment Ohridski Blvd., 1756 Sofia (Bulgaria); Raicheva, Z. [Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia (Bulgaria); Szilágyi, I.M. [MTA-BME Technical Analytical Chemistry Research Group, Szent Gellért tér 4, Budapest, H-1111 (Hungary); Budapest University of Technology and Economics, Department of Inorganic and Analytical Chemistry, Szent Gellért tér 4, Budapest, H-1111 (Hungary)

    2016-11-30

    Highlights: • For the first time the gas sensing towards NO{sub 2} of very thin ALD ZnO films is studied. • The very thin ALD ZnO films showed excellent sensitivity to NO{sub 2} at room temperature. • These very thin film ZnO-based QCM sensors very well register even low concentrations. • The sensors have fully reversible sorption and are able to be recovered in short time. • Described fast and cost-effective ALD deposition of ZnO thin films for QCM gas sensor. - Abstract: Applying atomic layer deposition (ALD), very thin zinc oxide (ZnO) films were deposited on quartz resonators, and their gas sensing properties were studied using the quartz crystal microbalance (QCM) method. The gas sensing of the ZnO films to NO{sub 2} was tested in the concentration interval between 10 and 5000 ppm. On the basis of registered frequency change of the QCM, for each concentration the sorbed mass was calculated. Further characterization of the films was carried out by various techniques, i.e. by SEM-EDS, XRD, ellipsometry, and FTIR spectroscopy. Although being very thin, the films were gas sensitive to NO{sub 2} already at room temperature and could register very well as low concentrations as 100 ppm, while the sorption was fully reversible. Our results for very thin ALD ZnO films show that the described fast, simple and cost-effective technology could be implemented for producing gas sensors working at room temperature and being capable to detect in real time low concentrations of NO{sub 2}.

  19. Low Temperature Hydrothermal Growth of ZnO Nanorod Films for Schottky Diode Application

    International Nuclear Information System (INIS)

    Singh, Shaivalini; Park, Si-Hyun

    2016-01-01

    The purpose of this research is to report on the fabrication and characterizations of Pd/ZnO nanorod-based Schottky diodes for optoelectronic applications. ZnO nanorods (NRs) were grown on silicon (Si) substrates by a two step hydrothermal method. In the first step, a seed layer of pure ZnO was deposited from a solution of zinc acetate and ethyl alcohol, and then in the second step, the main growth of the ZnO NRs was done over the seed layer. The structural morphology and optical properties of the ZnO NR films were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-vis spectroscopy. The electrical characterization of the Pd/ZnO NR contacts was studied using a current-voltage (I-V) tool. The ZnO NR films exhibited a wurtzite ZnO structure,and the average length of the ZnO NRs were in the range of 750 nm to 800 nm. The values of ideality factor, turn-on voltage and reverse saturation current were calculated from the I-V characteristics of Pd/ZnO NR-based Schottky diodes. The study demonstrates that Pd/ZnO NR Schottky contacts fabricated by a simple and inexpensive method can be used as a substitute for conventional Schottky diodes for optoelectronic applications.

  20. Surface roughness of sputtered ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Y S [Department of Materials Science and Engineering, National Dong Hwa University, 1, Sec. 2, Da Hsueh Rd. Shou-Feng, Hualien, Taiwan (China); Hsu, K C [Department of Photonics and Institute of Electro-Optical Engineering, National Chiao-Tung University, Hsinchu, Taiwan (China); Huang, Y M [Institute of Electronics Engineering, Southern Taiwan University of Technology, 1 Nan-Tai Street, Taiwan (China)

    2006-09-01

    ZnO films are grown on Si and glass substrates by radio-frequency (RF) magnetron sputtering. The crystalline structures are investigated by x-ray diffraction (XRD). Moreover, the roughness characteristics of the films are examined by atomic force microscopy (AFM) and field-emission scanning electron microscopy (FE-SEM). All films exhibit strong (002) preferential orientation. The influence of the RF power and target-to-substrate distance (D{sub ts}) on the properties of ZnO is studied. Under the optimized conditions of the RF power and D{sub ts}, root-mean-square (RMS) surface roughnesses of <0.8 nm are achieved.

  1. Surface roughness of sputtered ZnO films

    International Nuclear Information System (INIS)

    Lin, Y S; Hsu, K C; Huang, Y M

    2006-01-01

    ZnO films are grown on Si and glass substrates by radio-frequency (RF) magnetron sputtering. The crystalline structures are investigated by x-ray diffraction (XRD). Moreover, the roughness characteristics of the films are examined by atomic force microscopy (AFM) and field-emission scanning electron microscopy (FE-SEM). All films exhibit strong (002) preferential orientation. The influence of the RF power and target-to-substrate distance (D ts ) on the properties of ZnO is studied. Under the optimized conditions of the RF power and D ts , root-mean-square (RMS) surface roughnesses of <0.8 nm are achieved

  2. Easy Formation of Nanodisk-Dendritic ZnO Film via Controlled Electrodeposition Process

    Directory of Open Access Journals (Sweden)

    Nur Azimah Abd Samad

    2015-01-01

    Full Text Available A facile electrodeposition synthesis was introduced to prepare the nanodisk-dendritic ZnO film using a mixture solution of zinc chloride (ZnCl2 with potassium chloride (KCl that acted as a directing agent. This study aims to determine the best photoelectrochemical response for solar-induced water splitting. Based on our results obtained, it was found that an average diagonal of nanodisk was approximately 1.70 µm with the thickness of ≈150 nm that was successfully grown on the surface of substrate. The photocatalytic and photoelectrochemical responses of the resultant wurtzite type based-nanodisk-dendrite ZnO film as compared to the as-prepared ZnO film were monitored and evaluated. A photocurrent density of 19.87 mA/cm2 under ultraviolet rays and 14.05 mA/cm2 under visible light (500 nm was recorded for the newly developed nanodisk-dendritic ZnO thin film. It was believed that nanodisk-dendritic ZnO film can harvest more incident photons from the illumination to generate more photoinduced charge carriers to trigger the photocatalytic and photoelectrochemical reactions. Moreover, strong light scattering effects and high specific surface area of 2D nanostructures aid in the incident light absorption from any direction.

  3. 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

  4. Properties and characterization of bionanocomposite films prepared with various biopolymers and ZnO nanoparticles.

    Science.gov (United States)

    Kanmani, Paulraj; Rhim, Jong-Whan

    2014-06-15

    This study was aimed to develop biopolymer based antimicrobial films for active food packaging and to reduce environmental pollution caused by accumulation of synthetic packaging. The ZnO NPs were incorporated as antimicrobials into different biopolymers such as agar, carrageenan and CMC. Solvent casting method was performed to prepare active nanocomposite films. Methods such as FE-SEM, FT-IR and XRD were used to characterize resulting films. Physical, mechanical, thermal and antimicrobial properties were also examined. Remarkable surface morphological differences were observed between control and nanocomposite films. The crystallinity of ZnO was confirmed by XRD analysis. The addition of ZnO NPs increased color, UV barrier, moisture content, hydrophobicity, elongation and thermal stability of the films, while decreased WVP, tensile strength and elastic modulus. ZnO NPs impregnated films inhibited growth of L. monocytogenes and E. coli. So these newly prepared nanocomposite films can be used as active packaging film to extend shelf-life of food. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. The effect of post-annealing on surface acoustic wave devices based on ZnO thin films prepared by magnetron sputtering

    International Nuclear Information System (INIS)

    Phan, Duy-Thach; Chung, Gwiy-Sang

    2011-01-01

    Zinc oxide (ZnO) thin films were deposited on unheated silicon substrates via radio frequency (RF) magnetron sputtering, and the post-deposition annealing of the ZnO thin films was performed at 400 deg. C, 600 deg. C, 800 deg. C, and 1000 deg. C. The characteristics of the thin films were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The films were then used to fabricate surface acoustic wave (SAW) resonators. The effects of post-annealing on the SAW devices are discussed in this work. Resulting in the 600 deg. C is determined as optimal annealing temperature for SAW devices. At 400 deg. C, the microvoids exit between the grains yield large root mean square (RMS) surface roughness and higher insertion losses in SAW devices. The highest RMS surface roughness, crack and residual stress cause a reduction of surface velocity (about 40 m/s) and increase dramatically insertion loss at 1000 deg. C. The SAW devices response becomes very weak at this temperature, the electromechanical coupling coefficient (k 2 ) of ZnO film decrease from 3.8% at 600 deg. C to 1.49% at 1000 deg. C.

  6. An Enhanced UV-Vis-NIR an d Flexible Photodetector Based on Electrospun ZnO Nanowire Array/PbS Quantum Dots Film Heterostructure.

    Science.gov (United States)

    Zheng, Zhi; Gan, Lin; Zhang, Jianbing; Zhuge, Fuwei; Zhai, Tianyou

    2017-03-01

    ZnO nanostructure-based photodetectors have a wide applications in many aspects, however, the response range of which are mainly restricted in the UV region dictated by its bandgap. Herein, UV-vis-NIR sensitive ZnO photodetectors consisting of ZnO nanowires (NW) array/PbS quantum dots (QDs) heterostructures are fabricated through modified electrospining method and an exchanging process. Besides wider response region compared to pure ZnO NWs based photodetectors, the heterostructures based photodetectors have faster response and recovery speed in UV range. Moreover, such photodetectors demonstrate good flexibility as well, which maintain almost constant performances under extreme (up to 180°) and repeat (up to 200 cycles) bending conditions in UV-vis-NIR range. Finally, this strategy is further verified on other kinds of 1D nanowires and 0D QDs, and similar enhancement on the performance of corresponding photodetecetors can be acquired, evidencing the universality of this strategy.

  7. An integrated optic ethanol vapor sensor based on a silicon-on-insulator microring resonator coated with a porous ZnO film.

    Science.gov (United States)

    Yebo, Nebiyu A; Lommens, Petra; Hens, Zeger; Baets, Roel

    2010-05-24

    Optical structures fabricated on silicon-on-insulator technology provide a convenient platform for the implementation of highly compact, versatile and low cost devices. In this work, we demonstrate the promise of this technology for integrated low power and low cost optical gas sensing. A room temperature ethanol vapor sensor is demonstrated using a ZnO nanoparticle film as a coating on an SOI micro-ring resonator of 5 microm in radius. The local coating on the ring resonators is prepared from colloidal suspensions of ZnO nanoparticles of around 3 nm diameter. The porous nature of the coating provides a large surface area for gas adsorption. The ZnO refractive index change upon vapor adsorption shifts the microring resonance through evanescent field interaction. Ethanol vapor concentrations down to 100 ppm are detected with this sensing configuration and a detection limit below 25 ppm is estimated.

  8. Effect of annealing on electrical properties of plasmatron deposited ZnO films

    International Nuclear Information System (INIS)

    Joa, Sang Beom; Penkov, Oteksiy V.; Plaksin, Vadim Yu; Mansur, Rakib; Kim, Ji Hun; Lee, Heon Ju

    2009-01-01

    Transparent conductive zinc oxide (ZnO) has been extensively studied in recent several years because they have very interesting properties. Besides this, zinc oxide is non-poisonous, abundant and cheap material. ZnO films are employed in different applications like transparent conductive layers in solar cells, protective coatings and so on. Wide industrial application of the ZnO films requires of development of cheap, effective and scalable technology. Typically used technology like RF sputtering, pyrolysis and metal-organic CVD don't completely satisfy the industrial requirements. In our previous publications the new perspective ZnO deposition technology based DC Arc Plasmatron was described. This technology has several advantages (low cost, high deposition rate, low substrate temperature). Currently, films deposited using this technology has can be used only as protective or insulation coatings because of very high resistance. Applying of plasmatron technology in the microelectronics or solar cell production requires the improvement of electrical properties of the films. This can be achieved by optimization of deposition parameters, using of doping, or by post-deposition treatment such as annealing, or by combination of mentioned. It was shown that proposed technology can be used for the deposition of pure ZnO film with good electrical and optical properties. Proposed technology has several disadvantages which can be overcome in the near-term outlook

  9. Hydrogen absorption in thin ZnO films prepared by pulsed laser deposition

    OpenAIRE

    Meilkhova, O.; Čížek, J.; Lukáč,, F.; Vlček, M.; Novotný, M.; Bulíř, J.; Lančok, J.; Anwand, W.; Brauer, G.; Connolly, J.; McCarthy, E.; Krishnamurthy, S.; Mosnier, J.-P.

    2013-01-01

    ZnO films with thickness of ~80 nm were grown by pulsed laser deposition (PLD) on MgO (1 0 0) single crystal and amorphous fused silica (FS) substrates. Structural studies of ZnO films and a high quality reference ZnO single crystal were performed by slow positron implantation spectroscopy (SPIS). It was found that ZnO films exhibit significantly higher density of defects than the reference ZnO crystal. Moreover, the ZnO film deposited on MgO substrate exhibits higher concentration of defects...

  10. Plasmonic materials based on ZnO films and their potential for developing broadband middle-infrared absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Kesim, Yunus E., E-mail: yunus.kesim@bilkent.edu.tr; Battal, Enes [Department of Electrical and Electronics Engineering, Bilkent University, Ankara, 06800 (Turkey); UNAM-National Nanotechnology Research Center, Bilkent University, Ankara, 06800 (Turkey); Okyay, Ali K. [Department of Electrical and Electronics Engineering, Bilkent University, Ankara, 06800 (Turkey); UNAM-National Nanotechnology Research Center, Bilkent University, Ankara, 06800 (Turkey); Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800 (Turkey)

    2014-07-15

    Noble metals such as gold and silver have been extensively used for plasmonic applications due to their ability to support plasmons, yet they suffer from high intrinsic losses. Alternative plasmonic materials that offer low loss and tunability are desired for a new generation of efficient and agile devices. In this paper, atomic layer deposition (ALD) grown ZnO is investigated as a candidate material for plasmonic applications. Optical constants of ZnO are investigated along with figures of merit pertaining to plasmonic waveguides. We show that ZnO can alleviate the trade-off between propagation length and mode confinement width owing to tunable dielectric properties. In order to demonstrate plasmonic resonances, we simulate a grating structure and computationally demonstrate an ultra-wide-band (4–15 μm) infrared absorber.

  11. A comparative study of ultraviolet photoconductivity relaxation in zinc oxide (ZnO) thin films deposited by different techniques

    International Nuclear Information System (INIS)

    Yadav, Harish Kumar; Gupta, Vinay

    2012-01-01

    Photoresponse characteristics of ZnO thin films deposited by three different techniques namely rf diode sputtering, rf magnetron sputtering, and electrophoretic deposition has been investigated in the metal-semiconductor-metal (MSM) configuration. A significant variation in the crystallinity, surface morphology, and photoresponse characteristics of ZnO thin film with change in growth kinetics suggest that the presence of defect centers and their density govern the photodetector relaxation properties. A relatively low density of traps compared to the true quantum yield is found very crucial for the realization of practical ZnO thin film based ultraviolet (UV) photodetector.

  12. A comparative study of ultraviolet photoconductivity relaxation in zinc oxide (ZnO) thin films deposited by different techniques

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Harish Kumar; Gupta, Vinay [Department of Physics and Astrophysics, University of Delhi, Delhi 110 007 (India)

    2012-05-15

    Photoresponse characteristics of ZnO thin films deposited by three different techniques namely rf diode sputtering, rf magnetron sputtering, and electrophoretic deposition has been investigated in the metal-semiconductor-metal (MSM) configuration. A significant variation in the crystallinity, surface morphology, and photoresponse characteristics of ZnO thin film with change in growth kinetics suggest that the presence of defect centers and their density govern the photodetector relaxation properties. A relatively low density of traps compared to the true quantum yield is found very crucial for the realization of practical ZnO thin film based ultraviolet (UV) photodetector.

  13. A high power ZnO thin film piezoelectric generator

    Science.gov (United States)

    Qin, Weiwei; Li, Tao; Li, Yutong; Qiu, Junwen; Ma, Xianjun; Chen, Xiaoqiang; Hu, Xuefeng; Zhang, Wei

    2016-02-01

    A highly efficient and large area piezoelectric ZnO thin film nanogenerator (NG) was fabricated. The ZnO thin film was deposited onto a Si substrate by pulsed laser ablation at a substrate temperature of 500 °C. The deposited ZnO film exhibited a preferred c-axis orientation and a high piezoelectric value of 49.7 pm/V characterized using Piezoelectric Force Microscopy (PFM). Thin films of ZnO were patterned into rectangular power sources with dimensions of 0.5 × 0.5 cm2 with metallic top and bottom electrodes constructed via conventional semiconductor lithographic patterning processes. The NG units were subjected to periodic bending/unbending motions produced by mechanical impingement at a fixed frequency of 100 Hz at a pressure of 0.4 kg/cm2. The output electrical voltage, current density, and power density generated by one ZnO NG were recorded. Values of ∼95 mV, 35 μA cm-2 and 5.1 mW cm-2 were recorded. The level of power density is typical to that produced by a PZT NG on a flexible substrate. Higher energy NG sources can be easily created by adding more power units either in parallel or in series. The thin film ZnO NG technique is highly adaptable with current semiconductor processes, and as such, is easily integrated with signal collecting circuits that are compatible with mass production. A typical application would be using the power harvested from irregular human foot motions to either to operate blue LEDs directly or to drive a sensor network node in mille-power level without any external electric source and circuits.

  14. Nanostructured ZnO thin films by chemical bath deposition in basic aqueous ammonia solutions for photovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    Chu, J.B.; Huang, S.M.; Zhang, D.W.; Bian, Z.Q.; Li, X.D.; Sun, Z. [East China Normal University, Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, Shanghai (China); Yin, X.J. [Singapore Polytechnic, Advanced Materials Technology Center, Singapore (Singapore)

    2009-06-15

    This paper presents further insights and observations of the chemical bath deposition (CBD) of ZnS thin films using an aqueous medium involving Zn-salt, ammonium sulfate, aqueous ammonia, and thiourea. Results on physical and chemical properties of the grown layers as a function of ammonia concentration are reported. Physical and chemical properties were analyzed using scanning electron microscopy (SEM), X-ray energy dispersive (EDX), and X-ray diffraction (XRD). Rapid growth of nanostructured ZnO films on fluorine-doped SnO{sub 2} (FTO) glass substrates was developed. ZnO films crystallized in a wurtzite hexagonal structure and with a very small quantity of Zn(OH){sub 2} and ZnS phases were obtained for the ammonia concentration ranging from 0.75 to 2.0 M. Flower-like and columnar nanostructured ZnO films were deposited in two ammonia concentration ranges, respectively: one between 0.75 and 1.0 M and the other between 1.4 and 2.0 M. ZnS films were formed with a high ammonia concentration of 3.0 M. The formation mechanisms of ZnO, Zn(OH){sub 2}, and ZnS phases were discussed in the CBD process. The developed technique can be used to directly and rapidly grow nanostructured ZnO film photoanodes. Annealed ZnO nanoflower and columnar nanoparticle films on FTO substrates were used as electrodes to fabricate the dye sensitized solar cells (DSSCs). The DSSC based on ZnO-nanoflower film showed an energy conversion efficiency of 0.84%, which is higher compared to that (0.45%) of the cell being constructed using a photoanode of columnar nanoparticle ZnO film. The results have demonstrated the potential applications of CBD nanostructured ZnO films for photovoltaic cells. (orig.)

  15. Transient behaviors of ZnO thin films on a transparent, flexible polyethylene terephthalate substrate

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yong Jun [Department of Nano-Physics, Gachon University, 1342 Seongnamdaero, Sujeong-gu, Seongnam-si, Gyeonggi-do 461-701 (Korea, Republic of); Lee, Ho Seok [Department of Materials Science and Engineering, Korea University, 5-1 Anam-dong, Seongbuk-gu, Seoul 136-713 (Korea, Republic of); Noh, Jin-Seo, E-mail: jinseonoh@gachon.ac.kr [Department of Nano-Physics, Gachon University, 1342 Seongnamdaero, Sujeong-gu, Seongnam-si, Gyeonggi-do 461-701 (Korea, Republic of)

    2016-03-31

    Thickness-dependent electrical, structural, and optical properties of zinc oxide (ZnO) thin films on polyethylene terephthalate (PET) substrates have been investigated in the very thin thickness range of 20 to 120 nm. In this thickness range, the electrical resistance of ZnO film increased with an increase in film thickness. This unusual transition behavior was explained in terms of structural evolution from Zn-phase-incorporating non-crystalline ZnO to hexagonal-structured ZnO. A critical thickness for the full development of hexagonal ZnO crystal was estimated at approximately 80 nm in this study. ZnO thin films on PET substrates exhibit a high optical transmittance of > 70% and good endurance to bending cycles over the measured thickness range. The results of this study indicate that a trade-off should be sought between structural, electrical, optical, and mechanical properties for practical applications of very thin ZnO films on organic substrates. - Highlights: • Very thin ZnO films were sputter-deposited on the PET substrate. • The ZnO film resistance increases with an increase in film thickness until saturation. • Hexagonal crystal structures gradually develop with increasing film thickness. • A Zn phase appears in a 20-nm-thick ZnO film. • ZnO films show high optical transmittance of > 80% and good endurance to bending.

  16. Transient behaviors of ZnO thin films on a transparent, flexible polyethylene terephthalate substrate

    International Nuclear Information System (INIS)

    Kim, Yong Jun; Lee, Ho Seok; Noh, Jin-Seo

    2016-01-01

    Thickness-dependent electrical, structural, and optical properties of zinc oxide (ZnO) thin films on polyethylene terephthalate (PET) substrates have been investigated in the very thin thickness range of 20 to 120 nm. In this thickness range, the electrical resistance of ZnO film increased with an increase in film thickness. This unusual transition behavior was explained in terms of structural evolution from Zn-phase-incorporating non-crystalline ZnO to hexagonal-structured ZnO. A critical thickness for the full development of hexagonal ZnO crystal was estimated at approximately 80 nm in this study. ZnO thin films on PET substrates exhibit a high optical transmittance of > 70% and good endurance to bending cycles over the measured thickness range. The results of this study indicate that a trade-off should be sought between structural, electrical, optical, and mechanical properties for practical applications of very thin ZnO films on organic substrates. - Highlights: • Very thin ZnO films were sputter-deposited on the PET substrate. • The ZnO film resistance increases with an increase in film thickness until saturation. • Hexagonal crystal structures gradually develop with increasing film thickness. • A Zn phase appears in a 20-nm-thick ZnO film. • ZnO films show high optical transmittance of > 80% and good endurance to bending.

  17. The optical properties of ZnO films grown on porous Si templates

    International Nuclear Information System (INIS)

    Liu, Y L; Liu, Y C; Yang, H; Wang, W B; Ma, J G; Zhang, J Y; Lu, Y M; Shen, D Z; Fan, X W

    2003-01-01

    ZnO films were electrodeposited on porous silicon templates with different porosities. The photoluminescence (PL) spectra of the samples before and after deposition of ZnO were measured to study the effect of template porosity on the luminescence properties of ZnO/porous Si composites. As-prepared porous Si (PS) templates emit strong red light. The red PL peak of porous Si after deposition of ZnO shows an obvious blueshift, and the trend of blueshift increases with an increase in template porosity. A green emission at about 550 nm was also observed when the porosity of template increases, which is ascribed to the deep-level emission band of ZnO. A model-based band diagram of the ZnO/porous Si composite is suggested to interpret the properties of the composite

  18. Synthesis and characterization of thermally oxidized ZnO films

    Indian Academy of Sciences (India)

    Administrator

    Synthesis and characterization of thermally oxidized ZnO films. A P RAMBU1,* and N IFTIMIE2 .... R. −. Δ. = = (1) where Ra is the sensor resistance in the air and Rg is the .... ple, Aida and coworkers (2006) reported that the total oxidation is ...

  19. Single-Crystal Mesoporous ZnO Thin Films Composed of Nanowalls

    KAUST Repository

    Wang, Xudong

    2009-02-05

    This paper presents a controlled, large scale fabrication of mesoporous ZnO thin films. The entire ZnO mesoporous film is one piece of a single crystal, while high porosity made of nanowalls is present. The growth mechanism was proposed in comparison with the growth of ZnO nanowires. The ZnO mesoporous film was successfully applied as a gas sensor. The fabrication and growth analysis of the mesoporous ZnO thin film gi ve general guidance for the controlled growth of nanostructures. It also pro vides a unique structure with a superhigh surface-to-volume ratio for surface-related applications. © 2009 American Chemical Society.

  20. Nanostructured ZnO films: A study of molecular influence on transport properties by impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sappia, Luciano D.; Trujillo, Matias R. [Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET, Chacabuco 461, T4000ILI San Miguel de Tucumán (Argentina); Laboratorio de Medios e Interfases (LAMEIN), Departamento de Bioingeniería, Fac. de Cs. Exactas y Tecnología, Universidad Nacional de Tucumán, Av. Independencia 1800, 4000 San Miguel de Tucumán (Argentina); Lorite, Israel [Division of Superconductivity and Magnetism, Institute for Experimental Physics II, University of Leipzig, Linnéstrasse 5, 04103 Leipzig (Germany); Madrid, Rossana E., E-mail: rmadrid@herrera.unt.edu.ar [Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET, Chacabuco 461, T4000ILI San Miguel de Tucumán (Argentina); Laboratorio de Medios e Interfases (LAMEIN), Departamento de Bioingeniería, Fac. de Cs. Exactas y Tecnología, Universidad Nacional de Tucumán, Av. Independencia 1800, 4000 San Miguel de Tucumán (Argentina); Tirado, Monica [NanoProject and Laboratorio de Nanomateriales y Propiedades Dieléctricas, Departamento de Física, Universidad Nacional de Tucumán, Avenida Independencia 1800, Tucumán (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina); and others

    2015-10-15

    Graphical abstract: - Highlights: • We study electrical transport in nanostructured ZnO films by impedance spectroscopy. • Bioaggregates on the surface produce strong changes in film transport properties. • This behavior is explained by modeling data with RC parallel circuits. • Electrical responses of ZnO films to aggregates are promising for biosensing. - Abstract: Nanomaterials based on ZnO have been used to build glucose sensors due to its high isoelectric point, which is important when a protein like Glucose Oxidase (GOx) is attached to a surface. It also creates a biologically friendly environment to preserve the activity of the enzyme. In this work we study the electrical transport properties of ZnO thin films (TFs) and single crystals (SC) in contact with different solutions by using impedance spectroscopy. We have found that the composition of the liquid, by means of the charge of the ions, produces strong changes in the transport properties of the TF. The enzyme GOx and phosphate buffer solutions have the major effect in the conduction through the films, which can be explained by the entrapment of carriers at the grain boundaries of the TFs. These results can help to design a new concept in glucose biosensing.

  1. Mott-Schottky analysis of thin ZnO films

    International Nuclear Information System (INIS)

    Windisch, Charles F. Jr.; Exarhos, Gregory J.

    2000-01-01

    Thin ZnO films, both native and doped with secondary metal ions, have been prepared by sputter deposition and also by casting from solutions containing a range of precursor salts. The conductivity and infrared reflectivity of these films are subsequently enhanced chemically following treatment in H 2 gas at 400 degree sign C or by cathodic electrochemical treatment in a neutral (pH=7) phosphate buffer solution. While Hall-type measurements usually are used to evaluate the electrical properties of such films, the present study investigated whether a conventional Mott-Schottky analysis could be used to monitor the change in concentration of free carriers in these films before and after chemical and electrochemical reduction. The Mott-Schottky approach would be particularly appropriate for electrochemically modified films since the measurements could be made in the same electrolyte used for the post-deposition electrochemical processing. Results of studies on sputtered pure ZnO films in ferricyanide solution were promising. Mott-Schottky plots were linear and gave free carrier concentrations typical for undoped semiconductors. Film thicknesses estimated from the Mott-Schottky data were also reasonably close to thicknesses calculated from reflectance measurements. Studies on solution-deposited films were less successful. Mott-Schottky plots were nonlinear, apparently due to film porosity. A combination of dc polarization and atomic force microscopy measurements confirmed this conclusion. The results suggest that Mott-Schottky analysis would be suitable for characterizing solution-deposited ZnO films only after extensive modeling was performed to incorporate the effects of film porosity on the characteristics of the space-charge region of the semiconductor. (c) 2000 American Vacuum Society

  2. Nitrogen binding behavior in ZnO films with time-resolved cathodoluminescence

    International Nuclear Information System (INIS)

    Mei, Y.F.; Fu, Ricky K.Y.; Siu, G.G.; Wong, K.W.; Chu, Paul K.; Wang, R.S.; Ong, H.C.

    2006-01-01

    ZnO film with (1 0 0) orientation was produced on silicon substrate and doped with nitrogen using plasma immersion ion implantation. The effects due to N doping were investigated using cathodoluminescence (CL). In the heavily nitrogen-doped ZnO film, the intensity of ultraviolet (UV) band decreases and that of the visible band increases as a function of the electron bombardment cycle i.e. time. Based on the X-ray photoelectron spectroscopy (XPS) analysis, the unstable Zn-N bond is responsible for the CL behavior and the experimental results agree well with the first-principle calculation. Our work is helpful to our understanding of the role of p-type dopants in ZnO

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

    Directory of Open Access Journals (Sweden)

    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.

  4. Hydrothermal Growth of Quasi-Monocrystal ZnO Thin Films and Their Application in Ultraviolet Photodetectors

    Directory of Open Access Journals (Sweden)

    Yung-Chun Tu

    2015-01-01

    Full Text Available Quasi-monocrystal ZnO film grown using the hydrothermal growth method is used for the fabrication of Cu2O/ZnO heterojunction (HJ ultraviolet photodetectors (UV-PDs. The HJ was formed via the sputtering deposition of p-type Cu2O onto hydrothermally grown ZnO film (HTG-ZnO-film. The effect of annealing temperature in the nitrogen ambient on the photoluminescence spectra of the synthesized ZnO film was studied. The optoelectronic properties of Cu2O/ZnO film with various Cu2O thicknesses (250–750 nm under UV light (365 nm; intensity: 3 mW/cm2 were determined. The UV sensitivity of the HTG-ZnO-film-based UV-PDs and the sputtered ZnO-film-based UV-PDs were 55.6-fold (SHTG and 8.8-fold (Ssputter, respectively. The significant gain in sensitivity (SHTG/Ssputter = 630% of the proposed ZnO-film-based device compared to that for the device based on sputtered film can be attributed to the improved photoelectric properties of quasi-monocrystal ZnO film.

  5. Hydrothermal Growth and Application of ZnO Nanowire Films with ZnO and TiO2Buffer Layers in Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Jiang Chunhua

    2009-01-01

    Full Text Available Abstract This paper reports the effects of the seed layers prepared by spin-coating and dip-coating methods on the morphology and density of ZnO nanowire arrays, thus on the performance of ZnO nanowire-based dye-sensitized solar cells (DSSCs. The nanowire films with the thick ZnO buffer layer (~0.8–1 μm thick can improve the open circuit voltage of the DSSCs through suppressing carrier recombination, however, and cause the decrease of dye loading absorbed on ZnO nanowires. In order to further investigate the effect of TiO2buffer layer on the performance of ZnO nanowire-based DSSCs, compared with the ZnO nanowire-based DSSCs without a compact TiO2buffer layer, the photovoltaic conversion efficiency and open circuit voltage of the ZnO DSSCs with the compact TiO2layer (~50 nm thick were improved by 3.9–12.5 and 2.4–41.7%, respectively. This can be attributed to the introduction of the compact TiO2layer prepared by sputtering method, which effectively suppressed carrier recombination occurring across both the film–electrolyte interface and the substrate–electrolyte interface.

  6. UV-Enhanced Ethanol Sensing Properties of RF Magnetron-Sputtered ZnO Film.

    Science.gov (United States)

    Huang, Jinyu; Du, Yu; Wang, Quan; Zhang, Hao; Geng, Youfu; Li, Xuejin; Tian, Xiaoqing

    2017-12-26

    ZnO film was deposited by the magnetron sputtering method. The thickness of ZnO film is approximately 2 μm. The influence of UV light illumination on C₂H₅OH sensing properties of ZnO film was investigated. Gas sensing results revealed that the UV-illuminated ZnO film displays excellent C₂H₅OH characteristics in terms of high sensitivity, excellent selectivity, rapid response/recovery, and low detection limit down to 0.1 ppm. The excellent sensing performance of the sensor with UV activation could be attributed to the photocatalytic oxidation of ethanol on the surface of the ZnO film, the planar film structure with high utilizing efficiency of UV light, high electron mobility, and a good surface/volume ratio of of ZnO film with a relatively rough and porous surface.

  7. Development of novel control system to grow ZnO thin films by reactive evaporation

    Directory of Open Access Journals (Sweden)

    Gerardo Gordillo

    2016-07-01

    Full Text Available This work describes a novel system implemented to grow ZnO thin films by plasma assisted reactive evaporation with adequate properties to be used in the fabrication of photovoltaic devices with different architectures. The innovative aspect includes both an improved design of the reactor used to activate the chemical reaction that leads to the formation of the ZnO compound as an electronic system developed using the virtual instrumentation concept. ZnO thin films with excellent opto-electrical properties were prepared in a reproducible way, controlling the deposition system through a virtual instrument (VI with facilities to control the amount of evaporated zinc involved in the process that gives rise to the formation of ZnO, by means of the incorporation of PID (proportional integral differential and PWM (pulse width modulation control algorithms. The effectiveness and reliability of the developed system was verified by obtaining with good reproducibility thin films of n+-ZnO and i-ZnO grown sequentially in situ with thicknesses and resistivities suitable for use as window layers in chalcopyrite based thin film solar cells.

  8. Structural, optical, and LED characteristics of ZnO and Al doped ZnO thin films

    Science.gov (United States)

    Sandeep, K. M.; Bhat, Shreesha; Dharmaprakash, S. M.

    2017-05-01

    ZnO (pristine) and Al doped ZnO (AZO) films were prepared using sol-gel spin coating method. The XRD analysis showed the enhanced compressive stress in AZO film. The presence of extended states below the conduction band edge in AZO accounts for the redshift in optical bandgap. The PL spectra of AZO showed significant blue emission due to the carrier recombination from defect states. The TRPL curves showed the dominant DAP recombination in ZnO film, whereas defect related recombination in Al doped ZnO film. Color parameters viz: the dominant wavelength, color coordinates (x,y), color purity, luminous efficiency and correlated color temperature (CCT) of ZnO and AZO films are calculated using 1931 (CIE) diagram. Further, a strong blue emission with color purity more than 96% is observed in both the films. The enhanced blue emission in AZO significantly increased the luminous efficiency (22.8%) compared to ZnO film (10.8%). The prepared films may be used as blue phosphors in white light generation.

  9. Oxygen vacancy-induced ferromagnetism in un-doped ZnO thin films

    Science.gov (United States)

    Zhan, Peng; Wang, Weipeng; Liu, Can; Hu, Yang; Li, Zhengcao; Zhang, Zhengjun; Zhang, Peng; Wang, Baoyi; Cao, Xingzhong

    2012-02-01

    ZnO films became ferromagnetic when defects were introduced by thermal-annealing in flowing argon. This ferromagnetism, as shown by the photoluminescence measurement and positron annihilation analysis, was induced by the singly occupied oxygen vacancy with a saturated magnetization dependent positively on the amount of this vacancy. This study clarified the origin of the ferromagnetism of un-doped ZnO thin films and provides possibly an alternative way to prepare ferromagnetic ZnO films.

  10. Development of glucose biosensor based on ZnO nanoparticles film and glucose oxidase-immobilized eggshell membrane

    Directory of Open Access Journals (Sweden)

    Bohari Noor Aini

    2015-06-01

    Full Text Available A novel electrochemical glucose biosensor was developed by depositing an ionic liquid (IL (e.g., 1-ethyl-3-methylimidazolium trifluoromethanesulfonate; [EMIM][Otf], ZnO nanoparticles (ZnONPs and eggshell membrane (ESM on a modified glassy carbon electrode (GCE for determination of glucose. Glucose oxidase (GOx was covalently immobilized on eggshell membrane with glutaraldehyde as a cross-linker. Methylene blue was used as a redox indicator to enhance the electron transfer capacity and to ensure stability of both the oxidized and reduced forms in the reaction of enzyme and substrate. The morphological characteristics of microstructures eggshell membranes, chitosan, GOx/ESM, GOx/ZnONPs/IL/ESM and GOx/ZnONPs-IL/CHIT were observed using scanning electron microscopy (SEM. The effects of scan rate, time and pH on the response of glucose biosensors were studied in detail. Under optimal conditions (pH 6.5, 50 s, cyclic voltammetry showed different glucose concentrations on the range of 1 × 10−12 to 0.6 M, with a detection limit of 1 × 10−13 M. The GOx/ZnONPs/IL/ESM was found to be more sensitive as compared to GOx/ZnONPs-IL/CHIT. This developed glucose biosensor detection approach has several advantages such as fast, simple and convenient method, sensitivity, low cost, eco-friendly, low concentrations and remarkable catalytic activities of current signals during glucose reaction.

  11. Optoelectronic properties of doped hydrothermal ZnO thin films

    KAUST Repository

    Mughal, Asad J.

    2017-03-10

    Group III impurity doped ZnO thin films were deposited on MgAl2O3 substrates using a simple low temperature two-step deposition method involving atomic layer deposition and hydrothermal epitaxy. Films with varying concentrations of either Al, Ga, or In were evaluated for their optoelectronic properties. Inductively coupled plasma atomic emission spectroscopy was used to determine the concentration of dopants within the ZnO films. While Al and Ga-doped films showed linear incorporation rates with the addition of precursors salts in the hydrothermal growth solution, In-doped films were shown to saturate at relatively low concentrations. It was found that Ga-doped films showed the best performance in terms of electrical resistivity and optical absorbance when compared to those doped with In or Al, with a resistivity as low as 1.9 mΩ cm and an optical absorption coefficient of 441 cm−1 at 450 nm.

  12. Room-temperature deposition of crystalline patterned ZnO films by confined dewetting lithography

    Energy Technology Data Exchange (ETDEWEB)

    Sepulveda-Guzman, S., E-mail: selene.sepulvedagz@uanl.edu.mx [Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia. UANL, PIIT Monterrey, CP 66629, Apodaca NL (Mexico); Reeja-Jayan, B. [Texas Materials Institute, University of Texas at Austin, Austin, TX 78712 (United States); De la Rosa, E. [Centro de Investigacion en Optica, Loma del Bosque 115 Col. Lomas del Campestre C.P. 37150 Leon, Gto. Mexico (Mexico); Ortiz-Mendez, U. [Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia. UANL, PIIT Monterrey, CP 66629, Apodaca NL (Mexico); Reyes-Betanzo, C. [Instituto Nacional de Astrofisica Optica y Electronica, Calle Luis Enrique Erro No. 1, Santa Maria Tonanzintla, Puebla. Apdo. Postal 51 y 216, C.P. 72000 Puebla (Mexico); Cruz-Silva, R. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, UAEM. Av. Universidad 1001, Col. Chamilpa, CP 62210 Cuernavaca, Mor. (Mexico); Jose-Yacaman, M. [Physics and Astronomy Department University of Texas at San Antonio 1604 campus San Antonio, TX 78249 (United States)

    2010-03-15

    In this work patterned ZnO films were prepared at room-temperature by deposition of {approx}5 nm size ZnO nanoparticles using confined dewetting lithography, a process which induces their assembly, by drying a drop of ZnO colloidal dispersion between a floating template and the substrate. Crystalline ZnO nanoparticles exhibit a strong visible (525 nm) light emission upon UV excitation ({lambda} = 350 nm). The resulting films were characterized by scanning electron microscopy (SEM) and atomic force microscope (AFM). The method described herein presents a simple and low cost method to prepare crystalline ZnO films with geometric patterns without additional annealing. Such transparent conducting films are attractive for applications like light emitting diodes (LEDs). As the process is carried out at room temperature, the patterned crystalline ZnO films can even be deposited on flexible substrates.

  13. Efficient solution route to transparent ZnO semiconductor films using colloidal nanocrystals

    Directory of Open Access Journals (Sweden)

    Satoshi Suehiro

    2016-09-01

    Full Text Available ZnO nanocrystals (NCs were synthesized by heating Zn (II acetylacetonate in oleic acid/oleylamine in the presence of 1,2-hexadecanediol at 220 °C. Transmission electron microscopy (TEM and dynamic light scattering (DLS measurements revealed the formation of monodispersed ZnO NCs of ca. 7 nm. ZnO NC assembled films were fabricated on a glass substrate by deposition with the colloidal ZnO NCs dispersed in toluene. The film composed of the NCs showed good optical transparency in the visible to near-infrared region. A device coupling the ZnO NC film with a p-type Cu2ZnSnS4 (CZTS NC film exhibited an obvious diode-like current–voltage behavior. The results suggest that the transparent ZnO film has a potentiality to be used for an n-type window layer in some optoelectronic applications.

  14. Room-temperature deposition of crystalline patterned ZnO films by confined dewetting lithography

    International Nuclear Information System (INIS)

    Sepulveda-Guzman, S.; Reeja-Jayan, B.; De la Rosa, E.; Ortiz-Mendez, U.; Reyes-Betanzo, C.; Cruz-Silva, R.; Jose-Yacaman, M.

    2010-01-01

    In this work patterned ZnO films were prepared at room-temperature by deposition of ∼5 nm size ZnO nanoparticles using confined dewetting lithography, a process which induces their assembly, by drying a drop of ZnO colloidal dispersion between a floating template and the substrate. Crystalline ZnO nanoparticles exhibit a strong visible (525 nm) light emission upon UV excitation (λ = 350 nm). The resulting films were characterized by scanning electron microscopy (SEM) and atomic force microscope (AFM). The method described herein presents a simple and low cost method to prepare crystalline ZnO films with geometric patterns without additional annealing. Such transparent conducting films are attractive for applications like light emitting diodes (LEDs). As the process is carried out at room temperature, the patterned crystalline ZnO films can even be deposited on flexible substrates.

  15. Direct current magnetron sputter-deposited ZnO thin films

    International Nuclear Information System (INIS)

    Hoon, Jian-Wei; Chan, Kah-Yoong; Krishnasamy, Jegenathan; Tou, Teck-Yong; Knipp, Dietmar

    2011-01-01

    Zinc oxide (ZnO) is a very promising electronic material for emerging transparent large-area electronic applications including thin-film sensors, transistors and solar cells. We fabricated ZnO thin films by employing direct current (DC) magnetron sputtering deposition technique. ZnO films with different thicknesses ranging from 150 nm to 750 nm were deposited on glass substrates. The deposition pressure and the substrate temperature were varied from 12 mTorr to 25 mTorr, and from room temperature to 450 deg. C, respectively. The influence of the film thickness, deposition pressure and the substrate temperature on structural and optical properties of the ZnO films was investigated using atomic force microscopy (AFM) and ultraviolet-visible (UV-Vis) spectrometer. The experimental results reveal that the film thickness, deposition pressure and the substrate temperature play significant role in the structural formation and the optical properties of the deposited ZnO thin films.

  16. Improved luminescence intensity and stability of thermal annealed ZnO incorporated Alq3 composite films.

    Science.gov (United States)

    Cuba, M; Muralidharan, G

    2015-11-01

    The 30 wt% of ZnO (weight percentage of ZnO has been optimised) incorporated tris- (8-hydroxyquinoline)aluminum (Alq3) has been synthesised and coated on to glass substrates using dip coating method. The structural and optical properties of the Alq3/ZnO composite film after thermal annealing from 50 to 300 °C insteps 50° has been studied and reported. XRD pattern reveals the presence of crystalline ZnO in all the annealed films. The films annealed above 150 °C reveal the presence of crystalline Alq3 along with crystalline ZnO. The FTIR spectra confirm the presence of hydroxyquinoline and ZnO vibration in all the annealed composite films. The composite films annealed above 150 °C show a partial sublimation and degradation of hydroxyquinoline compounds. The ZnO incorporated composite films (Alq3/ZnO) exhibit two emission peaks, one corresponding to ZnO at 487 nm and another at 513 nm due to Alq3. The films annealed at 200 °C exhibit maximum photoluminescence (PL) intensity than pristine film at 513 nm when excited at 390 nm.

  17. An Optoelectronic Sensor Configuration Using ZnO Thick Film for Detection of Methanol

    Directory of Open Access Journals (Sweden)

    Shobhna DIXIT

    2007-08-01

    Full Text Available In the present paper sensitivity of a nanocrystalline ZnO thick film to methanol vapors is reported. The sensing mechanism is the modulation in the intensity of light reflected from glass film interface. Modulation occurs due to the change in refractive index of ZnO film upon adsorption of vapor molecules. The film has been characterized by XRD, SEM, and optical transmission studies. XRD pattern reveals polycrystalline structure of the film with grain size 33.5 nm.

  18. Effect of substrate temperature on the structure, electrical and optical properties of Mo doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Guifeng; Zhao, Xiaoli; Zhang, Hui; Wang, He; Liu, Feifei; Zhang, Xiaoqiang [Key Lab. for New Type of Functional Materials in Hebei Province, School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Gao, Jianbo [China Institute of Atomic Energy, Beijing 102413 (China); Zhao, Yanmin; Zhang, Chao [No. 18TH Research Institute, China Electronics Technology Group Corporation, Tianjin 300384 (China); Tao, Junguang, E-mail: taojunguang@163.com [Key Lab. for New Type of Functional Materials in Hebei Province, School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130 (China)

    2016-09-15

    Highlights: • MZO thin films were prepared by RF magnetron sputtering from ZnO target and DC magnetron sputtering from Mo target. • All films are polycrystalline with preferential c-axis growth. • The various properties of films fabricated at varied substrate temperature have been studied. • The valence of the Mo ions in the ZnO matrix is mixture of +5 and +6. - Abstract: Mo-doped ZnO (MZO) transparent conductive thin films were prepared on glass substrate under various substrate temperature from 50 °C to 200 °C. The microstructural, electrical and optical properties of the MZO films were investigated by X-ray diffraction (XRD), Hall effect and UV–vis spectrophotometer. Based on XRD measurements, all films are polycrystalline with preferential c-axis growth. The lowest resistivity was obtained to be 2.8 × 10{sup −3} Ω·cm. According to X-ray photoelectron spectroscopy (XPS) measurement, the valence of the Mo ions in the ZnO matrix is a mixture of +5 and +6. In addition, the transmittance of the film is ∼80% throughout the visible light region. Our results indicate that the MZO films are suitable for potential transparent optoelectronic applications.

  19. Appraisal on Textured Grain Growth and Photoconductivity of ZnO Thin Film SILAR

    Directory of Open Access Journals (Sweden)

    Deepu Thomas

    2014-01-01

    Full Text Available ZnO thin films were prepared by successive ionic layer adsorption reaction (SILAR method. The textured grain growth along c-axis in pure ZnO thin films and doped with Sn was studied. The structural analysis of the thin films was done by X-ray diffraction and surface morphology by scanning electron microscopy. Textured grain growth of the samples was measured by comparing the peak intensities. Textured grain growth and photo current in ZnO thin films were found to be enhanced by doping with Sn. ZnO thin film having good crystallinity with preferential (002 orientation is a semiconductor with photonic properties of potential benefit to biophotonics. From energy dispersive X-ray analysis, it is inferred that oxygen vacancy creation is responsible for the enhanced textured grain growth in ZnO thin films.

  20. High photocurrent gain in NiO thin film/M-doped ZnO nanorods (M=Ag, Cd and Ni) heterojunction based ultraviolet photodiodes

    Energy Technology Data Exchange (ETDEWEB)

    Echresh, Ahmad, E-mail: ahmadechresh@gmail.com [Department of Science and Technology, Physical Electronics and Nanotechnology Division, Campus Norrköping, Linköping University, SE-601 74 Norrköping (Sweden); Echresh, Mohammad [Department of Physics, Sanati Hoveizeh University, Ahvaz (Iran, Islamic Republic of); Khranovskyy, Volodymyr [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-5818358183 Linköping (Sweden); Nur, Omer; Willander, Magnus [Department of Science and Technology, Physical Electronics and Nanotechnology Division, Campus Norrköping, Linköping University, SE-601 74 Norrköping (Sweden)

    2016-10-15

    The thermal evaporation method has been used to deposit p-type NiO thin film, which was combined with hydrothermally grown n-type pure and M-doped ZnO nanorods (M=Ag, Cd and Ni) to fabricate a high performance p-n heterojunction ultraviolet photodiodes. The fabricated photodiodes show high rectification ratio and relatively low leakage current. The p-NiO/n-Zn{sub 0.94}Ag{sub 0.06}O heterojunction photodiode displays the highest photocurrent gain (~1.52×10{sup 4}), a photoresponsivity of ~4.48×10{sup 3} AW{sup −1} and a photosensitivity of ~13.56 compared with the other fabricated photodiodes. The predominated transport mechanisms of the p-n heterojunction ultraviolet photodiodes at low and high applied forward bias may be recombination-tunneling and space charge limited current, respectively.

  1. Two different mechanisms on UV emission enhancement in Ag-doped ZnO thin films

    International Nuclear Information System (INIS)

    Xu, Linhua; Zheng, Gaige; Zhao, Lilong; Pei, Shixin

    2015-01-01

    Ag-doped ZnO thin films were prepared by a sol–gel method. The structural, morphological and optical properties of the samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV–vis and photoluminescence spectra. The results show that the Ag in the ZnO thin films annealed at 500 °C for 1 h substitutes for Zn and exists in the form of Ag + ion (Ag Zn ) while the Ag in the ZnO thin films without a post-annealing mainly exists in the form of simple substance (Ag 0 ). The incorporation of Ag indeed can improve the ultraviolet emission of ZnO thin films and suppress the visible emissions at the same time. However, the mechanisms on the ultraviolet emission enhancement in the annealed and unannealed Ag-doped ZnO thin films are very different. As for the post-annealed Ag-doped ZnO thin films, the UV emission enhancement maybe mainly results from more electron–hole pairs (excitons) due to Ag-doping while for the unannealed Ag-doped ZnO thin films; the UV emission enhancement is attributed to the resonant coupling between exciton emission in ZnO and localized surface plasmon in Ag nanoparticles. - Highlights: • Ag-doped ZnO thin films have been prepared by the sol–gel method. • Ag-doping can enhance ultraviolet emission of ZnO thin films and depress the visible emissions at the same time. • There are two different mechanisms on UV emission enhancement in Ag-doped ZnO thin films. • The UV emission enhancement from the resonant coupling between excitonic emissions and localized surface plasmon in Ag nanoparticle is very attractive

  2. Investigation of sensitivity and selectivity of ZnO thin film to volatile organic compounds

    Science.gov (United States)

    Teimoori, F.; Khojier, K.; Dehnavi, N. Z.

    2017-06-01

    This research addresses a detailed study on the sensitivity and selectivity of ZnO thin film to volatile organic compound (VOC) vapors that can be used for the development of VOC sensors. The ZnO thin film of 100 nm thickness was prepared by post-annealing of e-beam evaporated Zn thin film. The sample was structurally, morphologically, and chemically characterized by X-ray diffraction and field emission scanning electron microscopy analyses. The sensitivity, selectivity, and detection limit of the sample were tested with respect to a wide range of common VOC vapors, including acetone, formaldehyde, acetic acid, formic acid, acetylene, toluene, benzene, ethanol, methanol, and isopropanol in the temperature range of 200-400 °C. The results show that the best sensitivity and detection limit of the sample are related to acetone vapor in the studied temperature range. The ZnO thin film-based acetone sensor also shows a good reproducibility and stability at the operating temperature of 280 °C.

  3. Textured ZnO thin films by RF magnetron sputtering

    CERN Document Server

    Ginting, M; Kang, K H; Kim, S K; Yoon, K H; Park, I J; Song, J S

    1999-01-01

    Textured thin films ZnO has been successfully grown by rf magnetron sputtering method using a special technique of introducing a small amount of water and methanol on the deposition chamber. The grain size of the textured surface is highly dependent on the argon pressure during the deposition. The pressure in this experiment was varied from 50 mTorr down to 5 mTorr and the highest grain size of the film is obtained at 5 mTorr. The total transmittance of the films are more than 85% in the wavelength of 400 to 800 nm, and haze ratio of about 14% is obtained at 400 nm wavelength. Beside the textured surface, these films also have very low resistivity, which is lower than 1.4x10 sup - sup 3 OMEGA centre dot cm. X-ray analysis shows that the films with textured surface have four diffraction peaks on the direction of (110), (002), (101) and (112), while the non-textured films have only (110) and (002) peaks. Due to the excellent characteristics of this film, it will make the film very good TCO alternatives for the ...

  4. Single-Crystal Mesoporous ZnO Thin Films Composed of Nanowalls

    KAUST Repository

    Wang, Xudong; Ding, Yong; Li, Zhou; Song, Jinhui; Wang, Zhong Lin

    2009-01-01

    This paper presents a controlled, large scale fabrication of mesoporous ZnO thin films. The entire ZnO mesoporous film is one piece of a single crystal, while high porosity made of nanowalls is present. The growth mechanism was proposed

  5. Chemical route to synthesis of mesoporous ZnO thin films and their liquefied petroleum gas sensor performance

    International Nuclear Information System (INIS)

    Dhawale, D.S.; Lokhande, C.D.

    2011-01-01

    Highlights: → Low temperature synthesis of mesoporous ZnO thin films by CBD method with urea containing bath. → Wurtzite crystal structure of mesoporous ZnO has been confirmed from the XRD study. → SEM images reveal the formation of hydrophobic mesoporous ZnO thin films. → Maximum LPG response of 52% has been achieved with high stability. - Abstract: In the present work, we report base free chemical bath deposition (CBD) of mesoporous zinc oxide (ZnO) thin films from urea containing bath for liquefied petroleum gas (LPG) sensor application. Mesoporous morphology with average pore size ∼2 μm and wurtzite crystal structure are confirmed from scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The surface of ZnO is hydrophobic with water contact angle 128 ± 1 o . Optical study reveals the presence of direct bad gap with energy 3.24 eV. The gas sensing study reveals the mesoporous ZnO is highly selective towards LPG as compared with CO 2 and maximum LPG response of 52% is achieved upon the exposure of 3900 ppm LPG at 573 K as well as good reproducibility and short response/recovery times.

  6. Defect-induced magnetic order in pure ZnO films

    Science.gov (United States)

    Khalid, M.; Ziese, M.; Setzer, A.; Esquinazi, P.; Lorenz, M.; Hochmuth, H.; Grundmann, M.; Spemann, D.; Butz, T.; Brauer, G.; Anwand, W.; Fischer, G.; Adeagbo, W. A.; Hergert, W.; Ernst, A.

    2009-07-01

    We have investigated the magnetic properties of pure ZnO thin films grown under N2 pressure on a -, c -, and r -plane Al2O3 substrates by pulsed-laser deposition. The substrate temperature and the N2 pressure were varied from room temperature to 570°C and from 0.007 to 1.0 mbar, respectively. The magnetic properties of bare substrates and ZnO films were investigated by SQUID magnetometry. ZnO films grown on c - and a -plane Al2O3 substrates did not show significant ferromagnetism. However, ZnO films grown on r -plane Al2O3 showed reproducible ferromagnetism at 300 K when grown at 300-400°C and 0.1-1.0 mbar N2 pressure. Positron annihilation spectroscopy measurements as well as density-functional theory calculations suggest that the ferromagnetism in ZnO films is related to Zn vacancies.

  7. Laser molecular beam epitaxy of ZnO thin films and heterostructures

    International Nuclear Information System (INIS)

    Opel, Matthias; Geprägs, Stephan; Althammer, Matthias; Brenninger, Thomas; Gross, Rudolf

    2014-01-01

    We report on the growth of epitaxial ZnO thin films and ZnO-based heterostructures on sapphire substrates by laser molecular beam epitaxy (MBE). We first discuss some recent developments in laser-MBE such as flexible ultraviolet laser beam optics, infrared laser heating systems or the use of atomic oxygen and nitrogen sources, and describe the technical realization of our advanced laser-MBE system. Then we describe the optimization of the deposition parameters for ZnO films such as laser fluence and substrate temperature and the use of buffer layers. The detailed structural characterization by x-ray analysis and transmission electron microscopy shows that epitaxial ZnO thin films with high structural quality can be achieved, as demonstrated by a small out-of-plane and in-plane mosaic spread as well as the absence of rotational domains. We also demonstrate the heteroepitaxial growth of ZnO-based multilayers as a prerequisite for spin transport experiments and the realization of spintronic devices. As an example, we show that TiN/Co/ZnO/Ni/Au multilayer stacks can be grown on (0 0 0 1)-oriented sapphire with good structural quality of all layers and well defined in-plane epitaxial relations. (paper)

  8. Growth and characterization of polar and nonpolar ZnO film grown on sapphire substrates by using atomic layer deposition

    International Nuclear Information System (INIS)

    Kim, Ki-Wook; Son, Hyo-Soo; Choi, Nak-Jung; Kim, Jihoon; Lee, Sung-Nam

    2013-01-01

    We investigated the electrical and the optical properties of polar and nonpolar ZnO films grown on sapphire substrates with different crystallographic planes. High resolution X-ray results revealed that polar c-plane (0001), nonpolar m-plane (10-10) and a-plane (11-20) ZnO thin films were grown on c-plane, m- and r-sapphire substrates by atomic layer deposition, respectively. Compared with the c-plane ZnO film, nonpolar m-plane and a-plane ZnO films showed smaller surface roughness and anisotropic surface structures. Regardless of ZnO crystal planes, room temperature photoluminescence spectra represented two emissions which consisted of the near bandedge (∼ 380 nm) and the deep level emission (∼ 500 nm). The a-plane ZnO films represented better optical and electrical properties than c-plane ZnO, while m-plane ZnO films exhibited poorer optical and electrical properties than c-plane ZnO. - Highlights: • Growth and characterization of a-, c- and m-plane ZnO film by atomic layer deposition. • The a-plane ZnO represented better optical and electrical properties than c-plane ZnO. • The m-plane ZnO exhibited poorer optical and electrical properties than c-plane ZnO

  9. Fabrication and Photo-Detecting Performance of 2D ZnO Inverse Opal Films

    Directory of Open Access Journals (Sweden)

    Xin Lin

    2016-09-01

    Full Text Available Two-dimensional (2D ZnO inverse opal (IO films were fabricated by co-assembly of sacrificed polystyrene (PS microspheres and citric acid/zinc acetate (CA/ZA aqueous solution at an oil–water interface followed by calcination. Their morphologies could be controlled by the surface property of polymer templates and CA/ZA molar ratio. Moreover, photo-detecting devices based on such films were constructed, which showed high photocurrent (up to 4.6 μA, excellent spectral selectivity, and reversible response to optical switch.

  10. Electrosynthesis and characterization of ZnO nanoparticles as inorganic component in organic thin-film transistor active layers

    International Nuclear Information System (INIS)

    Picca, Rosaria Anna; Sportelli, Maria Chiara; Hötger, Diana; Manoli, Kyriaki; Kranz, Christine; Mizaikoff, Boris; Torsi, Luisa; Cioffi, Nicola

    2015-01-01

    Highlights: • PSS-capped ZnO NPs were synthesized via a green electrochemical-thermal method • The influence of electrochemical conditions and temperature was studied • Spectroscopic data show that PSS functionalities are retained in the annealed NPs • Nanostructured ZnO improved the performance of P3HT-based thin film transistors - Abstract: ZnO nanoparticles have been prepared via a green electrochemical synthesis method in the presence of a polymeric anionic stabilizer (poly-sodium-4-styrenesulfonate, PSS), and then applied as inorganic component in poly-3-hexyl-thiophene thin-film transistor active layers. Different parameters (i.e. current density, electrolytic media, PSS concentration, and temperature) influencing nanoparticle synthesis have been studied. The resulting nanomaterials have been investigated by transmission electron microscopy (TEM) and spectroscopic techniques (UV-Vis, infrared, and x-ray photoelectron spectroscopies), assessing the most suitable conditions for the synthesis and thermal annealing of nanostructured ZnO. The proposed ZnO nanoparticles have been successfully coupled with a poly-3-hexyl-thiophene thin-film resulting in thin-film transistors with improved performance.

  11. Synthesis, microstructural characterization and optical properties of undoped, V and Sc doped ZnO thin films

    International Nuclear Information System (INIS)

    Amezaga-Madrid, P.; Antunez-Flores, W.; Ledezma-Sillas, J.E.; Murillo-Ramirez, J.G.; Solis-Canto, O.; Vega-Becerra, O.E.; Martinez-Sanchez, R.; Miki-Yoshida, M.

    2011-01-01

    Research highlights: → Undoped, V and Sc doped ZnO thin films by Aerosol Assisted Chemical Vapour Deposition. → Optimum substrate temperatures of 673 K and 623 K for Sc and V doped films. → Around one third of the dopants in solution were deposited into the films. → Crystallite and grain size decreased with the increase of dopant concentration. → Optical band gap increased from 3.29 to 3.32 eV for undoped to 7 Sc/Zn at. %. - Abstract: Many semiconductor oxides (ZnO, TiO 2 , SnO 2 ) when doped with a low percentage of non-magnetic (V, Sc) or magnetic 3d (Co, Mn, Ni, Fe) cation behave ferromagnetically. They have attracted a great deal of interest due to the integration of semiconducting and magnetic properties in a material. ZnO is one of the most promising materials to carry out these tasks in view of the fact that it is optically transparent and has n or p type conductivity. Here, we report the synthesis, microstructural characterization and optical properties of undoped, V and Sc doped zinc oxide thin films. ZnO based thin films with additions of V and Sc were deposited by the Aerosol Assisted Chemical Vapour Deposition method. V and Sc were incorporated separately in the precursor solution. The films were uniform, transparent and non-light scattering. The microstructure of the films was characterized by Grazing Incidence X-ray Diffraction, Scanning Electron Microscopy, and Scanning Probe Microscopy. Average grain size and surface rms roughness were estimated by the measurement of Atomic Force Microscopy. The microstructure of doped ZnO thin films depended on the type and amount of dopant material incorporated. The optical properties were determined from specular reflectance and transmittance spectra. Results were analyzed to determine the optical constant and band gap of the films. An increase in the optical band gap with the content of Sc dopant was obtained.

  12. Effect of hydrogen on ZnO films and Au/ZnO Schottky contacts

    International Nuclear Information System (INIS)

    Tsiarapas, C; Girginoudi, D; Georgoulas, N

    2014-01-01

    The structural, optical and electrical properties of ZnO films for different amounts of incorporated hydrogen (H), as well as the electrical characteristics of Au Schottky contacts based on these ZnO layers have been investigated. The films were deposited with the dc-magnetron sputtering technique, varying the H flow rate in the Ar/H sputtering gas. We found a significant improvement of the crystallinity (as obtained from x-ray diffraction spectra), Hall mobility and resistivity as the H concentration per vol. [H 2 ] (during deposition) increases from 0% to 33.3%, which is followed by degradation for further [H 2 ] increase. A high dependence of the carrier mobility on the grain size is also noted. The Schottky diodes were characterized through current–voltage (I–V) and capacitance–voltage (C–V) measurements at room temperature. In correlation with the basic film properties, we obtained the best results for the Schottky diodes with [H 2 ] = 33.3%, in terms of higher rectification ratio, lower ideality factor (η) and series resistance (R s ). Both the electron concentration n and the ionized donors' concentration N D (obtained from C–V curves) increase constantly with [H 2 ] increase, and that seems to be consistent with our suggestion that H acts as a donor in ZnO. (paper)

  13. 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.

  14. Micro-patterned ZnO semiconductors for high performance thin film transistors via chemical imprinting with a PDMS stamp.

    Science.gov (United States)

    Seong, Kieun; Kim, Kyongjun; Park, Si Yun; Kim, Youn Sang

    2013-04-07

    Chemical imprinting was conducted on ZnO semiconductor films via a chemical reaction at the contact regions between a micro-patterned PDMS stamp and ZnO films. In addition, we applied the chemical imprinting on Li doped ZnO thin films for high performance TFTs fabrication. The representative micro-patterned Li doped ZnO TFTs showed a field effect mobility of 4.2 cm(2) V(-1) s(-1) after sintering at 300 °C.

  15. Optical and Electrical Performance of ZnO Films Textured by Chemical Etching

    Directory of Open Access Journals (Sweden)

    Shiuh-Chuan HER

    2015-11-01

    Full Text Available Zinc oxide (ZnO films were prepared by radio frequency (RF magnetron sputtering on the glass substrate as transparent conductive oxide films. For silicon solar cells, a proper surface texture is essential to introduce light scattering and subsequent light trapping to enhance the current generation. In this study, the magnetron-sputtered ZnO films were textured by wet-chemical etching in diluted hydrochloric acid (HCl for better light scattering. The diffuse transmittance of the surface textured ZnO films was measured to evaluate the light scattering. The influence of hydrochloric acid concentration on the morphology, optical and electrical properties of the surface-textured ZnO film was investigated. The ZnO film etched in 0.05M HCl solution for 30 s exhibited average diffuse transmittance in the visible wavelength range of 9.52 % and good resistivity of 1.10 x 10-3 W×cm while the as-deposited ZnO film had average diffuse transmittance of 0.51 % and relatively high resistivity of 5.84 x 10-2 W×cm. Experimental results illustrated that the optical and electrical performance of ZnO films can be significantly improved by introducing the surface texture through the wet-chemical etching process.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9624

  16. Substrate effect on the room-temperature ferromagnetism in un-doped ZnO films

    Science.gov (United States)

    Zhan, Peng; Wang, Weipeng; Xie, Zheng; Li, Zhengcao; Zhang, Zhengjun; Zhang, Peng; Wang, Baoyi; Cao, Xingzhong

    2012-07-01

    Room-temperature ferromagnetism was achieved in un-doped ZnO films on silicon and quartz substrates. Photoluminescence measurement and positron annihilation analysis suggested that the ferromagnetism was originated from singly occupied oxygen vacancies (roughly estimated as ˜0.55 μB/vacancy), created in ZnO films by annealing in argon. The saturated magnetization of ZnO films was enhanced from ˜0.44 emu/g (on quartz) to ˜1.18 emu/g (on silicon) after annealing at 600 °C, as silicon acted as oxygen getter and created more oxygen vacancies in ZnO films. This study clarified the origin of ferromagnetism in un-doped ZnO and provides an idea to enhance the ferromagnetism.

  17. Piezoelectric Response Evaluation of ZnO Thin Film Prepared by RF Magnetron Sputtering

    Directory of Open Access Journals (Sweden)

    Cheng Da-Long

    2017-01-01

    Full Text Available The most important parameter of piezoelectric materials is piezoelectric coefficient (d33. In this study, the piezoelectric ZnO thin films were deposited on the SiNx/Si substrate. The 4 inches substrate is diced into 8 cm× 8 cm piece. During the deposition process, a zinc target (99.999 wt% of 2 inches diameter was used. The vertical distance between the target and the substrate holder was fixed at 5 cm. The piezoelectric response of zinc oxide (ZnO thin films were obtained by using a direct measurement system. The system adopts a mini impact tip to generate an impulsive force and read out the piezoelectric signals immediately. Experimentally, a servo motor is used to produce a fixed quantity of force, for giving an impact against to the piezoelectric film. The ZnO thin films were deposited using the reactive radio frequency (RF magnetron sputtering method. The electric charges should be generated because of the material’s extrusion. This phenomenon was investigated through the oscilloscope by one shot trigger. It was apparent that all ZnO films exhibit piezoelectric responses evaluated by our measurement system, however, its exhibit a significant discrepancy. The piezoelectric responses of ZnO thin film at various deposition positions were measured and the crystal structures of the sputtering pressure were also discussed. The crystalline characteristics of ZnO thin films are investigated through the XRD and SEM. The results show the ZnO thin film exhibits good crystalline pattern and surface morphology with controlled sputtering condition. The ZnO thin films sputtered using 2 inches target present various piezoelectric responses. With the exactly related position, a best piezoelectric response of ZnO thin film can be achieved.

  18. ZnO thin films and nanostructures for emerging optoelectronic applications

    Science.gov (United States)

    Rogers, D. J.; Teherani, F. H.; Sandana, V. E.; Razeghi, M.

    2010-02-01

    ZnO-based thin films and nanostructures grown by PLD for various emerging optoelectronic applications. AZO thin films are currently displacing ITO for many TCO applications due to recent improvements in attainable AZO conductivity combined with processing, cost and toxicity advantages. Advances in the channel mobilities and Id on/off ratios in ZnO-based TTFTs have opened up the potential for use as a replacement for a-Si in AM-OLED and AM-LCD screens. Angular-dependent specular reflection measurements of self-forming, moth-eye-like, nanostructure arrays grown by PLD were seen to have green gap in InGaN-based LEDs was combated by substituting low Ts PLD n-ZnO for MOCVD n-GaN in inverted hybrid heterojunctions. This approach maintained the integrity of the InGaN MQWs and gave LEDs with green emission at just over 510 nm. Hybrid n-ZnO/p-GaN heterojunctions were also seen to have the potential for UV (375 nm) EL, characteristic of ZnO NBE emission. This suggests that there was significant hole injection into the ZnO and that such LEDs could profit from the relatively high exciton binding energy of ZnO.

  19. Fabrication of nanostructured Al-doped ZnO thin film for methane sensing applications

    Energy Technology Data Exchange (ETDEWEB)

    Shafura, A. K., E-mail: shafura@ymail.com; Azhar, N. E. I.; Uzer, M.; Mamat, M. H. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Sin, N. D. Md. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Faculty of Electrical Engineering, Universiti Teknologi MARA Cawangan Johor, Kampus Pasir Gudang, 81750 Masai, Johor (Malaysia); Saurdi, I. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Faculty of Electrical Engineering, Universiti Teknologi MARA Sarawak, Kampus Kota Samarahan Jalan Meranek, Sarawak (Malaysia); Shuhaimi, A. [Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, University ofMalaya, 50603 Kuala Lumpur (Malaysia); Alrokayan, Salman A. H.; Khan, Haseeb A. [Research Chair of Targeting and Treatment Cancer Using Nanoparticles, Department Of Biochemistry, College Of Science, King Saud University, P.O: 2454 Riyadh 11451 (Saudi Arabia); Rusop, M., E-mail: nanouitm@gmail.com [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre (NST), Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia)

    2016-07-06

    CH{sub 4} gas sensor was fabricated using spin-coating method of the nanostructured ZnO thin film. Effect of annealing temperature on the electrical and structural properties of the film was investigated. Dense nanostructured ZnO film are obtained at higher annealing temperature. The optimal condition of annealing temperature is 500°C which has conductivity and sensitivity value of 3.3 × 10{sup −3} S/cm and 11.5%, respectively.

  20. Comparison on electrically pumped random laser actions of hydrothermal and sputtered ZnO films

    International Nuclear Information System (INIS)

    Wang, Canxing; Jiang, Haotian; Li, Yunpeng; Ma, Xiangyang; Yang, Deren

    2013-01-01

    Random lasing (RL) in polycrystalline ZnO films is an intriguing research subject. Here, we have comparatively investigated electrically pumped RL behaviors of two metal-insulator-semiconductor structured devices using the hydrothermal and sputtered ZnO films as the semiconductor components, i.e., the light-emitting layers, respectively. It is demonstrated that the device using the hydrothermal ZnO film exhibits smaller threshold current and larger output optical power of the electrically pumped RL. The morphological characterization shows that the hydrothermal ZnO film is somewhat porous and is much rougher than the sputtered one, suggesting that in the former stronger multiple light scattering can occur. Moreover, the photoluminescence characterization indicates that there are fewer defects in the hydrothermal ZnO film than in the sputtered one, which means that the photons can pick up larger optical gain through stimulated emission in the hydrothermal ZnO film. Therefore, it is believed that the stronger multiple light scattering and larger optical gain contribute to the improved performance of the electrically pumped RL from the device using the hydrothermal ZnO film

  1. Mn{sup 2+} ions distribution in doped sol–gel deposited ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Stefan, Mariana, E-mail: mstefan@infim.ro [National Institute of Materials Physics, P.O. Box MG-7, 077125 Magurele (Romania); Ghica, Daniela; Nistor, Sergiu V.; Maraloiu, Adrian V. [National Institute of Materials Physics, P.O. Box MG-7, 077125 Magurele (Romania); Plugaru, Rodica [National Institute for R & D in Microtechnologies (IMT), Erou Iancu Nicolae Str. 126A, 077190 Bucharest (Romania)

    2017-02-28

    Highlights: • Several Mn{sup 2+} centers observed by EPR in sol–gel ZnO films. • Mn{sup 2+} ions localized at Zn{sup 2+} sites in ZnO grains and disordered ZnO phase. • Sixfold coordinated Mn{sup 2+} ions localized in inter-grain region. • Aggregated Mn in insular-like regions between ZnO grains in the ZnO:5%Mn film. • Aggregated Mn phase presence and distribution observed by EPR and EDX-STEM. - Abstract: The localization and distribution of the Mn{sup 2+} ions in two sol–gel deposited ZnO films doped with different manganese concentrations were investigated by electron paramagnetic resonance spectroscopy and analytical transmission electron microscopy. In the lightly doped sample the Mn{sup 2+} ions are mainly localized substitutionally at isolated tetrahedrally coordinated Zn{sup 2+} sites in both crystalline ZnO nanograins (34%) and surrounding disordered ZnO (52%). In the highly doped ZnO film, a much smaller proportion of manganese substitutes Zn{sup 2+} in the crystalline and disordered ZnO (10%). The main amount (85%) of manganese aggregates in a secondary phase as an insular-like distribution between the ZnO nanograins. The remaining Mn{sup 2+} ions (14% and 5% at low and high doping levels, respectively) are localized at isolated, six-fold coordinated sites, very likely in the disordered intergrain region. Annealing at 600 °C induced changes in the Mn{sup 2+} ions distribution, reflecting the increase of the ZnO crystallization degree, better observed in the lightly doped sample.

  2. Microstructures and photocatalytic properties of porous ZnO films synthesized by chemical bath deposition method

    International Nuclear Information System (INIS)

    Wang Huihu; Dong, Shijie; Chang Ying; Zhou Xiaoping; Hu Xinbin

    2012-01-01

    Different porous ZnO film structures on the surface of alumina substrates were prepared through a simple chemical bath deposition method in the methanolic zinc acetate solution. The surface morphology and phase structure of porous ZnO film were determined by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. Both initial zinc acetate concentration and sintering temperature have great impact on the final film structures. With the increase of initial zinc acetate concentration, the porous structures can be finely tuned from circular nest like assemblies composed film into successive nest like film, and finally to globular aggregates composed film. By increasing the sintering temperature, the porous structure of successive nest like film can be further controlled. Furthermore, the crystallinity of photocatalysts also can be greatly improved. The photodegradation results of Methyl Orange revealed that porous ZnO film with successive nest like structure sintered at 500 °C exhibited the highest photocatalytic activity under UV illumination.

  3. Electrical properties of ZnO thin films grown by MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    Pagni, O. [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa); Somhlahlo, N.N. [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa); Weichsel, C. [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa); Leitch, A.W.R. [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa)]. E-mail: andrew.leitch@nmmu.ac.za

    2006-04-01

    We report on the electrical characterization of ZnO films grown by MOCVD on glass and sapphire substrates. After correcting our temperature variable Hall measurements by applying the standard two-layer model, which takes into account an interfacial layer, scattering mechanisms in the ZnO films were studied as well as donor activation energies determined. ZnO films grown at different oxygen partial pressures indicated the importance of growth conditions on the defect structure by means of their conductivities and conductivity activation energies.

  4. Electrical properties of ZnO thin films grown by MOCVD

    International Nuclear Information System (INIS)

    Pagni, O.; Somhlahlo, N.N.; Weichsel, C.; Leitch, A.W.R.

    2006-01-01

    We report on the electrical characterization of ZnO films grown by MOCVD on glass and sapphire substrates. After correcting our temperature variable Hall measurements by applying the standard two-layer model, which takes into account an interfacial layer, scattering mechanisms in the ZnO films were studied as well as donor activation energies determined. ZnO films grown at different oxygen partial pressures indicated the importance of growth conditions on the defect structure by means of their conductivities and conductivity activation energies

  5. Slow positron beam study of hydrogen ion implanted ZnO thin films

    Science.gov (United States)

    Hu, Yi; Xue, Xudong; Wu, Yichu

    2014-08-01

    The effects of hydrogen related defect on the microstructure and optical property of ZnO thin films were investigated by slow positron beam, in combination with x-ray diffraction, infrared and photoluminescence spectroscopy. The defects were introduced by 90 keV proton irradiation with doses of 1×1015 and 1×1016 ions cm-2. Zn vacancy and OH bonding (VZn+OH) defect complex were identified in hydrogen implanted ZnO film by positron annihilation and infrared spectroscopy. The formation of these complexes led to lattice disorder in hydrogen implanted ZnO film and suppressed the luminescence process.

  6. Properties of antimony doped ZnO thin films deposited by spray pyrolysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Sadananda Kumar, N., E-mail: sadanthara@gmail.com; Bangera, Kasturi V.; Shivakumar, G. K. [National Institute of Technology Karnataka, Surathkal, Thin Films Laboratory, Department of Physics (India)

    2015-07-15

    Antimony (Sb) doped zinc oxide (ZnO) thin films were deposited on the glass substrate at 450°C using spray pyrolysis technique. Effect of Sb doping on surface morphology structural, optical and electrical properties were studied. X-ray diffraction (XRD) analysis showed that both the undoped and doped ZnO thin films are polycrystalline in nature with (101) preferred orientation. SEM analysis showed a change in surface morphology of Sb doped ZnO thin films. Doping results in a marked increase in conductivity without affecting the transmittance of the films. ZnO films prepared with 3 at % Sb shows the lowest resistivity of 0.185 Ohm cm with a Hall mobility of 54.05 cm{sup 2} V{sup –1} s{sup –1}, and a hole concentration of 6.25 × 10{sup 17} cm{sup –3}.

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

    International Nuclear Information System (INIS)

    Water, Walter; Yan, Y.-S.

    2007-01-01

    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

  8. Implanted ZnO thin films: Microstructure, electrical and electronic properties

    International Nuclear Information System (INIS)

    Lee, J.; Metson, J.; Evans, P.J.; Kinsey, R.; Bhattacharyya, D.

    2007-01-01

    Magnetron sputtered polycrystalline ZnO thin films were implanted using Al, Ag, Sn, Sb and codoped with TiN in order to improve the conductivity and to attempt to achieve p-type behaviour. Structural and electrical properties of the implanted ZnO thin films were examined with X-ray diffractometry (XRD), scanning electron microscopy (SEM), secondary ion mass spectrometry (SIMS), atomic force microscopy (AFM) and conductivity measurements. Depth profiles of the implanted elements varied with the implant species. Implantation causes a partial amorphisation of the crystalline structure and decreases the effective grain size of the films. One of the findings is the improvement, as a consequence of implantation, in the conductivity of initially poorly conductive samples. Heavy doping may help for the conversion of conduction type of ZnO thin films. Annealing in vacuum mitigated structural damage and stress caused by implantation, and improved the conductivity of the implanted ZnO thin films

  9. ZnO film for application in surface acoustic wave device

    International Nuclear Information System (INIS)

    Du, X Y; Fu, Y Q; Tan, S C; Luo, J K; Flewitt, A J; Maeng, S; Kim, S H; Choi, Y J; Lee, D S; Park, N M; Park, J; Milne, W I

    2007-01-01

    High quality, c-axis oriented zinc oxide (ZnO) thin films were grown on silicon substrate using RF magnetron sputtering. Surface acoustic wave (SAW) devices were fabricated with different thickness of ZnO ranging from 1.2 to 5.5 μmUm and the frequency responses were characterized using a network analyzer. Thick ZnO films produce the strongest transmission and reflection signals from the SAW devices. The SAW propagation velocity is also strongly dependent on ZnO film thickness. The performance of the ZnO SAW devices could be improved with addition of a SiO 2 layer, in name of reflection signal amplitude and phase velocity of Rayleigh wave

  10. Formation of p-type ZnO thin film through co-implantation

    Science.gov (United States)

    Chuang, Yao-Teng; Liou, Jhe-Wei; Woon, Wei-Yen

    2017-01-01

    We present a study on the formation of p-type ZnO thin film through ion implantation. Group V dopants (N, P) with different ionic radii are implanted into chemical vapor deposition grown ZnO thin film on GaN/sapphire substrates prior to thermal activation. It is found that mono-doped ZnO by N+ implantation results in n-type conductivity under thermal activation. Dual-doped ZnO film with a N:P ion implantation dose ratio of 4:1 is found to be p-type under certain thermal activation conditions. Higher p-type activation levels (1019 cm-3) under a wider thermal activation range are found for the N/P dual-doped ZnO film co-implanted by additional oxygen ions. From high resolution x-ray diffraction and x-ray photoelectron spectroscopy it is concluded that the observed p-type conductivities are a result of the promoted formation of PZn-4NO complex defects via the concurrent substitution of nitrogen at oxygen sites and phosphorus at zinc sites. The enhanced solubility and stability of acceptor defects in oxygen co-implanted dual-doped ZnO film are related to the reduction of oxygen vacancy defects at the surface. Our study demonstrates the prospect of the formation of stable p-type ZnO film through co-implantation.

  11. Improving the conductance of ZnO thin film doping with Ti by using a cathodic vacuum arc deposition process

    International Nuclear Information System (INIS)

    Wu, Chun-Sen; Lin, Bor-Tsuen; Jean, Ming-Der

    2011-01-01

    The Ti-doped ZnO films compared to un-doped ZnO films were deposited onto Corning XG glass substrates by using a cathodic vacuum arc deposition process in a mixture of oxygen and argon gases. The structural, electrical and optical properties of un-doped and Ti-doped ZnO films have been investigated. When the Ti target power is about 750 W, the incorporation of titanium atoms into zinc oxide films is obviously effective. Additionally, the resistivity of un-doped ZnO films is high and reduces to a value of 3.48 x 10 -3 Ω-cm when Ti is incorporated. The Ti doped in the ZnO films gave rise to the improvement of the conductivity of the films obviously. The Ti-doped ZnO films have > 85% transmittance in a range of 400-700 nm.

  12. Photoconductive ZnO Films Printed on Flexible Substrates by Inkjet and Aerosol Jet Techniques

    Science.gov (United States)

    Winarski, D. J.; Kreit, E.; Heckman, E. M.; Flesburg, E.; Haseman, M.; Aga, R. S.; Selim, F. A.

    2018-02-01

    Zinc oxide (ZnO) thin films have remarkable versatility in sensor applications. Here, we report simple ink synthesis and printing methods to deposit ZnO photodetectors on a variety of flexible and transparent substrates, including polyimide (Kapton), polyethylene terephthalate, cyclic olefin copolymer (TOPAS), and quartz. X-ray diffraction analysis revealed the dependence of the film orientation on the substrate type and sintering method, and ultraviolet-visible (UV-Vis) absorption measurements revealed a band edge near 380 nm. van der Pauw technique was used to measure the resistivity of undoped ZnO and indium/gallium-codoped ZnO (IGZO) films. IGZO films showed lower resistivity and larger average grain size compared with undoped ZnO films due to addition of In3+ and Ga3+, which act as donors. A 365-nm light-emitting diode was used to photoirradiate the films to study their photoconductive response as a function of light intensity at 300 K. The results revealed that ZnO films printed by aerosol jet and inkjet techniques exhibited five orders of magnitude photoconductivity, indicating that such films are viable options for use in flexible photodetectors.

  13. Studies on nonvolatile resistance memory switching in ZnO thin films

    Indian Academy of Sciences (India)

    Six decades of research on ZnO has recently sprouted a new branch in the domain of resistive random access memories. Highly resistive and c-axis oriented ZnO thin films were grown by us using d.c. discharge assisted pulsed laser deposition on Pt/Ti/SiO2/Si substrates at room temperature. The resistive switching ...

  14. Impact of thiol and amine functionalization on photoluminescence properties of ZnO films

    International Nuclear Information System (INIS)

    Jayalakshmi, G.; Saravanan, K.; Balasubramanian, T.

    2013-01-01

    In the present study, we have investigated surface functionalization of ZnO films with dodecanethiol (Thiol) and trioctylamine (amine) by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), contact angle (CA) and photoluminescence (PL) measurements. The chemical bondings of thiol and amine with ZnO have been confirmed via the formation of Zn–S and Zn–N bonds by XPS measurements. AFM measurements on ZnO films before and after surface functionalization with thiol and amine provide evidence for the successful functionalization of thiol and amine on ZnO surfaces without any island formation. The CA measurements on ZnO films before and after surface functionalization with thiol and amine show the hydrophobic nature. PL measurements of thiol and amine functionalized ZnO show enhancements of UV emission and quenching of visible emission. The enhanced UV emissions in thiol and amine functionalized ZnO films suggest that the surface defects such as oxygen vacancies are passivated by thiol and amine functionalization. -- Highlights: ► Surface functionalization is a new approach to reduce surface dependent non-radiative process. ► Oxygen vacancies are passivated on surface functionalization. ► Thiol and amine functionalized ZnO show enhancements of UV emission

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

    Indian Academy of Sciences (India)

    Administrator

    In electrical characterization as well, when annealing temperature was increased .... of ZnO (002) peaks and (c) crystallite size and stress generation on ZnO thin films ... sufficient kinetic energy and surface mobility to occupy stable positions ...

  16. Defect studies of thin ZnO films prepared by pulsed laser deposition

    International Nuclear Information System (INIS)

    Vlček, M; Čížek, J; Procházka, I; Novotný, M; Bulíř, J; Lančok, J; Anwand, W; Brauer, G; Mosnier, J-P

    2014-01-01

    Thin ZnO films were grown by pulsed laser deposition on four different substrates: sapphire (0 0 0 1), MgO (1 0 0), fused silica and nanocrystalline synthetic diamond. Defect studies by slow positron implantation spectroscopy (SPIS) revealed significantly higher concentration of defects in the studied films when compared to a bulk ZnO single crystal. The concentration of defects in the films deposited on single crystal sapphire and MgO substrates is higher than in the films deposited on amorphous fused silica substrate and nanocrystalline synthetic diamond. Furthermore, the effect of deposition temperature on film quality was investigated in ZnO films deposited on synthetic diamond substrates. Defect studies performed by SPIS revealed that the concentration of defects firstly decreases with increasing deposition temperature, but at too high deposition temperatures it increases again. The lowest concentration of defects was found in the film deposited at 450° C.

  17. Giant coercivity in ferromagnetic Co doped ZnO single crystal thin film

    International Nuclear Information System (INIS)

    Loukya, B.; Negi, D.S.; Dileep, K.; Kumar, N.; Ghatak, Jay; Datta, R.

    2013-01-01

    The origin of ferromagnetism in ZnO doped with transition metal impurities has been discussed extensively and appeared to be a highly controversial and challenging topic in today's solid state physics. Magnetism observed in this system is generally weak and soft. We have grown Co:ZnO up to 30 at% Co in single crystal thin film form on c-plane sapphire. A composition dependent coercivity is observed in this system which reaches peak value at 25 at% Co, the values are 860 Oe and 1149 Oe with applied field along parallel and perpendicular to the film substrate interface respectively. This giant coercivity might pave the way to exploit this material as a magnetic semiconductor with novel logic functionalities. The findings are explained based on defect band itinerant ferromagnetism and its partial interaction with localized d electrons of Co through charge transfer. Besides large coercivity, an increase in the band gap with Co concentration has also been observed along with blue emission peak with long tail confirming the formation of extended point defect levels in the host lattice band gap. - Highlights: • Co doped ZnO ferromagnetic single crystal thin film. • Giant coercivity in Co:ZnO thin film which may help to turn this material into application. • Cathodoluminescence (CL) data showing increase in band gap with Co concentrations. • A theoretical proposal is made to explain the observed giant coercivity

  18. Transparent conductive Ga-doped ZnO films fabricated by MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    Behrends, Arne; Wagner, Alexander; Al-Suleiman, Mohamed Aid Mansur; Waag, Andreas; Bakin, Andrey [Institute of Semiconductor Technology, University of Technology Braunschweig, Hans-Sommer-Str. 66, 38106 Braunschweig (Germany); Lugauer, Hans-Juergen; Strassburg, Martin; Walter, Robert; Weimar, Andreas [OSRAM Opto Semiconductors GmbH, Leibnizstr. 4, 93055 Regensburg (Germany)

    2012-04-15

    Transparent conductive oxides (TCOs) are used for a variety of different applications, e.g., in solar cells and light emitting diodes (LEDs). Mostly, sputtering is used, which often results in a degradation of the underlying semiconductor material. In this work we report on a ''soft'' method for the fabrication of ZnO films as TCO layers by using metal organic chemical vapor deposition (MOCVD) at particularly low temperatures. The MOCVD approach has been studied focusing on the TCO key issues: fabrication temperature, morphology, optical, and electrical properties. Very smooth ZnO films with rms values down to 0.8 nm were fabricated at a substrate temperature of only 300 C. Ga-doping is well controllable even for high carrier concentrations up to 2 x 10{sup 20} cm{sup -3}, which is above the Mott-density leading to metallic-like behavior of the films. Furthermore all films show excellent optical transparency in the visible spectral range. As a consequence, our MOCVD approach is well suited for the soft fabrication of ZnO-based TCO layers. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Nonpolar ZnO film growth and mechanism for anisotropic in-plane strain relaxation

    International Nuclear Information System (INIS)

    Pant, P.; Budai, J.D.; Narayan, J.

    2010-01-01

    Using high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction, we investigated the strain relaxation mechanisms for nonpolar (1 1 -2 0) a-plane ZnO epitaxy on (1 -1 0 2) r-plane sapphire, where the in-plane misfit ranges from -1.5% for the [0 0 0 1]ZnO-parallel [1 -1 0 -1]sapphire to -18.3% for the [-1 1 0 0]ZnO-parallel [-1 -1 2 0]sapphire direction. For the large misfit [-1 1 0 0]ZnO direction the misfit strains are fully relaxed at the growth temperature, and only thermal misfit and defect strains, which cannot be relaxed fully by slip dislocations, remain on cooling. For the small misfit direction, lattice misfit is not fully relaxed at the growth temperature. As a result, additive unrelaxed lattice and thermal misfit and defect strains contribute to the measured strain. Our X-ray diffraction measurements of lattice parameters show that the anisotropic in-plane biaxial strain leads to a distortion of the hexagonal symmetry of the ZnO basal plane. Based on the anisotropic strain relaxation observed along the orthogonal in-plane [-1 1 0 0] and [0 0 0 1]ZnO stress directions and our HRTEM investigations of the interface, we show that the plastic relaxation occurring in the small misfit direction [0 0 0 1]ZnO by dislocation nucleation is incomplete. These results are consistent with the domain-matching paradigm of a complete strain relaxation for large misfits and a difficulty in relaxing the film strain for small misfits.

  20. Photovoltaic Properties of Co-doped ZnO Thin Film on Glass Substrate

    International Nuclear Information System (INIS)

    Sabia Aye; Zin Ma Ma; May Nwe Oo; Than Than Win; Yin Maung Maung; Ko Ko Kyaw Soe

    2011-12-01

    Cobalt (Co) 0.4 mol doped zinc oxide (ZnO) fine powder was prepared by solid state mixed oxide route. Phase formation and crystal structure of Co-doped ZnO (CZO) powder were examined by X-ray diffraction (XRD). Scanning Electron Microscopy (SEM) was used to observe the micro structure of Co doped ZnO powder. Energy Dispersive X-ray Fluorescent (EDXRF) technique gave the elemental content of cobalt and zinc. Co-doped ZnO film was formed on glass substrate by spin coating technique. Photovoltaic properties of CZO/glass cell were measured.

  1. Characterizations of multilayer ZnO thin films deposited by sol-gel spin coating technique

    Directory of Open Access Journals (Sweden)

    M.I. Khan

    Full Text Available In this work, zinc oxide (ZnO multilayer thin films are deposited on glass substrate using sol-gel spin coating technique and the effect of these multilayer films on optical, electrical and structural properties are investigated. It is observed that these multilayer films have great impact on the properties of ZnO. X-ray Diffraction (XRD confirms that ZnO has hexagonal wurtzite structure. Scanning Electron Microscopy (SEM showed the crack-free films which have uniformly distributed grains structures. Both micro and nano particles of ZnO are present on thin films. Four point probe measured the electrical properties showed the decreasing trend between the average resistivity and the number of layers. The optical absorption spectra measured using UV–Vis. showed the average transmittance in the visible region of all films is 80% which is good for solar spectra. The performance of the multilayer as transparent conducting material is better than the single layer of ZnO. This work provides a low cost, environment friendly and well abandoned material for solar cells applications. Keywords: Multilayer films, Semiconductor, ZnO, XRD, SEM, Optoelectronic properties

  2. Controlled morphologies and optical properties of ZnO films and their photocatalytic activities

    Energy Technology Data Exchange (ETDEWEB)

    Duan Jingjing [Key Laboratory for Soft Chemistry and Functional Materials, Nanjing University of Science and Technology, Ministry of Education, Nanjing 210094 (China); Liu Xiaoheng, E-mail: xhliu@mail.njust.edu.cn [Key Laboratory for Soft Chemistry and Functional Materials, Nanjing University of Science and Technology, Ministry of Education, Nanjing 210094 (China); Han Qiaofeng [Key Laboratory for Soft Chemistry and Functional Materials, Nanjing University of Science and Technology, Ministry of Education, Nanjing 210094 (China); Wang Xin, E-mail: wangx@mail.njust.edu.cn [Key Laboratory for Soft Chemistry and Functional Materials, Nanjing University of Science and Technology, Ministry of Education, Nanjing 210094 (China)

    2011-09-15

    Highlights: > Gelatin acts as a capping reagent in the morphology synthesis of ZnO films. > The microstructures of ZnO films are hexagonal prisms, plates and rose-like crystals. > The hexagonal prisms and rose-like films exhibit excellent photocatalytic activities. - Abstract: ZnO films with three different microstructures including hexagonal prisms, plates and rose-like twinned crystals were fabricated using chemical bath deposition with different concentration of gelatin. The growth mechanisms of ZnO films were discussed, and the gelatin played a vital role as a polyelectrolyte capping the formation of microstructures. The photoluminescence and Raman properties were found sensitive to the crystal morphologies of ZnO films. Significantly, the photodegradation efficiencies of methylene blue under UV light irradiation in the presence of ZnO films consisted of hexagonal prisms and rose-like twinned crystals were 95% and 96%, respectively. The excellent photocatalytic activities can be ascribed to the high oxygen vacancies concentration and high percentage of polar planes, and this result was important in addressing the origin of high photocatalytic activity.

  3. Structural characterization of ZnO thin films grown on various substrates by pulsed laser deposition

    International Nuclear Information System (INIS)

    Novotný, M; Bulíř, J; Lančok, J; Čížek, J; Kužel, R; Connolly, J; McCarthy, E; Krishnamurthy, S; Mosnier, J-P; Anwand, W; Brauer, G

    2012-01-01

    ZnO thin films were grown by pulsed laser deposition on three different substrates: sapphire (0 0 0 1), MgO (1 0 0) and fused silica (FS). The structure and morphology of the films were characterized by x-ray diffraction and scanning electron microscopy and defect studies were carried out using slow positron implantation spectroscopy (SPIS). Films deposited on all substrates studied in this work exhibit the wurtzite ZnO structure and are characterized by an average crystallite size of 20-100 nm. However, strong differences in the microstructure of films deposited on various substrates were found. The ZnO films deposited on MgO and sapphire single-crystalline substrates exhibit local epitaxy, i.e. a well-defined relation between film crystallites and the substrate. Domains with different orientation relationships with the substrate were found in both films. On the other hand, the film deposited on the FS substrate exhibits fibre texture with random lateral orientation of crystallites. Extremely high compressive in-plane stress of σ ∼ 14 GPa was determined in the film deposited on the MgO substrate, while the film deposited on sapphire is virtually stress-free, and the film deposited on the FS substrate exhibits a tensile in-plane stress of σ ∼ 0.9 GPa. SPIS investigations revealed that the concentration of open-volume defects in the ZnO films is substantially higher than that in a bulk ZnO single crystal. Moreover, the ZnO films deposited on MgO and sapphire single-crystalline substrates exhibit a significantly higher density of defects than the film deposited on the amorphous FS substrate. (paper)

  4. Influence of a ZnO Buffer Layer on the Structural, Optical, and Electrical Properties of ITO/ZnO Bi-Layered Films

    International Nuclear Information System (INIS)

    Heo, Sung-Bo; Moon, Hyun-Joo; Kim, Daeil; Kim, Jun-Ho

    2016-01-01

    Sn-doped indium oxide (ITO) films and ITO/ZnO bi-layered films were prepared on polycarbonate substrates by RF magnetron sputtering without intentional substrate heating. In order to consider the influence of the ZnO thickness on the structural, optical, and electrical properties of ITO/ZnO films, the thickness of the ZnO buffer layer was varied from 5 to 20 nm. As-deposited ITO films show an average optical transmittance of 79.2% in the visible range and an electrical resistivity of 3.0×10"-"4 Ωcm, while films with a 5-nm thick ZnO buffer layer film show an electrical resistivity of 2.6×10"-"4 Ωcm and films with a 20-nm thick ZnO buffer layer show an optical transmittance of 82.0%. Based on the figure of merit, it is concluded that the ZnO buffer layer enhances the optical and electrical performance of ITO films used as transparent conducting oxides in flexible display applications.

  5. Hybrid AC EL structures with thin protective ZnO film

    International Nuclear Information System (INIS)

    Tsvetkova, E; Dikov, H; Kolentsov, K; Yourukova, L; Zhechev, D; Steflekova, V

    2008-01-01

    Alternating current hybrid electroluminescent Al/SnO 2 /ZnS: Cu/ZnO/Al structures with blue emission have been prepared. In these ZnO films are used as protective layers. The optical properties of different RF magnetron sputtered ZnO films have been studied. The voltage - brightness characteristics of AC EL structures with a ZnO protective film and conventional structures with a TiO 2 protective layer are compared. The investigation shows that the brightness of the structures with a ZnO protective film is higher. The improved characteristics of these new hybrid structures could be used in preparing various systems for representation of permanent or variable light information

  6. Characterization of homoepitaxial and heteroepitaxial ZnO films grown by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Z.Q. [Japan Atomic Energy Research Institute, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan)]. E-mail: chenzq@taka.jaeri.go.jp; Yamamoto, S. [Japan Atomic Energy Research Institute, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Kawasuso, A. [Japan Atomic Energy Research Institute, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Xu, Y. [Japan Atomic Energy Research Institute, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Sekiguchi, T. [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2005-05-15

    Homo- and heteroepitaxial ZnO films were grown on ZnO (0001) and Al{sub 2}O{sub 3} (1-bar 1-bar 2-bar -bar 0) substrates by using pulsed laser deposition. The X-ray diffraction and Raman measurements for these films show good correspondence with the bulk ZnO substrate, which confirms successful growth of c-axis oriented ZnO layer. Strong UV emission was also observed in these films, indicating good optical quality. However, the surface roughness differs very much for the homo- and heteroepitaxial film, that is, much less for the homoepitaxial layer. Positron annihilation measurements reveal a higher vacancy concentration in the homoepitaxial layer.

  7. Electrodeposited Mesoporous ZnO Thin Films as Efficient Photocatalysts for the degradation of dye pollutants

    Czech Academy of Sciences Publication Activity Database

    Pauporté, T.; Rathouský, Jiří

    2007-01-01

    Roč. 111, č. 21 (2007), s. 7639-7644 ISSN 1932-7447 Institutional research plan: CEZ:AV0Z40400503 Keywords : ZnO films * photocatalysis * pollutants Subject RIV: CF - Physical ; Theoretical Chemistry

  8. Smoothing of ZnO films by gas cluster ion beam

    International Nuclear Information System (INIS)

    Chen, H.; Liu, S.W.; Wang, X.M.; Iliev, M.N.; Chen, C.L.; Yu, X.K.; Liu, J.R.; Ma, K.; Chu, W.K.

    2005-01-01

    Planarization of wide-band-gap semiconductor ZnO surface is crucial for thin-film device performance. In this study, the rough initial surfaces of ZnO films deposited by r.f. magnetron sputtering on Si substrates were smoothed by gas cluster ion beams. AFM measurements show that the average surface roughness (R a ) of the ZnO films could be reduced considerably from 16.1 nm to 0.9 nm. Raman spectroscopy was used to monitor the structure of both the as-grown and the smoothed ZnO films. Rutherford back-scattering in combination with channeling effect was used to study the damage production induced by the cluster bombardment

  9. Thin film epitaxy and structure property correlations for non-polar ZnO films

    International Nuclear Information System (INIS)

    Pant, P.; Budai, J.D.; Aggarwal, R.; Narayan, Roger J.; Narayan, J.

    2009-01-01

    Heteroepitaxial growth and strain relaxation were investigated in non-polar a-plane (1 1 -2 0)ZnO films grown on r-plane (1 0 -1 2)sapphire substrates in the temperature range 200-700 deg. C by pulsed laser deposition. The lattice misfit in the plane of the film for this orientation varied from -1.26% in [0 0 0 1] to -18.52% in the [-1 1 0 0] direction. The alignment of (1 1 -2 0)ZnO planes parallel to (1 0 -1 2)sapphire planes was confirmed by X-ray diffraction θ-2θ scans over the entire temperature range. X-ray φ-scans revealed the epitaxial relationship:[0 0 0 1]ZnO-parallel [-1 1 0 1]sap; [-1 1 0 0]ZnO-parallel [-1 -1 2 0]sap. Depending on the growth temperature, variations in the structural, optical and electrical properties were observed in the grown films. Room temperature photoluminescence for films grown at 700 deg. C shows a strong band-edge emission. The ratio of the band-edge emission to green band emission is 135:1, indicating reduced defects and excellent optical quality of the films. The resistivity data for the films grown at 700 deg. C shows semiconducting behavior with room temperature resistivity of 2.2 x 10 -3 Ω-cm.

  10. Mango core inner shell membrane template-directed synthesis of porous ZnO films and their application for enzymatic glucose biosensor

    Science.gov (United States)

    Zhou, Yu; Wang, Lei; Ye, Zhizhen; Zhao, Minggang; Cai, Hui; Huang, Jingyun

    2013-11-01

    Micro/nano-porous ZnO films were synthesized through a simple biotemplate-directed method using mango core inner shell membranes as templates. The achieved ZnO films with wrinkles on the surface are combined of large holes and small pores in the bulk. High specific surface area, numerous microspaces, and small channels for fluid circulation provided by this unique structure along with the good biocompatibility and electron communication features of ZnO material make the product an ideal platform for the immobilization of enzymes The fabricated glucose biosensor based on the porous ZnO films exhibits good selective detection ability of analyte with good stability, high sensitivity of 50.58 μA cm-2 mM-1 and a wide linear range of 0.2-5.6 mM along with a low detection limit of 10 μM.

  11. Mango core inner shell membrane template-directed synthesis of porous ZnO films and their application for enzymatic glucose biosensor

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Yu; Wang, Lei [Department of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, 310027 (China); Ye, Zhizhen [Department of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, 310027 (China); Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University (China); Zhao, Minggang; Cai, Hui [Department of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, 310027 (China); Huang, Jingyun, E-mail: huangjy@zju.edu.cn [Department of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, 310027 (China); Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University (China)

    2013-11-15

    Micro/nano-porous ZnO films were synthesized through a simple biotemplate-directed method using mango core inner shell membranes as templates. The achieved ZnO films with wrinkles on the surface are combined of large holes and small pores in the bulk. High specific surface area, numerous microspaces, and small channels for fluid circulation provided by this unique structure along with the good biocompatibility and electron communication features of ZnO material make the product an ideal platform for the immobilization of enzymes The fabricated glucose biosensor based on the porous ZnO films exhibits good selective detection ability of analyte with good stability, high sensitivity of 50.58 μA cm{sup −2} mM{sup −1} and a wide linear range of 0.2–5.6 mM along with a low detection limit of 10 μM.

  12. Radio-frequency magnetron sputtering and wet thermal oxidation of ZnO thin film

    International Nuclear Information System (INIS)

    Liu, H. F.; Chua, S. J.; Hu, G. X.; Gong, H.; Xiang, N.

    2007-01-01

    The authors studied the growth and wet thermal oxidation (WTO) of ZnO thin films using a radio-frequency magnetron sputtering technique. X-ray diffraction reveals a preferred orientation of [1010]ZnO(0002)//[1120]Al 2 O 3 (0002) coexisted with a small amount of ZnO (1011) and ZnO (1013) crystals on the Al 2 O 3 (0001) substrate. The ZnO (1011) and ZnO (1013) crystals, as well as the in-plane preferred orientation, are absent from the growth of ZnO on the GaAs(001) substrate. WTO at 550 deg. C improves the crystalline and the photoluminescence more significantly than annealing in air, N 2 and O 2 ambient; it also tends to convert the crystal from ZnO (1011) and ZnO (1013) to ZnO (0002). The evolution of the photoluminescence upon WTO and annealing reveals that the green and orange emissions, centered at 520 and 650 nm, are likely originated from oxygen vacancies and oxygen interstitials, respectively; while the 420 nm emission, which is very sensitive to the postgrowth thermal processing regardless of the substrate and the ambient gas, is likely originated from the surface-state related defects

  13. Pure and Sn-doped ZnO films produced by pulsed laser deposition

    DEFF Research Database (Denmark)

    Holmelund, E.; Schou, Jørgen; Tougaard, S.

    2002-01-01

    A new technique, metronome doping, has been used for doping of films during pulsed laser deposition (PLD). This technique makes it possible to dope continuously during film growth with different concentrations of a dopant in one deposition sequence. Films of pure and doped ZnO have been produced...

  14. Effect of indium dopant on surface and mechanical characteristics of ZnO : In nanostructured films

    Energy Technology Data Exchange (ETDEWEB)

    Fang, T.-H.; Kang, S.-H. [Institute of Mechanical and Electromechanical Engineering, National Formosa University, No 64, Wenhua Rd., Huwei, Yunlin 632, Taiwan (China)], E-mail: fang.tehua@msa.hinet.net

    2008-12-21

    Epitaxial ZnO : In nanorod films were grown on SiO{sub 2} substrates using a chemical solution method with a pre-coated ZnO sputtered seed layer. Structural and surface characterizations of the ZnO : In nanostructured films were achieved by means of x-ray diffraction, a scanning electron microscope, an atomic force microscope and contact angle measurements. The hardness and Young's modulus of the nanostructured films were investigated by nanoindentation measurements. The results showed that when the indium dopant was increased, the hardness and Young's modulus of the films also rose. The films exhibited hydrophobic behaviour with contact angles of about 128-138 deg., and a decrease in the hardness and Young's modulus with decreasing loads or indentation depths. Buckling behaviour took place during the indentation process, and the fracture strength of the films was also discussed.

  15. Influence of surface defects in ZnO thin films on its biosensing response characteristic

    Energy Technology Data Exchange (ETDEWEB)

    Saha, Shibu; Gupta, Vinay [Department of Physics and Astrophysics, University of Delhi, Delhi-110007 (India)

    2011-09-15

    Highly c-axis oriented zinc oxide (ZnO) thin films deposited by rf magnetron sputtering under varying processing pressure (20-50 mT) in a reactive gas mixture of argon and oxygen were studied for biosensing application. The as-deposited ZnO thin films were in a state of compressive stress having defects related to interstitial Zn and antisite oxygen. Glucose oxidase has been chosen as the model enzyme in the present study and was immobilized on the surface of ZnO thin films deposited on indium tin oxide coated Corning Glass substrate. The studies reveal a correlation between the biosensing characteristic and the presence of defects in the ZnO films. The ZnO films deposited under high pressure (50 mT) are found to be more sensitive for biosensing application due to availability of more surface area for effective immobilization of biomolecules and exhibits a suitable microenvironment with good electron transfer characteristic. The obtained results highlight the importance of desired microstate besides availability of suitable native defects in the ZnO thin film for exhibiting enhanced biosensing response.

  16. Synthesis and characterization of ZnO thin film by low cost modified SILAR technique

    Directory of Open Access Journals (Sweden)

    Haridas D. Dhaygude

    2016-03-01

    Full Text Available The ZnO thin film is prepared on Fluorine Tin Oxide (FTO coated glass substrate by using SILAR deposition technique containing ZnSO4.7H2O and NaOH as precursor solution with 150 deeping cycles at 70 °C temperature. Nanocrystalline diamond like ZnO thin film is characterized by different characterization techniques such as X-ray diffraction (XRD, Fourier transform (FT Raman spectrometer, Field Emission Scanning Electron Microscopy (FE-SEM with Energy dispersive X-Ray Analysis (EDAX, optical absorption, surface wettability and photoelectrochemical cell performance measurement. The X-ray diffraction analysis shows that the ZnO thin film is polycrystalline in nature having hexagonal crystal structure. The FT-Raman scattering exhibits a sharp and strong mode at 383 cm−1 which confirms hexagonal ZnO nanostructure. The surface morphology study reveals that deposited ZnO film consists of nanocrystalline diamond like morphology all over the substrate. The synthesized thin film exhibited absorption wavelength around 309 nm. Optical study predicted the direct band gap and band gap energy of this film is found to be 3.66 eV. The photoelectrochemical cell (PEC parameter measurement study shows that ZnO sample confirmed the highest values of, short circuit current (Isc - 629 mAcm−2, open circuit voltage (Voc - 878 mV, fill factor (FF - 0.48, and maximum efficiency (η - 0.89%, respectively.

  17. Structure and morphology of magnetron sputter deposited ultrathin ZnO films on confined polymeric template

    Science.gov (United States)

    Singh, Ajaib; Schipmann, Susanne; Mathur, Aakash; Pal, Dipayan; Sengupta, Amartya; Klemradt, Uwe; Chattopadhyay, Sudeshna

    2017-08-01

    The structure and morphology of ultra-thin zinc oxide (ZnO) films with different film thicknesses on confined polymer template were studied through X-ray reflectivity (XRR) and grazing incidence small angle X-ray scattering (GISAXS). Using magnetron sputter deposition technique ZnO thin films with different film thicknesses (weight of polystyrene). The detailed internal structure, along the surface/interfaces and the growth direction of the system were explored in this study, which provides insight into the growth procedure of ZnO on confined polymer and reveals that a thin layer of ZnO, with very low surface and interface roughness, can be grown by DC magnetron sputtering technique, with approximately full coverage (with bulk like electron density) even in nm order of thickness, in 2-7 nm range on confined polymer template, without disturbing the structure of the underneath template. The resulting ZnO-polystyrene hybrid systems show strong ZnO near band edge (NBE) and deep-level (DLE) emissions in their room temperature photoluminescence spectra, where the contribution of DLE gets relatively stronger with decreasing ZnO film thickness, indicating a significant enhancement of surface defects because of the greater surface to volume ratio in thinner films.

  18. Influence of surface defects in ZnO thin films on its biosensing response characteristic

    International Nuclear Information System (INIS)

    Saha, Shibu; Gupta, Vinay

    2011-01-01

    Highly c-axis oriented zinc oxide (ZnO) thin films deposited by rf magnetron sputtering under varying processing pressure (20-50 mT) in a reactive gas mixture of argon and oxygen were studied for biosensing application. The as-deposited ZnO thin films were in a state of compressive stress having defects related to interstitial Zn and antisite oxygen. Glucose oxidase has been chosen as the model enzyme in the present study and was immobilized on the surface of ZnO thin films deposited on indium tin oxide coated Corning Glass substrate. The studies reveal a correlation between the biosensing characteristic and the presence of defects in the ZnO films. The ZnO films deposited under high pressure (50 mT) are found to be more sensitive for biosensing application due to availability of more surface area for effective immobilization of biomolecules and exhibits a suitable microenvironment with good electron transfer characteristic. The obtained results highlight the importance of desired microstate besides availability of suitable native defects in the ZnO thin film for exhibiting enhanced biosensing response.

  19. Photoluminescence of ZnO thin films deposited at various substrate temperatures

    International Nuclear Information System (INIS)

    Kao, Kuo-Sheng; Shih, Wei-Che; Ye, Wei-Tsuen; Cheng, Da-Long

    2016-01-01

    This study investigated surface acoustic wave devices with an Al/ZnO/Si structure for use in ultraviolet sensors. ZnO thin films were fabricated using a reactive radio frequency magnetron sputtering system. The substrate temperature of ZnO thin films can be varied to obtain highly crystalline properties. The surface morphologies and c-axis preferred orientation of the ZnO thin films were determined using scanning electron microscopy and X-ray diffraction. In addition, bright-field images of ZnO crystallization were investigated using a transmission electron microscope. From photoluminescence analysis, four peaks were obtained at 377.8, 384.9, 391.4, and 403.4 nm. Interdigital transducers of an aluminum electrode were fabricated on the ZnO/Si structure by using a direct current sputtering system and photolithography, combined with the lift-off method, thereby obtaining a surface acoustic wave device. Finally, frequency responses were measured using a network analyzer, and an illuminating test was adopted for the ultraviolet sensor, using a wavelength of 355 nm from a light-emitting diode. The sensitivities of the ultraviolet sensor were also discussed. - Highlights: • The ZnO/Si SAW devices exhibit the Rayleigh and Sezawa modes. • The crystalline of ZnO affects the EHP recombination and generation. • The PL spectrum of ZnO shows Gaussian fitting distributions. • The CTD_U_V is influenced by SAW types and ZnO film characteristics.

  20. Photoluminescence of ZnO thin films deposited at various substrate temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Kao, Kuo-Sheng [Department of Computer and Communication, SHU-TE University, Kaohsiung, Taiwan (China); Shih, Wei-Che [Department of Electrical Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Ye, Wei-Tsuen [Department of Computer and Communication, SHU-TE University, Kaohsiung, Taiwan (China); Cheng, Da-Long, E-mail: dlcheng@stu.edu.tw [Department of Computer and Communication, SHU-TE University, Kaohsiung, Taiwan (China)

    2016-04-30

    This study investigated surface acoustic wave devices with an Al/ZnO/Si structure for use in ultraviolet sensors. ZnO thin films were fabricated using a reactive radio frequency magnetron sputtering system. The substrate temperature of ZnO thin films can be varied to obtain highly crystalline properties. The surface morphologies and c-axis preferred orientation of the ZnO thin films were determined using scanning electron microscopy and X-ray diffraction. In addition, bright-field images of ZnO crystallization were investigated using a transmission electron microscope. From photoluminescence analysis, four peaks were obtained at 377.8, 384.9, 391.4, and 403.4 nm. Interdigital transducers of an aluminum electrode were fabricated on the ZnO/Si structure by using a direct current sputtering system and photolithography, combined with the lift-off method, thereby obtaining a surface acoustic wave device. Finally, frequency responses were measured using a network analyzer, and an illuminating test was adopted for the ultraviolet sensor, using a wavelength of 355 nm from a light-emitting diode. The sensitivities of the ultraviolet sensor were also discussed. - Highlights: • The ZnO/Si SAW devices exhibit the Rayleigh and Sezawa modes. • The crystalline of ZnO affects the EHP recombination and generation. • The PL spectrum of ZnO shows Gaussian fitting distributions. • The CTD{sub UV} is influenced by SAW types and ZnO film characteristics.

  1. Textured surface boron-doped ZnO transparent conductive oxides on polyethylene terephthalate substrates for Si-based thin film solar cells

    International Nuclear Information System (INIS)

    Chen Xinliang; Lin Quan; Ni Jian; Zhang Dekun; Sun Jian; Zhao Ying; Geng Xinhua

    2011-01-01

    Textured surface boron-doped zinc oxide (ZnO:B) thin films were directly grown via low pressure metal organic chemical vapor deposition (LP-MOCVD) on polyethylene terephthalate (PET) flexible substrates at low temperatures and high-efficiency flexible polymer silicon (Si) based thin film solar cells were obtained. High purity diethylzinc and water vapors were used as source materials, and diborane was used as an n-type dopant gas. P-i-n silicon layers were fabricated at ∼ 398 K by plasma enhanced chemical vapor deposition. These textured surface ZnO:B thin films on PET substrates (PET/ZnO:B) exhibit rough pyramid-like morphology with high transparencies (T ∼ 80%) and excellent electrical properties (Rs ∼ 10 Ω at d ∼ 1500 nm). Finally, the PET/ZnO:B thin films were applied in flexible p-i-n type silicon thin film solar cells (device structure: PET/ZnO:B/p-i-n a-Si:H/Al) with a high conversion efficiency of 6.32% (short-circuit current density J SC = 10.62 mA/cm 2 , open-circuit voltage V OC = 0.93 V and fill factor = 64%).

  2. Exploration of Al-Doped ZnO in Photovoltaic Thin Films

    Science.gov (United States)

    Ciccarino, Christopher; Sahiner, M. Alper

    The electrical properties of Al doped ZnO-based thin films represent a potential advancement in the push for increasing solar cell efficiency. Doping with Aluminum will theoretically decrease resistivity of the film and therefore achieve this potential as a viable option in the P-N junction phase of photovoltaic cells. The n-type semi-conductive characteristics of the ZnO layer will theoretically be optimized with the addition of Aluminum carriers. In this study, Aluminum doping concentrations ranging from 1-3% by mass were produced, analyzed, and compared. Films were developed onto ITO coated glass using the Pulsed Laser Deposition technique. Target thickness was 250 nm and ellipsometry measurements showed uniformity and accuracy in this regard. Active dopant concentrations were determined using Hall Effect measurements. Efficiency measurements showed possible applications of this doped compound, with upwards of 7% efficiency measured, using a Keithley 2602 SourceMeter set-up. XRD scans showed highly crystalline structures, with effective Al intertwining of the hexagonal wurtzile ZnO molecular structure. This alone indicates a promising future of collaboration between these two materials.

  3. Ga-doped ZnO thin film surface characterization by wavelet and fractal analysis

    Energy Technology Data Exchange (ETDEWEB)

    Jing, Chenlei; Tang, Wu, E-mail: tang@uestc.edu.cn

    2016-02-28

    Graphical abstract: - Highlights: • Multi-resolution signal decomposition of wavelet transform is applied to Ga-doped ZnO thin films with various thicknesses. • Fractal properties of GZO thin films are investigated by box counting method. • Fractal dimension is not in conformity with original RMS roughness. • Fractal dimension mainly depends on the underside diameter (grain size) and distance between adjacent grains. - Abstract: The change in roughness of various thicknesses Ga-doped ZnO (GZO) thin films deposited by magnetron reactive sputtering on glass substrates at room temperature was measured by atomic force microscopy (AFM). Multi-resolution signal decomposition based on wavelet transform and fractal geometry was applied to process surface profiles, to evaluate the roughness trend of relevant frequency resolution. The results give a six-level decomposition and the results change with deposited time and surface morphology. Also, it is found that fractal dimension is closely connected to the underside diameter (grain size) and the distance between adjacent grains that affect the change rate of surface and the increase of the defects such as abrupt changes lead to a larger value of fractal dimension.

  4. Magnetoresistance of magnetically doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Behan, A J; Mokhtari, A; Blythe, H J; Fox, A M; Gehring, G A [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom); Ziese, M, E-mail: G.A.Gehring@sheffield.ac.u [Division of Superconductivity and Magnetism, University of Leipzig, D-04103, Leipzig (Germany)

    2009-08-26

    Magnetoresistance measurements have been made at 5 K on doped ZnO thin films grown by pulsed laser deposition. ZnCoO, ZnCoAlO and ZnMnAlO samples have been investigated and compared to similar films containing no transition metal dopants. It is found that the Co-doped samples with a high carrier concentration have a small negative magnetoresistance, irrespective of their magnetic moment. On decreasing the carrier concentration, a positive contribution to the magnetoresistance appears and a further negative contribution. This second, negative contribution, which occurs at very low carrier densities, correlates with the onset of ferromagnetism due to bound magnetic polarons suggesting that the negative magnetoresistance results from the destruction of polarons by a magnetic field. An investigation of the anisotropic magnetoresistance showed that the orientation of the applied magnetic field, relative to the sample, had a large effect. The results for the ZnMnAlO samples showed less consistent trends.

  5. The electrical properties of low pressure chemical vapor deposition Ga doped ZnO thin films depending on chemical bonding configuration

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Hanearl [School of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Kim, Doyoung [School of Electrical and Electronic Engineering, Ulsan College, 57 Daehak-ro, Nam-gu, Ulsan 680-749 (Korea, Republic of); Kim, Hyungjun, E-mail: hyungjun@yonsei.ac.kr [School of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of)

    2014-04-01

    Highlights: • Undoped and Ga doped ZnO thin films were deposited using DEZ and TMGa. • Effects of Ga doping using TMGa in Ga doped ZnO were investigated. • Degraded properties from excessive doping were analyzed using chemical bondings. - Abstract: The electrical and chemical properties of low pressure chemical vapor deposition (LP-CVD) Ga doped ZnO (ZnO:Ga) films were systematically investigated using Hall measurement and X-ray photoemission spectroscopy (XPS). Diethylzinc (DEZ) and O{sub 2} gas were used as precursor and reactant gas, respectively, and trimethyl gallium (TMGa) was used as a Ga doping source. Initially, the electrical properties of undoped LP-CVD ZnO films depending on the partial pressure of DEZ and O{sub 2} ratio were investigated using X-ray diffraction (XRD) by changing partial pressure of DEZ from 40 to 140 mTorr and that of O{sub 2} from 40 to 80 mTorr. The resistivity was reduced by Ga doping from 7.24 × 10{sup −3} Ω cm for undoped ZnO to 2.05 × 10{sup −3} Ω cm for Ga doped ZnO at the TMG pressure of 8 mTorr. The change of electric properties of Ga doped ZnO with varying the amount of Ga dopants was systematically discussed based on the structural crystallinity and chemical bonding configuration, analyzed by XRD and XPS, respectively.

  6. Use of chemically synthesized ZnO thin film as a liquefied petroleum gas sensor

    International Nuclear Information System (INIS)

    Shinde, V.R.; Gujar, T.P.; Lokhande, C.D.; Mane, R.S.; Han, Sung-Hwan

    2007-01-01

    Liquefied petroleum gas (LPG) sensing properties of ZnO thin films consisting of sub-micron rods synthesized by chemical bath deposition (CBD) method are presented in depth. The scanning electron microscopy observation reveals that ZnO sub-micron rods are of hexagonal in phase grown perpendicular to the substrate surface. Due to large surface area, the ZnO thin films of sub-micron rods were sensitive to the explosive LPG, which was studied for different time depositions and for different operating temperatures. The maximum response of 28% at 673 K was recorded under the exposure of 10% of lower explosive level (LEL) of LPG. The ZnO thin films of sub-micron rods exhibited good sensitivity and rapid response-recovery characteristics towards LPG

  7. Performance improvement for solution-processed high-mobility ZnO thin-film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Li Chensha; Loutfy, Rafik O [Department of Chemical Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4L7 (Canada); Li Yuning; Wu Yiliang; Ong, Beng S [Materials Design and Integration Laboratory, Xerox Research Centre of Canada, 2660 Speakman Drive, Mississauga, Ontario L5K 2L1 (Canada)], E-mail: lichnsa@163.com

    2008-06-21

    The fabrication technology of stable, non-toxic, transparent, high performance zinc oxide (ZnO) thin-film semiconductors via the solution process was investigated. Two methods, which were, respectively, annealing a spin-coated precursor solution and annealing a drop-coated precursor solution, were compared. The prepared ZnO thin-film semiconductor transistors have well-controlled, preferential crystal orientation and exhibit superior field-effect performance characteristics. But the ZnO thin-film transistor (TFT) fabricated by annealing a drop-coated precursor solution has a distinctly elevated linear mobility, which further approaches the saturated mobility, compared with that fabricated by annealing a spin-coated precursor solution. The performance of the solution-processed ZnO TFT was further improved when substituting the spin-coating process by the drop-coating process.

  8. Performance improvement for solution-processed high-mobility ZnO thin-film transistors

    International Nuclear Information System (INIS)

    Li Chensha; Loutfy, Rafik O; Li Yuning; Wu Yiliang; Ong, Beng S

    2008-01-01

    The fabrication technology of stable, non-toxic, transparent, high performance zinc oxide (ZnO) thin-film semiconductors via the solution process was investigated. Two methods, which were, respectively, annealing a spin-coated precursor solution and annealing a drop-coated precursor solution, were compared. The prepared ZnO thin-film semiconductor transistors have well-controlled, preferential crystal orientation and exhibit superior field-effect performance characteristics. But the ZnO thin-film transistor (TFT) fabricated by annealing a drop-coated precursor solution has a distinctly elevated linear mobility, which further approaches the saturated mobility, compared with that fabricated by annealing a spin-coated precursor solution. The performance of the solution-processed ZnO TFT was further improved when substituting the spin-coating process by the drop-coating process

  9. Ultraviolet Sensing by Al-doped ZnO Thin Films

    International Nuclear Information System (INIS)

    Rashid, A.R.A.; Menon, P.S.; Shaari, S.

    2011-01-01

    We report the fabrication and characterization of an ultraviolet photoconductive sensing by using Al-doped ZnO films. Undoped ZnO, 1 at.% and 2 at% of Al were prepared on quartz glass by sol gel method with annealing temperature of 500 degree Celsius for 1 hour. The presence of spherical shaped nanoparticles were detected for undoped ZnO by using FESEM. The absorption edge shifted to a lower wavelength by doping with Al and excitonic peak can be observed. The band gap values increased by adding Al. I-V curves reveal an improvement in electrical properties when the samples are illuminated by ultraviolet (UV) light with a wavelength of 365 nm. At 1 at.% of Al, the film have a larger increment in photocurrent response when illuminated with UV light compared to undoped ZnO and 2 at.% Al. The thin films have a longer recovery time than response time. (author)

  10. Atomic layer deposition of Al-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Tynell, Tommi; Yamauchi, Hisao; Karppinen, Maarit; Okazaki, Ryuji; Terasaki, Ichiro [Department of Chemistry, Aalto University, FI-00076 Aalto (Finland); Department of Physics, Nagoya University, Nagoya 464-8602 (Japan)

    2013-01-15

    Atomic layer deposition has been used to fabricate thin films of aluminum-doped ZnO by depositing interspersed layers of ZnO and Al{sub 2}O{sub 3} on borosilicate glass substrates. The growth characteristics of the films have been investigated through x-ray diffraction, x-ray reflection, and x-ray fluorescence measurements, and the efficacy of the Al doping has been evaluated through optical reflectivity and Seebeck coefficient measurements. The Al doping is found to affect the carrier density of ZnO up to a nominal Al dopant content of 5 at. %. At nominal Al doping levels of 10 at. % and higher, the structure of the films is found to be strongly affected by the Al{sub 2}O{sub 3} phase and no further carrier doping of ZnO is observed.

  11. Crystallinity Improvement of ZnO Thin Film on Different Buffer Layers Grown by MBE

    Directory of Open Access Journals (Sweden)

    Shao-Ying Ting

    2012-01-01

    Full Text Available The material and optical properties of ZnO thin film samples grown on different buffer layers on sapphire substrates through a two-step temperature variation growth by molecular beam epitaxy were investigated. The thin buffer layer between the ZnO layer and the sapphire substrate decreased the lattice mismatch to achieve higher quality ZnO thin film growth. A GaN buffer layer slightly increased the quality of the ZnO thin film, but the threading dislocations still stretched along the c-axis of the GaN layer. The use of MgO as the buffer layer decreased the surface roughness of the ZnO thin film by 58.8% due to the suppression of surface cracks through strain transfer of the sample. From deep level emission and rocking curve measurements it was found that the threading dislocations play a more important role than oxygen vacancies for high-quality ZnO thin film growth.

  12. Influence of PANI Additions on Methanol Sensing Properties of ZnO Thin Films

    International Nuclear Information System (INIS)

    Mohammad Hafizuddin Jumali; Norhashimah Ramli; Izura Izzuddin; Muhammad Yahaya; Muhamad Mat Salleh

    2011-01-01

    The influence of PANI additions on methanol sensing properties of ZnO thin films at room temperature had been investigated. Commercial poly aniline powder (PANI) was mixed into 3 mL ZnO solution in five different weight percentages namely 1.25, 2.50, 3.75, 5.00 and 6.25 % to obtain ZnO/ PANI composite solutions. These solutions were spin coated onto glass substrate to form thin films. Microstructural studies by FESEM indicated that ZnO/ PANI films showed porous structures with nano size grains. The thickness of the film increased from 55 to 256 nm, proportionate to increment of PANI. The presence of 2 adsorption peaks at ∼310 nm and ∼610 nm in UV-Vis spectrum proved that addition of PANI has modified the adsorption peak of ZnO film. Methanol vapour detection showed that addition of PANI into ZnO dramatically improved the sensing properties of the sensor. The sensors also exhibited good repeatability and reversibility. Sensor with the amount of PANI of 3.75 wt % exhibited the highest sensitivity with response and recovery time was about 10 and 80 s, respectively. The possible sensing mechanism of the sensor was also discussed in this article. (author)

  13. Highly doped ZnO films deposited by spray-pyrolysis. Design parameters for optoelectronic applications

    Energy Technology Data Exchange (ETDEWEB)

    Garcés, F.A., E-mail: felipe.garces@santafe-conicet.gov.ar [Instituto de Física del Litoral (UNL-CONICET), Güemes 3450, Santa Fe S3000GLN (Argentina); Budini, N. [Instituto de Física del Litoral (UNL-CONICET), Güemes 3450, Santa Fe S3000GLN (Argentina); Schmidt, J.A.; Arce, R.D. [Instituto de Física del Litoral (UNL-CONICET), Güemes 3450, Santa Fe S3000GLN (Argentina); Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santiago del Estero 2829, Santa Fe S3000AOM (Argentina)

    2016-04-30

    Synthesis and preparation of ZnO films are relevant subjects for obtaining transparent and conducting layers with interesting applications in optoelectronics and photovoltaics. Optimization of parameters such as dopant type and concentration, deposition time and substrate temperature is important for obtaining ZnO layers with optimal properties. In this work we present a study about the induced effects of deposition time on optical and electrical properties of ZnO thin films. These films were deposited by spray pyrolysis of a suitable Zn precursor, obtained through the sol–gel method. The deposition time has direct incidence on internal stress in the crystal structure, generating defects that may affect transparency and electrical transport into the layers. We performed mosaicity measurements, through X-ray diffraction, and used it as a tool to get an insight on structural characteristics and homogeneity of ZnO layers. Also, through this technique, we analyzed thickness and doping effects on crystallinity and carrier transport properties. - Highlights: • Al-doped ZnO films with high conductivity and moderate Hall mobility were obtained. • Mosaicity between crystalline domains increased with film thickness. • Lattice parameters a and c diminished linearly as a function of Al concentration. • First steps for developing porous silicon/doped ZnO heterojunctions were presented.

  14. Highly doped ZnO films deposited by spray-pyrolysis. Design parameters for optoelectronic applications

    International Nuclear Information System (INIS)

    Garcés, F.A.; Budini, N.; Schmidt, J.A.; Arce, R.D.

    2016-01-01

    Synthesis and preparation of ZnO films are relevant subjects for obtaining transparent and conducting layers with interesting applications in optoelectronics and photovoltaics. Optimization of parameters such as dopant type and concentration, deposition time and substrate temperature is important for obtaining ZnO layers with optimal properties. In this work we present a study about the induced effects of deposition time on optical and electrical properties of ZnO thin films. These films were deposited by spray pyrolysis of a suitable Zn precursor, obtained through the sol–gel method. The deposition time has direct incidence on internal stress in the crystal structure, generating defects that may affect transparency and electrical transport into the layers. We performed mosaicity measurements, through X-ray diffraction, and used it as a tool to get an insight on structural characteristics and homogeneity of ZnO layers. Also, through this technique, we analyzed thickness and doping effects on crystallinity and carrier transport properties. - Highlights: • Al-doped ZnO films with high conductivity and moderate Hall mobility were obtained. • Mosaicity between crystalline domains increased with film thickness. • Lattice parameters a and c diminished linearly as a function of Al concentration. • First steps for developing porous silicon/doped ZnO heterojunctions were presented.

  15. Post-annealing effect on the room-temperature ferromagnetism in Cu-doped ZnO thin films

    International Nuclear Information System (INIS)

    Hu, Yu-Min; Kuang, Chein-Hsiun; Han, Tai-Chun; Yu, Chin-Chung; Li, Sih-Sian

    2015-01-01

    In this work, we investigated the structural and magnetic properties of both as-deposited and post-annealed Cu-doped ZnO thin films for better understanding the possible mechanisms of room-temperature ferromagnetism (RT-FM) in ZnO-based diluted magnetic oxides. All of the films have a c-axis-oriented wurtzite structure and display RT-FM. X-ray photoelectron spectroscopy results showed that the incorporated Cu ions in as-deposited films are in 1+ valence state merely, while an additional 2+ valence state occurs in post-annealed films. The presence of Cu 2+ state in post-annealed film accompanies a higher magnetization value than that of as-deposited film and, in particular, the magnetization curves at 10 K and 300 K of the post-annealed film separate distinctly. Since Cu 1+ ion has a filled 3d band, the RT-FM in as-deposited Cu-doped ZnO thin films may stem solely from intrinsic defects, while that in post-annealed films is enhanced due to the presence of CuO crystallites

  16. A flexible UV nanosensor based on reduced graphene oxide decorated ZnO nanostructures

    Science.gov (United States)

    Wang, Zhenxing; Zhan, Xueying; Wang, Yajun; Muhammad, Safdar; Huang, Ying; He, Jun

    2012-03-01

    A low-cost, compatible with flexible electronics, high performance UV sensor has been achieved from a reduced graphene oxide (RGO) decorated hydrangea-like ZnO film on a PDMS substrate. The hydrangea-like ZnO UV sensor has the best UV sensing performance among devices made of three kinds of ZnO nanostructures synthesized by a hydrothermal method, and demonstrated a dramatic enhancement in on/off ratio and photoresponse current by introducing an appropriate weight ratio of RGO. The on/off ratio of the 0.05% RGO/ZnO sensor increases almost one order of magnitude compared to that of a pristine hydrangea-like ZnO UV sensor. While for the 5% RGO decorated ZnO sensor, the photoresponse current reaches as high as ~1 μA and exceeds 700 times that of a ZnO UV sensor. These results indicate that RGO is an appropriate material to enhance the performance of ZnO nanostructure UV sensors based on its unique features, especially the high optical transparency and excellent electronic conductivity. Our findings will make RGO/ZnO nanohybrids extraordinarily promising in optoelectronics, flexible electronics and sensor applications.

  17. Structure and morphology of magnetron sputter deposited ultrathin ZnO films on confined polymeric template

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Ajaib [Discipline of Metallurgy Engineering and Materials Science, Indian Institute of Technology Indore, Indore 453552 (India); Schipmann, Susanne [II. Insatitute of Physics and JARA-FIT, RWTH Aachen University, 52056 Aachen (Germany); Mathur, Aakash; Pal, Dipayan [Discipline of Metallurgy Engineering and Materials Science, Indian Institute of Technology Indore, Indore 453552 (India); Sengupta, Amartya [Department of Physics, Indian Institute of Technology Delhi, Delhi 110016 (India); Klemradt, Uwe [II. Insatitute of Physics and JARA-FIT, RWTH Aachen University, 52056 Aachen (Germany); Chattopadhyay, Sudeshna, E-mail: sudeshna@iiti.ac.in [Discipline of Metallurgy Engineering and Materials Science, Indian Institute of Technology Indore, Indore 453552 (India); Discipline of Physics, Indian Institute of Technology Indore, Indore 453552 (India); Centre for Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Indore 453552 (India)

    2017-08-31

    Highlights: • Ultra-thin ZnO films grown on confined polymeric (polystyrene, PS) template. • XRR and GISAXS explore the surface/interfaces structure and morphology of ZnO/PS. • Insights into the growth mechanism of magnetron sputtered ZnO thin film on PS template. • Nucleated disk-like cylindrical particles are the basis of the formation of ZnO layers. • Effect of ZnO film thickness on room temperature PL spectra in ZnO/PS systems. - Abstract: The structure and morphology of ultra-thin zinc oxide (ZnO) films with different film thicknesses on confined polymer template were studied through X-ray reflectivity (XRR) and grazing incidence small angle X-ray scattering (GISAXS). Using magnetron sputter deposition technique ZnO thin films with different film thicknesses (<10 nm) were grown on confined polystyrene with ∼2R{sub g} film thickness, where R{sub g} ∼ 20 nm (R{sub g} is the unperturbed radius of gyration of polystyrene, defined by R{sub g} = 0.272 √M{sub 0}, and M{sub 0} is the molecular weight of polystyrene). The detailed internal structure, along the surface/interfaces and the growth direction of the system were explored in this study, which provides insight into the growth procedure of ZnO on confined polymer and reveals that a thin layer of ZnO, with very low surface and interface roughness, can be grown by DC magnetron sputtering technique, with approximately full coverage (with bulk like electron density) even in nm order of thickness, in 2–7 nm range on confined polymer template, without disturbing the structure of the underneath template. The resulting ZnO-polystyrene hybrid systems show strong ZnO near band edge (NBE) and deep-level (DLE) emissions in their room temperature photoluminescence spectra, where the contribution of DLE gets relatively stronger with decreasing ZnO film thickness, indicating a significant enhancement of surface defects because of the greater surface to volume ratio in thinner films.

  18. Improvement of physical properties of ZnO thin films by tellurium doping

    Energy Technology Data Exchange (ETDEWEB)

    Sönmezoğlu, Savaş, E-mail: svssonmezoglu@kmu.edu.tr; Akman, Erdi

    2014-11-01

    Highlights: • We report the synthesis of tellurium-doped zinc oxide (Te–ZnO) thin films using sol–gel method. • Highly c-axis oriented Te-doped ZnO thin films were grown on FTO glasses as substrate. • 1.5% Te-doping ratio could improve the physical properties of ZnO thin films. - Abstract: This investigation addressed the structural, optical and morphological properties of tellurium incorporated zinc oxide (Te–ZnO) thin films. The obtained results indicated that Te-doped ZnO thin films exhibit an enhancement of band gap energy and crystallinity compared with non-doped films. The optical transmission spectra revealed a shift in the absorption edge toward lower wavelengths. X-ray diffraction measurement demonstrated that the film was crystallized in the hexagonal (wurtzite) phase and presented a preferential orientation along the c-axis. The XRD obtained patterns indicate that the crystallite size of the thin films, ranging from 23.9 to 49.1 nm, changed with the Te doping level. The scanning electron microscopy and atomic force microscopy results demonstrated that the grain size and surface roughness of the thin films increased as the Te concentration increased. Most significantly, we demonstrate that it is possible to control the structural, optical and morphological properties of ZnO thin films with the isoelectronic Te-incorporation level.

  19. Energy efficiency of a photovoltaic cell based thin films CZTS by ...

    African Journals Online (AJOL)

    Energy efficiency of a photovoltaic cell based thin films CZTS by SCAPS. ... use of natural resources, the use of renewable energy including solar photovoltaic ... η for typical structures of ZnO / i- ZnO / CdS / CZTS and ITO / ZnO / CdS / CZTS.

  20. Improved electrical conduction properties in unintentionally-doped ZnO thin films treated by rapid thermal annealing

    International Nuclear Information System (INIS)

    Lee, Youngmin; Lee, Choeun; Shim, Eunhee; Jung, Eiwhan; Lee, Jinyong; Kim, Deukyoung; Lee, Sejoon; Fu, Dejun; Yoon, Hyungdo

    2011-01-01

    The effects of thermal treatments on the electrical conduction properties for the unintentionally doped ZnO thin films were investigated. Despite the decreased carrier density in the annealed ZnO thin films, the conductivity was increased because the contribution of the effective carrier mobility to the conductivity of the unintentionally-doped ZnO thin films is greater than that of the carrier density. The resistivity exponentially decreased with increasing RTA temperature, and this result was confirmed to come from the enhanced effective carrier-mobility, which originated from the increased crystallite size in the annealed ZnO thin films.

  1. Improved electrical conduction properties in unintentionally-doped ZnO thin films treated by rapid thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Youngmin; Lee, Choeun; Shim, Eunhee; Jung, Eiwhan; Lee, Jinyong; Kim, Deukyoung; Lee, Sejoon [Dongguk University-Seoul, Seoul (Korea, Republic of); Fu, Dejun [Wuhan University, Wuhan (China); Yoon, Hyungdo [Korea Electronics Technology Institute, Seongnam (Korea, Republic of)

    2011-10-15

    The effects of thermal treatments on the electrical conduction properties for the unintentionally doped ZnO thin films were investigated. Despite the decreased carrier density in the annealed ZnO thin films, the conductivity was increased because the contribution of the effective carrier mobility to the conductivity of the unintentionally-doped ZnO thin films is greater than that of the carrier density. The resistivity exponentially decreased with increasing RTA temperature, and this result was confirmed to come from the enhanced effective carrier-mobility, which originated from the increased crystallite size in the annealed ZnO thin films.

  2. Activation of room temperature ferromagnetism in ZnO films by surface functionalization with thiol and amine

    International Nuclear Information System (INIS)

    Jayalakshmi, G.; Gopalakrishnan, N.; Balasubramanian, T.

    2013-01-01

    Highlights: ► Room temperature ferromagnetism (RTFM) is observed in surface functionalized ZnO films. ► Surface functionalization is a new approach to make ZnO as ferromagnetic. ► The RTFM is attributed to the interaction between the adsorbates and the surface of ZnO. ► The oxygen vacancies are passivated upon surface functionalization. - Abstract: In this paper, we report the activation of room temperature ferromagnetism in ZnO films by surface functionalization with thiol and amine. The pure and surface functionalized ZnO films have been examined by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) and vibrating sample magnetometer (VSM) measurements. XRD measurements show that all the films have single phase and (0 0 2) preferred orientation. The chemical bonding of ZnO with thiol and amine molecules has been confirmed by XPS measurements. The quenching of visible emission in PL spectra indicates that the surface defects are passivated by functionalization with thiol and amine. Surface functionalization of ZnO films with thiol and amine induces robust room temperature ferromagnetism in ZnO films as evidenced from VSM measurements. It is concluded that the observed ferromagnetic behavior in functionalized ZnO films is attributed to the different electronegativity of the atom in the thiol (or amine) and the surface of ZnO.

  3. Porous nanostructured ZnO films deposited by picosecond laser ablation

    International Nuclear Information System (INIS)

    Sima, Cornelia; Grigoriu, Constantin; Besleaga, Cristina; Mitran, Tudor; Ion, Lucian; Antohe, Stefan

    2012-01-01

    Highlights: ► We deposite porous nanostructured ZnO films by picoseconds laser ablation (PLA). ► We examine changes of the films structure on the experimental parameter deposition. ► We demonstrate PLA capability to produce ZnO nanostructured films free of particulates. - Abstract: Porous nanostructured polycrystalline ZnO films, free of large particulates, were deposited by picosecond laser ablation. Using a Zn target, zinc oxide films were deposited on indium tin oxide (ITO) substrates using a picosecond Nd:YVO 4 laser (8 ps, 50 kHz, 532 nm, 0.17 J/cm 2 ) in an oxygen atmosphere at room temperature (RT). The morpho-structural characteristics of ZnO films deposited at different oxygen pressures (150–900 mTorr) and gas flow rates (0.25 and 10 sccm) were studied. The post-deposition influence of annealing (250–550 °C) in oxygen on the film characteristics was also investigated. At RT, a mixture of Zn and ZnO formed. At substrate temperatures above 350 °C, the films were completely oxidized, containing a ZnO wurtzite phase with crystallite sizes of 12.2–40.1 nm. At pressures of up to 450 mTorr, the porous films consisted of well-distinguished primary nanoparticles with average sizes of 45–58 nm, while at higher pressures, larger clusters (3.1–14.7 μm) were dominant, leading to thicker films; higher flow rates favored clustering.

  4. Electric-field driven insulator-metal transition and tunable magnetoresistance in ZnO thin film

    Science.gov (United States)

    Zhang, Le; Chen, Shanshan; Chen, Xiangyang; Ye, Zhizhen; Zhu, Liping

    2018-04-01

    Electrical control of the multistate phase in semiconductors offers the promise of nonvolatile functionality in the future semiconductor spintronics. Here, by applying an external electric field, we have observed a gate-induced insulator-metal transition (MIT) with the temperature dependence of resistivity in ZnO thin films. Due to a high-density carrier accumulation, we have shown the ability to inverse change magnetoresistance in ZnO by ionic liquid gating from 10% to -2.5%. The evolution of photoluminescence under gate voltage was also consistent with the MIT, which is due to the reduction of dislocation. Our in-situ gate-controlled photoluminescence, insulator-metal transition, and the conversion of magnetoresistance open up opportunities in searching for quantum materials and ZnO based photoelectric devices.

  5. Interfacial passivation of CdS layer to CdSe quantum dots-sensitized electrodeposited ZnO nanowire thin films

    International Nuclear Information System (INIS)

    Zhang, Jingbo; Sun, Chuanzhen; Bai, Shouli; Luo, Ruixian; Chen, Aifan; Sun, Lina; Lin, Yuan

    2013-01-01

    ZnO porous thin films with nanowire structure were deposited by the one-step electrochemical deposition method. And a CdS layer was coated on the as-deposited ZnO nanowire thin films by successive ionic layer adsorption and reaction (SILAR) method to passivate surface states. Then the films were further sensitized by CdSe quantum dots (QDs) to serve as a photoanode for fabricating quantum dots-sensitized solar cells (QDSSCs). The effect of the CdS interfacial passivation layer on the performance of the QDSSCs was systematically investigated by varying the SILAR cycle number and heating the passivation layer. The amorphous CdS layer with an optimized thickness can effectively suppress the recombination of the injected electrons with holes on QDs and the redox electrolyte. The newly formed CdS layer on the surface of the ZnO nanowire thin film obviously prolongs the electron lifetime in the passivated ZnO nanoporous thin film because of the lower surface trap density in the ZnO nanowires after CdS deposition, which is favorable to the higher short-circuit photocurrent density (J sc ). For the CdSe QDs-sensitized ZnO nanoporous thin film with the interfacial passivation layer, the J sc and conversion efficiency can reach a maximum of 8.36 mA cm −2 and 2.36%, respectively. The conversion efficiency was improved by 83.47% compared with that of the cell based on the CdSe QDs-sensitized ZnO nanoporous thin film without CdS interfacial passivation (0.39%)

  6. Microstructure of ZnO thin films deposited by high power impulse magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Reed, A.N., E-mail: amber.reed.5@us.af.mil [Materials and Manufacturing Directorate, Air Force Research Laboratory, 3005 Hobson Way, Wright Patterson Air Force Base, OH 45433 (United States); Department of Chemical and Materials Engineering, University of Dayton, Dayton, OH 45469 (United States); Shamberger, P.J. [Department of Materials Science and Engineering, Texas A& M University, College Station, TX 77843 (United States); Hu, J.J. [Materials and Manufacturing Directorate, Air Force Research Laboratory, 3005 Hobson Way, Wright Patterson Air Force Base, OH 45433 (United States); University of Dayton Research Institute, University of Dayton, Dayton, OH 45469 (United States); Muratore, C. [Department of Chemical and Materials Engineering, University of Dayton, Dayton, OH 45469 (United States); Bultman, J.E. [Materials and Manufacturing Directorate, Air Force Research Laboratory, 3005 Hobson Way, Wright Patterson Air Force Base, OH 45433 (United States); University of Dayton Research Institute, University of Dayton, Dayton, OH 45469 (United States); Voevodin, A.A., E-mail: andrey.voevodin@us.af.mil [Materials and Manufacturing Directorate, Air Force Research Laboratory, 3005 Hobson Way, Wright Patterson Air Force Base, OH 45433 (United States)

    2015-03-31

    High power impulse magnetron sputtering was used to deposit thin (~ 100 nm) zinc oxide (ZnO) films from a ceramic ZnO target onto substrates heated to 150 °C. The resulting films had strong crystallinity, highly aligned (002) texture and low surface roughness (root mean square roughness less than 10 nm), as determined by X-ray diffraction, transmission electron microscopy, scanning electron microscopy and atomic force spectroscopy measurements. Deposition pressure and target–substrate distance had the greatest effect on film microstructure. The degree of alignment in the films was strongly dependent on the gas pressure. Deposition at pressures less than 0.93 Pa resulted in a bimodal distribution of grain sizes. An initial growth layer with preferred orientations (101) and (002) parallel to the interface was observed at the film–substrate interface under all conditions examined here; the extent of that competitive region was dependent on growth conditions. Time-resolved current measurements of the target and ion energy distributions, determined using energy resolved mass spectrometry, were correlated to film microstructure in order to investigate the effect of plasma conditions on film nucleation and growth. - Highlights: • Low temperature growth of nanocrystalline zinc oxide (ZnO) films. • ZnO films had a highly (002) textured, smooth, dense microstructure. • Dominant (002) orientation of films was pressure dependent. • Interfacial (101)/(002) mixed orientation layer controlled by substrate location.

  7. Preparation of Ga-doped ZnO films by pulsed dc magnetron sputtering with cylindrical rotating target for thin film solar cell applications

    International Nuclear Information System (INIS)

    Shin, Beom-Ki; Lee, Tae-Il; Park, Ji-Hyeon; Park, Kang-Il; Ahn, Kyung-Jun; Park, Sung-Kee; Lee, Woong; Myoung, Jae-Min

    2011-01-01

    Applicability of Ga-doped ZnO (GZO) films for thin film solar cells (TFSCs) was investigated by preparing GZO films via pulsed dc magnetron sputtering (PDMS) with rotating target. The GZO films showed improved crystallinity and increasing degree of Ga doping with increasing thickness to a limit of 1000 nm. The films also fulfilled requirements for the transparent electrodes of TFSCs in terms of electrical and optical properties. Moreover, the films exhibited good texturing potential based on etching studies with diluted HCl, which yielded an improved light trapping capability without significant degradation in electrical propreties. It is therefore suggested that the surface-textured GZO films prepared via PDMS and etching are promising candidates for indium-free transparent electrodes for TFSCs.

  8. Preparation of Ga-doped ZnO films by pulsed dc magnetron sputtering with cylindrical rotating target for thin film solar cell applications

    Science.gov (United States)

    Shin, Beom-Ki; Lee, Tae-Il; Park, Ji-Hyeon; Park, Kang-Il; Ahn, Kyung-Jun; Park, Sung-Kee; Lee, Woong; Myoung, Jae-Min

    2011-11-01

    Applicability of Ga-doped ZnO (GZO) films for thin film solar cells (TFSCs) was investigated by preparing GZO films via pulsed dc magnetron sputtering (PDMS) with rotating target. The GZO films showed improved crystallinity and increasing degree of Ga doping with increasing thickness to a limit of 1000 nm. The films also fulfilled requirements for the transparent electrodes of TFSCs in terms of electrical and optical properties. Moreover, the films exhibited good texturing potential based on etching studies with diluted HCl, which yielded an improved light trapping capability without significant degradation in electrical propreties. It is therefore suggested that the surface-textured GZO films prepared via PDMS and etching are promising candidates for indium-free transparent electrodes for TFSCs.

  9. Photoelectrochemical study of nanostructured ZnO thin films for hydrogen generation from water splitting

    Energy Technology Data Exchange (ETDEWEB)

    Wolcott, Abraham; Zhang, Jin Z. [Department of Chemistry and Biochemistry, University of California, Santa Cruz 1156 High St. Santa Cruz, CA 95064 (United States); Smith, Wilson A.; Zhao, Yiping [Department of Physics and Astronomy, University of Georgia, Athens, GA 30602 (United States); Kuykendall, Tevye R. [Department of Chemistry, University of California, Berkeley Berkeley, CA 94720 (United States)

    2009-06-23

    Photoelectrochemical cells based on traditional and nanostructured ZnO thin films are investigated for hydrogen generation from water splitting. The ZnO thin films are fabricated using three different deposition geometries: normal pulsed laser deposition, pulsed laser oblique-angle deposition, and electron-beam glancing-angle deposition. The nanostructured films are characterized by scanning electron microscopy, X-ray diffraction, UV-vis spectroscopy and photoelectrochemical techniques. Normal pulsed laser deposition produces dense thin films with ca. 200 nm grain sizes, while oblique-angle deposition produces nanoplatelets with a fishscale morphology and individual features measuring ca. 900 by 450 nm on average. In contrast, glancing-angle deposition generates a highly porous, interconnected network of spherical nanoparticles of 15-40 nm diameter. Mott-Schottky plots show the flat band potential of pulsed laser deposition, oblique-angle deposition, and glancing-angle deposition samples to be -0.29, -0.28 and +0.20 V, respectively. Generation of photocurrent is observed at anodic potentials and no limiting photocurrents were observed with applied potentials up to 1.3 V for all photoelectrochemical cells. The effective photon-to-hydrogen efficiency is found to be 0.1%, 0.2% and 0.6% for pulsed laser deposition, oblique-angle deposition and glancing-angle deposition samples, respectively. The photoelectrochemical properties of the three types of films are understood to be a function of porosity, crystal defect concentration, charge transport properties and space charge layer characteristics. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  10. ZnO thin films on single carbon fibres fabricated by Pulsed Laser Deposition (PLD)

    Energy Technology Data Exchange (ETDEWEB)

    Krämer, André; Engel, Sebastian [Otto Schott Institute of Materials Research (OSIM), Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena (Germany); Sangiorgi, Nicola [Institute of Science and Technology for Ceramics – National Research Council of Italy (CNR-ISTEC), via Granarolo 64, 48018 Faenza, RA (Italy); Department of Chemical Science and Technologies, University of Rome Tor Vergata, via della Ricerca Scientifica, 00133 Rome (Italy); Sanson, Alessandra [Institute of Science and Technology for Ceramics – National Research Council of Italy (CNR-ISTEC), via Granarolo 64, 48018 Faenza, RA (Italy); Bartolomé, Jose F. [Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), C/Sor Juana Inés de la Cruz 3, 28049 Madrid (Spain); Gräf, Stephan, E-mail: stephan.graef@uni-jena.de [Otto Schott Institute of Materials Research (OSIM), Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena (Germany); Müller, Frank A. [Otto Schott Institute of Materials Research (OSIM), Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena (Germany); Center for Energy and Environmental Chemistry Jena (CEEC Jena), Friedrich Schiller University Jena, Philosophenweg 7a, 07743 Jena (Germany)

    2017-03-31

    Highlights: • Carbon fibres were entirely coated with thin films consisting of aligned ZnO crystals. • A Q-switched CO2 laser was utilised as radiation source. • Suitability of ZnO thin films on carbon fibres as photo anodes for DSSC was studied. - Abstract: Single carbon fibres were 360° coated with zinc oxide (ZnO) thin films by pulsed laser deposition using a Q-switched CO{sub 2} laser with a pulse duration τ ≈ 300 ns, a wavelength λ = 10.59 μm, a repetition frequency f{sub rep} = 800 Hz and a peak power P{sub peak} = 15 kW in combination with a 3-step-deposition technique. In a first set of experiments, the deposition process was optimised by investigating the crystallinity of ZnO films on silicon and polished stainless steel substrates. Here, the influence of the substrate temperature and of the oxygen partial pressure of the background gas were characterised by scanning electron microscopy and X-ray diffraction analyses. ZnO coated carbon fibres and conductive glass sheets were used to prepare photo anodes for dye-sensitised solar cells in order to investigate their suitability for energy conversion devices. To obtain a deeper insight of the electronic behaviour at the interface between ZnO and substrate I–V measurements were performed.

  11. Structural and optical properties of pentacene films grown on differently oriented ZnO surfaces

    International Nuclear Information System (INIS)

    El Helou, M; Lietke, E; Helzel, J; Heimbrodt, W; Witte, G

    2012-01-01

    Pentacene films have been grown on two polar zinc oxide surfaces, i.e., ZnO(0001) and ZnO(0 0 0 1-bar ), as well as on the mixed-terminated ZnO(1 0 1-bar 0) and are characterized by means of atomic force microscopy (AFM), x-ray diffraction (XRD), and thermal desorption spectroscopy (TDS). In all cases, pentacene aggregates in an upright orientation without any evidence for the formation of an interface stabilized wetting layer. Additional films deposited on a highly-defective, oxygen-depleted ZnO(0 0 0 1-bar ) reveal no altered growth mode. Nearly identical optical absorption spectra have been measured for all films, thus corroborating a weak molecule-substrate interaction. Upon cooling, however, a slightly different relaxation behavior could be resolved for pentacene films on polar ZnO surfaces compared to pentacene on the mixed-terminated ZnO(1 0 1-bar 0) surface.

  12. A carbon nanotube-based transparent conductive substrate for flexible ZnO dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Du, Juan; Bittner, Florian [Institute of Physical Chemistry and Electrochemistry, Leibniz University Hannover, Callinstr. 3a, 30167 Hannover (Germany); Hecht, David S.; Ladous, Corinne [Unidym, 1244 Reamwood Avenue, Sunnyvale, CA (United States); Ellinger, Jan [Tesa SE, Quickbornstr. 24, 20253 Hamburg (Germany); Oekermann, Torsten, E-mail: torstensan@t-online.de [Institute of Physical Chemistry and Electrochemistry, Leibniz University Hannover, Callinstr. 3a, 30167 Hannover (Germany); Wark, Michael, E-mail: michael.wark@techem.ruhr-uni-bochum.de [Institute of Physical Chemistry and Electrochemistry, Leibniz University Hannover, Callinstr. 3a, 30167 Hannover (Germany); Laboratory of Industrial Chemistry, Ruhr University Bochum, Universitaetsstr. 150, 44801 Bochum (Germany)

    2013-03-01

    A transparent carbon nanotube (CNT)-coated polyethylenterephthalat film was used as conducting substrate for the photoanode of a flexible ZnO-based dye-sensitized solar cell (DSSC). The porous ZnO films were fabricated by an electrochemical deposition method at low temperature. Electrochemical impedance spectroscopy revealed that the CNT/ZnO interface adds to the overall impedance of the cell, leading to a higher series resistance compared to DSSCs based on substrates employing a transparent conducting oxide. Nevertheless, an overall conversion efficiency of 2.5% was obtained with porous ZnO films electrodeposited on the CNT substrate for 60 min. Thicker films led to an increased loss by recombination, which could not be compensated by faster electron transport due to the decrease of the light intensity inside the ZnO film with increasing distance from the back contact. - Highlights: ► ZnO was electrochemically deposited on carbon nanotube (CNT) coated polymer. ► Highly porous ZnO was obtained at temperatures not exceeding 70 °C. ► The porous ZnO was tested as photoanode in dye-sensitized solar cells. ► Conversion efficiency of 2.5% was found on the high resistance CNT substrates. ► Barriers formed at the CNT–ZnO interface are determined by impedance spectroscopy.

  13. A carbon nanotube-based transparent conductive substrate for flexible ZnO dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Du, Juan; Bittner, Florian; Hecht, David S.; Ladous, Corinne; Ellinger, Jan; Oekermann, Torsten; Wark, Michael

    2013-01-01

    A transparent carbon nanotube (CNT)-coated polyethylenterephthalat film was used as conducting substrate for the photoanode of a flexible ZnO-based dye-sensitized solar cell (DSSC). The porous ZnO films were fabricated by an electrochemical deposition method at low temperature. Electrochemical impedance spectroscopy revealed that the CNT/ZnO interface adds to the overall impedance of the cell, leading to a higher series resistance compared to DSSCs based on substrates employing a transparent conducting oxide. Nevertheless, an overall conversion efficiency of 2.5% was obtained with porous ZnO films electrodeposited on the CNT substrate for 60 min. Thicker films led to an increased loss by recombination, which could not be compensated by faster electron transport due to the decrease of the light intensity inside the ZnO film with increasing distance from the back contact. - Highlights: ► ZnO was electrochemically deposited on carbon nanotube (CNT) coated polymer. ► Highly porous ZnO was obtained at temperatures not exceeding 70 °C. ► The porous ZnO was tested as photoanode in dye-sensitized solar cells. ► Conversion efficiency of 2.5% was found on the high resistance CNT substrates. ► Barriers formed at the CNT–ZnO interface are determined by impedance spectroscopy

  14. Photocatalytic Performance of ZnO: Al Films under Different Light Sources

    Directory of Open Access Journals (Sweden)

    Prashant Pradhan

    2012-01-01

    Full Text Available ZnO and Al doped ZnO films were produced by spray pyrolysis. The films were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, UV-vis spectroscopy, and photoluminescence. Their photocatalytic activity was evaluated by the decomposition of the methyl orange dye using different light sources: ultraviolet light, artificial white light, and direct sunlight. The films were also tested under darkness for comparison. The ZnO films were able to degrade the test pollutant under UV and sunlight in more than a 60% after 180 min of irradiation and a scarce degradation was obtained using white light. However, the Al doped ZnO films presented a very high degradation rate not only under UV and sunlight (100% degradation, but also under white light (90% degradation after the same irradiation time. An unexpected high degradation was also obtained in the dark, which indicates that a nonphotonic process is taking place parallel to the photocatalytic process. This can be due to the extra electrons—provided by the aluminum atoms—that migrate to the surface and produce radicals favoring the decomposition process even in the dark. The high activity achieved by the ZnO: Al films under natural conditions can be potentially applied to water treatment processes.

  15. Annealing effect on optical properties of ZnO films fabricated by cathodic electrodeposition

    International Nuclear Information System (INIS)

    Wang Qingtao; Wang Guanzhong; Jie Jiansheng; Han Xinhai; Xu Bo; Hou, J.G.

    2005-01-01

    (001)-oriented ZnO films on Zn substrates were synthesized by cathodic electrodeposition from an aqueous solution composed only of 0.05 M zinc nitrate at 65 deg. C. A bound exciton emission band around 3.34 eV along with three longitudinal optical (LO) phonon replicas and an intensive broad emission band around 2.17 eV were observed from the photoluminescence (PL) spectra of ZnO films prepared at more positive potential (- 0.6∼- 0.8 V). When more negative potential (- 1.0∼- 1.4 V) was applied, the ultraviolet emission band disappeared. These results indicate that more positive electrodeposition potential favors the high quality ZnO film growth. The PL spectra of the annealed ZnO films prepared at more positive electrodeposition potentials - 0.6∼- 1.0 V exhibit the ultraviolet emission at 3.35 eV and a negligibly weak emission from defects. Annealing resulted in the enhancement and sharpening of the excitonic emission band and decrease of the deep level emission. The bandgap (E g ) of the ZnO film prepared at - 1.0 V on indium tin oxide (ITO) substrate decreased from 3.56 to 3.29 eV due to the removing of Zn(OH) 2 from the film after annealing

  16. Blue shift in the luminescence spectra of MEH-PPV films containing ZnO nanoparticles

    International Nuclear Information System (INIS)

    Ton-That, Cuong; Phillips, Matthew R.; Nguyen, Thien-Phap

    2008-01-01

    Luminescence properties of nanocomposites consisting of ZnO nanoparticles in a conjugated polymer, poly [2-methoxy-5-(2'-ethyl hexyloxy)-phenylene vinylene] (MEH-PPV), were investigated. Photoluminescence measurements reveal a blue shift in the emission spectrum of MEH-PPV upon incorporation of ZnO nanoparticles into the polymer film while the emission is increasingly quenched with increasing ZnO concentration. In contrast, the structure of the polymer and its conjugation length are not affected by the presence of ZnO nanoparticles (up to 16 wt% ZnO) as revealed by Raman spectroscopy. The blue shift and photoluminescence quenching are explained by the separation of photogenerated electron-hole pairs at the MEH-PPV/ZnO interface and the charging of the nanoparticles

  17. Improved ITO thin films for photovoltaic applications with a thin ZnO layer by sputtering

    International Nuclear Information System (INIS)

    Herrero, J.; Guillen, C.

    2004-01-01

    The improvement of the optical and electrical characteristics of indium tin oxide (ITO) layers is pursued to achieve a higher efficiency in its application as frontal electrical contacts in thin film photovoltaic devices. In order to take advantage of the polycrystalline structure of ZnO films as growth support, the properties of ITO layers prepared at room temperature by sputtering onto bare and ZnO-coated substrates have been analyzed using X-ray diffraction, optical and electrical measurements. It has been found that by inserting a thin ZnO layer, the ITO film resistivity can be reduced as compared to that of a single ITO film with similar optical transmittance. The electrical quality improvement is related to ITO grain growth enhancement onto the polycrystalline ZnO underlayer

  18. Synthesis and Characterization of Molybdenum Doped ZnO Thin Films by SILAR Deposition Method

    Science.gov (United States)

    Radha, R.; Sakthivelu, A.; Pradhabhan, D.

    2016-08-01

    Molybdenum (Mo) doped zinc oxide (ZnO) thin films were deposited on the glass substrate by Successive Ionic Layer Adsorption and Reaction (SILAR) deposition method. The effect of Mo dopant concentration of 5, 6.6 and 10 mol% on the structural, morphological, optical and electrical properties of n-type Mo doped ZnO films was studied. The X-ray diffraction (XRD) results confirmed that the Mo doped ZnO thin films were polycrystalline with wurtzite structure. The field emission scanning electron microscopy (FESEM) studies shows that the surface morphology of the films changes with Mo doping. A blue shift of the optical band gap was observed in the optical studies. Effect of Mo dopant concentration on electrical conductivity was studied and it shows comparatively high electrical conductivity at 10 mol% of Mo doping concentration.

  19. Temperature dependent optical properties of (002) oriented ZnO thin film using surface plasmon resonance

    Science.gov (United States)

    Saha, Shibu; Mehan, Navina; Sreenivas, K.; Gupta, Vinay

    2009-08-01

    Temperature dependent optical properties of c-axis oriented ZnO thin film were investigated using surface plasmon resonance (SPR) technique. SPR data for double layer (prism-Au-ZnO-air) and single layer (prism-Au-air) systems were taken over a temperature range (300-525 K). Dielectric constant at optical frequency and real part of refractive index of the ZnO film shows an increase with temperature. The bandgap of the oriented ZnO film was found to decrease with rise in temperature. The work indicates a promising application of the system as a temperature sensor and highlights an efficient scientific tool to study optical properties of thin film under varying ambient conditions.

  20. Scintillation characteristic of In, Ga-doped ZnO thin films with different dopant concentrations

    International Nuclear Information System (INIS)

    Fujimoto, Yutaka; Yanagida, Takayuki; Yokota, Yuui; Chani, Valery; Yoshikawa, Akira; Sekiwa, Hideyuki

    2011-01-01

    The present study describes the first detailed evaluation of the rise and the decay time of scintillation phenomenon in In 3+ - and Ga 3+ -doped ZnO thin films with different dopant concentrations. In 3+ -(25, 55, and 141 ppm) and Ga 3+ -(33, 67, 333, and 1374 ppm) doped ZnO films were grown by the Liquid Phase Epitaxy (LPE) method. The characterization was performed using the pulse X-ray equipped streak camera system. Both the rise and the decay times were shortened considerably with increasing content of In 3+ and Ga 3+ in the films. However, the scintillation light yield under 241 Am α-ray excitation reduced when concentration of In 3+ and Ga 3+ in the ZnO films was high. (author)

  1. Zinc Vacancy-Induced Room-Temperature Ferromagnetism in Undoped ZnO Thin Films

    Directory of Open Access Journals (Sweden)

    Hongtao Ren

    2012-01-01

    Full Text Available Undoped ZnO thin films are prepared by polymer-assisted deposition (PAD and treated by postannealing at different temperatures in oxygen or forming gases (95%  Ar+5% H2. All the samples exhibit ferromagnetism at room temperature (RT. SQUID and positron annihilation measurements show that post-annealing treatments greatly enhance the magnetizations in undoped ZnO samples, and there is a positive correlation between the magnetization and zinc vacancies in the ZnO thin films. XPS measurements indicate that annealing also induces oxygen vacancies that have no direct relationship with ferromagnetism. Further analysis of the results suggests that the ferromagnetism in undoped ZnO is induced by Zn vacancies.

  2. Properties of Nb-doped ZnO transparent conductive thin films ...

    Indian Academy of Sciences (India)

    Administrator

    by rf magnetron sputtering using a high quality ceramic target ... Guangxi Key Laboratory of Information Materials, Guilin University of Electronic ... films are highly textured along the c axis and perpendicular to the surface of the substrate. ... ZnO films; Nb-doped; magnetron sputtering; optical and electrical properties. 1.

  3. Structural and optical properties of ZnO films grown on silicon and ...

    Indian Academy of Sciences (India)

    TECS

    Abstract. Photoluminescence (PL) properties of undoped ZnO thin films grown by rf magnetron sputtering on silicon .... voluted O1 s and (c) typical Zr 3d spectra of ZrO2/ZnO/Si film. .... strate doping concentration (NB) of ≈ 2⋅5 × 1015 cm–3 is.

  4. Characteristics of hydrogen co-doped ZnO : Al thin films

    International Nuclear Information System (INIS)

    Lee, S H; Lee, T S; Lee, K S; Cheong, B; Kim, W M; Kim, Y D

    2008-01-01

    ZnO films co-doped with H and Al (HAZO) were prepared by sputtering ZnO targets containing 1 wt% Al 2 O 3 on Corning glass at a substrate temperature of 150 deg. C with Ar and H 2 /Ar gas mixtures. The effects of hydrogen addition to Al-doped ZnO (AZO) films with low Al content on the electrical, the optical and the structural properties of the as-grown films as well as the vacuum- and air-annealed films were examined. Secondary ion mass spectroscopy analysis showed that the hydrogen concentration increased with increasing H 2 in sputter gas. For the as-deposited films, the free carrier number increased with increasing H 2 . The Hall mobility increased at low hydrogen content, reaching a maximum before decreasing with a further increase of H 2 content in sputter gas. Annealing at 300 deg. C resulted in the removal of hydrogen, causing a decrease in the carrier concentration. It was shown that hydrogen might exist as single isolated interstitial hydrogen bound with oxygen, thereby acting like an anionic dopant. Also, it was shown that the addition of hydrogen to ZnO films doped with low metallic dopant concentration could yield transparent conducting films with very low absorption loss as well as with proper electrical properties, which is suitable for thin film solar cell applications

  5. Pulsed laser deposition of aluminum-doped ZnO films at 355 nm

    DEFF Research Database (Denmark)

    Holmelund, E.; Schou, Jørgen; Thestrup Nielsen, Birgitte

    2004-01-01

    Conducting, transparent films of aluminium-doped ZnO (AZO) have been produced at the laser wavelength 355 nm. The most critical property, the electric resistivity, is up to a factor of 8 above that for films produced at shorter wavelengths. In contrast, the transmission of visible light through...

  6. Controllable growth and characterization of highly aligned ZnO nanocolumnar thin films

    Energy Technology Data Exchange (ETDEWEB)

    Onuk, Zuhal [Department of Physics, Recep Tayyip Erdogan University, Rize, 53100 (Turkey); Department of Materials Science and Engineering, University of Delaware, Newark, DE, 19716 (United States); Rujisamphan, Nopporn [Nanoscience and Nanotechnology Graduate Program, Faculty of Science, King Mongkut’s University of Technology Thonburi, 10140, Bangkok (Thailand); Theoretical and Computational Science Center (TaCS), Faculty of Science, King Mongkut’s University of Technology Thonburi, Bangkok 10140 (Thailand); Murray, Roy [Department of Physics and Astronomy, University of Delaware, Newark, DE, 19716 (United States); Bah, Mohamed [Department of Materials Science and Engineering, University of Delaware, Newark, DE, 19716 (United States); Tomakin, Murat [Department of Physics, Recep Tayyip Erdogan University, Rize, 53100 (Turkey); Shah, S.Ismat, E-mail: ismat@udel.edu [Department of Materials Science and Engineering, University of Delaware, Newark, DE, 19716 (United States); Department of Physics and Astronomy, University of Delaware, Newark, DE, 19716 (United States)

    2017-02-28

    Graphical abstract: Scanning electron micrographs of the top view surfaces (left column) and cross sections of sputtered ZnO thin films prepared at various Ar:O{sub 2} ratios: (a) and (b) 10:0, (c) and (d) 7.5:2.5, (e) and (f) 5:5, (g) and (h) 2.5:7.5. - Highlights: • Nanocolumnar ZnO films were prepared by controlling the argon-oxygen sputtering gas ratio. • Oxygen partial pressure affects the band gap alignment of the ZnO films. • Optical transmission spectroscopy and XPS were used to study band gap shifts. - Abstract: We investigated the effects of growth conditions during magnetron sputtering on the structural, morphological, and optical properties of nanostructured ZnO thin films. Undoped ZnO thin films are deposited onto p-type Si (100) and corning 7059 glass substrates by RF magnetron sputtering using a ZnO target in combination with various Ar-O{sub 2} sputtering gas mixtures at room temperature. The effect of the partial pressure of oxygen on the morphology of ZnO thin film structure and band alignment were investigated. Thickness, and therefore the growth rate of the samples measured from the cross-sectional SEM micrographs, is found to be strongly correlated with the oxygen partial pressure in the sputtering chamber. The optical transmittance spectrometry results show that the absorption edge shifts towards the longer wavelength at higher oxygen partial pressure. X-ray photoelectron spectroscopy (XPS) used for determining the surface chemical structure and valence band offsets show that conduction band can be controlled by changing the sputtering atmosphere.

  7. Defect studies of ZnO films prepared by pulsed laser deposition on various substrates

    International Nuclear Information System (INIS)

    Melikhova, O; Čížek, J; Procházka, I; Kužel, R; Novotný, M; Bulír, J; Lancok, J; Anwand, W; Brauer, G; Connolly, J; McCarthy, E; Krishnamurthy, S; Mosnier, J-P

    2013-01-01

    ZnO thin films deposited on various substrates were characterized by slow positron implantation spectroscopy (SPIS) combined with X-ray diffraction (XRD). All films studied exhibit wurtzite structure and crystallite size 20–100 nm. The mosaic spread of crystallites is relatively small for the films grown on single crystalline substrates while it is substantial for the film grown on amorphous substrate. SPIS investigations revealed that ZnO films deposited on single crystalline substrates exhibit significantly higher density of defects than the film deposited on amorphous substrate. This is most probably due to a higher density of misfit dislocations, which compensate for the lattice mismatch between the film and the substrate.

  8. Synthesis and characterization of DC magnetron sputtered ZnO thin films under high working pressures

    International Nuclear Information System (INIS)

    Hezam, M.; Tabet, N.; Mekki, A.

    2010-01-01

    ZnO thin films were deposited on glass substrates using direct current (dc) magnetron sputtering under high working pressures. A pure zinc target was used, and sputtering was carried out in an oxygen atmosphere. The working pressure was varied between 50 and 800 mTorr. XRD characterization showed that for a window of working pressures between 300 and 500 mTorr, the deposited films were polycrystalline, with strong preferential orientation of grains along the c-axis. The film deposited at 400 mTorr had the highest (002) peak with the largest estimated grain size. Outside this window, the crystallinity and c-orientation of grains are lost. The microstructure of the films was investigated by Atomic Force microscopy (AFM). Optical transparency of the films was about 85%. The films produced were highly resistive, which might provide new alternatives for the synthesis of ZnO thin films aimed for SAW devices.

  9. 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.

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

    International Nuclear Information System (INIS)

    Ahumada-Lazo, R.; Torres-Martínez, L.M.; Ruíz-Gómez, M.A.; Vega-Becerra, O.E.

    2014-01-01

    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

  11. Controlling growth rate anisotropy for formation of continuous ZnO thin films from seeded substrates

    International Nuclear Information System (INIS)

    Zhang, R H; Slamovich, E B; Handwerker, C A

    2013-01-01

    Solution-processed zinc oxide (ZnO) thin films are promising candidates for low-temperature-processable active layers in transparent thin film electronics. In this study, control of growth rate anisotropy using ZnO nanoparticle seeds, capping ions, and pH adjustment leads to a low-temperature (90 ° C) hydrothermal process for transparent and high-density ZnO thin films. The common 1D ZnO nanorod array was grown into a 2D continuous polycrystalline film using a short-time pure solution method. Growth rate anisotropy of ZnO crystals and the film morphology were tuned by varying the chloride (Cl − ) ion concentration and the initial pH of solutions of zinc nitrate and hexamethylenetetramine (HMTA), and the competitive adsorption effects of Cl − ions and HMTA ligands on the anisotropic growth behavior of ZnO crystals were proposed. The lateral growth of nanorods constituting the film was promoted by lowering the solution pH to accelerate the hydrolysis of HMTA, thereby allowing the adsorption effects from Cl − to dominate. By optimizing the growth conditions, a dense ∼100 nm thickness film was fabricated in 15 min from a solution of [Cl − ]/[Zn 2+ ] = 1.5 and pH= 4.8 ± 0.1. This film shows >80% optical transmittance and a field-effect mobility of 2.730 cm 2 V −1 s −1 at zero back-gate bias. (paper)

  12. ZnO nanostructures as electron extraction layers for hybrid perovskite thin films

    Science.gov (United States)

    Nikolaidou, Katerina; Sarang, Som; Tung, Vincent; Lu, Jennifer; Ghosh, Sayantani

    Optimum interaction between light harvesting media and electron transport layers is critical for the efficient operation of photovoltaic devices. In this work, ZnO layers of different morphologies are implemented as electron extraction and transport layers for hybrid perovskite CH3NH3PbI3 thin films. These include nanowires, nanoparticles, and single crystalline film. Charge transfer at the ZnO/perovskite interface is investigated and compared through ultra-fast characterization techniques, including temperature and power dependent spectroscopy, and time-resolved photoluminescence. The nanowires cause an enhancement in perovskite emission, which may be attributed to increased scattering and grain boundary formation. However, the ZnO layers with decreasing surface roughness exhibit better electron extraction, as inferred from photoluminescence quenching, reduction in the number of bound excitons, and reduced exciton lifetime in CH3NH3PbI3 samples. This systematic study is expected to provide an understanding of the fundamental processes occurring at the ZnO-CH3NH3PbI3 interface and ultimately, provide guidelines for the ideal configuration of ZnO-based hybrid Perovskite devices. This research was supported by National Aeronautics and Space administration (NASA) Grant No: NNX15AQ01A.

  13. Probing magnetism and electronic structure of Fe-doped ZnO thin films

    International Nuclear Information System (INIS)

    El Amiri, A.; Moubah, R.; Lmai, F.; Abid, M.; Hassanain, N.; Hlil, E.K.; Lassri, H.

    2016-01-01

    Ab-initio calculations using Korringa–Kohn–Rostoker method combined with the coherent potential approximation were performed in order to study the magnetic properties of Fe-doped ZnO thin films with different Fe contents. The extracted parameters are compared with those determined experimentally. Based on total and partial densities of state curves, we demonstrate that there is a competition between p–d exchange and superexchange mechanisms leading to weak ferromagnetic and antiferromagnetic contributions, respectively. The dominant mechanism is found to be antiferromagnetic. However, with increasing Fe content the ferromagnetic contribution increases. In addition, the effect of structural defects on the magnetism of the system is reported. It is shown that both Zn and O vacancies increase ferromagnetism, which is more pronounced in case of Zn. - Highlights: • The KKR–CPA approach was used to study the magnetism of Fe-doped ZnO thin films. • There is a competition between p–d exchange and superexchange mechanisms leading to weak ferromagnetic and antiferromagnetic contributions. • Zn vacancies are more significant than the O ones for obtaining ferromagnetism.

  14. Probing magnetism and electronic structure of Fe-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    El Amiri, A., E-mail: aelamiri@casablanca.ma [LPFA, Faculté des Sciences Ain Chock, Université Hassan II, BP 5366 Mâarif, Casablanca (Morocco); Moubah, R., E-mail: reda.moubah@hotmail.fr [LPMMAT, Faculté des Sciences Ain Chock, Université Hassan II, BP 5366 Mâarif, Casablanca (Morocco); Lmai, F. [LPTA, Faculté des Sciences Ain Chock, Université Hassan II, BP 5366 Mâarif, Casablanca (Morocco); Abid, M. [LPFA, Faculté des Sciences Ain Chock, Université Hassan II, BP 5366 Mâarif, Casablanca (Morocco); Hassanain, N. [Laboratoire de Physique des Matériaux, Faculté des Sciences, BP 1014 Rabat (Morocco); Hlil, E.K. [Institut Néel, CNRS et Université Joseph Fourier, BP 166, 38042 Grenoble (France); Lassri, H. [LPMMAT, Faculté des Sciences Ain Chock, Université Hassan II, BP 5366 Mâarif, Casablanca (Morocco)

    2016-01-15

    Ab-initio calculations using Korringa–Kohn–Rostoker method combined with the coherent potential approximation were performed in order to study the magnetic properties of Fe-doped ZnO thin films with different Fe contents. The extracted parameters are compared with those determined experimentally. Based on total and partial densities of state curves, we demonstrate that there is a competition between p–d exchange and superexchange mechanisms leading to weak ferromagnetic and antiferromagnetic contributions, respectively. The dominant mechanism is found to be antiferromagnetic. However, with increasing Fe content the ferromagnetic contribution increases. In addition, the effect of structural defects on the magnetism of the system is reported. It is shown that both Zn and O vacancies increase ferromagnetism, which is more pronounced in case of Zn. - Highlights: • The KKR–CPA approach was used to study the magnetism of Fe-doped ZnO thin films. • There is a competition between p–d exchange and superexchange mechanisms leading to weak ferromagnetic and antiferromagnetic contributions. • Zn vacancies are more significant than the O ones for obtaining ferromagnetism.

  15. Electrochemical and hydrothermal deposition of ZnO on silicon: from continuous films to nanocrystals

    International Nuclear Information System (INIS)

    Balucani, M.; Nenzi, P.; Chubenko, E.; Klyshko, A.; Bondarenko, V.

    2011-01-01

    This article presents the study of the electrochemical deposition of zinc oxide from the non-aqueous solution based on dimethyl sulfoxide and zinc chloride into the porous silicon matrix. The features of the deposition process depending on the thickness of the porous silicon layer are presented. It is shown that after deposition process the porous silicon matrix is filled with zinc oxide nanocrystals with a diameter of 10–50 nm. The electrochemically deposited zinc oxide layers on top of porous silicon are shown to have a crystalline structure. It is also shown that zinc oxide crystals formed by hydrothermal method on the surface of electrochemically deposited zinc oxide film demonstrate ultra-violet luminescence. The effect of the porous silicon layer thickness on the morphology of the zinc oxide is shown. The structures obtained demonstrated two luminescence bands peaking at the 375 and 600 nm wavelengths. Possible applications of ZnO nanostructures, porous and continuous polycrystalline ZnO films such as gas sensors, light-emitting diodes, photovoltaic devices, and nanopiezo energy generators are considered. Aspects of integration with conventional silicon technology are also discussed.

  16. Pulsed laser deposited Al-doped ZnO thin films for optical applications

    Directory of Open Access Journals (Sweden)

    Gurpreet Kaur

    2015-02-01

    Full Text Available Highly transparent and conducting Al-doped ZnO (Al:ZnO thin films were grown on glass substrates using pulsed laser deposition technique. The profound effect of film thickness on the structural, optical and electrical properties of Al:ZnO thin films was observed. The X-ray diffraction depicts c-axis, plane (002 oriented thin films with hexagonal wurtzite crystal structure. Al-doping in ZnO introduces a compressive stress in the films which increase with the film thickness. AFM images reveal the columnar grain formation with low surface roughness. The versatile optical properties of Al:ZnO thin films are important for applications such as transparent electromagnetic interference (EMI shielding materials and solar cells. The obtained optical band gap (3.2–3.08 eV was found to be less than pure ZnO (3.37 eV films. The lowering in the band gap in Al:ZnO thin films could be attributed to band edge bending phenomena. The photoluminescence spectra gives sharp visible emission peaks, enables Al:ZnO thin films for light emitting devices (LEDs applications. The current–voltage (I–V measurements show the ohmic behavior of the films with resistivity (ρ~10−3 Ω cm.

  17. Preparation and characterization of ZnO transparent semiconductor thin films by sol-gel method

    International Nuclear Information System (INIS)

    Tsay, Chien-Yie; Fan, Kai-Shiung; Chen, Sih-Han; Tsai, Chia-Hao

    2010-01-01

    Transparent semiconductor thin films of zinc oxide (ZnO) were deposited onto alkali-free glass substrates by the sol-gel method and spin-coating technique. In this study, authors investigate the influence of the heating rate of the preheating process (4 or 10 o C/min) on the crystallization, surface morphology, and optical properties of sol-gel derived ZnO thin films. The ZnO sol was synthesized by dissolving zinc acetate dehydrate in ethanol, and then adding monoethanolamine. The as-coated films were preheated at 300 o C for 10 min and annealed at 500 o C for 1 h in air ambiance. Experimental results indicate that the heating rate of the preheating process strongly affected the surface morphology and transparency of ZnO thin film. Specifically, a heating rate of 10 o C/min for the preheating process produces a preferred orientation along the (0 0 2) plane and a high transmittance of 92% at a wavelength of 550 nm. Furthermore, this study reports the fabrication of thin-film transistors (TFTs) with a transparent ZnO active channel layer and evaluates their electrical performance.

  18. Effects of seed layers on controlling of the morphology of ZnO nanostructures and superhydrophobicity of ZnO nanostructure/stearic acid composite films

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jing; Liu, Zhihua, E-mail: sdwfliu@163.com; Liu, Junqi; E, Lei; Liu, Zhifeng, E-mail: tjulzf@163.com

    2016-11-01

    Hydrophobic ZnO self-cleaning thin films with the nanobundles and nanocarpets structures fabricated on indium tin oxides (ITO) glass substrate are reported. The water contact angle of ZnO nanobundles and nanocarpets structures (79° and 67° respectively) is higher than that of unmodified ZnO nanorods. A subsequent chemical treatment with stearic acid (SA) contributed to a superhydrophobic surface with a water contact angle of 159°. Its superhydrophobic property is originated from the nanobundles or nanocarpets structures and surface energy of SA/ZnO nanobundles and SA/ZnO nanocarpets composite nanostructures. Moreover, this promising ZnO nanostructured materials show an important application in self-cleaning smart coatings. - Highlights: • PEG and CTAB are firstly introduced to modify the morphology of ZnO seed layers. • ZnO nanobundles and nanocarpets obtained from different seed layers. • Superhydrophobic surfaces obtained by chemcial treatment using SA.

  19. Boron doped nanostructure ZnO films deposited by ultrasonic spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Karakaya, Seniye, E-mail: seniyek@ogu.edu.tr; Ozbas, Omer

    2015-02-15

    Highlights: • Nanostructure undoped and boron doped ZnO films were deposited by USP technique. • Influences of doping on the surface and optical properties of the ZnO films were investigated. • XRD spectra of the films exhibited a variation in crystalline quality depending on the B content. - Abstract: ZnO is an II–VI compound semiconductor with a wide direct band gap of 3.3 eV at room temperature. Doped with group III elements (B, Al or Ga), it becomes an attractive candidate to replace tin oxide (SnO{sub 2}) or indium tin oxide (ITO) as transparent conducting electrodes in solar cell devices and flat panel display due to competitive electrical and optical properties. In this work, ZnO and boron doped ZnO (ZnO:B) films have been deposited onto glass substrates at 350 ± 5 °C by a cost-efficient ultrasonic spray pyrolysis technique. The optical, structural, morphological and electrical properties of nanostructure undoped and ZnO:B films have been investigated. Electrical resistivity of films has been analyzed by four-probe technique. Optical properties and thicknesses of the films have been examined in the wavelength range 1200–1600 nm by using spectroscopic ellipsometry (SE) measurements. The optical constants (refractive index (n) and extinction coefficient (k)) and the thicknesses of the films have been fitted according to Cauchy model. The optical method has been used to determine the band gap value of the films. Transmission spectra have been taken by UV spectrophotometer. It is found that both ZnO and ZnO:B films have high average optical transmission (≥80%). X-ray diffraction (XRD) patterns indicate that the obtained ZnO has a hexagonal wurtzite type structure. The morphological properties of the films were studied by atomic force microscopy (AFM). The surface morphology of the nanostructure films is found to depend on the concentration of B. As a result, ZnO:B films are promising contender for their potential use as transparent window layer and

  20. Acoustoelectric Effect on the Responses of SAW Sensors Coated with Electrospun ZnO Nanostructured Thin Film

    Directory of Open Access Journals (Sweden)

    Zafer Ziya Ozturk

    2012-08-01

    Full Text Available In this study, zinc oxide (ZnO was a very good candidate for improving the sensitivity of gas sensor technology. The preparation of an electrospun ZnO nanostructured thin film on a 433 MHz Rayleigh wave based Surface Acoustic Wave (SAW sensor and the investigation of the acoustoelectric effect on the responses of the SAW sensor are reported. We prepared an electrospun ZnO nanostructured thin film on the SAW devices by using an electrospray technique. To investigate the dependency of the sensor response on the structure and the number of the ZnO nanoparticles, SAW sensors were prepared with different coating loads. The coating frequency shifts were adjusted to fall between 100 kHz and 2.4 MHz. The sensor measurements were performed against VOCs such as acetone, trichloroethylene, chloroform, ethanol, n-propanol and methanol vapor. The sensor responses of n-propanol have opposite characteristics to the other VOCs, and we attributed these characteristics to the elastic effect/acoustoelectric effect.

  1. Enhanced luminescence properties of hybrid Alq{sub 3}/ZnO (organic/inorganic) composite films

    Energy Technology Data Exchange (ETDEWEB)

    Cuba, M.; Muralidharan, G., E-mail: muraligru@gmail.com

    2014-12-15

    Pristine tris-(8-hydroxyquionoline)aluminum(Alq{sub 3}) and (Alq{sub 3}/ZnO hybrid) composites containing different weight percentages (5 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt% and 50 wt%) of ZnO in Alq{sub 3} were synthesized and coated on to a glass substrate using the dip coating method. The optimum concentration of ZnO in Alq{sub 3} films to get the best luminescence yield has been identified. XRD pattern reveals the amorphous nature of pure Alq{sub 3} film. The Alq{sub 3} films containing different weight percentages of ZnO show the presence of crystalline ZnO in Alq{sub 3}/ZnO composite films. The FTIR spectrum confirms the formation of quinoline with absorption in the region 600−800 cm{sup −1}. The hybrid Alq{sub 3}/ZnO composite films indicate the presence of Zn−O vibration band along with the corresponding Alq{sub 3} band. The band gap (HOMO–LUMO) of Alq{sub 3} film was calculated using absorption spectra and it is 2.87 eV for pristine films while it is 3.26 eV, 3.21 eV, 3.14 eV, 3.10 eV, 3.13 eV and 3.20 eV for the composite films containing 5–50 wt% of ZnO. The photoluminescence (PL) spectra of Alq{sub 3} films show a maximum PL intensity at 514 nm when excited at 390 nm. The ZnO incorporated composite films (Alq{sub 3}/ZnO) exhibit an emission in 485 nm and 514 nm. The composite films containing 30 wt% of ZnO exhibit maximum luminescence yield. - Highlights: • The pure Alq{sub 3} and Alq{sub 3}/ZnO composite were synthesized and coated on to a glass substrate using dip coating method. • Alq{sub 3}/ZnO composite film containing 30 wt% of ZnO exhibits two fold increases in luminescence intensity. • The shielding effect of ZnO on the Alq{sub 3} material suppresses the interactions among the host molecules in the excited state. • This leads to enhance the luminescence intensity in composite films.

  2. Growth and characterization of ZnO thin films prepared by electrodeposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Fahoume, M.; Maghfoul, O.; Aggour, M. [L.P.M.C., Faculte des Sciences, Universite Ibn Tofail, BP. 133-14000 Kenitra (Morocco); Hartiti, B. [L.P.M.A.E.R., Faculte des Sciences et Techniques, B.P. 146 Mohammedia (Morocco); Chraibi, F.; Ennaoui, A. [L.P.M., Faculte des Sciences, Universite Mohammed V, BP.1014 Rabat (Morocco)

    2006-06-15

    ZnO thin films were deposited on either indium tin oxide-coated glass or copper substrate by the electrodeposition process, using zinc chloride and flowing air as precursors. The effect of pH on the structural and morphological ZnO films was studied and the optimum deposition conditions have been outlined. The kinetics of the growth of the films have been investigated. We note that the rate of deposition of ZnO in an acidic solution was larger than in a basic solution. The structure of the films was studied using X-ray diffractometry (XRD) and transmission electron microscopy (TEM). The surface morphology and thickness of the films were determined using scanning electron microscopy. The X-ray diffraction analysis shows that the films are polycrystalline with hexagonal crystal structure (zincite) at pH 4. The optical transmittance of ZnO decreases with varying film thickness. The optical energy bandgap was found to be 3.26eV. (author)

  3. Excimer laser processing of ZnO thin films prepared by the sol-gel process

    International Nuclear Information System (INIS)

    Winfield, R.J.; Koh, L.H.K.; O'Brien, Shane; Crean, Gabriel M.

    2007-01-01

    ZnO thin films were prepared on soda-lime glass from a single spin-coating deposition of a sol-gel prepared with anhydrous zinc acetate [Zn(C 2 H 3 O 2 ) 2 ], monoethanolamine [H 2 NC 2 H 4 OH] and isopropanol. The deposited films were dried at 50 and 300 deg. C. X-ray analysis showed that the films were amorphous. Laser annealing was performed using an excimer laser. The laser pulse repetition rate was 25 Hz with a pulse energy of 5.9 mJ, giving a fluence of 225 mJ cm -2 on the ZnO film. Typically, five laser pulses per unit area of the film were used. After laser processing, the hexagonal wurtzite phase of zinc oxide was observed from X-ray diffraction pattern analysis. The thin films had a transparency of greater than 70% in the visible region. The optical band-gap energy was 3.454 eV. Scanning electron microscopy and profilometry analysis highlighted the change in morphology that occurred as a result of laser processing. This comparative study shows that our sol-gel processing route differs significantly from ZnO sol-gel films prepared by conventional furnace annealing which requires temperatures above 450 deg. C for the formation of crystalline ZnO

  4. ZnO film deposition by DC magnetron sputtering: Effect of target configuration on the film properties

    Energy Technology Data Exchange (ETDEWEB)

    Arakelova, E.; Khachatryan, A.; Kteyan, A.; Avjyan, K.; Grigoryan, S.

    2016-08-01

    Ballistic transport model for target-to-substrate atom transfer during magnetron sputter deposition was used to develop zinc target (cathode) configuration that enabled growth of uniform zinc oxide films on extensive surfaces and provided reproducibility of films characteristics irrespective of the cathode wear-out. The advantage of the developed target configuration for high-quality ZnO film deposition was observed in the sputtering pressure range of 5− 50 mTorr, and in the range of cathode-to-substrate distances 7–20 cm. Characteristics of the deposited films were demonstrated by using X-ray diffraction analysis, as well as optical and electrical measurements. - Highlights: • Change of target configuration for optimization of magnetron sputtering deposition is proposed. • Improvement of ZnO film properties due to use of this target is demonstrated. • This configuration provided reproducibility of the deposited films properties.

  5. Photovoltaic properties of undoped ZnO thin films prepared by the spray pyrolysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Ikhmayies, S.J. [Applied Science Private Univ., Amman (Jordan). Dept. of Physics; Abu El-Haija, N.M.; Ahmad-Bitar, R.N. [Jordan Univ., Amman (Jordan). Dept. of Physics

    2009-07-01

    Zinc oxide (ZnO) can be used as a window material, transparent electrode and active layer in different types of solar cells, UV emitters, and UV sensors. In addition to being low cost, ZnO is more abundant than indium tin oxide. ZnO is non toxic and has a high chemical stability in reduction environments. When ZnO films are made without any intentional doping, they exhibit n-type conductivity. ZnO thin films can be prepared by reactive sputtering, laser ablation, chemical-vapour deposition, laser molecular-beam epitaxy, thermal evaporation, sol-gel, atomic layer deposition and spray pyrolysis, with the latter being simple, inexpensive and adaptable to large area depositions. In this work ZnCl{sub 2} was used as a source of Zn where it was dissolved in distilled water. The structural, electrical and optical properties of the films were investigated due to their important characteristic for solar cell applications. Polycrystalline ZnO thin films were deposited on glass substrate by spray pyrolysis using a home-made spraying system at substrate temperature of 450 degrees C. The films were characterized by recording and analyzing their I-V plots, their transmittance, X-ray diffraction and SEM micrographs. There resistivity was found to be about 200 ohms per cm and their bandgap energy about 3.27 eV. X-ray diffraction patterns revealed that the films have a hexagonal wurtzite structure and are highly ordered with a preferential orientation (002). SEM images revealed that the substrates are continuously covered and the surface of the film is uniform. 16 refs., 4 figs.

  6. Nanostructured Zn and ZnO nanowire thin films for mechanical and self-cleaning applications

    Energy Technology Data Exchange (ETDEWEB)

    Shaik, Ummar Pasha [Advanced Centre of Research in High Energy Materials, University of Hyderabad, Prof. C R Rao Road, Gachibowli, Hyderabad 500046 (India); Purkayastha, Debarun Dhar, E-mail: ddebarun@yahoo.com [Department of Physics, National Institute of Technology Nagaland, Chumukedima, Dimapur 797103 (India); Krishna, M. Ghanashyam [Advanced Centre of Research in High Energy Materials, University of Hyderabad, Prof. C R Rao Road, Gachibowli, Hyderabad 500046 (India); School of Physics, University of Hyderabad, Prof. C R Rao Road, Gachibowli, Hyderabad 500046 (India); Madhurima, V. [Department of Physics, Central University of Tamil Nadu, Thiruvarur 610004 (India)

    2015-03-01

    Highlights: • Zn metal films were deposited by thermal evaporation, on various substrates. • Upon annealing Zn there is transformation of the Zn nanosheets into ZnO nanowires. • ZnO nanowires are superhydrophobic and exhibit wetting transition on UV exposure. • ZnO will be useful in self-cleaning, mechanical and oxidation resistance surfaces. - Abstract: Nanostructured Zn metal films were deposited by thermal evaporation, on borosilicate glass, Quartz, sapphire, lanthanum aluminate and yttria stabilized zirconia substrates. The as-deposited films are nanocrystalline and show a morphology that consists of triangular nanosheets. The films are hydrophobic with contact angles between 102° and 120° with hardness and Young's modulus between 0.15–0.8 GPa and 18–300 GPa, respectively. Thermal annealing of the films at 500 °C results only in partial oxidation of Zn to ZnO, which indicates good oxidation resistance. Annealing also causes transformation of the Zn nanosheets into ZnO nanowires that are polycrystalline in nature. The ZnO nanowires are superhydrophobic with contact angles between 159° and 162°, contact angle hysteresis between 5° and 10° and exhibit a reversible superhydrophobic–hydrophilic transition under UV irradiation. The nanowires are much softer than the as-deposited Zn metal films, with hardness between 0.02 and 0.4 GPa and Young's modulus between 3 and 35 GPa. The current study thus demonstrates a simple process for fabrication of nanostructured Zn metal films followed by a one-step transformation to nanowires with properties that will be very attractive for mechanical and self-cleaning applications.

  7. Correlation between structural and electrical properties of ZnO thin films

    International Nuclear Information System (INIS)

    Asadov, A.; Gao, W.; Li, Z.; Lee, J.; Hodgson, M.

    2005-01-01

    Thin ZnO films were deposited by radio frequency (r.f.) and direct current (d.c.) magnetron sputtering techniques onto glass substrates. Microstructural and electrical properties of ZnO films were studied using X-ray diffractometer (XRD), scanning electron microscope (SEM) and resistivity measurements. It was found that the size of the crystallites in the d.c. deposited films increased with increasing film thickness, while the crystallite size of r.f. deposited films remained unchanged. The d.c. deposited grains also had much stronger orientation related to the substrate than the r.f. films. XRD data indicated that the thin films with d<350 nm for r.f. and <750 nm for d.c. films have a very high degree of ZnO nonstoichiometry. This agreed well with the conductivity measurements and R(T) behaviour of the films with different resistance R. It was also found that the electrical resistivity of the samples increased exponentially with the thickness of films

  8. Electrical properties of solution-deposited ZnO thin-film transistors by low-temperature annealing.

    Science.gov (United States)

    Lim, Chul; Oh, Ji Young; Koo, Jae Bon; Park, Chan Woo; Jung, Soon-Won; Na, Bock Soon; Chu, Hye Yong

    2014-11-01

    Flexible oxide thin-film transistors (Oxide-TFTs) have emerged as next generation transistors because of their applicability in electronic device. In particular, the major driving force behind solution-processed zinc oxide film research is its prospective use in printing for electronics. A low-temperature process to improve the performance of solution-processed n-channel ZnO thin-film transistors (TFTs) fabricated via spin-coating and inkjet-printing is introduced here. ZnO nanoparticles were synthesized using a facile sonochemical method that was slightly modified based on a previously reported method. The influence of the annealing atmosphere on both nanoparticle-based TFT devices fabricated via spin-coating and those created via inkjet printing was investigated. For the inkjet-printed TFTs, the characteristics were improved significantly at an annealing temperature of 150 degrees C. The field effect mobility, V(th), and the on/off current ratios were 3.03 cm2/Vs, -3.3 V, and 10(4), respectively. These results indicate that annealing at 150 degrees C 1 h is sufficient to obtain a mobility (μ(sat)) as high as 3.03 cm2/Vs. Also, the active layer of the solution-based ZnO nanoparticles allowed the production of high-performance TFTs for low-cost, large-area electronics and flexible devices.

  9. A novel hierarchical ZnO disordered/ordered bilayer nanostructured film for dye sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Yamin, E-mail: yaminfengccnuphy@outlook.com; Wu, Fei; Jiang, Jian; Zhu, Jianhui; Fodjouong, Ghislain Joel; Meng, Gaoxiang; Xing, Yanmin; Wang, Wenwu; Huang, Xintang, E-mail: xthuang@phy.ccnu.edu.cn

    2013-12-25

    Graphical abstract: A novel hierarchical disordered/ordered bilayer ZnO nanostructured film in the length of 18 μm have been successfully synthesized on the FTO substrate; the hierarchical ZnO nanostructured film electrodes applied in DSSCs exhibit photoelectric conversion efficiency as high as 5.16%. Highlights: •A novel hierarchical ZnO structure film was fabricated on a FTO substrate. •Hierarchical ZnO film is applied as the electrodes for dye sensitized solar cells. •The film possess high specific surface area and fast electron transport effect. •The light-scattering effect of the hierarchical film is pronounced. •The energy conversion efficiency of hierarchical ZnO electrode reaches to 5.16%. -- Abstract: A novel hierarchical ZnO nanostructured film is synthesized via a chemical bath deposition (CBD) method followed by a treatment of thermal decomposition onto a fluorine-doped tin oxide (FTO) substrate. This hierarchical film is composed of disordered ZnO nanorods (NRs) (top layer) and ordered ZnO nanowires (NWs) (bottom layer). The products possess the following features such as high specific surface area, fast electron transport, and pronounced light-scattering effect, which are quite suitable for dye sensitized solar cells (DSSCs) applications. A light-to-electricity conversion efficiency of 5.16% is achieved when the hierarchical ZnO nanostructured film is used as the photoanode under 100 mW cm{sup −2} illumination. This efficiency is found to be much higher than that of the DSSCs with pure ordered ZnO NWs (1.45%) and disordered ZnO NRs (3.31%) photoanodes.

  10. A novel hierarchical ZnO disordered/ordered bilayer nanostructured film for dye sensitized solar cells

    International Nuclear Information System (INIS)

    Feng, Yamin; Wu, Fei; Jiang, Jian; Zhu, Jianhui; Fodjouong, Ghislain Joel; Meng, Gaoxiang; Xing, Yanmin; Wang, Wenwu; Huang, Xintang

    2013-01-01

    Graphical abstract: A novel hierarchical disordered/ordered bilayer ZnO nanostructured film in the length of 18 μm have been successfully synthesized on the FTO substrate; the hierarchical ZnO nanostructured film electrodes applied in DSSCs exhibit photoelectric conversion efficiency as high as 5.16%. Highlights: •A novel hierarchical ZnO structure film was fabricated on a FTO substrate. •Hierarchical ZnO film is applied as the electrodes for dye sensitized solar cells. •The film possess high specific surface area and fast electron transport effect. •The light-scattering effect of the hierarchical film is pronounced. •The energy conversion efficiency of hierarchical ZnO electrode reaches to 5.16%. -- Abstract: A novel hierarchical ZnO nanostructured film is synthesized via a chemical bath deposition (CBD) method followed by a treatment of thermal decomposition onto a fluorine-doped tin oxide (FTO) substrate. This hierarchical film is composed of disordered ZnO nanorods (NRs) (top layer) and ordered ZnO nanowires (NWs) (bottom layer). The products possess the following features such as high specific surface area, fast electron transport, and pronounced light-scattering effect, which are quite suitable for dye sensitized solar cells (DSSCs) applications. A light-to-electricity conversion efficiency of 5.16% is achieved when the hierarchical ZnO nanostructured film is used as the photoanode under 100 mW cm −2 illumination. This efficiency is found to be much higher than that of the DSSCs with pure ordered ZnO NWs (1.45%) and disordered ZnO NRs (3.31%) photoanodes

  11. Nanostructured ZnO thin films prepared by sol–gel spin-coating

    Energy Technology Data Exchange (ETDEWEB)

    Heredia, E., E-mail: heredia.edu@gmail.com [UNIDEF (CONICET-MINDEF), J.B. de La Salle 4397, 1603 Villa Martelli, Pcia. de Buenos Aires (Argentina); Bojorge, C.; Casanova, J.; Cánepa, H. [UNIDEF (CONICET-MINDEF), J.B. de La Salle 4397, 1603 Villa Martelli, Pcia. de Buenos Aires (Argentina); Craievich, A. [Instituto de Física, Universidade de São Paulo, Cidade Universitária, 66318 São Paulo, SP (Brazil); Kellermann, G. [Universidade Federal do Paraná, 19044 Paraná (Brazil)

    2014-10-30

    Highlights: • ZnO films synthesized by sol–gel were deposited by spin-coating on flat substrates. • Structural features of ZnO films with several thicknesses were characterized by means of different techniques. • The thicknesses of different ZnO thin films were determined by means of FESEM and AFM. • The nanoporous structures of ZnO thin films were characterized by GISAXS using IsGISAXS software. • The average densities of ZnO thin films were derived from (i) the critical angle in 1D XR patterns, (ii) the angle of Yoneda peak in 2D GISAXS images, (iii) minimization of chi2 using IsGISAXS best fitting procedure. - Abstract: ZnO thin films deposited on silica flat plates were prepared by spin-coating and studied by applying several techniques for structural characterization. The films were prepared by depositing different numbers of layers, each deposition being followed by a thermal treatment at 200 °C to dry and consolidate the successive layers. After depositing all layers, a final thermal treatment at 450 °C during 3 h was also applied in order to eliminate organic components and to promote the crystallization of the thin films. The total thickness of the multilayered films – ranging from 40 nm up to 150 nm – was determined by AFM and FESEM. The analysis by GIXD showed that the thin films are composed of ZnO crystallites with an average diameter of 25 nm circa. XR results demonstrated that the thin films also exhibit a large volume fraction of nanoporosity, typically 30–40 vol.% in thin films having thicknesses larger than ∼70 nm. GISAXS measurements showed that the experimental scattering intensity is well described by a structural model composed of nanopores with shape of oblate spheroids, height/diameter aspect ratio within the 0.8–0.9 range and average diameter along the sample surface plane in the 5–7 nm range.

  12. Piezoelectricity and charge trapping in ZnO and Co-doped ZnO thin films

    Directory of Open Access Journals (Sweden)

    Domenico D’Agostino

    2017-05-01

    Full Text Available Piezoelectricity and charge storage of undoped and Co-doped ZnO thin films were investigated by means of PiezoResponse Force Microscopy and Kelvin Probe Force Microscopy. We found that Co-doped ZnO exhibits a large piezoelectric response, with the mean value of piezoelectric matrix element d33 slightly lower than in the undoped sample. Moreover, we demonstrate that Co-doping affects the homogeneity of the piezoelectric response, probably as a consequence of the lower crystalline degree exhibited by the doped samples. We also investigate the nature of the interface between a metal electrode, made up of the PtIr AFM tip, and the films as well as the phenomenon of charge storage. We find Schottky contacts in both cases, with a barrier value higher in PtIr/ZnO than in PtIr/Co-doped ZnO, indicating an increase in the work function due to Co-doping.

  13. Native defects in ZnO films studied by slow positron beam

    International Nuclear Information System (INIS)

    Peng Chengxiao; Weng Huimin; Ye Bangjiao; Zhou Xianyi; Han Rongdian; Yang Xiaojie

    2005-01-01

    Native defects in ZnO films grown by radio frequency (RF) reactive magnetron sputtering under variable oxygen fraction conditions have been investigated by using monoenergetic positrons beam technique. The results show that the same type defects dominate in these ZnO samples grown at oxygen fraction less than 70% in the process chamber; and zinc vacancies are preponderant in the ZnO films fabricated in richer oxygen environment. The concentration of zinc vacancies increases with oxygen partial fraction rising. While oxygen fraction reaches 85%, zinc vacancies that could trap positrons decrease, which suggests that impurities could shield zinc vacancies. A combination between hydrogen atoms and the dangling bonds in the lattice could weaken the trap of positrons under the 50% oxygen fraction condition. The concentration of zinc vacancies varies in different oxygen fraction films, which is in agreement with the conclusion of photoluminescence spectroscopy. (authors)

  14. Slow positron beam study of hydrogen ion implanted ZnO thin films

    International Nuclear Information System (INIS)

    Hu, Yi; Xue, Xudong; Wu, Yichu

    2014-01-01

    The effects of hydrogen related defect on the microstructure and optical property of ZnO thin films were investigated by slow positron beam, in combination with x-ray diffraction, infrared and photoluminescence spectroscopy. The defects were introduced by 90 keV proton irradiation with doses of 1×10 15 and 1×10 16 ions cm −2 . Zn vacancy and OH bonding (V Zn +OH) defect complex were identified in hydrogen implanted ZnO film by positron annihilation and infrared spectroscopy. The formation of these complexes led to lattice disorder in hydrogen implanted ZnO film and suppressed the luminescence process. - Highlights: • Hydrogen introduced by ion implantation can form hydrogen-related defect complex. • V Zn +OH defect complex is identified by positron annihilation and IR spectroscopy. • Irradiation defects suppress the luminescence process

  15. Hydrophobic ZnO nanostructured thin films on glass substrate by simple successive ionic layer absorption and reaction (SILAR) method

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, P. Suresh; Raj, A. Dhayal [Thin Film and Nanomaterials Laboratory, Department of Physics, Bharathiar University, Coimbatore-641046 (India); Mangalaraj, D., E-mail: dmraj800@yahoo.co [Department of Nanoscience and Technology, Bharathiar University, Coimbatore-641046 (India); Nataraj, D. [Thin Film and Nanomaterials Laboratory, Department of Physics, Bharathiar University, Coimbatore-641046 (India)

    2010-10-01

    In the present work, ZnO nanostructured thin films were grown on glass substrates by a simple successive ionic layer absorption and reaction method (SILAR) process at relatively low temperature for its self cleaning application. X-ray diffraction, scanning electron microscopy and Photoluminescence (PL) spectra were used to characterize the prepared ZnO nanostructured film. XRD pattern clearly reviles that the grown ZnO nanostructure film reflect (002) orientation with c-direction. SEM image clearly shows the surface morphology with cluster of spindle and flower-like nanostructured with diameter various around 350 nm. Photoluminescence (PL) spectra of ZnO nanostructures film exhibit a UV emission around 385nm and visible emission in the range around 420-500 nm. Good water repellent behavior were observed for ZnO nanostructured film without any surface modification.

  16. Hydrophobic ZnO nanostructured thin films on glass substrate by simple successive ionic layer absorption and reaction (SILAR) method

    International Nuclear Information System (INIS)

    Kumar, P. Suresh; Raj, A. Dhayal; Mangalaraj, D.; Nataraj, D.

    2010-01-01

    In the present work, ZnO nanostructured thin films were grown on glass substrates by a simple successive ionic layer absorption and reaction method (SILAR) process at relatively low temperature for its self cleaning application. X-ray diffraction, scanning electron microscopy and Photoluminescence (PL) spectra were used to characterize the prepared ZnO nanostructured film. XRD pattern clearly reviles that the grown ZnO nanostructure film reflect (002) orientation with c-direction. SEM image clearly shows the surface morphology with cluster of spindle and flower-like nanostructured with diameter various around 350 nm. Photoluminescence (PL) spectra of ZnO nanostructures film exhibit a UV emission around 385nm and visible emission in the range around 420-500 nm. Good water repellent behavior were observed for ZnO nanostructured film without any surface modification.

  17. Effects of Doping Concentration on the Structural and Optical Properties of Spin-Coated In-doped ZnO Thin Films Grown on Thermally Oxidized ZnO Film/ZnO Buffer Layer/Mica Substrate

    International Nuclear Information System (INIS)

    Kim, Byunggu; Leem, Jae-Young

    2017-01-01

    ZnO buffer layers were deposited on mica substrates using a sol-gel spin coating method. Then, a thin film of metallic Zn was deposited onto the ZnO buffer layer/mica substrate using a thermal evaporator, and the deposited Zn thin films were then thermally oxidized in a furnace at 500 ℃ for 2 h in air. Finally, In-doped ZnO (IZO) thin films with different In concentrations were grown on the oxidized ZnO film/ZnO buffer layer/mica substrates using the sol-gel spin-coating method. All the IZO films showed ZnO peaks with similar intensities. The full width at half maximum values of the ZnO (002) peak for the IZO thin films decreased with an increase in the In concentration to 1 at%, because the crystallinity of the films was enhanced. However, a further increase in the In concentration caused the crystal quality to degrade. This might be attributed to the fact that the higher In doping resulted in an increase in the number of ionized impurities. The Urbach energy (EU) values of the IZO thin film decreased with an increase in the In concentration to 1 at % because of the enhanced crystal quality of the films. The EU values for the IZO thin films increased with the In concentration from 1 at%to 3 at%, reflecting the broadening of localized band tail state near the conduction band edge of the films.

  18. Effects of Doping Concentration on the Structural and Optical Properties of Spin-Coated In-doped ZnO Thin Films Grown on Thermally Oxidized ZnO Film/ZnO Buffer Layer/Mica Substrate

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Byunggu; Leem, Jae-Young [Inje University, Gimhae (Korea, Republic of)

    2017-01-15

    ZnO buffer layers were deposited on mica substrates using a sol-gel spin coating method. Then, a thin film of metallic Zn was deposited onto the ZnO buffer layer/mica substrate using a thermal evaporator, and the deposited Zn thin films were then thermally oxidized in a furnace at 500 ℃ for 2 h in air. Finally, In-doped ZnO (IZO) thin films with different In concentrations were grown on the oxidized ZnO film/ZnO buffer layer/mica substrates using the sol-gel spin-coating method. All the IZO films showed ZnO peaks with similar intensities. The full width at half maximum values of the ZnO (002) peak for the IZO thin films decreased with an increase in the In concentration to 1 at%, because the crystallinity of the films was enhanced. However, a further increase in the In concentration caused the crystal quality to degrade. This might be attributed to the fact that the higher In doping resulted in an increase in the number of ionized impurities. The Urbach energy (EU) values of the IZO thin film decreased with an increase in the In concentration to 1 at % because of the enhanced crystal quality of the films. The EU values for the IZO thin films increased with the In concentration from 1 at%to 3 at%, reflecting the broadening of localized band tail state near the conduction band edge of the films.

  19. Novel bilayer structure ZnO based photoanode for enhancing conversion efficiency in dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Jin [Electronic Materials Research Laboratory, School of Electronic and Information Engineering, Xi' an, Jiaotong University, Xi' an 710049, Shaanxi (China); Que Wenxiu, E-mail: wxque@mail.xjtu.edu.cn [Electronic Materials Research Laboratory, School of Electronic and Information Engineering, Xi' an, Jiaotong University, Xi' an 710049, Shaanxi (China); Jia Qiaoying; Zhong Peng; Liao Yulong [Electronic Materials Research Laboratory, School of Electronic and Information Engineering, Xi' an, Jiaotong University, Xi' an 710049, Shaanxi (China); Ye Xiangdong; Ding Yucheng [State Key Laboratory of Manufacturing Systems Engineering, Xi' an, Jiaotong University, Xi' an 710049, Shaanxi (China)

    2011-07-07

    Highlights: > The ZnO nanocrystallite aggregates on the ZnO nanowire arrays (ZnO-(NCAs/NWs)) photoanode are successfully fabricated. > Results indicate that such a configuration of the ZnO-(NCAs/NWs) photoanode can significantly improve the efficiency of the DSSC. > The electron transport properties of the DSSC based on the ZnO-(NCAs/NWs) photoanode is discussed deeply. - Abstract: ZnO film with a novel bilayer structure, which consists of ZnO nanowire (ZnO NW) arrays as underlayer and polydisperse ZnO nanocrystallite aggregates (ZnO NCAs) as overlayer, is fabricated and studied as dye-sensitized solar-cell (DSSC) photoanode. Results indicate that such a configuration of the ZnO nanocrystallite aggregates on the ZnO nanowire arrays (ZnO-(NCAs/NWs)) can significantly improve the efficiency of the DSSC due to its fast electron transport, relatively high surface area and enhanced light-scattering capability. The short-circuit current density (J{sub sc}) and the energy-conversion efficiency ({eta}) of the DSSC based on the ZnO-(NCAs/NWs) photoanode are estimated and the values are 9.19 mA cm{sup -2} and 3.02%, respectively, which are much better than those of the cells formed only by the ZnO NWs (J{sub sc} = 4.02 mA cm{sup -2}, {eta} = 1.04%) or the ZnO NCAs (J{sub sc} = 7.14 mA cm{sup -2}, {eta} = 2.56%) photoanode. Moreover, the electron transport properties of the DSSC based on the ZnO-(NCAs/NWs) photoanode are also discussed.

  20. Superhydrophobic nanostructured ZnO thin films on aluminum alloy substrates by electrophoretic deposition process

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Ying; Sarkar, D.K., E-mail: dsarkar@uqac.ca; Chen, X-Grant

    2015-02-01

    Graphical abstract: - Highlights: • Fabrication of superhydrophobic ZnO thin films surfaces by electrophoretic deposition process on aluminum substrates. • Effect of bath temperature on the physical and superhydrophobic properties of thin films. • The water contact angle of 155° ± 3 with roll off property has been observed on the film that was grown at bath temperatures of 50 °C. • The activation energy for electrophoretic deposition of SA-functionalized ZnO nanoparticle is calculated to be 0.50 eV. - Abstract: Superhydrophobic thin films have been fabricated on aluminum alloy substrates by electrophoretic deposition (EPD) process using stearic acid (SA) functionalized zinc oxide (ZnO) nanoparticles suspension in alcohols at varying bath temperatures. The deposited thin films have been characterized using both X-ray diffraction (XRD) and infrared (IR) spectroscopy and it is found that the films contain low surface energy zinc stearate and ZnO nanoparticles. It is also observed that the atomic percentage of Zn and O, roughness and water contact angle of the thin films increase with the increase of the deposited bath temperature. Furthermore, the thin film deposited at 50 °C, having a roughness of 4.54 ± 0.23 μm, shows superhydrophobic properties providing a water contact angle of 155 ± 3° with rolling off properties. Also, the activation energy of electrophoretic deposition of stearic-acid-functionalized ZnO nanoparticles is calculated to be 0.5 eV.

  1. Ionized zinc vacancy mediated ferromagnetism in copper doped ZnO thin films

    Directory of Open Access Journals (Sweden)

    Shi-Yi Zhuo

    2012-03-01

    Full Text Available This paper reports the origin of ferromagnetism in Cu-doped ZnO thin films. Room-temperature ferromagnetism is obtained in all the thin films when deposited at different oxygen partial pressure. An obviously enhanced peak corresponding to zinc vacancy is observed in the photoluminescence spectra, while the electrical spin resonance measurement implies the zinc vacancy is negative charged. After excluding the possibility of direct exchange mechanisms (via free carriers, we tentatively propose a quasi-indirect exchange model (via ionized zinc vacancy for Cu-doped ZnO system.

  2. Microwave Characterization of Ba-Substituted PZT and ZnO Thin Films.

    Science.gov (United States)

    Tierno, Davide; Dekkers, Matthijn; Wittendorp, Paul; Sun, Xiao; Bayer, Samuel C; King, Seth T; Van Elshocht, Sven; Heyns, Marc; Radu, Iuliana P; Adelmann, Christoph

    2018-05-01

    The microwave dielectric properties of (Ba 0.1 Pb 0.9 )(Zr 0.52 Ti 0.48 )O 3 (BPZT) and ZnO thin films with thicknesses below were investigated. No significant dielectric relaxation was observed for both BPZT and ZnO up to 30 GHz. The intrinsic dielectric constant of BPZT was as high as 980 at 30 GHz. The absence of strong dielectric dispersion and loss peaks in the studied frequency range can be linked to the small grain diameters in these ultrathin films.

  3. Physical and electrochemical properties of ZnO films fabricated from highly cathodic electrodeposition potentials

    Science.gov (United States)

    Ismail, Abdul Hadi; Abdullah, Abdul Halim; Sulaiman, Yusran

    2017-03-01

    The physical and electrochemical properties of zinc oxide (ZnO) film electrode that were prepared electrochemically were studied. ZnO was electrodeposited on ITO glass substrate by applying three different highly cathodic potentials (-1.3 V, -1.5 V, -1.7 V) in a solution containing 70 mM of Zn(NO3)2.xH2O and 0.1 M KCl with bath temperatures of 70 °C and 80 °C. The presence of ZnO was asserted from XRD analysis where the corresponding peaks in the spectra were assigned. SEM images revealed the plate-like hexagonal morphology of ZnO which is in agreement with the XRD analysis. The areal capacitance of the ZnO was observed to increase when the applied electrodeposition potential is increased from -1.3 V to -1.5 V. However, the areal capacitance is found to decrease when the applied electrodeposition potential is further increased to -1.7 V. The resistance of charge transfer (Rct) of the ZnO decreased when the applied electrodeposition potential varies from -1.3 V to -1.7 V due to the decreased particle size of ZnO when more cathodic electrodeposition potential is applied.

  4. ZnO synthesized in air by fs laser irradiation on metallic Zn thin films

    Science.gov (United States)

    Esqueda-Barrón, Y.; Herrera, M.; Camacho-López, S.

    2018-05-01

    We present results on rapid femtosecond laser synthesis of nanostructured ZnO. We used metallic Zn thin films to laser scan along straight tracks, until forming nanostructured ZnO. The synthesis dependence on laser irradiation parameters such as the per pulse fluence, integrated fluence, laser scan speed, and number of scans were explored carefully. SEM characterization showed that the morphology of the obtained ZnO is dictated by the integrated fluence and the laser scan speed; micro Raman and XRD results allowed to identify optimal laser processing conditions for getting good quality ZnO; and cathodoluminescence measurements demonstrated that a single laser scan at high per pulse laser fluence, but a medium integrated laser fluence and a medium laser scan speed favors a low density of point-defects in the lattice. Electrical measurements showed a correlation between resistivity of the laser produced ZnO and point-defects created during the synthesis. Transmittance measurements showed that, the synthesized ZnO can reach down to the supporting fused silica substrate under the right laser irradiation conditions. The physical mechanism for the formation of ZnO, under ultrashort pulse laser irradiation, is discussed in view of the distinct times scales given by the laser pulse duration and the laser pulse repetition rate.

  5. Ultra violet sensors based on nanostructured ZnO spheres in network of nanowires: a novel approach

    OpenAIRE

    Hullavarad, SS; Hullavarad, NV; Karulkar, PC; Luykx, A; Valdivia, P

    2007-01-01

    AbstractThe ZnO nanostructures consisting of micro spheres in a network of nano wires were synthesized by direct vapor phase method. X-ray Photoelectron Spectroscopy measurements were carried out to understand the chemical nature of the sample. ZnO nanostructures exhibited band edge luminescence at 383 nm. The nanostructure based ZnO thin films were used to fabricate UV sensors. The photoresponse measurements were carried out and the responsivity was measured to be 50 mA W−1. The rise a...

  6. Ultra violet sensors based on nanostructured ZnO spheres in network of nanowires: a novel approach

    Directory of Open Access Journals (Sweden)

    Luykx A

    2007-01-01

    Full Text Available AbstractThe ZnO nanostructures consisting of micro spheres in a network of nano wires were synthesized by direct vapor phase method. X-ray Photoelectron Spectroscopy measurements were carried out to understand the chemical nature of the sample. ZnO nanostructures exhibited band edge luminescence at 383 nm. The nanostructure based ZnO thin films were used to fabricate UV sensors. The photoresponse measurements were carried out and the responsivity was measured to be 50 mA W−1. The rise and decay time measurements were also measured.

  7. In and Ga Codoped ZnO Film as a Front Electrode for Thin Film Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Duy Phong Pham

    2014-01-01

    Full Text Available Doped ZnO thin films have attracted much attention in the research community as front-contact transparent conducting electrodes in thin film silicon solar cells. The prerequisite in both low resistivity and high transmittance in visible and near-infrared region for hydrogenated microcrystalline or amorphous/microcrystalline tandem thin film silicon solar cells has promoted further improvements of this material. In this work, we propose the combination of major Ga and minor In impurities codoped in ZnO film (IGZO to improve the film optoelectronic properties. A wide range of Ga and In contents in sputtering targets was explored to find optimum optical and electrical properties of deposited films. The results show that an appropriate combination of In and Ga atoms in ZnO material, followed by in-air thermal annealing process, can enhance the crystallization, conductivity, and transmittance of IGZO thin films, which can be well used as front-contact electrodes in thin film silicon solar cells.

  8. Reversible superhydrophobic-superhydrophilic transition of ZnO nanorod/epoxy composite films.

    Science.gov (United States)

    Liu, Yan; Lin, Ziyin; Lin, Wei; Moon, Kyoung Sik; Wong, C P

    2012-08-01

    Tuning the surface wettability is of great interest for both scientific research and practical applications. We demonstrated reversible transition between superhydrophobicity and superhydrophilicity on a ZnO nanorod/epoxy composite film. The epoxy resin serves as an adhesion and stress relief layer. The ZnO nanorods were exposed after oxygen reactive ion etching of the epoxy matrix. A subsequent chemcial treatment with fluoroalkyl and alkyl silanes resulted in a superhydrophobic surface with a water contact angle up to 158.4° and a hysteresis as low as 1.3°. Under UV irradiation, the water contact angle decreased gradually, and the surface eventually became superhydrophilic because of UV induced decomposition of alkyl silanes and hydroxyl absorption on ZnO surfaces. A reversible transition of surface wettability was realized by alternation of UV illumination and surface treatment. Such ZnO nanocomposite surface also showed improved mechanical robustness.

  9. Effect of sapphire substrate nitridation on the elimination of rotation domains in ZnO epitaxial films

    International Nuclear Information System (INIS)

    Ying Minju; Du Xiaolong; Mei Zengxia; Zeng Zhaoquan; Zheng Hao; Wang Yong; Jia Jinfeng; Zhang Ze; Xue Qikun

    2004-01-01

    The rotation domain structures in ZnO films grown on sapphire substrates under different pre-treatment conditions have been investigated by in situ reflection high-energy electron diffraction and ex situ x-ray diffraction (XRD). It was found that by appropriate nitridation treatment, forming a thin AlN film on the substrate, the rotation domains in ZnO films could be completely suppressed, and a full width at half maximum of only 180 arcsec was observed in the (0 0 0 2) reflection of XRD rocking curves. The mechanisms for the elimination of rotation domains in the ZnO films are discussed

  10. Theoretical study of the multiferroic properties in M-doped (M=Co, Cr, Mg) ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bahoosh, S.G. [Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle (Germany); Apostolov, A.T. [University of Architecture, Civil Engineering and Geodesy, Faculty of Hydrotechnics, Department of Physics, 1, Hristo Smirnenski Blvd., 1046 Sofia (Bulgaria); Apostolova, I.N. [University of Forestry, Faculty of Forest Industry, 10, Kl. Ohridsky Blvd., 1756 Sofia (Bulgaria); Trimper, S. [Institute of Physics, Martin-Luther-University, D-06099 Halle (Germany); Wesselinowa, Julia M. [University of Sofia, Department of Physics, Blvd. J. Bouchier 5, 1164 Sofia (Bulgaria)

    2015-01-01

    The origin of multiferroism is still an open problem in ZnO. We propose a microscopic model to clarify the occurrence of multiferroism in this material. Using Green's function technique we study the influence of ion doping and size effects on the magnetization and polarization of ZnO thin films. The calculations for magnetic Co- and Cr-ions are based on the s–d model, the transverse Ising model in terms of pseudo-spins and a biquadratic magnetoelectric coupling, whereas in case of nonmagnetic Mg-ions the model takes into account the Coulomb interaction and an indirect coupling between the pseudo-spins via the conduction electrons. We show that the magnetization M exhibits a maximum for a fixed concentration of the doping ions. Furthermore M increases with decreasing film thickness N. The polarization increases with increasing concentration of the dopant and decreasing N. The results are in good agreement with the experimental data. - Highlights: • The paper analyzes the multiferroic properties of doped ZnO thin films by a microscopic model. • The magnetization exhibits a maximum at a fixed doping concentration. • The polarization increases with growing dopant concentration. • The ferroelectric transition temperature is enhanced for increasing dopant concentration.

  11. Effect of High Temperature Annealing on Conduction-Type ZnO Films Prepared by Direct-Current Magnetron Sputtering

    International Nuclear Information System (INIS)

    Sun Li-Jie; He Dong-Kai; Xu Xiao-Qiu; Zhong Ze; Wu Xiao-Peng; Lin Bi-Xia; Fu Zhu-Xi

    2010-01-01

    We experimentally find that the ZnO thin films deposited by dc-magnetron sputtering have different conduction types after annealing at high temperature in different ambient. Hall measurements show that ZnO films annealed at 1100°C in N 2 and in O 2 ambient become n-type and p-type, respectively. This is due to the generation of different intrinsic defects by annealing in different ambient. X-ray photoelectron spectroscopy and photolumi-nescence measurements indicate that zinc interstitial becomes a main defects after annealing at 1100°C in N 2 ambient, and these defects play an important role for n-type conductivity of ZnO. While the ZnO films annealed at 1100°C in O 2 ambient, the oxygen antisite contributes ZnO films to p-type. (condensed matter: structure, mechanical and thermal properties)

  12. The effects of ZnO buffer layers on the properties of phosphorus doped ZnO thin films grown on sapphire by pulsed laser deposition

    International Nuclear Information System (INIS)

    Kim, K-W; Lugo, F J; Lee, J H; Norton, D P

    2012-01-01

    The properties of phosphorus doped ZnO thin films grown on sapphire by pulsed laser deposition were examined, specifically focusing on the effects of undoped ZnO buffer layers. In particular, buffer layers were grown under different conditions; the transport properties of as-deposited and rapid thermal annealed ZnO:P films were then examined. As-deposited films showed n-type conductivity. After rapid thermal annealing, the film on buffer layer grown at a low temperature showed the conversion of carrier type to p-type for specific growth conditions while the films deposited on buffer layer grown at a high temperature remained n-type regardless of growth condition. The films deposited on buffer layer grown at a low temperature showed higher resistivity and more significant change of the transport properties upon rapid thermal annealing. These results suggest that more dopants are incorporated in films with higher defect density. This is consistent with high resolution x-ray diffraction results for phosphorus doped ZnO films on different buffer layers. In addition, the microstructure of phosphorus doped ZnO films is substantially affected by the buffer layer.

  13. Optical properties of Mn doped ZnO films and wires synthesized by thermal oxidation of ZnMn alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sima, M., E-mail: msima@infim.ro [National Institute of Materials Physics, 105bis Atomistilor Street, 077125 Magurele (Romania); Mihut, L. [National Institute of Materials Physics, 105bis Atomistilor Street, 077125 Magurele (Romania); Vasile, E. [University “Politehnica”of Bucharest, Faculty of Applied Chemistry and Material Science, Department of Oxide Materials and Nanomaterials, No. 1-7 Gh. Polizu Street, 011061 Bucharest (Romania); Sima, Ma.; Logofatu, C. [National Institute of Materials Physics, 105bis Atomistilor Street, 077125 Magurele (Romania)

    2015-09-01

    Mn doped ZnO films and wires, having different manganese concentrations were synthesized by thermal oxidation of the corresponding ZnMn alloy films and wires electrodeposited on a gold substrate. Structural and optical properties were addressed with scanning electron microscopy, X-ray diffraction (XRD), Raman scattering and photoluminescence (PL). To estimate the manganese concentration in Mn doped ZnO films, X-ray photoelectron spectroscopy was used. XRD patterns indicate that the incorporation of Mn{sup 2+} ions into the Zn{sup 2+} site of ZnO lattice takes place. Quenching of the ZnO PL appears due to Mn{sup 2+} ions in the ZnO lattice. Moreover, a significant decrease in the green emission of ZnO is reported in the case of the Mn doped ZnO wire array with a Mn concentration of 1.45%. The wurtzite ZnO has a total of 12 phonon modes, namely, one longitudinal acoustic (LA), two transverse acoustic (TA), three longitudinal optical (LO), and six transverse optical branches. Compared to the undoped ZnO, a gradual up-shift of the Raman lines assigned to the 2LA and A{sub 1} (LO) vibrational modes, from 482 and 567 cm{sup −1} to 532 and 580 cm{sup −1}, respectively, takes place for the Mn doped ZnO films having a Mn concentration between 2 and 15%. Additionally, in the case of the Mn doped ZnO films with 7 and 15% Mn concentration, Raman spectra show the appearance and increase in the relative intensity of the ZnO Raman line assigned to the TA + LO vibrational mode in the 600–750 cm{sup −1} spectral range. For the Mn-doped ZnO wires, the presence of the Raman line peaking at 527 cm{sup −1} confirms the insertion of Mn{sup 2+} ions in ZnO lattice. - Highlights: • Mn doped ZnO films and wires grown by thermal oxidation of ZnMn alloy • Incorporation of Mn{sup 2+} ions into Zn{sup 2+} site of ZnO lattice • Appearance of a strong Raman line in the spectral range 600–800 cm{sup −1} at high Mn concentration • Compensation of the oxygen vacancy at higher

  14. Optical properties of Mn doped ZnO films and wires synthesized by thermal oxidation of ZnMn alloy

    International Nuclear Information System (INIS)

    Sima, M.; Mihut, L.; Vasile, E.; Sima, Ma.; Logofatu, C.

    2015-01-01

    Mn doped ZnO films and wires, having different manganese concentrations were synthesized by thermal oxidation of the corresponding ZnMn alloy films and wires electrodeposited on a gold substrate. Structural and optical properties were addressed with scanning electron microscopy, X-ray diffraction (XRD), Raman scattering and photoluminescence (PL). To estimate the manganese concentration in Mn doped ZnO films, X-ray photoelectron spectroscopy was used. XRD patterns indicate that the incorporation of Mn 2+ ions into the Zn 2+ site of ZnO lattice takes place. Quenching of the ZnO PL appears due to Mn 2+ ions in the ZnO lattice. Moreover, a significant decrease in the green emission of ZnO is reported in the case of the Mn doped ZnO wire array with a Mn concentration of 1.45%. The wurtzite ZnO has a total of 12 phonon modes, namely, one longitudinal acoustic (LA), two transverse acoustic (TA), three longitudinal optical (LO), and six transverse optical branches. Compared to the undoped ZnO, a gradual up-shift of the Raman lines assigned to the 2LA and A 1 (LO) vibrational modes, from 482 and 567 cm −1 to 532 and 580 cm −1 , respectively, takes place for the Mn doped ZnO films having a Mn concentration between 2 and 15%. Additionally, in the case of the Mn doped ZnO films with 7 and 15% Mn concentration, Raman spectra show the appearance and increase in the relative intensity of the ZnO Raman line assigned to the TA + LO vibrational mode in the 600–750 cm −1 spectral range. For the Mn-doped ZnO wires, the presence of the Raman line peaking at 527 cm −1 confirms the insertion of Mn 2+ ions in ZnO lattice. - Highlights: • Mn doped ZnO films and wires grown by thermal oxidation of ZnMn alloy • Incorporation of Mn 2+ ions into Zn 2+ site of ZnO lattice • Appearance of a strong Raman line in the spectral range 600–800 cm −1 at high Mn concentration • Compensation of the oxygen vacancy at higher Mn concentration in ZnO lattice

  15. Temperature dependent optical properties of ZnO thin film using ellipsometry and photoluminescence

    Science.gov (United States)

    Bouzourâa, M.-B.; Battie, Y.; Dalmasso, S.; Zaïbi, M.-A.; Oueslati, M.; En Naciri, A.

    2018-05-01

    We report the temperature dependence of the dielectric function, the exciton binding energy and the electronic transitions of crystallized ZnO thin film using spectroscopic ellipsometry (SE) and photoluminescence (PL). ZnO layers were prepared by sol-gel method and deposited on crystalline silicon (Si) by spin coating technique. The ZnO optical properties were determined between 300 K and 620 K. Rigorous study of optical responses was achieved in order to demonstrate the quenching exciton of ZnO as a function of temperature. Numerical technique named constrained cubic splines approximation (CCS), Tauc-Lorentz (TL) and Tanguy dispersion models were selected for the ellipsometry data modeling in order to obtain the dielectric function of ZnO. The results reveals that the exciton bound becomes widely flattening at 470 K on the one hand, and on the other that the Tanguy dispersion law is more appropriate for determining the optical responses of ZnO thin film in the temperature range of 300 K-420 K. The Tauc-Lorentz, for its part, reproduces correctly the ZnO dielectric function in 470 K-620 K temperature range. The temperature dependence of the electronic transition given by SE and PL shows that the exciton quenching was observed in 420 K-∼520 K temperature range. This quenching effect can be explained by the equilibrium between the Coulomb force of exciton and its kinetic energy in the film. The kinetic energy was found to induce three degrees of freedom of the exciton.

  16. A comparative study of physico-chemical properties of CBD and SILAR grown ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jambure, S.B.; Patil, S.J.; Deshpande, A.R.; Lokhande, C.D., E-mail: l_chandrakant@yahoo.com

    2014-01-01

    Graphical abstract: Schematic model indicating ZnO nanorods by CBD (Z{sub 1}) and nanograins by SILAR (Z{sub 2}). - Highlights: • Simple methods for the synthesis of ZnO thin films. • Comparative study of physico-chemical properties of ZnO thin films prepared by CBD and SILAR methods. • CBD outperforms SILAR method. - Abstract: In the present work, nanocrystalline zinc oxide (ZnO) thin films have been successfully deposited onto glass substrates by simple and economical chemical bath deposition (CBD) and successive ionic layer adsorption reaction (SILAR) methods. These films were further characterized for their structural, optical, surface morphological and wettability properties. The X-ray diffraction (XRD) patterns for both CBD and SILAR deposited ZnO thin films reveal the highly crystalline hexagonal wurtzite structure. From optical studies, band gaps obtained are 2.9 and 3.0 eV for CBD and SILAR deposited thin films, respectively. The scanning electron microscope (SEM) patterns show growth of well defined randomly oriented nanorods and nanograins on the CBD and SILAR deposited samples, respectively. The resistivity of CBD deposited films (10{sup 2} Ω cm) is lower than that of SILAR deposited films (10{sup 5} Ω cm). Surface wettability studies show hydrophobic nature for both films. From the above results it can be concluded that CBD grown ZnO thin films show better properties as compared to SILAR method.

  17. A comparative study of physico-chemical properties of CBD and SILAR grown ZnO thin films

    International Nuclear Information System (INIS)

    Jambure, S.B.; Patil, S.J.; Deshpande, A.R.; Lokhande, C.D.

    2014-01-01

    Graphical abstract: Schematic model indicating ZnO nanorods by CBD (Z 1 ) and nanograins by SILAR (Z 2 ). - Highlights: • Simple methods for the synthesis of ZnO thin films. • Comparative study of physico-chemical properties of ZnO thin films prepared by CBD and SILAR methods. • CBD outperforms SILAR method. - Abstract: In the present work, nanocrystalline zinc oxide (ZnO) thin films have been successfully deposited onto glass substrates by simple and economical chemical bath deposition (CBD) and successive ionic layer adsorption reaction (SILAR) methods. These films were further characterized for their structural, optical, surface morphological and wettability properties. The X-ray diffraction (XRD) patterns for both CBD and SILAR deposited ZnO thin films reveal the highly crystalline hexagonal wurtzite structure. From optical studies, band gaps obtained are 2.9 and 3.0 eV for CBD and SILAR deposited thin films, respectively. The scanning electron microscope (SEM) patterns show growth of well defined randomly oriented nanorods and nanograins on the CBD and SILAR deposited samples, respectively. The resistivity of CBD deposited films (10 2 Ω cm) is lower than that of SILAR deposited films (10 5 Ω cm). Surface wettability studies show hydrophobic nature for both films. From the above results it can be concluded that CBD grown ZnO thin films show better properties as compared to SILAR method

  18. Electrical and optical properties of a n-type ZnO thin film deposited on a Si substrate by using a double RF Co-sputtering method

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jonghyun; Choi, Wonjoon; Kim, Chaeok; Hong, Jinpyo; Nahm, Tschanguh [Hanyang University, Seoul (Korea, Republic of); Cheong, Hyeonsik [Sogang University, Seoul (Korea, Republic of)

    2006-09-15

    Outstanding n-type ZnO thin films were prepared on Si substrates by utilizing a double RF cosputtering method. Our unique double RF technique has many attractive merits for synthesizing ZnO thin films with excellent optoelectronic properties at various temperatures. The ZnO thin films were also post-annealed at various temperatures. The X-ray diffraction patterns and X-ray photoelectron spectroscopy indicated well-grown ZnO films with a (002) orientation and with gorgeous chemically bond states, respectively. In addition, photoluminescence measurements indicated a band-gap of 3.4 eV in the ZnO films. The scanning electron microscopy images showed that the as-grown ZnO thin film had hexagonal column shapes, such as hexagonal rods. The ZnO film exhibited an UV light response with a cut-off wavelength of {approx}370 nm at room temperature.

  19. Template-controlled piezoactivity of ZnO thin films grown via a bioinspired approach

    Directory of Open Access Journals (Sweden)

    Nina J. Blumenstein

    2017-01-01

    Full Text Available Biomaterials are used as model systems for the deposition of functional inorganic materials under mild reaction conditions where organic templates direct the deposition process. In this study, this principle was adapted for the formation of piezoelectric ZnO thin films. The influence of two different organic templates (namely, a carboxylate-terminated self-assembled monolayer and a sulfonate-terminated polyelectrolyte multilayer on the deposition and therefore on the piezoelectric performance was investigated. While the low negative charge of the COOH-SAM is not able to support oriented attachment of the particles, the strongly negatively charged sulfonated polyelectrolyte leads to texturing of the ZnO film. This texture enables a piezoelectric performance of the material which was measured by piezoresponse force microscopy. This study shows that it is possible to tune the piezoelectric properties of ZnO by applying templates with different functionalities.

  20. Optical characterization of Er-implanted ZnO films formed by sol-gel method

    International Nuclear Information System (INIS)

    Fukudome, T.; Kaminaka, A.; Isshiki, H.; Saito, R.; Yugo, S.; Kimura, T.

    2003-01-01

    In this paper, we report on the 1.54 μm photoluminescence (PL) of Er-implanted ZnO thin films formed by a sol-gel method on Si substrates. In spite of the polycrystalline structure of the sol-gel ZnO thin films, they showed strong PL emissions due to the near band edge recombination at 375 nm as well as the Er-related luminescence at 1.54 μm. The Er-related luminescence showed no decrease (quench) in the intensity up to the Er concentration of 1.5 x 10 21 cm -3 . The PL intensity of Er-implanted ZnO at 1.54 μm was found to be as strong as Er-doped PS (porous Si) at 20 K, and the intensity reduced to 1/3 at room temperature

  1. Role of vacancy defects in Al doped ZnO thin films for optoelectronic devices

    Science.gov (United States)

    Rotella, H.; Mazel, Y.; Brochen, S.; Valla, A.; Pautrat, A.; Licitra, C.; Rochat, N.; Sabbione, C.; Rodriguez, G.; Nolot, E.

    2017-12-01

    We report on the electrical, optical and photoluminescence properties of industry-ready Al doped ZnO thin films grown by physical vapor deposition, and their evolution after annealing under vacuum. Doping ZnO with Al atoms increases the carrier density but also favors the formation of Zn vacancies, thereby inducing a saturation of the conductivity mechanism at high aluminum content. The electrical and optical properties of these thin layered materials are both improved by annealing process which creates oxygen vacancies that releases charge carriers thus improving the conductivity. This study underlines the effect of the formation of extrinsic and intrinsic defects in Al doped ZnO compound during the fabrication process. The quality and the optoelectronic response of the produced films are increased (up to 1.52 mΩ \\cdotcm and 3.73 eV) and consistent with the industrial device requirements.

  2. Study of nanocluster-assembled ZnO thin films by nanocluster-beam deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Zhiwei; Lei, Wei; Zhang, Xiaobing [School of Electronic Science and Engieering, Southeast University, Nanjing (China); Tay, Beng Kang [School of Electronical and Electronic Engineering, Nanyang Technological University, Nanyang (Singapore)

    2012-01-15

    Nanocluster-assembled ZnO thin films were obtained by nanocluster-beam deposition, in which nanoclusters were produced by a magnetron sputtering gas aggregation source. Two kinds of ZnO thin films were obtained using this method with the one grown under the on-line heating temperature of 700 C, and the other grown without on-line heating. Film microstructure and optical properties are investigated by various diagnostic techniques. It was found that both of film microstructure of ZnO thin films keep wurtzite structure as that of ZnO bulk materials. The averaged particle size for the film grown without on-line heating is around 6 nm, which is a little lower than that grown with the on-line heating. It was also found that as increasing the wavelength, both of the absorbance spectra for the films decrease sharply near ultra-visible to extend slowly to the visible and infrared wavelength range. For the film grown without on-line heating, the bandgap energy was estimated to 3.77 eV, while for the film grown with on-line heating, the bandgap energy was redshift to 3.71 eV. Similar behavior was also found for PL spectra analysis, where PL spectrum exhibited a peak centered at 3.31 eV without on-line heating, while it redshift to 3.20 eV with on-line heating. The mechanisms behind these behaviors were presented in this article. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Formulation and Characterization of Cu Doped ZnO Thick Films as LPG Gas Sensor

    Directory of Open Access Journals (Sweden)

    A. V. PATIL

    2010-12-01

    Full Text Available Thick films of pure and various concentrations (1 wt. %, 3 wt. %, 5 wt. %, 7 wt. % and 10 wt. % of Cu-doped ZnO were prepared on alumina substrates using a screen printing technique. These films were fired at a temperature of 700ºC for two hours in an air atmosphere. Morphological, compositional and structural properties of the samples were obtained using the scanning electron microscopy (SEM, Energy dispersive spectroscopy (EDAX and X-ray diffraction techniques respectively. The LPG gas sensing properties of these thick films were investigated at different operating temperatures and LPG gas concentrations. The surface resistance of thick films decreases when exposed to LPG gas. The Cu doped films show significant sensitivity to LPG gas than pure ZnO film. 5 wt. % Cu-doped ZnO film was found to be more sensitive (87.3 % to LPG gas exposed at 300 oC than other doping concentrations with fast response and recovery time.

  4. TUNABLE MAGNETIC AND ELECTRICAL PROPERTIES OF Co-DOPED ZnO FILMS BY VARYING OXYGEN PARTIAL PRESSURE

    OpenAIRE

    L. G. WANG; H. W. ZHANG; X. L. TANG; Y. X. LI; Z. Y. ZHONG

    2011-01-01

    High quality Co-doped ZnO films with good reproducibility have been prepared under different oxygen partial pressure by radio-frequency magnetron sputtering. These films were characterized using numerous characterization techniques including X-ray diffraction, electrical transport, and magnetization measurements. The effect of oxygen partial pressure on the structural, magnetic, and electrical properties of Co-doped ZnO films has been systematically studied. It was found that the structural, ...

  5. Growth and characterization of nonpolar (10-10) ZnO transparent conductive oxide on semipolar (11–22) GaN-based light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki-Wook; Choi, Nak-Jung [Department of Nano-Optical Engineering, Korea Polytechnic University, Siheung, Gyeonggi-do, 429-839 (Korea, Republic of); Kim, Kyoung-Bo [Department of Metallurgical and Materials Engineering, Inha Technical College, Incheon, 402-752 (Korea, Republic of); Kim, Moojin [Department of Renewable Energy, Jungwon University, 85, Munmu-ro, Goesan-eup, Goesan-gun, Chungbuk, 367-805 (Korea, Republic of); Lee, Sung-Nam, E-mail: snlee@kpu.ac.kr [Department of Nano-Optical Engineering, Korea Polytechnic University, Siheung, Gyeonggi-do, 429-839 (Korea, Republic of)

    2016-05-05

    We have grown thin films of nonpolar m-plane (10-10) ZnO on a semipolar (11–22) GaN template by atomic layer deposition (ALD) at low growth temperatures (<200 °C). The surface morphology of the ZnO film is found to be an arrowhead-like structure, which is a typical surface structure of the semipolar (11–22) GaN films. On increasing the growth temperature of the ZnO films, the concentration and mobility of the charge carriers in the ZnO film are increased. However, the optical transmittance decreases with an increase in the growth temperature. Based on these results, we have fabricated semipolar (11–22) GaN-based light-emitting diodes (LEDs) with nonpolar m-plane ZnO film as a transparent conductive oxide (TCO) to improve the light extraction efficiency. In spite of a decrease in the optical transmittance, the operation voltage of semipolar (11–22) GaN-based LEDs is found to decrease with an increase in the growth temperature, which might be due to the improvements in the electrical properties and current spreading effect, resulting in an increase in the optical output power. - Highlights: • Polarity control of ZnO film grown in m-/c-sapphire and semipolar GaN template. • Achievement of high quality nonpolar m-plane ZnO flims on semipolar (11–22) GaN template. • The simultaneous improvements of carrier concentration and mobility in the nonpolar ZnO TCO flims. • Nonpolar ZnO TCO increases current spreading length and light output power of semipolar GaN-LED.

  6. Defect induced activation of Raman silent modes in rf co-sputtered Mn doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Harish Kumar [Department of Physics and Astrophysics, University of Delhi, Delhi-110007 (India); Sreenivas, K [Department of Physics and Astrophysics, University of Delhi, Delhi-110007 (India); Katiyar, R S [Department of Physics, University of Puerto Rico, San Juan, PR 00931-3343 (Puerto Rico); Gupta, Vinay [Department of Physics and Astrophysics, University of Delhi, Delhi-110007 (India)

    2007-10-07

    We study the influence of Mn doping on the vibrational properties of rf sputtered ZnO thin films. Raman spectra of the Mn doped ZnO samples reveal two additional vibrational modes, in addition to the host phonon modes, at 252 and 524 cm{sup -1}. The intensity of the additional modes increases continuously with Mn concentration in ZnO and can be used as an indication of Mn incorporation in ZnO. The modes are assigned to the activation of ZnO silent modes due to relaxation of Raman selection rules produced by the breakdown of the translational symmetry of the crystal lattice with the incorporation of Mn at the Zn site. Furthermore, the A{sub 1} (LO) mode is observed with very high intensity in the Raman spectra of undoped ZnO thin film and is attributed to the built-in electric field at the grain boundaries.

  7. Defect induced activation of Raman silent modes in rf co-sputtered Mn doped ZnO thin films

    International Nuclear Information System (INIS)

    Yadav, Harish Kumar; Sreenivas, K; Katiyar, R S; Gupta, Vinay

    2007-01-01

    We study the influence of Mn doping on the vibrational properties of rf sputtered ZnO thin films. Raman spectra of the Mn doped ZnO samples reveal two additional vibrational modes, in addition to the host phonon modes, at 252 and 524 cm -1 . The intensity of the additional modes increases continuously with Mn concentration in ZnO and can be used as an indication of Mn incorporation in ZnO. The modes are assigned to the activation of ZnO silent modes due to relaxation of Raman selection rules produced by the breakdown of the translational symmetry of the crystal lattice with the incorporation of Mn at the Zn site. Furthermore, the A 1 (LO) mode is observed with very high intensity in the Raman spectra of undoped ZnO thin film and is attributed to the built-in electric field at the grain boundaries

  8. Characterization of CBD grown ZnO films with high c-axis orientation

    Energy Technology Data Exchange (ETDEWEB)

    Kahraman, S., E-mail: suleymanmku@gmail.com [Physics Department, Mustafa Kemal University, 31034 Hatay (Turkey); Bayansal, F.; Cetinkara, H.A.; Cakmak, H.M.; Gueder, H.S. [Physics Department, Mustafa Kemal University, 31034 Hatay (Turkey)

    2012-06-15

    Highly c-axis oriented ZnO films were deposited on seeded glass substrates. Successive ionic layer adsorption and reaction (SILAR) method and chemical bath deposition (CBD) method were used to obtain seed layers and ZnO films. To see the effects of seed layer and deposition time, structural (e.g. grain size, microstrain and dislocation density), morphological, and electrical (e.g. resistivity, activation energy) properties of the films were investigated by scanning electron microscopy, X-ray diffraction, and four point probe method. From the SEM images, resultant structures were found as well defined nanorods nearly perpendicular to the substrate surfaces and densely cover the substrates. The XRD patterns showed that ZnO films have hexagonal wurtzite structure with a preferred c-axis orientation along (002) plane. C-axis orientation was also supported by texture coefficient calculations. The lattice parameters of the structures were determined as a = 3.2268 A, b = 5.2745 A, {alpha} = {beta} = 90 Degree-Sign and {gamma} = 120 Degree-Sign . From the XRD patterns, it was revealed that, microstrain and dislocation density values of the structures decreased whereas grain size increased. This was attributed to enhancement occurred in lattice structure of the ZnO films. Activation energy values of the films were found in between 0.12 and 0.15 eV from the dark electrical resistivity-temperature characteristics in a temperature range of 300-500 K. - Highlights: Black-Right-Pointing-Pointer Hexagonal wurtzite structured ZnO nanorods (preferred orientation along (002) plane). Black-Right-Pointing-Pointer Electrical activation energies were calculated in between 0.12 and 0.15 eV. Black-Right-Pointing-Pointer Microstrain and dislocation density decreased with increasing deposition time. Black-Right-Pointing-Pointer Increasing deposition time was resulted in an increase in preferred orientation.

  9. Effect of Er3+ doping on structural, morphological and photocatalytical properties of ZnO thin films

    Science.gov (United States)

    Bouhouche, S.; Bensouici, F.; Toubane, M.; Azizi, A.; Otmani, A.; Chebout, K.; Kezzoula, F.; Tala-Ighil, R.; Bououdina, M.

    2018-05-01

    In this research work, structure, microstructure, optical and photocatalytic properties of undoped and Erbium doped nanostructured ZnO thin films prepared by sol-gel dip-coating are investigated. X-ray diffraction (XRD) analysis indicates that the deposited films crystallize within the hexagonal wurtzite-type structure with a preferential growth orientation along (002) plane. Morphological observations using scanning electron microscopy (SEM) reveal important influence of Er concentration; displaying homogeneous and dense aspect for undoped to 0.3% then grid-like morphology for 0.4 and 0.5%. UV/vis/NIR transmittance spectroscopy spectra display a transmittance over 70%, and small variation in the energy gap energy 3.263–3.278 eV. Wettability test of ZnO thin films surface ranges from hydrophilic aspect for pure ZnO to hydrophobic one for Er doped ZnO, and the contact angle is found to increase from 58.7° for pure ZnO up to 98.4° for 0.4% Er doped ZnO. The photocatalytic activity measurements evaluated using the degradation of methylene blue (MB) under UV light irradiation demonstrate that undoped ZnO film shows higher photocatalytic activity compared to Er doped ZnO films, which may be attributed to the deterioration of films’crystallinity resulting in lower transmittance.

  10. Enhanced optical band-gap of ZnO thin films by sol-gel technique

    Energy Technology Data Exchange (ETDEWEB)

    Raghu, P., E-mail: dpr3270@gmail.com; Naveen, C. S.; Shailaja, J.; Mahesh, H. M., E-mail: hm-mahesh@rediffmail.com [Thin Film and Solar Cell Laboratory, Department of Electronic Science, Bangalore University, Jnanabharathi, Bangalore -560056 (India)

    2016-05-06

    Transparent ZnO thin films were prepared using different molar concentration (0.1 M, 0.2 M & 0.8 M) of zinc acetate on soda lime glass substrates by the sol-gel spin coating technique. The optical properties revealed that the transmittance found to decrease with increase in molar concentration. Absorption edge showed that the higher concentration film has increasingly red shifted. An increased band gap energy of the thin films was found to be direct allowed transition of ∼3.9 eV exhibiting their relevance for photovoltaic applications. The extinction coefficient analysis revealed maximum transmittance with negligible absorption coefficient in the respective wavelengths. The results of ZnO thin film prepared by sol-gel technique reveal its suitability for optoelectronics and as a window layer in solar cell applications.

  11. Transition from diamagnetic to ferromagnetic state in laser ablated nitrogen doped ZnO thin films

    Directory of Open Access Journals (Sweden)

    Kajal Jindal

    2015-02-01

    Full Text Available Transition from room temperature diamagnetic to ferromagnetic state in N doped ZnO (ZnO:N films grown by pulsed laser deposition with tunable energy density has been identified. ZnO:N films deposited with moderate laser energy density of 2.5 J/cm2 are single phase and nearly defect free having N dopant substitution at O sites in ZnO lattice, exhibiting intrinsic ferromagnetism. When energy density reduces (<2.5 J/cm2, defects in ZnO:N film degrades ferromagnetism and exhibit diamagnetic phase when grown at energy density of 1.0 J/cm2. Growth kinetics, which in turn depends on laser energy density is playing important role in making transition from ferromagnetic to diamagnetic in ZnO:N films.

  12. Near band edge emission characteristics of sputtered nano-crystalline ZnO films

    International Nuclear Information System (INIS)

    Kunj, Saurabh; Sreenivas, K.

    2016-01-01

    Sputtered zinc oxide (ZnO) thin films deposited on unheated glass substrate under different sputtering gas mixtures (Ar+O_2) have been investigated using X-ray diffraction and photo luminescence spectroscopy. Earlier reported studies on ZnO films prepared by different techniques exhibit either a sharp/broad near band edge (NBE) emission peak depending on the crystalline quality of the film. In the present study zinc oxide films, grown on unheated substrates, are seen to possess a preferred (002) orientation with a microstructure consisting of clustered nano-sized crystallites. The splitting in the near band edge emission (NBE) into three characteristic peaks is attributed to quantum confinement effect, and is observed specifically under an excitation of 270 nm. Deep level emission (DLE) in the range 400 to 700 nm is not observed indicating absence of deep level radiative defects.

  13. Near band edge emission characteristics of sputtered nano-crystalline ZnO films

    Science.gov (United States)

    Kunj, Saurabh; Sreenivas, K.

    2016-05-01

    Sputtered zinc oxide (ZnO) thin films deposited on unheated glass substrate under different sputtering gas mixtures (Ar+O2) have been investigated using X-ray diffraction and photo luminescence spectroscopy. Earlier reported studies on ZnO films prepared by different techniques exhibit either a sharp/broad near band edge (NBE) emission peak depending on the crystalline quality of the film. In the present study zinc oxide films, grown on unheated substrates, are seen to possess a preferred (002) orientation with a microstructure consisting of clustered nano-sized crystallites. The splitting in the near band edge emission (NBE) into three characteristic peaks is attributed to quantum confinement effect, and is observed specifically under an excitation of 270 nm. Deep level emission (DLE) in the range 400 to 700 nm is not observed indicating absence of deep level radiative defects.

  14. Near band edge emission characteristics of sputtered nano-crystalline ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Kunj, Saurabh; Sreenivas, K. [Department of Physics & Astrophysics, University of Delhi, Delhi 110007 INDIA (India)

    2016-05-06

    Sputtered zinc oxide (ZnO) thin films deposited on unheated glass substrate under different sputtering gas mixtures (Ar+O{sub 2}) have been investigated using X-ray diffraction and photo luminescence spectroscopy. Earlier reported studies on ZnO films prepared by different techniques exhibit either a sharp/broad near band edge (NBE) emission peak depending on the crystalline quality of the film. In the present study zinc oxide films, grown on unheated substrates, are seen to possess a preferred (002) orientation with a microstructure consisting of clustered nano-sized crystallites. The splitting in the near band edge emission (NBE) into three characteristic peaks is attributed to quantum confinement effect, and is observed specifically under an excitation of 270 nm. Deep level emission (DLE) in the range 400 to 700 nm is not observed indicating absence of deep level radiative defects.

  15. A study on the evolution of dielectric function of ZnO thin films with decreasing film thickness

    International Nuclear Information System (INIS)

    Li, X. D.; Chen, T. P.; Liu, P.; Liu, Y.; Liu, Z.; Leong, K. C.

    2014-01-01

    Dielectric function, band gap, and exciton binding energies of ultrathin ZnO films as a function of film thickness have been obtained with spectroscopic ellipsometry. As the film thickness decreases, both real (ε 1 ) and imaginary (ε 2 ) parts of the dielectric function decrease significantly, and ε 2 shows a blue shift. The film thickness dependence of the dielectric function is shown related to the changes in the interband absorption, discrete-exciton absorption, and continuum-exciton absorption, which can be attributed to the quantum confinement effect on both the band gap and exciton binding energies

  16. Annealing impact on the structural and photoluminescence properties of ZnO thin films on Ag substrates

    International Nuclear Information System (INIS)

    Xu, Linhua; Zheng, Gaige; Lai, Min; Pei, Shixin

    2014-01-01

    Graphical abstract: The Gaussian fitting indicates that the PL spectra of the ZnO thin films include four emission peaks which are centered at 380, 520, 570 and 610 nm, respectively. The ZnO thin film deposited on an Ag substrate shows a stronger green emission and a weaker UV emission than the ZnO thin film directly deposited on a Si substrate annealed at 400 °C. With the rise of annealing temperature, the visible emission intensity and wavelength are largely changed. Highlights: • ZnO thin films have been prepared on Ag substrates by sol–gel method. • The Ag substrates have a great effect on the photoluminescence of ZnO thin films. • All the films exhibit three visible emission bands including green, yellow and red. • Annealing causes a large change of the visible emission intensity and wavelength. -- Abstract: In this work, ZnO thin films were prepared by sol–gel method on Ag substrates. The structural and optical properties of the films annealed at different temperatures were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence, respectively. The results of XRD showed that all the ZnO thin films had a wurtzite phase and were preferentially oriented along the c-axis direction. The sample annealed at 400 °C exhibited better crystalline quality than the ZnO thin film directly deposited on a Si substrate annealed at the same temperature. The photoluminescence spectra showed that ZnO thin films had an ultraviolet emission band and three visible emission bands including green, yellow and red band. The sample annealed at 400 °C exhibited a stronger green emission and a weaker ultraviolet emission compared with the ZnO thin film deposited on a Si substrate annealed at the same temperature. The difference of the luminescence properties was thought to be originated from different substrates. As for the ZnO films on Ag substrates, the increase of annealing temperature led to different changes of visible emissions

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

    Indian Academy of Sciences (India)

    Administrator

    of zinc acetate on glass substrates at 450 °C. Effect of precursor concentration on structural and optical pro- perties has ... dependence of photoresponse properties of sprayed ZnO thin films on ... randomly oriented flake-like grains. The grains ...

  18. Study on Crystallographic Properties of Li Doped ZnO Thin Films

    International Nuclear Information System (INIS)

    Khine Khine Linn; Than Than Win; Yin Maung Maung; Ko Ko Kyaw Soe

    2008-03-01

    Li-doped ZnO film is prepared on highly polished Si substrate. The process temperature are range from 400 0 C to 600 0 C and maintained 1 hr for homogenization. According to the experimental results, it is significant that the growth chemistry is quite feasible and expected to be crystalline at above-mentioned temperatures.

  19. Hydrogen absorption in thin ZnO films prepared by pulsed laser deposition

    Czech Academy of Sciences Publication Activity Database

    Melikhova, O.; Čížek, J.; Lukáč, F.; Vlček, M.; Novotný, Michal; Bulíř, Jiří; Lančok, Ján; Anwand, W.; Brauer, G.; Connolly, J.; McCarthy, E.; Krishnamurthy, S.; Mosnier, J.-P.

    2013-01-01

    Roč. 580, suppl. 1 (2013), S40-S43 ISSN 0925-8388 R&D Projects: GA ČR(CZ) GAP108/11/0958 Institutional support: RVO:68378271 Keywords : defects * hydrogen * positron annihilation * thin films * ZnO Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.726, year: 2013

  20. Research on the properties of ZnO films by 1/f noise measurement

    NARCIS (Netherlands)

    Leroy, G.; Gest, J.; Yang, L.; Vandamme, L.K.J.

    2013-01-01

    ZnO films were deposited by de sputtering technique on glass and Pt/Si substrates. The effect of growth parameters is investigated on sheet resistance and noise. The 1/f noise normalized for bias, frequency and unit area, Cus is proportional with the sheet resistance Rsh. We found that the noise

  1. Fabricating ZnO single microwire light-emitting diode with transparent conductive ITO film

    International Nuclear Information System (INIS)

    Xu, Yingtian; Dai, Jun; Shi, Zhifeng; Long, Beihong; Wu, Bin; Cai, Xupu; Chu, Xianwei; Du, Guotong; Zhang, Baolin; Yin, Jingzhi

    2014-01-01

    In this paper, n-ZnO single microwire/p + -Si heterojunction LEDs are fabricated using the transparent conductive ITO film as an electrode. A distinct UV emission resulting from free exciton recombination in a ZnO single microwire is observed in the electroluminescence. Size difference of ZnO single microwire shows significant influence on emission efficiency. The EL spectra of n-ZnO single microwire/p-Si heterostructure exhibited relatively stronger UV emission which was compared with the EL spectra of n-ZnO single nanowire/p-Si heterostructure and n-ZnO film/p-Si heterostructure, respectively. - Highlights: • The ZnO microwires were synthesized with a vapor phase transport method. • ZnO single microwire/Si LEDs were fabricated using the ITO film as an electrode. • The EL spectra had been compared with n-ZnO film/p-Si heterostructure. • The EL spectra had been compared with n-ZnO single nanowire/p-Si heterostructure

  2. Preparation of cadmium-doped ZnO thin films by SILAR and their ...

    Indian Academy of Sciences (India)

    Cadmium-doped zinc oxide (Cd : ZnO) thin films were deposited from sodium zincate bath .... of complex ion on the substrate followed by reaction of the .... Intensity (a.u.). 0. 500 .... trum confirmed the presence of Zn, O and Cd elements in the.

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

    International Nuclear Information System (INIS)

    Vähä-Nissi, Mika; Pitkänen, Marja; Salo, Erkki; Kenttä, Eija; Tanskanen, Anne; Sajavaara, Timo; Putkonen, Matti; Sievänen, Jenni; Sneck, Asko; Rättö, Marjaana; Karppinen, Maarit; Harlin, Ali

    2014-01-01

    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 2 O 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 2 O 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 2 O 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

  4. Characterization of n and p-type ZnO thin films grown by pulsed filtered cathodic vacuum arc system

    International Nuclear Information System (INIS)

    Kavak, H.; Erdogan, E.N.; Ozsahin, I.; Esen, R.

    2010-01-01

    Full text : Semiconductor ZnO thin films with wide band gap attract much interest due to their properties such as chemical stability in hydrogen plasma, high optical transparency in the visible and nearinfrared region. Due to these properties ZnO oxide is a promising materials for electronic or optoelectronic applications such as solar cell (as an antireflecting coating and a transparent conducting material), gas sensors, surface acoustic wave devices. The purpose of this research is to improve the properties of n and p-type ZnO thin films for device applications. Polycrystalline ZnO is naturally n-type and very difficult to dope to make p-type. Therefore nowadays hardly produced p-type ZnO attracts a lot of attention. Nitrogen considered as the best dopant for p-type ZnO thin films.The transparent, conductive and very precise thickness controlled n and p-type semiconducting nanocrystalline ZnO thin films were prepared by pulsed filtered cathodic vacuum arc deposition (PFCVAD) method. Structural, optical and electrical properties of these films were investigated. And also photoluminescence properties of these films were investigated. Transparent p-type ZnO thin films were produced by oxidation of PFCVAD deposited zinc nitride. Zinc nitride thin films were deposited with various thicknesses and under different oxygen pressures on glass substrates. Zinc nitride thin films, which were deposited at room temperatures, were amorphous and the optical transmission was below 70%. For oxidation zinc nitride, the sample was annealed in air starting from 350 degrees Celsium up to 550 degrees Celsium for one hour duration. These XRD patterns imply that zinc nitride thin films converted to zinc oxide thin films with the same hexagonal crystalline structures of ZnO. The optical measurements were made for each annealing temperature and the optical transmissions of ZnO thin films were found better than 90 percent in visible range after annealing over 350 degrees Celsium. By

  5. Enhanced magnetic properties of chemical solution deposited BiFeO3 thin film with ZnO buffer layer

    International Nuclear Information System (INIS)

    Rajalakshmi, R.; Kambhala, Nagaiah; Angappane, S.

    2012-01-01

    Highlights: ► Enhanced magnetization of BiFeO 3 is important for strong magnetoelectric coupling. ► BiFeO 3 film with ZnO buffer layer was successfully synthesized by chemical method. ► Magnetization of BiFeO 3 has increased by more than 10 times with ZnO buffer layer. ► A mechanism for enhancement in ferromagnetism of BiFeO 3 film is proposed. - Abstract: Magnetic properties of BiFeO 3 films deposited on Si substrates with and without ZnO buffer layer have been studied in this work. We adopted the chemical solution deposition method for the deposition of BiFeO 3 as well as ZnO films. The x-ray diffraction measurements on the deposited films confirm the formation of crystalline phase of BiFeO 3 and ZnO films, while our electron microscopy measurements help to understand the morphology of few micrometers thick films. It is found that the deposited ZnO film exhibit a hexagonal particulate surface morphology, whereas BiFeO 3 film fully covers the ZnO surface. Our magnetic measurements reveal that the magnetization of BiFeO 3 has increased by more than ten times in BiFeO 3 /ZnO/Si film compared to BiFeO 3 /Si film, indicating the major role played by ZnO buffer layer in enhancing the magnetic properties of BiFeO 3 , a technologically important multiferroic material.

  6. 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.

  7. Formation mechanisms of metallic Zn nanodots by using ZnO thin films deposited on n-Si substrates

    International Nuclear Information System (INIS)

    Yuk, J. M.; Lee, J. Y.; Kim, Y.; No, Y. S.; Kim, T. W.; Choi, W. K.

    2010-01-01

    High-resolution transmission electron microscopy and energy dispersive x-ray spectroscopy results showed that metallic Zn nanodots (NDs) were fabricated through transformation of ZnO thin films by deposition of SiO x on ZnO/n-Si (100) heterostructures. The Zn NDs with various sizes and densities were formed due to the occurrence of the mass diffusion of atoms along the grain boundaries in the ZnO thin films. The fabrication mechanisms of metallic Zn NDs through transformation of ZnO thin films deposited on n-Si substrates are described on the basis of the experimental results.

  8. Effect of R.F. Power to the Structural Properties of ZnO Thin Films Deposited by Magnetron Sputtering

    International Nuclear Information System (INIS)

    Sin, N.D.M.; Rusop, M.

    2011-01-01

    The effect of RF power variation (100 watt∼400 watt ) on the zinc oxide (ZnO) thin films electrical, optical and structural properties were examined using current voltage (I-V) measurement, UV-Vis-NIR spectrophotometer, x-ray diffraction (XRD) and atomic force microscope (AFM). ZnO thin films were prepared at room temperature in pure argon atmosphere by a RF magnetron sputtering using ZnO target. The resistivity of thin film show the lowest at 300 watt. The absorption coefficient spectra obtained from UV-Vis-NIR spectrophotometer measurement show all films have low absorbance in visible and near infrared (IR) region but have high UV absorption properties using UV-VIS spectrophotometer (JASCO 670) . Highly oriented ZnO thin films [002] direction were obtained by using Rigaku Ultima IV. (author)

  9. 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.

  10. Single fiber UV detector based on hydrothermally synthesized ZnO nanorods for wearable computing devices

    Science.gov (United States)

    Eom, Tae Hoon; Han, Jeong In

    2018-01-01

    There has been increasing interest in zinc oxide (ZnO) based ultraviolet (UV) sensing devices over the last several decades owing to their diverse range of applications. ZnO has extraordinary properties, such as a wide band gap and high exciton binding energy, which make it a beneficial material for UV sensing device. Herein, we show a ZnO UV sensing device fabricated on a cylindrical Polyethylene terephthalate (PET) monofilament. The ZnO active layer was synthesized by hydrothermal synthesis and the Cu electrodes were deposited by radio frequency (RF) magnetron sputtering. Cu thin film was deposited uniformly on a single PET fiber by rotating it inside the sputtering chamber. Various characteristics were investigated by changing the concentration of the seed solution and the growth solution. The growth of ZnO nanorods was confirmed by Field Emission Scanning Electron Microscopy (FESEM) to see the surface state and structure, followed by X-ray Diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. Also, current-voltage (I-V) curves were obtained to measure photocurrent and conductance. Furthermore, falling response time, rising response time, and responsivity were calculated by analyzing current-time (I-t) curves.

  11. Improvement of Flame-made ZnO Nanoparticulate Thick Film Morphology for Ethanol Sensing

    Directory of Open Access Journals (Sweden)

    Sukon Phanichphant

    2007-05-01

    Full Text Available ZnO nanoparticles were produced by flame spray pyrolysis using zinc naphthenate as a precursor dissolved in toluene/acetonitrile (80/20 vol%. The particles properties were analyzed by XRD, BET. The ZnO particle size and morphology was observed by SEM and HR-TEM revealing spheroidal, hexagonal, and rod-like morphologies. The crystallite sizes of ZnO spheroidal and hexagonal particles ranged from 10-20 nm. ZnO nanorods were ranged from 10-20 nm in width and 20-50 nm in length. Sensing films were produced by mixing the nanoparticles into an organic paste composed of terpineol and ethyl cellulose as a vehicle binder. The paste was doctor-bladed onto Al2O3 substrates interdigitated with Au electrodes. The morphology of the sensing films was analyzed by optical microscopy and SEM analysis. Cracking of the sensing films during annealing process was improved by varying the heating conditions. The gas sensing of ethanol (25-250 ppm was studied at 400 °C in dry air containing SiC as the fluidized particles. The oxidation of ethanol on the surface of the semiconductor was confirmed by mass spectroscopy (MS. The effect of micro-cracks was quantitatively accounted for as a provider of extra exposed edges. The sensitivity decreased notably with increasing crack of sensing films. It can be observed that crack widths were reduced with decreasing heating rates. Crack-free of thick (5 μm ZnO films evidently showed higher sensor signal and faster response times (within seconds than cracked sensor. The sensor signal increased and the response time decreased with increasing ethanol concentration.

  12. Regulating effect of SiO2 interlayer on optical properties of ZnO thin films

    International Nuclear Information System (INIS)

    Xu, Linhua; Zheng, Gaige; Miao, Juhong; Su, Jing; Zhang, Chengyi; Shen, Hua; Zhao, Lilong

    2013-01-01

    ZnO/SiO 2 nanocomposite films with periodic structure were prepared by electron beam evaporation technique. Regulating effect of SiO 2 interlayer with various thicknesses on the optical properties of ZnO/SiO 2 thin films was investigated deeply. The analyses of X-ray diffraction show that the ZnO layers in ZnO/SiO 2 nanocomposite films have a wurtzite structure and are preferentially oriented along the c-axis while the SiO 2 layers are amorphous. The scanning electron microscope images display that the ZnO layers are composed of columnar grains and the thicknesses of ZnO and SiO 2 layers are all very uniform. The SiO 2 interlayer presents a significant modulation effect on the optical properties of ZnO thin films, which is reflected in the following two aspects: (1) the transmittance of ZnO/SiO 2 nanocomposite films is increased; (2) the photoluminescence (PL) of ZnO/SiO 2 nanocomposite films is largely enhanced compared with that of pure ZnO thin films. The ZnO/SiO 2 nanocomposite films have potential applications in light-emitting devices and flat panel displays. -- Highlights: ► ZnO/SiO 2 nanocomposite films with periodic structure were prepared by electron beam evaporation technique. ► The SiO 2 interlayer presents a significant modulation effect on the optical properties of ZnO thin films. ► The photoluminescence of ZnO/SiO 2 nanocomposite films is largely enhanced compared with that of pure ZnO thin films. ► The ZnO/SiO 2 nanocomposite films have potential applications in light-emitting devices and flat panel displays

  13. Residual stress and bending strength of ZnO films deposited on polyimide sheet by RF sputtering system

    Energy Technology Data Exchange (ETDEWEB)

    Kusaka, Kazuya, E-mail: kusaka@tokushima-u.ac.jp [Institute of Technology and Science, Tokushima University, 2-1, Minamijosanjima, Tokushima, Tokushima 7708506 (Japan); Maruoka, Yutaka, E-mail: ymaruoka1116@gmail.com [Graduate School of Advanced Technology and Science, Tokushima University, 2-1, Minamijosanjima, Tokushima, Tokushima 7708506 (Japan); Matsue, Tatsuya, E-mail: tmatsue@mat.niihama-nct.ac.jp [Department of Environmental Materials Engineering National Institute of Technology, NIIHAMA College, 7-1, Yakumo-cho, Niihama, Ehime 7928580 (Japan)

    2016-05-15

    Zinc oxide (ZnO) films were deposited on a soft polyimide sheet substrate by radio frequency sputtering with a ZnO powder target, and the films' crystal orientations and residual stress were investigated using x-ray diffraction as a function of substrate temperature. C-axis oriented ZnO films were achieved using this ZnO powder target method. The ZnO films exhibited high compressive residual stresses between −0.7 and −1.4 GPa. Finally, the authors examined the strength of the obtained film by applying tensile bending loads. No cracks were observed on the surfaces of the ZnO films after a bending test using cylinders with diameters >25 mm. After a bending test using a cylinder with a diameter of 19 mm, large cracks were formed on the films. Therefore, the authors concluded that the tensile bending strength of the obtained films was greater than ∼420 MPa.

  14. Growth of Ag thin films on ZnO(0 0 0 -1) investigated by AES and STM

    Energy Technology Data Exchange (ETDEWEB)

    Duriau, E. [Interuniversity Microelectronic Center (IMEC), SPDT-MCA, Kapeldreef 75, B-3001 Leuven (Belgium); Agouram, S. [Dpto. Fisica Aplicada y Electromagnetismo c/Dr. Moliner no. 50, 46100 Burjassot, Valencia (Spain); Laboratoire de Physique des Materiaux Electroniques (LPME), University of Namur, Rue de Bruxelles 61, B-5000 Namur (Belgium); Morhain, C. [Centre de Recherche sur l' HeteroEpitaxie et ses Applications (CRHEA), CNRS, Rue Bernard Gregory, F-06560 Valbonne Sophia-Antipolis (France); Seldrum, T. [Laboratoire de Physique des Materiaux Electroniques (LPME), University of Namur, Rue de Bruxelles 61, B-5000 Namur (Belgium); Sporken, R. [Laboratoire de Physique des Materiaux Electroniques (LPME), University of Namur, Rue de Bruxelles 61, B-5000 Namur (Belgium); Dumont, J. [Laboratoire de Physique des Materiaux Electroniques (LPME), University of Namur, Rue de Bruxelles 61, B-5000 Namur (Belgium)]. E-mail: jacques.dumont@fundp.ac.be

    2006-11-15

    The growth of Ag films on ZnO(0 0 0 -1) has been investigated by Auger electron spectroscopy (AES) and scanning tunneling microscopy (STM). A high density of islands is nucleated at the earliest stages of the growth. An upstepping mechanism causes these islands to coalesce while the uncovered fraction of the ZnO surface remains constant (30%)

  15. Red photoluminescence and band edge shift from ZnO thin films

    International Nuclear Information System (INIS)

    Marotti, Ricardo E.; Badan, Juan A.; Quagliata, Eduardo; Dalchiele, Enrique A.

    2007-01-01

    The red photoluminescence (PL) band (peaked between 610 and 640 nm) from electrochemically deposited ZnO thin films is studied. The absorption coefficient is obtained from diffuse reflectance measurements. The absorption band edge depends on deposition conditions. The PL peak follows the shift of the band edge. A similar correlation appears when cooling down to 20 K. This suggests that PL is due to a transition from an intrinsic shallow state to an intrinsic deep state. Comparing against ZnO samples showing green PL, the shallow nature of the state is confirmed

  16. Contact Resistance Reduction of ZnO Thin Film Transistors (TFTs) with Saw-Shaped Electrode

    KAUST Repository

    Park, Woojin

    2018-05-15

    We report a saw-shaped electrode architecture ZnO thin film transistor (TFT) for effectively increase channel width. Such a saw-shaped electrode has ~2 times longer contact line at the contact metal/ZnO channel junction. We experimentally observed an enhancement in the output drive current by 50% and reduction in the contact resistance by over 50%, when compared to a typical shaped electrode ZnO TFT consuming the same chip area. This performance enhancement is attributed to extension of channel width. This technique can contribute to device performance enhancement and especially reduction in the contact resistance which is a serious challenge.

  17. Optical and structural properties of thin films of ZnO at elevated temperature

    International Nuclear Information System (INIS)

    Kayani, Zohra N.; Afzal, Tosif; Riaz, Saira; Naseem, Shahzad

    2014-01-01

    Highlights: • Thin films of ZnO are prepared on glass substrates using dip-coating. • The X-ray diffraction showed that films are crystalline. • Optical measurements show that the film possesses high transmittance in visible region. • The transmission decreased with increased withdrawal speed. • The films has direct band gap in range 3.78-3.48 eV. - Abstract: Zinc oxide (ZnO) thin films were prepared on glass substrate by sol–gel dip-coating method. The paper presents the properties of zinc oxide thin films deposited on soda-lime-glass substrate via dip-coating technique, using zinc acetate dehydrate and ethanol as raw materials. The effect of withdrawal speed on the crystalline structure, surface morphology and optical properties of the thin films has been investigated using XRD, SEM and UV–Vis spectrophotometer. X-ray diffraction study shows that all the films have hexagonal wurtzite structure with preferred orientation in (0 0 2) direction and transmission spectra showed highly transparent films with band gap ranging from 3.78 to 3.48 eV

  18. Improvements to the hierarchically structured ZnO nanosphere based dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yongzhe; Wu Lihui; Liu Yanping; Xie Erqing, E-mail: zhangyzh04@126.co, E-mail: xieeq@lzu.edu.c [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China)

    2009-04-21

    Hierarchically structured ZnO nanospheres are synthesized by a wet-chemical method and ZnO sphere-consisting films are applied to dye-sensitized solar cells (DSSCs). It is found that the overall light-to-electricity conversion efficiency ({eta}) is significantly enhanced from 0.474% to 1.03% due to light scattering compared with the ZnO nanoparticle-based DSSC. However, the fill factor (FF) and open-circuit voltage (V{sub oc}) decrease obviously. After annealing the films in an oxygen environment and placing a ZnO blocking layer on the fluorine-doped SnO{sub 2} (FTO) conducting substrate, the FF and V{sub oc} are greatly improved and {eta} increases from 1.03% to 1.59% and 2.25%, respectively. According to the results of x-ray diffraction and photoluminescence, the significant improvements in the cell performances might be due to the suppression of the recombination and the decrease in the resistances existing in the cell.

  19. The effect of laser irradiation on electrical and structural properties of ZnO thin films

    Directory of Open Access Journals (Sweden)

    P Kameli

    2013-03-01

    Full Text Available  In this paper, ZnO thin film was prepared by sol-gel process on glass substrates. The deposited films were dried at 100 and 240 ˚C and then annealed at 300, 400 and 500 ˚C. The two-probe measurement showed that resistance of as-prepared films is very high. The KrF excimer (λ=248 nm laser irradiation with 1000 pulses, frequency of 1 Hz and 90 mJ/cm2 energy on surface of film resulted in the reduction of the films electrical resistance. X-ray diffraction (XRD patterns confirmed the improved hexagonal wurtzite structure of film, and AFM and FE-SEM analyses showed regular and spherical grain was formed on the surface. The particle size was increased from ~10 to ~30 nm after leaser irradiation. Generally, it was showed that electrical, structural and morphological properties of films improve considerably by laser irradiation.

  20. Microstructure and optical properties of nanocrystalline ZnO and ZnO:(Li or Al) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Oral, A. Yavuz [Department of Materials Science and Engineering, Gebze Institute of Technology, Gebze 41400 (Turkey)]. E-mail: aoral@gyte.edu.tr; Bahsi, Z. Banu [Department of Materials Science and Engineering, Gebze Institute of Technology, Gebze 41400 (Turkey); Aslan, M. Hasan [Department of Physics, Gebze Institute of Technology, Gebze 41400 (Turkey)

    2007-03-15

    Zinc oxide thin films (ZnO, ZnO:Li, ZnO:Al) were deposited on glass substrates by a sol-gel technique. Zinc acetate, lithium acetate, and aluminum chloride were used as metal ion sources in the precursor solutions. XRD analysis revealed that Li doped and undoped ZnO films formed single phase zincite structure in contrast to Al:ZnO films which did not fully crystallize at the annealing temperature of 550 deg. C. Crystallized films had a grain size under 50 nm and showed c-axis grain orientation. All films had a very smooth surface with RMS surface roughness values between 0.23 and 0.35 nm. Surface roughness and optical band tail values increased by Al doping. Compared to undoped ZnO films, Li doping slightly increased the optical band gap of the films.

  1. Investigation of electrical and optical properties of MEH-PPV: ZnO nanocomposite films for OLED applications

    Energy Technology Data Exchange (ETDEWEB)

    Azhar, N. E. A., E-mail: najwaezira@yahoo.com; Shafura, A. K., E-mail: shafura@ymail.com; Affendi, I. H. H., E-mail: irmahidayanti.halim@gmail.com; Shariffudin, S. S., E-mail: sobihana@gmail.com [NANO-ElecTronic Centre, Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Saurdi, I., E-mail: saurdy788@gmail.com [Faculty of Electrical Engineering, UiTM Sarawak, Kampus Kota Meranek, Sarawak (Malaysia); Alrokayan, Salman A. H., E-mail: dr.salman@alrokayan.com; Khan, Haseeb A., E-mail: khan-haseeb@yahoo.com [Research Chair of Targeting and Treatment of Cancer Using Nanoparticles Department of Biochemistry, College of Science, King Saud University (KSU), 245 Riyadh 11454 (Saudi Arabia); Rusop, M., E-mail: rusop@salam.uitm.edu.my [NANO-ElecTronic Centre, Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre, Institute of Science, Universiti Teknologi MARA (UiTM), Shah Alam, Selangor (Malaysia)

    2016-07-06

    Recent investigations of the promising materials for optoelectronic have been demonstrated by introducing n-type inorganic material into conjugated polymer. The optical and electrical of nanocomposite films based on poly[2-methoxy-5-(2’-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) and zinc oxide (ZnO) nanostructured of various deposition layers (1 to 3 layers) have been investigated. The MEH-PPV: ZnO nanocomposite films were deposited using spin-coating technique. The surface morphology nanocomposite films were characterized using field emission scanning electron microscope. From surface profiler measurement, we found that the thickness of nanocomposite films increased as deposition time increased. The optical properties were measured using photoluminescence spectroscope. The photoluminescence (PL) spectra showed that two deposition layers is the highest intensity at visible region (green emission) due to high energy transfer from particles to the polymer. The current density for two layers sample is due to aggregation of conjugated polymer chain hence form excited interchain exciton for optical excitation. This study will provide better performance and suitable for optoelectronic device especially OLEDs application.

  2. Structural and optical properties of Na-doped ZnO films

    Science.gov (United States)

    Akcan, D.; Gungor, A.; Arda, L.

    2018-06-01

    Zn1-xNaxO (x = 0.0-0.05) solutions have been synthesized by the sol-gel technique using Zinc acetate dihydrate and Sodium acetate which were dissolved into solvent and chelating agent. Na-doped ZnO nanoparticles were obtained from solutions to find phase and crystal structure. Na-doped ZnO films have been deposited onto glass substrate by using sol-gel dip coating system. The effects of dopant concentration on the structure, morphology, and optical properties of Na-doped ZnO thin films deposited on glass substrate are investigated. Characterization of Zn1-xNaxO nanoparticles and thin films are examined using differential thermal analysis (DTA)/thermogravimetric analysis (TGA), Scanning electron microscope (SEM) and X-Ray diffractometer (XRD). Optical properties of Zn1-xNaxO thin films were obtained by using PG Instruments UV-Vis-NIR spectrophotometer in 190-1100 nm range. The structure, morphology, and optical properties of thin films are presented.

  3. Superior environment resistance of quartz crystal microbalance with anatase TiO2/ZnO nanorod composite films

    International Nuclear Information System (INIS)

    Qiang, Wei; Wei, Li; Shaodan, Wang; Yu, Bai

    2015-01-01

    Graphical abstract: ZnO nanorod array being prepared by an in situ method on the QCM coated with Au film via hydrothermal process and surface modification with coated TiO 2 by sol–gel methods to form a superhydrophobic TiO 2 /ZnO composite film the anatase TiO 2 /ZnO nanorod composite film with a sharp, pencil-like structure exhibiting excellent superhydrophobicity (water contact angle of 155°), non-sticking water properties, and an autonomous cleaning property under UV irradiation. The anatase TiO 2 /ZnO nanorod composite film facilitates the precise measurement and extended lifetime of the QCM for the detection of organic gas molecules. - Highlights: • This work combines, for the first time, the advantage of the TiO 2 /ZnO composite film on photocatalysis and reversible super-hydrophobic and super-hydrophilic transition, and puts forward a solution to satisfy weatherability of quartz crystal microbalance in long-term application. • The anatase TiO 2 /ZnO nanorod composite film with pencil structure exhibit excellent super-hydrophobicity (water contact angle can reach 155°), no-sticking water properties and self-cleaning property under UV irradiation. • The photocatalysis and reversible super-hydrophobic and super-hydrophilic transition of the TiO 2 /ZnO nanorod composite film is stable in long-term application. - Abstract: The precise measurement of quartz crystal microbalance (QCM) in the detection and weighing of organic gas molecules is achieved due to excellent superhydrophobicity of a deposited film composite. Photocatalysis is utilized as a method for the self-cleaning of organic molecules on the QCM for extended long-term stability in the precision of the instrument. In this paper, ZnO nanorod array is prepared via in situ methods on the QCM coated with Au film via hydrothermal process. Subsequently, a TiO 2 /ZnO composite film is synthesized by surface modification with TiO 2 via sol–gel methods. Results show the anatase TiO 2 /ZnO nanorod

  4. Tuning the photovoltage of dye-sensitized solar cells based on electrodeposited ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Oekermann, Torsten [Institute of Physical Chemistry and Electrochemistry, Leibniz Universitaet Hannover, Callinstrasse 3- 3A, 30167 Hannover (Germany); Peter, Laurence [Department of Chemistry, University of Bath, Bath BA2 7AY (United Kingdom); Yoshida, Tsukasa [Graduate School of Engineering, Gifu University, Yanagido 1-1, Gifu 501-1193 (Japan)

    2007-07-01

    Nanoporous, fully crystalline ZnO films can be prepared by cathodic electrodeposition from aqueous solutions of Zn salts under the influence of structure-directing agents such as surfactants. Dye-sensitized solar cells (DSSC) based on such films have emerged as a possible alternative for nanocrystalline TiO2-based DSSC due to the very high porosity and good electron transport properties of the films. In this study, we have investigated the influence of the sensitizer dye molecules on the photovoltage of the ZnO-based DSSC. Impedance measurements show that the adsorbed dye molecules lead to a shift of the flatband potential of the ZnO. Electron pushing or withdrawing effects of the dye molecules and protonation or deprotonation of the ZnO surface are discussed as possible explanations. The shifts in the flatband potential partly explain the differences in the photovoltages caused by different dyes, however, differences in the electron injection efficiency and the blocking of electron back reaction by the dye molecules have to be taken into account, too, for a complete description.

  5. Effects of preannealing temperature of ZnO thin films on the performance of dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Kao, M.C.; Chen, H.Z.; Young, S.L. [Hsiuping Institute of Technology, Department of Electronic Engineering, Taichung (China)

    2010-03-15

    The preferred (002) orientation zinc oxide (ZnO) nanocrystalline thin films have been deposited on FTO-coated glass substrates by sol-gel spin-coating technology and rapid thermal annealing for use in dye-sensitized solar cells (DSSC). The effects of preannealing temperature (100 and 300 C) on the microstructure, morphology and optical properties of ZnO thin films were studied. The ZnO thin films were characterized by X-ray diffraction (XRD), scanning electron microscopic (SEM) and Brunauer-Emmett-Teller (BET) analysis. The photoelectric performance of DSSC was studied by I-V curve and the incident photon-to-current conversion efficiency (IPCE), respectively. From the results, the intensities of (002) peaks of ZnO thin films increases with increasing preannealing temperature from 100 C to 300 C. The increase in pore size and surface area of ZnO films crystallized at the increased preannealing temperature contributed to the improvement on the absorption of N3 dye onto the films, the short-circuit photocurrent (J{sub sc}) and open-circuit voltage (V{sub oc}) of DSSC. The higher efficiency ({eta}) of 2.5% with J{sub sc} and V{sub oc} of 8.2 mA/cm{sup 2} and 0.64 V, respectively, was obtained by the ZnO film preannealed at 300 C. (orig.)

  6. Annealing effect on the structural, morphological and electrical properties of TiO2/ZnO bilayer thin films

    Science.gov (United States)

    Khan, M. I.; Imran, S.; Shahnawaz; Saleem, Muhammad; Ur Rehman, Saif

    2018-03-01

    The effect of annealing temperature on the structural, morphological and electrical properties of TiO2/ZnO (TZ) thin films has been observed. Bilayer thin films of TiO2/ZnO are deposited on FTO glass substrate by spray pyrolysis method. After deposition, these films are annealed at 573 K, 723 K and 873 K. XRD shows that TiO2 is present in anatase phase only and ZnO is present in hexagonal phase. No other phases of TiO2 and ZnO are present. Also, there is no evidence of other compounds like Zn-Ti etc. It also shows that the average grain size of TiO2/ZnO films is increased by increasing annealing temperature. AFM (Atomic force microscope) showed that the average roughness of TiO2/ZnO films is decreased at temperature 573-723 K and then increased at 873 K. The calculated average sheet resistivity of thin films annealed at 573 K, 723 K and 873 K is 152.28 × 102, 75.29 × 102 and 63.34 × 102 ohm-m respectively. This decrease in sheet resistivity might be due to the increment of electron concentration with increasing thickness and the temperature of thin films.

  7. Synthesis and Characterization of Nanostructured ZnO Thick Film Gas Sensors Prepared by Screen Printing Method

    Directory of Open Access Journals (Sweden)

    R. Y. BORSE

    2010-12-01

    Full Text Available Nanosized ZnO was prepared by self propagating solution combustion synthesis method. The synthesized ZnO thick films were deposited on alumina substrate by using standard screen printing technique and fired at 700 0C. The films were characterized by X-ray diffractometer (XRD, Scanning Electron Microscopy (SEM and energy dispersive analysis of X-ray (EDAX. The electrical behaviors of ZnO thick films were investigated. From XRD spectra it is revealed that ZnO films are polycrystalline in nature. The average grain size of 87.44 nm has been estimated for the film fired at 700 0C using Scherrer’s formula. EDAX clearly shows the peaks corresponding to Zn and O element which confirms the successful growth of ZnO films. Gas sensing study for these samples shows high sensitivity and selectivity towards NO2 at all operating temperatures. The resistivity, TCR and activation energy of the ZnO films have been evaluated and discussed.

  8. Improvement in Performance of ZnO based DSC Prepared by Spraying Method

    Directory of Open Access Journals (Sweden)

    Rangga Winantyo

    2013-09-01

    Full Text Available This paper reports the effect of TiCl4 on the performance of ZnO based DSC. ZnO was used due to its stability against photo-corrosion  and  photochemical  properties  similar  to  TiO2.  Thin  films  of  nanocrystalline  ZnO  were  deposited  on transparent conducting oxide glass using spray  method. The ZnO  films  were treated using TiCl4. The cell’s efficiency was found to be 2.5% with TiCl4 post-treatment and 1.9% without TiCl4 post-treatment.

  9. Enhanced luminescence in Eu-doped ZnO nanocrystalline films

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Keigo, E-mail: ksuzuki@murata.com; Murayama, Koji; Tanaka, Nobuhiko [Murata Manufacturing Co., Ltd., 10-1, Higashikotari 1-chome, Nagaokakyo, Kyoto 617-8555 (Japan)

    2015-07-20

    We found an enhancement of Eu{sup 3+} emissions in Eu-doped ZnO nanocrystalline films fabricated by microemulsion method. The Eu{sup 3+} emission intensities were increased by reducing annealing temperatures from 633 K to 533 K. One possible explanation for this phenomenon is that the size reduction enhances the energy transfer from ZnO nanoparticles to Eu{sup 3+} ions. Also, the shift of the charge-transfer band into the low-energy side of the absorption edge is found to be crucial, which seems to expedite the energy transfer from O atoms to Eu{sup 3+} ions. These findings will be useful for the material design of Eu-doped ZnO phosphors.

  10. Electrical characteristics of ZnO nanorods reinforced polymer nanocomposite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharjee, Snigdha; Roy, Asim, E-mail: 28.asim@gmail.com [Department of Physics National Institute Technology Silchar Silchar-788010, Assam (India)

    2015-05-15

    ZnO nanorods have been prepared by simple chemical method, which is used to fabricate organic bistable devices (OBDs). OBDs are fabricated by incorporating different weight percent (wt %) of chemically synthesized Zinc Oxide (ZnO) nanorods into polymethylmethacrylate (PMMA). Current-voltage (I-V) measurements of the spin coated ZnO+PMMA nanocomopsite thin film on indium tin oxide (ITO) coated glass substrate showed current hysteresis behaviour, which is an indication of memory effect. The samples exhibit two distinct resistance states, ON and OFF states, characterised by relatively low and high resistance of the OBDs, respectively. It is also observed that with change in ZnO dopant concentration the value of ON/OFF current changes. Higher ON/OFF current ratio is desired for practical applications. Current conduction mechanism of the devices has been explained invoking various existing models, and it has been found that the trapped-charge-limited conduction mechanism was dominant in our samples.

  11. Electrospray Deposition of ZnO Thin Films and Its Application to Gas Sensors

    Directory of Open Access Journals (Sweden)

    Wenwang Li

    2018-02-01

    Full Text Available Electrospray is a simple and cost-effective method to fabricate micro-structured thin films. This work investigates the electrospray process of ZnO patterns. The effects of experimental parameters on jet characteristics and electrosprayed patterns are studied. The length of stable jets increases with increasing applied voltage and flow rate, and decreases with increasing nozzle-to-substrate distance, while electrospray angles exhibit an opposite trend with respect to the stable jet lengths. The diameter of electrosprayed particles decreases with increasing applied voltage, and increases with flow rate. Furthermore, an alcohol gas sensor is presented. The ZnAc is calcined into ZnO, which reveals good repeatability and stability of response in target gas. The sensing response, defined as the resistance ratio of R0/Rg, where R0 and Rg are resistance of ZnO in air and alcohol gas, increases with the concentration of alcohol vapors and electrospray deposition time.

  12. Enhanced ZnO Thin-Film Transistor Performance Using Bilayer Gate Dielectrics

    KAUST Repository

    Alshammari, Fwzah Hamud; Nayak, Pradipta K.; Wang, Zhenwei; Alshareef, Husam N.

    2016-01-01

    We report ZnO TFTs using Al2O3/Ta2O5 bilayer gate dielectrics grown by atomic layer deposition. The saturation mobility of single layer Ta2O5 dielectric TFT was 0.1 cm2 V-1 s-1, but increased to 13.3 cm2 V-1 s-1 using Al2O3/Ta2O5 bilayer dielectric with significantly lower leakage current and hysteresis. We show that point defects present in ZnO film, particularly VZn, are the main reason for the poor TFT performance with single layer dielectric, although interfacial roughness scattering effects cannot be ruled out. Our approach combines the high dielectric constant of Ta2O5 and the excellent Al2O3/ZnO interface quality, resulting in improved device performance. © 2016 American Chemical Society.

  13. Enhanced ZnO Thin-Film Transistor Performance Using Bilayer Gate Dielectrics

    KAUST Repository

    Alshammari, Fwzah Hamud

    2016-08-24

    We report ZnO TFTs using Al2O3/Ta2O5 bilayer gate dielectrics grown by atomic layer deposition. The saturation mobility of single layer Ta2O5 dielectric TFT was 0.1 cm2 V-1 s-1, but increased to 13.3 cm2 V-1 s-1 using Al2O3/Ta2O5 bilayer dielectric with significantly lower leakage current and hysteresis. We show that point defects present in ZnO film, particularly VZn, are the main reason for the poor TFT performance with single layer dielectric, although interfacial roughness scattering effects cannot be ruled out. Our approach combines the high dielectric constant of Ta2O5 and the excellent Al2O3/ZnO interface quality, resulting in improved device performance. © 2016 American Chemical Society.

  14. (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.

  15. Defect characterization and magnetic properties in un-doped ZnO thin film annealed in a strong magnetic field

    Science.gov (United States)

    Ning, Shuai; Zhan, Peng; Wang, Wei-Peng; Li, Zheng-Cao; Zhang, Zheng-Jun

    2014-12-01

    Highly c-axis oriented un-doped zinc oxide (ZnO) thin films, each with a thickness of ~ 100 nm, are deposited on Si (001) substrates by pulsed electron beam deposition at a temperature of ~ 320 °C, followed by annealing at 650 °C in argon in a strong magnetic field. X-ray photoelectron spectroscopy (XPS), positron annihilation analysis (PAS), and electron paramagnetic resonance (EPR) characterizations suggest that the major defects generated in these ZnO films are oxygen vacancies. Photoluminescence (PL) and magnetic property measurements indicate that the room-temperature ferromagnetism in the un-doped ZnO film originates from the singly ionized oxygen vacancies whose number depends on the strength of the magnetic field applied in the thermal annealing process. The effects of the magnetic field on the defect generation in the ZnO films are also discussed.

  16. Defect characterization and magnetic properties in un-doped ZnO thin film annealed in a strong magnetic field

    International Nuclear Information System (INIS)

    Ning Shuai; Zhan Peng; Wang Wei-Peng; Li Zheng-Cao; Zhang Zheng-Jun

    2014-01-01

    Highly c-axis oriented un-doped zinc oxide (ZnO) thin films, each with a thickness of ∼ 100 nm, are deposited on Si (001) substrates by pulsed electron beam deposition at a temperature of ∼ 320 °C, followed by annealing at 650 °C in argon in a strong magnetic field. X-ray photoelectron spectroscopy (XPS), positron annihilation analysis (PAS), and electron paramagnetic resonance (EPR) characterizations suggest that the major defects generated in these ZnO films are oxygen vacancies. Photoluminescence (PL) and magnetic property measurements indicate that the room-temperature ferromagnetism in the un-doped ZnO film originates from the singly ionized oxygen vacancies whose number depends on the strength of the magnetic field applied in the thermal annealing process. The effects of the magnetic field on the defect generation in the ZnO films are also discussed. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  17. Effect of thickness on structural and electrical properties of Al-doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Garcés, F.A., E-mail: felipe.garces@santafe-conicet.gov.ar [Instituto de Física del Litoral (CONICET-UNL), Güemes 3450, Santa Fe S3000GLN (Argentina); Budini, N. [Instituto de Física del Litoral (CONICET-UNL), Güemes 3450, Santa Fe S3000GLN (Argentina); Arce, R.D.; Schmidt, J.A. [Instituto de Física del Litoral (CONICET-UNL), Güemes 3450, Santa Fe S3000GLN (Argentina); Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santiago del Estero 2829, Santa Fe S3000AOM (Argentina)

    2015-01-01

    In this work, we have investigated the influence of thickness on structural and electrical properties of Al-doped ZnO films. Transparent conducting oxide films were grown by the spray pyrolysis technique from precursors prepared via the sol–gel method. We determined the structural properties of the films by performing X-ray diffraction and mosaicity measurements, which evidenced an increase of disorder and inhomogeneity between crystalline domains as the films thickened. This behavior was contrasted with results obtained from electrical measurements and was attributed to plastic deformation of the films as their thickness increased. As a result, the carrier mobility, the optical gap and the activation energy are affected due to emerging grain boundaries and a higher degree of disorder. - Highlights: • Al-doped ZnO thin films on glass with different thicknesses • Film thickness affects the morphological and electrical properties. • Increasing time deposition allows modification of resistivity and Hall mobility. • Mosaicity between crystalline domains increases with film thickness.

  18. Effect of thickness on structural and electrical properties of Al-doped ZnO films

    International Nuclear Information System (INIS)

    Garcés, F.A.; Budini, N.; Arce, R.D.; Schmidt, J.A.

    2015-01-01

    In this work, we have investigated the influence of thickness on structural and electrical properties of Al-doped ZnO films. Transparent conducting oxide films were grown by the spray pyrolysis technique from precursors prepared via the sol–gel method. We determined the structural properties of the films by performing X-ray diffraction and mosaicity measurements, which evidenced an increase of disorder and inhomogeneity between crystalline domains as the films thickened. This behavior was contrasted with results obtained from electrical measurements and was attributed to plastic deformation of the films as their thickness increased. As a result, the carrier mobility, the optical gap and the activation energy are affected due to emerging grain boundaries and a higher degree of disorder. - Highlights: • Al-doped ZnO thin films on glass with different thicknesses • Film thickness affects the morphological and electrical properties. • Increasing time deposition allows modification of resistivity and Hall mobility. • Mosaicity between crystalline domains increases with film thickness

  19. Enhancing the numerical aperture of lenses using ZnO nanostructure-based turbid media

    International Nuclear Information System (INIS)

    Khokhra, Richa; Barman, Partha Bir; Kumar, Rajesh; Kumar, Manoj; Rawat, Nitin; Jang, Hwanchol; Lee, Heung-No

    2013-01-01

    Nanosheets, nanoparticles, and microstructures of ZnO were synthesized via a wet chemical method. ZnO films with a thickness of 44–46 μm were fabricated by spray coating, and these have been investigated for their potential use in turbid lens applications. A morphology-dependent comparative study of the transmittance of ZnO turbid films was conducted. Furthermore, these ZnO turbid films were used to enhance the numerical aperture (NA) of a Nikon objective lens. The variation in NA with different morphologies was explained using size-dependent scattering by the fabricated films. A maximum NA of around 1.971 of the objective lens with a turbid film of ZnO nanosheets was achieved. (paper)

  20. Evolution of ZnO architecture on a nanoporous TiO{sub 2} film by a hydrothermal method and the photoelectrochemical performance

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Yinhua; Wu Xiaoli; Zhang Wenli; Ni Liang [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Sun Yueming, E-mail: yms418@126.com [School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189 (China)

    2011-03-15

    The synthesis of ZnO architecture on a fluorine-doped SnO{sub 2} (FTO) conducting glass pre-coated with nanoporous TiO{sub 2} film has been achieved by a one-step hydrothermal method at a temperature of 70 deg. C. The effect of the reaction time on the morphology of the ZnO architecture has been investigated, and a possible growth mechanism for the formation of the ZnO architecture is discussed in detail. The morphology and phase structures of the as-obtained composite films have been investigated by field-emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The results show that the growth time greatly affects the morphology of the obtained ZnO architecture. The photoelectrochemical performances of as-prepared composite films are measured by assembling them into dye sensitized solar cells (DSSCs). The DSSC based on the as-prepared composite film (2 h) has obtained the best power conversion efficiency of 1.845%. (semiconductor materials)

  1. Influence Applied Potential on the Formation of Self-Organized ZnO Nanorod Film and Its Photoelectrochemical Response

    Directory of Open Access Journals (Sweden)

    Nur Azimah Abd Samad

    2016-01-01

    Full Text Available The present paper reports on the facile formation of ZnO nanorod photocatalyst electrodeposited on Zn foil in the production of hydrogen gas via water photoelectrolysis. Based on the results, ZnO nanorod films were successfully grown via electrochemical deposition in an optimum electrolyte set of 0.5 mM zinc chloride and 0.1 M potassium chloride at pH level of 5-6 and electrochemical deposition temperature of around 70°C. The study was also conducted at a very low stirring rate with different applied potentials. Applied potential was one of the crucial aspects in the formation of self-organized ZnO nanorod film via control of the field-assisted dissolution and field-assisted deposition rates during the electrochemical deposition process. Interestingly, low applied potentials of 1 V during electrochemical deposition produced a high aspect ratio and density of self-organized ZnO nanorod distribution on the Zn substrate with an average diameter and length of ~37.9 nm and ~249.5 nm, respectively. Therefore, it exhibited a high photocurrent density that reached 17.8 mA/cm2 under ultraviolet illumination and 12.94 mA/cm2 under visible illumination. This behaviour was attributed to the faster transport of photogenerated electron/hole pairs in the nanorod’s one-dimensional wall surface, which prevented backward reactions and further reduced the number of recombination centres.

  2. Applying RF Magnetron sputtering to prepare ZnO thin films and their characterization

    International Nuclear Information System (INIS)

    Saad, M.; Kassis, A.

    2009-05-01

    ZnO thin films were prepared using Rf magnetron sputtering under several preparation conditions (different values of deposition pressure, Rf power, substrate temperature). The optical properties of these films were investigated by measuring their transmission in the spectral range (300-1000 nm), and the electrical properties were investigated by measuring their electrical resistance. Results have been discussed in terms of the modified Thornton model for sputtered thin metal oxide films. Preparation conditions for depositing the highly resistive transparent i-ZnO buffer layer and the highly conducting transparent n-ZnO window layer for solar cells were proposed. (author)

  3. Preparation, structural and luminescent properties of nanocrystalline ZnO films doped Ag by close space sublimation method

    Science.gov (United States)

    Khomchenko, Viktoriya; Mazin, Mikhail; Sopinskyy, Mykola; Lytvyn, Oksana; Dan'ko, Viktor; Piryatinskii, Yurii; Demydiuk, Pavlo

    2018-05-01

    The simple way for silver doping of ZnO films is presented. The ZnO films were prepared by reactive rf-magnetron sputtering on silicon and sapphire substrates. Ag doping is carried out by sublimation of the Ag source located at close space at atmospheric pressure in air. Then the ZnO and ZnO-Ag films were annealed in wet media. The microstructure and optical properties of the films were compared and studied by atomic force microscopy (AFM), X-ray diffraction (XRD), photoluminescence (PL) and cathodoluminescence (CL). XRD results indicated that all the ZnO films have a polycrystalline hexagonal structure and a preferred orientation with the c-axis perpendicular to the substrate. The annealing and Ag doping promote increasing grain's sizes and modification of grain size distribution. The effect of substrate temperature, substrate type, Ag doping and post-growth annealing of the films was studied by PL spectroscopy. The effect of Ag doping was obvious and identical for all the films, namely the wide visible bands of PL spectra are suppressed by Ag doping. The intensity of ultraviolet band increased 15 times as compared to their reference films on sapphire substrate. The ultraviolet/visible emission ratio was 20. The full width at half maximum (FWHM) for a 380 nm band was 14 nm, which is comparable with that of epitaxial ZnO. The data implies the high quality of ZnO-Ag films. Possible mechanisms to enhance UV emission are discussed.

  4. Current-voltage characterization of Au contact on sol-gel ZnO films with and without conducting polymer

    International Nuclear Information System (INIS)

    Lin, Yow-Jon; Jheng, Mei-Jyuan; Zeng, Jian-Jhou

    2010-01-01

    This study investigates the current density-voltage (J-V) characteristics of Au/n-type ZnO and Au/polyaniline (PANI)/n-type ZnO devices. ZnO films were prepared by the sol-gel method. For Au/n-type ZnO devices, native defects and impurities resident within the ZnO depletion region contribute to barrier thinning of, carrier hopping across, and tunneling through the Schottky barrier. This leads to the formation of nonalloyed ohmic contacts. However, rectifying junctions were formed on n-type ZnO by employing the simple technique of spin-coating PANI to act as the electron-blocking layer. Our present results suggest that the ZnO depletion region at the PANI/n-type ZnO interface is not the origin of the rectifying behavior of Au/PANI/n-type ZnO contact. In addition, the presence of the built-in potential of Au/PANI/n-type ZnO devices could result in the shift of the J-V curve toward negative voltage. Excellent agreement between simulated and measured data was obtained when the built-in potential was taken into account in the J-V relationship.

  5. Quantum corrections to temperature dependent electrical conductivity of ZnO thin films degenerately doped with Si

    International Nuclear Information System (INIS)

    Das, Amit K.; Ajimsha, R. S.; Kukreja, L. M.

    2014-01-01

    ZnO thin films degenerately doped with Si (Si x Zn 1−x O) in the concentrations range of ∼0.5% to 5.8% were grown by sequential pulsed laser deposition on sapphire substrates at 400 °C. The temperature dependent resistivity measurements in the range from 300 to 4.2 K revealed negative temperature coefficient of resistivity (TCR) for the 0.5%, 3.8%, and 5.8% doped Si x Zn 1−x O films in the entire temperature range. On the contrary, the Si x Zn 1−x O films with Si concentrations of 1.0%, 1.7%, and 2.0% showed a transition from negative to positive TCR with increasing temperature. These observations were explained using weak localization based quantum corrections to conductivity

  6. Mechanical properties of Al2O3-doped (2 wt.%) ZnO films

    International Nuclear Information System (INIS)

    Kuriki, Shina; Kawashima, Toshitaka

    2007-01-01

    We report a new method of evaluating the adhesion of Al 2 O 3 -doped (2 wt.%) ZnO (AZO) thin films. The AZO films were deposited by DC reactive magnetron sputtering on plastic film (PET: polyethyleneterephthalate) at various sputtering pressures, power, and reactive gas-flow ratios. The adhesion test of the films was carried out using the nanoindentation system. The fracture point as determined by the load-displacement curve occurred at the time of separation between the thin film and the substrate. The integration value of load and displacement to the fracture point is defined as the degree of adhesion (S W ). The AZO films showed that adhesion increase as sputtering power increases and sputtering pressure decreases

  7. Effect of high-energy electron beam irradiation on the transmittance of ZnO thin films on transparent substrates

    International Nuclear Information System (INIS)

    Yun, Eui-Jung; Jung, Jin-Woo; Han, Young-Hwan; Kim, Min-Wan; Lee, Byung Cheol

    2010-01-01

    We investigated in this study the effects of high-energy electron beam irradiation (HEEBI) on the optical transmittance of undoped ZnO films grown on transparent substrates, such as corning glass and polyethersulfone (PES) plastic substrates, with a radio frequency (rf) magnetron sputtering technique. The ZnO thin films were treated with HEEBI in air at RT with an electron beam energy of 1 MeV and doses of 4.7 x 10 14 - 4.7 x 10 16 electrons/cm 2 . The optical transmittance of the ZnO films was measured using an ultraviolet visible near-infrared spectrophotometer. The detailed estimation process for separating the transmittance of HEEBI-treated ZnO films from the total transmittance of ZnO films on transparent substrates treated with HEEBI is given in this paper. We concluded that HEEBI causes a slight suppression in the optical transmittance of ZnO thin films. We also concluded that HEEBI treatment with a high dose shifted the optical band gap (E g ) toward the lower energy region from 3.29 to 3.28 eV whereas that with a low dose unchanged E g at 3.25 eV. This shift suggested that HEEBI at RT at a high dose acts like an annealing treatment at high temperature.

  8. 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.

  9. Quenching of surface traps in Mn doped ZnO thin films for enhanced optical transparency

    International Nuclear Information System (INIS)

    Ilyas, Usman; Rawat, R.S.; Roshan, G.; Tan, T.L.; Lee, P.; Springham, S.V.; Zhang, Sam; Fengji Li; Chen, R.; Sun, H.D.

    2011-01-01

    The structural and photoluminescence analyses were performed on un-doped and Mn doped ZnO thin films grown on Si (1 0 0) substrate by pulsed laser deposition (PLD) and annealed at different post-deposition temperatures (500-800 deg. C). X-ray diffraction (XRD), employed to study the structural properties, showed an improved crystallinity at elevated temperatures with a consistent decrease in the lattice parameter 'c'. The peak broadening in XRD spectra and the presence of Mn 2p3/2 peak at ∼640 eV in X-ray Photoelectron Spectroscopic (XPS) spectra of the doped thin films confirmed the successful incorporation of Mn in ZnO host matrix. Extended near band edge emission (NBE) spectra indicated the reduction in the concentration of the intrinsic surface traps in comparison to the doped ones resulting in improved optical transparency. Reduced deep level emission (DLE) spectra in doped thin films with declined PL ratio validated the quenching of the intrinsic surface traps thereby improving the optical transparency and the band gap, essential for optoelectronic and spintronic applications. Furthermore, the formation and uniform distribution of nano-sized grains with improved surface features of Mn-doped ZnO thin films were observed in Field Emission Scanning Electron Microscopy (FESEM) images.

  10. Improvement of ZnO TCO film growth for photovoltaic devices by reactive plasma deposition (RPD)

    International Nuclear Information System (INIS)

    Iwata, K.; Sakemi, T.; Yamada, A.; Fons, P.; Awai, K.; Yamamoto, T.; Shirakata, S.; Matsubara, K.; Tampo, H.; Sakurai, K.; Ishizuka, S.; Niki, S.

    2005-01-01

    Reactive plasma deposition (RPD) is a technique for depositing a thin film on a substrate using a pressure-slope type plasma ion gun. This method offers the advantage of low-ion damage, low deposition temperature, large area deposition and high growth rates. Ga-doped zinc oxide (ZnO) thin film was grown on a moving glass substrate by RPD. Evaporation of very small quantity of tungsten from anode electrode by plasma collision lets the resistivity of grown ZnO transparent conductive oxide (TCO) film to increase. However, no reduction of carrier concentration was observed but only reduction of carrier mobility. It indicates that reduction of evaporation of tungsten from anode electrode induces increase of carrier mobility without any increase of carrier concentration. After installation of an anode cooling system in order to avoid the tungsten evaporation, increase of the mobility (37 cm 2 /Vsec) was observed and the lowest resistivity (2.0x10 -4 no. OMEGAno. cm) film was obtained from large size grown ZnO TCO of 200x200 mm at low growth temperature of 200 deg. C with high growth rate of 24 no. muno. m/h

  11. Morphological, structural and optical properties of ZnO thin films deposited by dip coating method

    Energy Technology Data Exchange (ETDEWEB)

    Marouf, Sara; Beniaiche, Abdelkrim; Guessas, Hocine, E-mail: aziziamor@yahoo.fr [Laboratoire des Systemes Photoniques et Optiques Non Lineaires, Institut d' Optique et Mecanique de Precision, Universite Ferhat Abbas-Setif 1, Setif (Algeria); Azizi, Amor [Laboratoire de Chimie, Ingenierie Moleculaire et Nanostructures, Universite Ferhat Abbas-Setif 1, Setif (Algeria)

    2017-01-15

    Zinc oxide (ZnO) thin films were deposited on glass substrate by dip coating technique. The effects of sol aging time on the deposition of ZnO films was studied by using the field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and optical transmission techniques. The morphology of the films strongly depends on preparation route and deposition technique. It is noteworthy that films deposited from the freshly prepared solution feature indistinct characteristics; had relatively poor crystalline quality and low optical transmittance in the visible region. The increase in sol aging time resulted in a gradual improvement in crystallinity (in terms of peak sharpness and peak intensity) of the hexagonal phase for all diffraction peaks. Effect of sol aging on optical transparency is quite obvious through increased transmission with prolonged sol aging time. Interestingly, 72-168 h sol aging time was found to be optimal to achieve smooth surface morphology, good crystallinity and high optical transmittance which were attributed to an ideal stability of solution. These findings present a better-defined and more versatile procedure for production of clean ZnO sols of readily adjustable nanocrystalline size. (author)

  12. Characterization and device applications of ZnO films deposited by high power impulse magnetron sputtering (HiPIMS)

    Science.gov (United States)

    Partridge, J. G.; Mayes, E. L. H.; McDougall, N. L.; Bilek, M. M. M.; McCulloch, D. G.

    2013-04-01

    ZnO films have been reactively deposited on sapphire substrates at 300 °C using a high impulse power magnetron sputtering deposition system and characterized structurally, optically and electronically. The unintentionally doped n-type ZnO films exhibit high transparency, moderate carrier concentration (˜5 × 1018 cm-3) and a Hall mobility of 8.0 cm2 V-1 s-1, making them suitable for electronic device applications. Pt/ZnO Schottky diodes formed on the HiPIMS deposited ZnO exhibited rectification ratios up to 104 at ±2 V and sensitivity to UV light.

  13. The role of seeding in the morphology and wettability of ZnO nanorods films on different substrates

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez, Juan [Facultad de Ciencias, Universidad Nacional de Ingeniería, P.O. Box 31-139, Lima 31, Perú (Peru); Onna, Diego [DQIAQF-INQUIMAE, FCEyN-Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, 1428 Buenos Aires (Argentina); Sánchez, Luis [Facultad de Ciencias, Universidad Nacional de Ingeniería, P.O. Box 31-139, Lima 31, Perú (Peru); Marchi, M. Claudia [DQIAQF-INQUIMAE, FCEyN-Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, 1428 Buenos Aires (Argentina); Centro de Microscopias Avanzadas, FCEyN-Universidad ed Buenos Aires, Ciudad Universitaria, Pab. I, 1428 Buenos Aires (Argentina); Candal, Roberto, E-mail: rjcandal@gmail.com [DQIAQF-INQUIMAE, FCEyN-Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, 1428 Buenos Aires (Argentina); ECyT, 3iA, Universidad Nacional de San Martín, Martín de Irigoyen No 3100 (1650), San Martín, Pcia de Buenos Aires (Argentina); Ponce, Silvia [Universidad de Lima, Av. Javier Prado Este s/n, Monterrico, Lima 33, Perú (Peru); Bilmes, Sara A. [DQIAQF-INQUIMAE, FCEyN-Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, 1428 Buenos Aires (Argentina)

    2013-08-15

    Spray pyrolysis (SP) and spray-gel (SG) techniques were used to deposit ZnO seeds on Fluor doped tin oxide glasses (FTO), heated at 350 °C or 130 °C, and PET heated at 90 °C. The effect of seeding on the morphology and wettability of ZnO nanorods (NRs) films grown by wet chemical methods was analyzed. The morphology and wettability of ZnO NRs films depend on the seeding process. SP seeds formed from zinc acetate dissolved in water ethanol mixtures yield vertically aligned ZnO NRs, whose diameters and dispersion size are determined by the ethanol/water ratio in the precursor solution. SG seeds formed from a methanol ZnO sol produce a ring patterned distribution on the FTO substrate. The drying of ZnO sol drops impinging on the substrate produces high density of seeds along a ring yielding textured films with NRs vertically oriented on the rings and multi-oriented outside them. This effect was not observed when ZnO NRs grown onto the ZnO/PET substrate, however rod diameter is related with the density of seeds. This way to control the density and diameter of NRs deposited onto a substrate modify the wettability and opens new possibilities for the design of tailored nanomaterials for photochemical applications. Both type of NRs films showed a strong luminescence emission in the UV and in the blue, associated with surface and intrinsic defects.

  14. The role of seeding in the morphology and wettability of ZnO nanorods films on different substrates

    International Nuclear Information System (INIS)

    Rodríguez, Juan; Onna, Diego; Sánchez, Luis; Marchi, M. Claudia; Candal, Roberto; Ponce, Silvia; Bilmes, Sara A.

    2013-01-01

    Spray pyrolysis (SP) and spray-gel (SG) techniques were used to deposit ZnO seeds on Fluor doped tin oxide glasses (FTO), heated at 350 °C or 130 °C, and PET heated at 90 °C. The effect of seeding on the morphology and wettability of ZnO nanorods (NRs) films grown by wet chemical methods was analyzed. The morphology and wettability of ZnO NRs films depend on the seeding process. SP seeds formed from zinc acetate dissolved in water ethanol mixtures yield vertically aligned ZnO NRs, whose diameters and dispersion size are determined by the ethanol/water ratio in the precursor solution. SG seeds formed from a methanol ZnO sol produce a ring patterned distribution on the FTO substrate. The drying of ZnO sol drops impinging on the substrate produces high density of seeds along a ring yielding textured films with NRs vertically oriented on the rings and multi-oriented outside them. This effect was not observed when ZnO NRs grown onto the ZnO/PET substrate, however rod diameter is related with the density of seeds. This way to control the density and diameter of NRs deposited onto a substrate modify the wettability and opens new possibilities for the design of tailored nanomaterials for photochemical applications. Both type of NRs films showed a strong luminescence emission in the UV and in the blue, associated with surface and intrinsic defects.

  15. Investigation on the effect of Zr doping in ZnO thin films by spray pyrolysis

    International Nuclear Information System (INIS)

    Gokulakrishnan, V.; Parthiban, S.; Jeganathan, K.; Ramamurthi, K.

    2011-01-01

    Zirconium doped zinc oxide thin films with enhanced optical transparency were prepared on Corning 1737 glass substrates at the substrate temperature of 400 o C by spray pyrolysis method for various doping concentrations of zirconium (IV) chloride in the spray solution. The X-ray diffraction studies reveal that the films exhibit hexagonal crystal structure with polycrystalline grains oriented along (0 0 2) direction. The crystalline quality of the films is found to be deteriorating with the increase of doping concentration and acquires amorphous state for higher concentration of 8 at.% in precursor solution. The average transmittance for 5 at.% (solution) zirconium doped ZnO film is significantly increased to ∼92% in the visible region of 500-800 nm. The room temperature photoluminescence (PL) spectra of films show a band edge between 3.41 and 3.2 eV and strong blue emission at 2.8 eV irrespective of doping concentration and however intensity increases consistently with doping levels. The vacuum annealing at 400 o C reduced the resistivity of the films significantly due to the coalescence of grains and the lowest resistivity of 2 x 10 -3 Ω cm is observed for 3 at.% (solution) Zr doped ZnO films which envisages that it is a good candidate for stable TCO material.

  16. ZnO thin film as MSG for sensitive biosensor

    Science.gov (United States)

    Iftimie, N.; Savin, A.; Steigmann, R.; Faktorova, D.; Salaoru, I.

    2016-08-01

    In this paper, we investigate the cholesterol sensors consisting of a mixture of cholesterol oxidase (ChOx) and zinc oxide (ZnO) nanoparticles were grown on ITO/glass substrates by vacuum thermal evaporation method and their sensing characteristics are examined in air. Also, the interest in surface waves appeared due to evanescent waves in the metallic strip grating in sub-wavelength regime. Before testing the transducer with metamaterials lens in the sub-wavelength regime, a simulation of the evanescent wave's formation has been performed at the edge of Ag strips, with thicknesses in the range of micrometers.

  17. Formulation and Characterization of Cr2O3 Doped ZnO Thick Films as H2S Gas Sensor

    Directory of Open Access Journals (Sweden)

    A. V. PATIL

    2009-09-01

    Full Text Available Cr2O3 doped ZnO thick films have been prepared by screen printing technique and firing process. These films were characterized by X-ray diffraction (XRD, Scanning electron microscopy (SEM, and EDX. H2S gas sensing properties of these films were investigated at different operating temperatures and different H2S concentrations. The 7 wt. % Cr2O3 doped ZnO thick films exhibits excellent H2S gas sensing properties with maximum sensitivity of 99.12 % at 300 oC in air atmosphere with fast response and recovery time.

  18. Defect free C-axis oriented zinc oxide (ZnO) films grown at room temperature using RF magnetron sputtering

    International Nuclear Information System (INIS)

    Kunj, Saurabh; Sreenivas, K.

    2016-01-01

    Radio frequency Magnetron sputtering technique was employed to fabricate ZnO thin films on quartz substrate at room temperature. The effect of varying oxygen to argon (O_2/Ar) gas ratio on the structural and photoluminescence properties of the film is analyzed.X-ray diffraction (XRD) spectra reveals the formation of hexagonal wurtzite structured ZnO thin films with preferred orientation along (002) plane. Photoluminescence (PL) characterization reveals the preparation of highly crystalline films exhibiting intense Ultraviolet (UV) emission with negligible amount of defects as indicated by the absence of Deep Level Emission (DLE) in the PL spectra.

  19. Defect free C-axis oriented zinc oxide (ZnO) films grown at room temperature using RF magnetron sputtering

    Science.gov (United States)

    Kunj, Saurabh; Sreenivas, K.

    2016-05-01

    Radio frequency Magnetron sputtering technique was employed to fabricate ZnO thin films on quartz substrate at room temperature. The effect of varying oxygen to argon (O2/Ar) gas ratio on the structural and photoluminescence properties of the film is analyzed.X-ray diffraction (XRD) spectra reveals the formation of hexagonal wurtzite structured ZnO thin films with preferred orientation along (002) plane. Photoluminescence (PL) characterization reveals the preparation of highly crystalline films exhibiting intense Ultraviolet (UV) emission with negligible amount of defects as indicated by the absence of Deep Level Emission (DLE) in the PL spectra.

  20. Defect free C-axis oriented zinc oxide (ZnO) films grown at room temperature using RF magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Kunj, Saurabh, E-mail: saurabhkunj22@gmail.com; Sreenivas, K. [Department of Physics & Astrophysics, University of Delhi, Delhi-110007 (India)

    2016-05-23

    Radio frequency Magnetron sputtering technique was employed to fabricate ZnO thin films on quartz substrate at room temperature. The effect of varying oxygen to argon (O{sub 2}/Ar) gas ratio on the structural and photoluminescence properties of the film is analyzed.X-ray diffraction (XRD) spectra reveals the formation of hexagonal wurtzite structured ZnO thin films with preferred orientation along (002) plane. Photoluminescence (PL) characterization reveals the preparation of highly crystalline films exhibiting intense Ultraviolet (UV) emission with negligible amount of defects as indicated by the absence of Deep Level Emission (DLE) in the PL spectra.

  1. Characterization of piesoelectric ZnO thin films and the fabrication of piezoelectric micro-cantilevers

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Raegan Lynn [Iowa State Univ., Ames, IA (United States)

    2005-01-01

    In Atomic Force Microscopy (AFM), a microcantilever is raster scanned across the surface of a sample in order to obtain a topographical image of the sample's surface. In a traditional, optical AFM, the sample rests on a bulk piezoelectric tube and a control loop is used to control the tip-sample separation by actuating the piezo-tube. This method has several disadvantages--the most noticeable one being that response time of the piezo-tube is rather long which leads to slow imaging speeds. One possible solution aimed at improving the speed of imaging is to incorporate a thin piezoelectric film on top of the cantilever beam. This design not only improves the speed of imaging because the piezoelectric film replaces the piezo-tube as an actuator, but the film can also act as a sensor. In addition, the piezoelectric film can excite the cantilever beam near its resonance frequency. This project aims to fabricate piezoelectric microcantilevers for use in the AFM. Prior to fabricating the cantilevers and also part of this project, a systematic study was performed to examine the effects of deposition conditions on the quality of piezoelectric ZnO thin films deposited by RF sputtering. These results will be presented. The deposition parameters that produced the highest quality ZnO film were used in the fabrication of the piezoelectric cantilevers. Unfortunately, the fabricated cantilevers warped due to the intrinsic stress of the ZnO film and were therefore not usable in the AFM. The complete fabrication process will be detailed, the results will be discussed and reasons for the warping will be examined.

  2. Polycrystalline ZnO: B grown by LPCVD as TCO for thin film silicon solar cells

    International Nuclear Information System (INIS)

    Fay, Sylvie; Steinhauser, Jerome; Nicolay, Sylvain; Ballif, Christophe

    2010-01-01

    Conductive zinc oxide (ZnO) grown by low pressure chemical vapor deposition (LPCVD) technique possesses a rough surface that induces an efficient light scattering in thin film silicon (TF Si) solar cells, which makes this TCO an ideal candidate for contacting such devices. IMT-EPFL has developed an in-house LPCVD process for the deposition of nanotextured boron doped ZnO films used as rough TCO for TF Si solar cells. This paper is a general review and synthesis of the study of the electrical, optical and structural properties of the ZnO:B that has been performed at IMT-EPFL. The influence of the free carrier absorption and the grain size on the electrical and optical properties of LPCVD ZnO:B is discussed. Transport mechanisms at grain boundaries are studied. It is seen that high doping of the ZnO grains facilitates the tunnelling of the electrons through potential barriers that are located at the grain boundaries. Therefore, even if these potential barriers increase after an exposition of the film to a humid atmosphere, the heavily doped LPCVD ZnO:B layers show a remarkable stable conductivity. However, the introduction of diborane in the CVD reaction induces also a degradation of the intra-grain mobility and increases over-proportionally the optical absorption of the ZnO:B films. Hence, the necessity to finely tune the doping level of LPCVD ZnO:B films is highlighted. Finally, the next challenges to push further the optimization of LPCVD ZnO:B films for thin film silicon solar cells are discussed, as well as some remarkable record cell results achieved with LPCVD ZnO:B as front electrode.

  3. Band-Gap Engineering in ZnO Thin Films: A Combined Experimental and Theoretical Study

    Science.gov (United States)

    Pawar, Vani; Jha, Pardeep K.; Panda, S. K.; Jha, Priyanka A.; Singh, Prabhakar

    2018-05-01

    Zinc oxide thin films are synthesized and characterized using x-ray diffraction, field-emission scanning electron microscopy, atomic force microscopy, and optical spectroscopy. Our results reveal that the structural, morphological, and optical properties are closely related to the stress of the sample provided that the texture of the film remains the same. The anomalous results are obtained once the texture is altered to a different orientation. We support this experimental observation by carrying out first-principles hybrid functional calculations for two different orientations of the sample and show that the effect of quantum confinement is much stronger for the (100) surface than the (001) surface of ZnO. Furthermore, our calculations provide a route to enhance the band gap of ZnO by more than 50% compared to the bulk band gap, opening up possibilities for wide-range industrial applications.

  4. Comparative study of ZnO thin films prepared by different sol-gel route

    Directory of Open Access Journals (Sweden)

    F Esmaieli Ghodsi

    2012-03-01

    Full Text Available   Retraction Notice    The paper "Comparative study of ZnO thin films prepared by different sol-gel route" by H. Absalan and F. E. Ghodsi, which appeared in Iranian Journal of Physics Research, Vol. 11, No. 4, 423-428 (in Farsi is translation of the paper "Comparative Study of ZnO Thin Films Prepared by Different Sol-Gel Route" by F. E. Ghodsi and H. Absalan, which appeared in ACTA PHYSICA POLONICA A, Vol 118 (2010 (in English and for this reason is retracted from this journal.The corresponding author  (and also the first author is the only responsible person for this action.   

  5. Sea-Urchin-Like ZnO Nanoparticle Film for Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Cheng-Wen Ma

    2015-01-01

    Full Text Available We present novel sea-urchin-like ZnO nanoparticles synthesized using a chemical solution method. Solution approaches to synthesizing ZnO nanostructures have several advantages including low growth temperatures and high potential for scaling up. We investigated the influence of reaction times on the thickness and morphology of sea-urchin-like ZnO nanoparticles, and XRD patterns show strong intensity in every direction. Dye-sensitized solar cells (DSSCs were developed using the synthesized ZnO nanostructures as photoanodes. The DSSCs comprised a fluorine-doped tin oxide (FTO glass with dense ZnO nanostructures as the working electrode, a platinized FTO glass as the counter electrode, N719-based dye, and I-/I3-liquid electrolyte. The DSSC fabricated using such nanostructures yielded a high power conversion efficiency of 1.16% with an incident photo-to-current efficiency (IPCE as high as 15.32%. Electrochemical impedance spectroscopy was applied to investigate the characteristics of DSSCs. An improvement in the electron transport in the ZnO photoanode was also observed.

  6. Temperature-dependent polarized luminescence of exciton polaritons in a ZnO film

    Energy Technology Data Exchange (ETDEWEB)

    Toropov, A.A.; Nekrutkina, O.V.; Shubina, T.V. [Ioffe Physico-Technical Institute, Russian Academy of Sciences, St. Petersburg 194021 (Russian Federation); Gruber, Th.; Kirchner, C. [Department of Semiconductor Physics, Ulm University, 89081 Ulm (Germany); Waag, A. [Institute of Semiconductor Technology, Braunschweig Technical University, 38106 Braunschweig (Germany); Karlsson, K.F.; Monemar, B. [Linkoeping University, 581 83 Linkoeping (Sweden)

    2005-02-01

    We report on the studies of linearly polarized photoluminescence (PL) in a (0001) oriented ZnO epitaxial film, grown by metal organic chemical vapor deposition on a GaN template. The emission of mixed longitudinal-transverse exciton polariton modes was observed up to 130 K that evidences polaritonic nature of the excitonic spectrum up to this elevated temperature. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Characterization of nanostructured ZnO thin films deposited through vacuum evaporation

    Directory of Open Access Journals (Sweden)

    Jose Alberto Alvarado

    2015-04-01

    Full Text Available This work presents a novel technique to deposit ZnO thin films through a metal vacuum evaporation technique using colloidal nanoparticles (average size of 30 nm, which were synthesized by our research group, as source. These thin films had a thickness between 45 and 123 nm as measured by profilometry. XRD patterns of the deposited thin films were obtained. According to the HRSEM micrographs worm-shaped nanostructures are observed in samples annealed at 600 °C and this characteristic disappears as the annealing temperature increases. The films obtained were annealed from 25 to 1000 °C, showing a gradual increase in transmittance spectra up to 85%. The optical band gaps obtained for these films are about 3.22 eV. The PL measurement shows an emission in the red and in the violet region and there is a correlation with the annealing process.

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

    International Nuclear Information System (INIS)

    Yu, Z.X.; Ma, Y.Z.; Zhao, Y.L.; Huang, J.B.; Wang, W.Z.; Moliere, M.; Liao, H.L.

    2017-01-01

    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_(_0_0_2_)_. 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

  9. 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

  10. Preparation and Study the Electrical, Structural and Gas Sensing Properties of ZnO Thick Film Resistor

    Directory of Open Access Journals (Sweden)

    M. K. DEORE

    2010-08-01

    Full Text Available Thick films of AR grade ZnO were prepared on glass substrate by screen-printing technique. These films were dried and fired at different temperatures between 550 oC, 600 oC and 650 oC for one hour in air atmosphere. The gas sensing performance of thick films was tested for various gases. ZnO films showed larger response (sensitivity to H2S gas (100 ppm at 250 oC for firing temperature 650 oC. The Morphological, Compositional and Structural properties of the ZnO thick films were performed by Scanning electron microscopy (SEM, Energy dispersive spectroscopy (EDX and XRD technique respectively. Chemical composition of ZnO film samples changes with firing temperature showing non-stoichiometric behaviours. XRD study indicated the formation of polycrystalline ZnO films with hexagonal wurtzite structure. The gas response (sensitivity, selectivity, response and recovery time of the sensor were measured and presented.

  11. Effect of nickel doping on the photocatalytic activity of ZnO thin films under UV and visible light

    International Nuclear Information System (INIS)

    Kaneva, Nina V.; Dimitrov, Dimitre T.; Dushkin, Ceco D.

    2011-01-01

    Nanostructured ZnO thin films with different concentrations of Ni 2+ doping (0, 1, 5, 10 and 15 wt.%) are prepared by the sol-gel method for the first time. The thin films are prepared from zinc acetate, 2-methoxyethanol and monoethanolamine on glass substrates by using dip coating method. The films comprise of ZnO nanocrystallites with hexagonal crystal structure, as revealed by X-ray diffraction. The film surface is with characteristic ganglia-like structure as observed by Scanning Electron Microscopy. Furthermore, the Ni-doped films are tested with respect to the photocatalysis in aqueous solutions of malachite green upon UV-light illumination, visible light and in darkness. The initial concentration of malachite green and the amount of catalyst are varied during the experiments. It is found that increasing of the amount of Ni 2+ ions with respect to ZnO generally lowers the photocatalytic activity in comparison with the pure ZnO films. Nevertheless, all films exhibit a substantial activity under both, UV and visible light and in darkness as well, which is promising for the development of new ZnO photocatalysts by the sol-gel method.

  12. Structural and morphological characterizations of ZnO films grown on GaAs substrates by MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    Agouram, S.; Zuniga Perez, J.; Munoz-Sanjose, V. [Universitat de Valencia, Departamento de Fisica Aplicada y Electromagnetismo, Burjassot (Spain)

    2007-07-15

    ZnO films were grown on GaAs(100), GaAs(111)A and GaAs(111)B substrates by metal organic chemical vapour deposition (MOCVD). Diethylzinc (DEZn) and tertiarybutanol (t-butanol) were used as Zn and O precursors, respectively. The influence of the growth temperature and GaAs substrate orientation on the crystalline orientation and morphology of the ZnO grown films has been analysed. Crystallinity of grown films was studied by X-ray diffraction (XRD); thickness and morphology of ZnO films were investigated by scanning electron microscopy (SEM). SEM results reveal significant differences between morphologies depending on growth temperature but not significant differences were detected on the texture of grown films. (orig.)

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

    Science.gov (United States)

    Yu, Z. X.; Ma, Y. Z.; Zhao, Y. L.; Huang, J. B.; Wang, W. Z.; Moliere, M.; Liao, H. L.

    2017-08-01

    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(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 favorable performances to be used as sensitive layer in gas sensing applications.

  14. XAFS study on ZnO films grown by molecular beam epitaxy

    International Nuclear Information System (INIS)

    Wu Zhihao; Zhou Yinxue; Zhang Xinyi; Fudan Univ., Shanghai; Yu Gencai; Wei Shiqiang; Chen Dongliang

    2004-01-01

    Effects of growth conditions including lattice mismatch and growth temperature on the local structures of ZnO films prepared by MBE have been investigated using fluorescence EXAFS at Zn K edge. The ZnO films were deposited on the Si substrate at 200 degree C and on sapphire substrate at 200 degree C or 300 degree C respectively. The coordination number N in the first shell (number of O atoms immediately surrounding a central Zn atom) remains constant 4 or so for all samples. However, the degree of disorder σ 2 (mean squared displacement) of the local structure is varied with the growth conditions. At the same growth temperature 200 degree C, the degree of disorder is reduced from 0.0080 (Angstrom) 2 to 0.0054 (Angstrom) 2 as the substrate is changed from Si to sapphire; on the same sapphire substrate, the degree of disorder decreases from 0.0054 (Angstrom) 2 to 0.0039 (Angstrom) 2 when the growth temperature is increased from 200 degree C to 300 degree C. Therefore, the higher growth temperature and smaller lattice mismatch can improve the disorder of local structures; the crystal quality of ZnO film will be improved as well . (authors)

  15. 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

    International Nuclear Information System (INIS)

    Malek, M.F.; Mamat, M.H.; Khusaimi, Z.; Sahdan, M.Z.; Musa, M.Z.; Zainun, A.R.; Suriani, A.B.; Md Sin, N.D.; Abd Hamid, S.B.; Rusop, M.

    2014-01-01

    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 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

  16. Water-assisted nitrogen mediated crystallisation of ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Muydinov, R. [Technical University Berlin, Institute of Semiconducting- and High-Frequency Technologies, Einsteinufer 25, 10587 Berlin (Germany); Steigert, A. [Helmholtz-Zentrum Berlin, Institute of Heterogeneous Material Systems, Albert-Einstein-Straße 15, 12489 Berlin (Germany); Schönau, S.; Ruske, F. [Helmholtz-Zentrum Berlin, Institute of Silicon Photovoltaics, Kekuléstraße 5, 12489 Berlin (Germany); Kraehnert, R.; Eckhardt, B. [Technical University Berlin, Institute of Technical Chemistry, Straße des 17. Juni 124, 10623 Berlin (Germany); Lauermann, I. [Helmholtz-Zentrum Berlin, Institute of Heterogeneous Material Systems, Albert-Einstein-Straße 15, 12489 Berlin (Germany); Szyszka, B. [Technical University Berlin, Institute of Semiconducting- and High-Frequency Technologies, Einsteinufer 25, 10587 Berlin (Germany)

    2015-09-01

    Nitrogen mediated crystallisation (NMC) being performed in oxygen atmosphere at T ≥ 600 °C is an effective approach to obtain very well (00l)-textured ZnO films. A use of NMC-seed layers remarkably improves electrical transport properties of subsequently deposited ZnO:Al contacts. In this work, crystallisation of quasi-amorphous, nitrogen doped ZnO seed layers has been performed using water vapours at overpressure and temperatures around 100 °C. This approach allows employment of soda-lime float-glass or temperature sensitive film stacks as a substrate. We propose here possible mechanism of water-assisted NMC and grope for optimised crystallisation conditions on the basis of optical, microscopic, and textural investigation. Low temperature water-assisted crystallisation of 20 nm thick ZnO layers was compared with high temperature annealing methods in terms of composition, microstructure and crystallinity. Electrical properties such as electron Hall mobility (μ{sub e}), concentration of free electrons (N{sub e}) and sheet resistance (R{sub sh}) have been evaluated and compared for functional ZnO:Al films obtained on glass and on differently crystallised NMC-seed layers. It was found that the crystallised with water assistance at low temperature ZnO seed layers provide comparable improvement in crystallinity and electrical properties of subsequently grown functional ZnO:Al films with respect to the ones crystallised at high temperature. Use of optimised water-assisted crystallisation of seed layers has allowed decreasing R{sub sh} of thin (130–270 nm) functional ZnO:Al films twice compared to the glass substrate. Both provide this effect: increase in μ{sub e} and increase of N{sub e}. - Highlights: • Amorphous ZnO:N films can be crystallised in autoclave at temperatures around 100 °C. • Such water-assisted crystallisation provides well-crystalline ZnO seed layers. • Use of these seed layers resulted in stress-free ZnO:Al contacts with twice lower R

  17. Superhydrophobic surface based on a coral-like hierarchical structure of ZnO.

    Directory of Open Access Journals (Sweden)

    Jun Wu

    2010-12-01

    Full Text Available Fabrication of superhydrophobic surfaces has attracted much interest in the past decade. The fabrication methods that have been studied are chemical vapour deposition, the sol-gel method, etching technique, electrochemical deposition, the layer-by-layer deposition, and so on. Simple and inexpensive methods for manufacturing environmentally stable superhydrophobic surfaces have also been proposed lately. However, work referring to the influence of special structures on the wettability, such as hierarchical ZnO nanostructures, is rare.This study presents a simple and reproducible method to fabricate a superhydrophobic surface with micro-scale roughness based on zinc oxide (ZnO hierarchical structure, which is grown by the hydrothermal method with an alkaline aqueous solution. Coral-like structures of ZnO were fabricated on a glass substrate with a micro-scale roughness, while the antennas of the coral formed the nano-scale roughness. The fresh ZnO films exhibited excellent superhydrophilicity (the apparent contact angle for water droplet was about 0°, while the ability to be wet could be changed to superhydrophobicity after spin-coating Teflon (the apparent contact angle greater than 168°. The procedure reported here can be applied to substrates consisting of other materials and having various shapes.The new process is convenient and environmentally friendly compared to conventional methods. Furthermore, the hierarchical structure generates the extraordinary solid/gas/liquid three-phase contact interface, which is the essential characteristic for a superhydrophobic surface.

  18. Annealing temperature dependence of the structures and properties of Co-implanted ZnO films

    International Nuclear Information System (INIS)

    Chen, Bin; Tang, Kun; Gu, Shulin; Ye, Jiandong; Huang, Shimin; Gu, Ran; Zhang, Yang; Yao, Zhengrong; Zhu, Shunming; Zheng, Youdou

    2014-01-01

    Highlights: • To avoid the forming of Co clusters and explore the origin of the magnetism, detailed investigation on the properties of the Co-implanted ZnO films with a rather low dose of 8 × 10 15 cm −2 and high implantation energy of 1 MeV were carried out. • The crystalline structure of the damaged region caused by ion-implantation has been recovered via the thermal annealing treatment at the temperature of 900 °C and above. • The low temperature magnetic hysteresis loops have indicated paramagnetism for the annealed films with weak ferromagnetic characteristics. • The zero-field cooling (ZFC) magnetization curves of the Co-implanted ZnO samples have varied from concave shape to convex one as the annealing temperature increased from 750 °C to 1000 °C. - Abstract: The effects of thermal annealing treatment on the structural, electrical, optical and magnetic properties of Co-implanted ZnO (0 0 0 1) films have been investigated in detail. The crystalline structure of the damaged region caused by ion implantation has been recovered via the thermal annealing at the temperature of 900 °C and above, and no Co clusters or its related oxide phases have been observed. The electrical and optical properties of the annealed films have shown strong dependence on the annealing temperature. The zero field cooling magnetization curves of the annealed films have varied from concave shape to convex one as the annealing temperature increased from 750 °C to 1000 °C, which are possibly tuned by the changes of the ratio of the itinerant carriers over the localized spin density. The low temperature magnetic hysteresis loops have indicated paramagnetic behavior for the annealed films with weak ferromagnetic characteristics. The ferromagnetism is attributed to the substituted Co 2+ ions and vacancy defects, while the paramagnetism could be induced by ionized interstitial Zn defects

  19. On the role of Al in ultrasonically sprayed ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Kurtaran, S., E-mail: skurtaran@ogu.edu.tr; Aldag, S.; Ofofoglu, G.; Akyuz, I.; Atay, F.

    2017-01-01

    In this work, Al incorporated ZnO films have been deposited by Ultrasonic Spray Pyrolysis technique. Behavior of Al element in the structure has been tried to be clarified by investigating the structural, optical, surface and electrical properties. Compositional analysis has been performed by EDX and Al contents in the coatings have been determined as 1.1, 2.8 and 3.1 at %. X-ray diffraction patterns have shown that all films are polycrystalline with hexagonal wurtzite structure and the dominant peak is (002) ZnO for films except the one containing the highest amount of Al. Above the Al content of 2.8 at %, appearance of new phases such as Al{sub 2}O{sub 3} and ZnAl{sub 2}O{sub 4} in XRD patterns refers a solubility limit at this doping rate. Thicknesses and optical constants (refractive index and extinction coefficient) have been determined by spectroscopic ellipsometry technique using Cauchy-Urbach model. Al doping above the solubility limit has caused ZnO films to have lower refractive index values. Also, AFM images have shown that surface morphologies of the films lose their spherical and granular texture and transform to a randomly clustered formation with sharper upper edges above the solubility limit. Transmittance and electrical resistivity measurements have shown that Al incorporation below solubility limit (1.1 and 2.8 at %) allows maintaining the transparency together with low resistivity values. These films have value to work on and may be promising materials for optoelectronic applications. - Highlights: • Resistivity was evaluated in terms of solubility limit using different mechanisms. • Spectroscopic ellipsometry was used to determine the optical constants. • Samples with 1.1–3.1 at %Al were obtained to express the behavior of Al.

  20. Detailed microstructure analysis of as-deposited and etched porous ZnO films

    International Nuclear Information System (INIS)

    Shang, Congcong; Thimont, Yohann; Barnabé, Antoine; Presmanes, Lionel; Pasquet, Isabelle; Tailhades, Philippe

    2015-01-01

    Graphical abstract: - Highlights: • Porous ZnO thin films were deposited by rf magnetron sputtering. • Surface enhancement factors were deduced from geometrical considerations. • Enlargement of the inter-grain spaces have been achieved by HCl chemical etching. • Microstructural parameters were deduced from SEM, AFM and optical measurements. - Abstract: ZnO nanostructured materials in thin film forms are of particular interest for photovoltaic or photocatalysis processes but they suffer from a lack of simple methods for optimizing their microstructure. We have demonstrated that microporous ZnO thin films with optimized inter grain accessibility can be produce by radio frequency magnetron sputtering process and chemical etching with 2.75 mM HCl solution for different duration. The as-deposited ZnO thin films were first characterized in terms of structure, grain size, inter grain space, open cavity depth and total thickness of the film by XRD, AFM, SEM, profilometry and optical measurements. A specific attention was dedicated to the determination of the surface enhancement factor (SEF) by using basic geometrical considerations and images treatments. In addition, the porous fraction and its distribution in the thickness have been estimated thanks to the optical simulation of the experimental UV–Visible–IR spectrums using the Bruggeman dielectric model and cross section SEM images analysis respectively. This study showed that the microstructure of the as-deposited films consists of a dense layer covered by a porous upper layer developing a SEF of 12–13 m 2 m −2 . This two layers architecture is not modified by the etching process. The etching process only affects the upper porous layer in which the overall porosity and the inter-grain space increase with the etching duration. Column diameter and total film thickness decrease at the same time when the films are soaked in the HCl bath. The microporous structure obtained after the etching process could

  1. Defect-band mediated ferromagnetism in Gd-doped ZnO thin films

    KAUST Repository

    Venkatesh, S.

    2015-01-07

    Gd-doped ZnO thin films prepared by pulsed laser deposition with Gd concentrations varying from 0.02–0.45 atomic percent (at. %) showed deposition oxygen pressure controlled ferromagnetism. Thin films prepared with Gd dopant levels (

  2. An investigation on the In doping of ZnO thin films by spray pyrolysis

    Science.gov (United States)

    Mahesh, Devika; Kumar, M. C. Santhosh

    2018-04-01

    Indium doped zinc oxide (IGZO)thin films are gaining much interest owing to its commercial application as transparent conductive oxide thin films. In the current study thin films indium doped ZnO thin films have been deposited on glass substrates by chemical spray pyrolysis technique with an indium concentration of 1, 2.5 and 4% in Zinc source. The films show a peak shift in the X-Ray Diffraction patterns with varying indium doping concentration. The (101) peak was enhanced for the 2.5 % indium doped films and variation in grain size with the different doping levels was studied. The as-deposited films are uniform and shown high transparency (>90%) in the visible region. Average thicknesses of films are found to be 800nm, calculated using the envelope method. The film with 2.5 % of indium content was found to be highly conducting than the rest, since for the lower and higher concentrations the conductivity was possibly halted by the limit in carrier concentration and indium segregation in the grain boundaries respectively. The enhancement of mobility and carrier concentration was clearly seen in the optimum films.

  3. Low-temperature deposition of ZnO thin films on PET and glass substrates by DC-sputtering technique

    International Nuclear Information System (INIS)

    Banerjee, A.N.; Ghosh, C.K.; Chattopadhyay, K.K.; Minoura, Hideki; Sarkar, Ajay K.; Akiba, Atsuya; Kamiya, Atsushi; Endo, Tamio

    2006-01-01

    The structural, optical and electrical properties of ZnO thin films (260 - 490 nm thick) deposited by direct-current sputtering technique, at a relatively low-substrate temperature (363 K), onto polyethylene terephthalate and glass substrates have been investigated. X-ray diffraction patterns confirm the proper phase formation of the material. Optical transmittance data show high transparency (80% to more than 98%) of the films in the visible portion of solar radiation. Slight variation in the transparency of the films is observed with a variation in the deposition time. Electrical characterizations show the room-temperature conductivity of the films deposited onto polyethylene terephthalate substrates for 4 and 5 h around 0.05 and 0.25 S cm -1 , respectively. On the other hand, for the films deposited on glass substrates, these values are 8.5 and 9.6 S cm -1 for similar variation in the deposition time. Room-temperature conductivity of the ZnO films deposited on glass substrates is at least two orders of magnitude higher than that of ZnO films deposited onto polyethylene terephthalate substrates under identical conditions. Hall-measurements show the maximum carrier concentration of the films on PET and glass substrate around 2.8 x 10 16 and 3.1 x 10 2 cm -3 , respectively. This report will provide newer applications of ZnO thin films in flexible display technology

  4. Synergistic effect of indium and gallium co-doping on the properties of RF sputtered ZnO thin films

    Science.gov (United States)

    Shaheera, M.; Girija, K. G.; Kaur, Manmeet; Geetha, V.; Debnath, A. K.; Karri, Malvika; Thota, Manoj Kumar; Vatsa, R. K.; Muthe, K. P.; Gadkari, S. C.

    2018-04-01

    ZnO thin films were synthesized using RF magnetron sputtering, with simultaneous incorporation of Indium (In) and Gallium (Ga). The structural, optical, chemical composition and surface morphology of the pure and co-doped (IGZO) thin films were characterized by X-Ray diffraction (XRD), UV-visible spectroscopy, Field Emission Scanning Electron Microscopy (FESEM), and Raman spectroscopy. XRD revealed that these films were oriented along c-axis with hexagonal wurtzite structure. The (002) diffraction peak in the co-doped sample was observed at 33.76° with a slight shift towards lower 2θ values as compared to pure ZnO. The surface morphology of the two thin films was observed to differ. For pure ZnO films, round grains were observed and for IGZO thin films round as well as rod type grains were observed. All thin films synthesized show excellent optical properties with more than 90% transmission in the visible region and band gap of the films is observed to decrease with co-doping. The co doping of In and Ga is therefore expected to provide a broad range optical and physical properties of ZnO thin films for a variety of optoelectronic applications.

  5. 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.

  6. Effect of doping concentration on the conductivity and optical properties of p-type ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Pathak, Trilok Kumar [Semiconductor Research Lab, Department of Physics, Gurukula Kangri University, Haridwar (India); Kumar, Vinod, E-mail: vinod.phy@gmail.com [Department of Physics, University of the Free State, Bloemfontein (South Africa); Swart, H.C., E-mail: swarthc@ufs.ac.za [Department of Physics, University of the Free State, Bloemfontein (South Africa); Purohit, L.P., E-mail: proflppurohitphys@gmail.com [Semiconductor Research Lab, Department of Physics, Gurukula Kangri University, Haridwar (India)

    2016-01-01

    Nitrogen doped ZnO (NZO) thin films were synthesized on glass substrates by the sol–gel and spin coating method. Zinc acetate dihydrates and ammonium acetate were used as precursors for zinc and nitrogen, respectively. X-ray diffraction study showed that the thin films have a hexagonal wurtzite structure corresponding (002) peak for undoped and doped ZnO thin films. The transmittance of the films was above 80% and the band gap of the film varies from 3.21±0.03 eV for undoped and doped ZnO. The minimum resistivity of NZO thin films was obtained as 0.473 Ω cm for the 4 at% of nitrogen (N) doping with a mobility of 1.995 cm{sup 2}/V s. The NZO thin films showed p-type conductivity at 2 and 3 at% of N doping. The AC conductivity measurements that were carried out in the frequency range 10 kHz to 0.1 MHz showed localized conduction in the NZO thin films. These highly transparent ZnO films can be used as a possible window layer in solar cells.

  7. Structural and Magnetic Properties of Mn doped ZnO Thin Film Deposited by Pulsed Laser Deposition

    KAUST Repository

    Baras, Abdulaziz

    2011-07-01

    Diluted magnetic oxide (DMO) research is a growing field of interdisciplinary study like spintronic devices and medical imaging. A definite agreement among researchers concerning the origin of ferromagnetism in DMO has yet to be reached. This thesis presents a study on the structural and magnetic properties of DMO thin films. It attempts to contribute to the understanding of ferromagnetism (FM) origin in DMO. Pure ZnO and Mn doped ZnO thin films have been deposited by pulsed laser deposition (PLD) using different deposition conditions. This was conducted in order to correlate the change between structural and magnetic properties. Structural properties of the films were characterized using x-ray diffraction (XRD) and scanning electron microscopy (SEM). The superconducting quantum interference device (SQUID) was used to investigate the magnetic properties of these films. The structural characterizations showed that the quality of pure ZnO and Mn doped ZnO films increased as oxygen pressure (PO) increased during deposition. All samples were insulators. In Mn doped films, Mn concentration decreased as PO increased. The Mn doped ZnO samples were deposited at 600˚C and oxygen pressure from 50-500mTorr. All Mn doped films displayed room temperature ferromagnetism (RTFM). However, at 5 K a superparamagnetic (SPM) behavior was observed in these samples. This result was accounted for by the supposition that there were secondary phase(s) causing the superparamagnetic behavior. Our findings hope to strengthen existing research on DMO origins and suggest that secondary phases are the core components that suppress the ferromagnetism. Although RTFM and SPM at low temperature has been observed in other systems (e.g., Co doped ZnO), we are the first to report this behavior in Mn doped ZnO. Future research might extend the characterization and exploration of ferromagnetism in this system.

  8. ZnO nanodisk based UV detectors with printed electrodes.

    Science.gov (United States)

    Alenezi, Mohammad R; Alshammari, Abdullah S; Alzanki, Talal H; Jarowski, Peter; Henley, Simon John; Silva, S Ravi P

    2014-04-08

    The fabrication of highly functional materials for practical devices requires a deep understanding of the association between morphological and structural properties and applications. A controlled hydrothermal method to produce single crystal ZnO hexagonal nanodisks, nanorings, and nanoroses using a mixed solution of zinc sulfate (ZnSO4) and hexamethylenetetramine (HMTA) without the need of catalysts, substrates, or templates at low temperature (75 °C) is introduced. Metal-semiconductor-metal (MSM) ultraviolet (UV) detectors were fabricated based on individual and multiple single-crystal zinc oxide (ZnO) hexagonal nanodisks. High quality single crystal individual nanodisk devices were fabricated with inkjet-printed silver electrodes. The detectors fabricated show record photoresponsivity (3300 A/W) and external quantum efficiency (1.2 × 10(4)), which we attribute to the absence of grain boundaries in the single crystal ZnO nanodisk and the polarity of its exposed surface.

  9. Annealing Temperature Dependent Structural and Optical Properties of RF Sputtered ZnO Thin Films.

    Science.gov (United States)

    Sharma, Shashikant; Varma, Tarun; Asokan, K; Periasamy, C; Boolchandani, Dharmendar

    2017-01-01

    This work investigates the effect of annealing temperature on structural and optical properties of ZnO thin films grown over Si 100 and glass substrates using RF sputtering technique. Annealing temperature has been varied from 300 °C to 600 °C in steps of 100, and different microstructural parameters such as grain size, dislocation density, lattice constant, stress and strain have been evaluated. The structural and surface morphological characterization has been done using X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM). XRD analysis reveals that the peak intensity of 002 crystallographic orientation increases with increased annealing temperature. Optical characterization of deposited films have been done using UV-Vis-NIR spectroscopy and photoluminescence spectrometer. An increase in optical bandgap of deposited ZnO thin films with increasing annealing temperature has been observed. The average optical transmittance was found to be more than 85% for all deposited films. Photoluminiscense spectra (PL) suggest that the crystalline quality of deposited film has increased at higher annealing temperature.

  10. Effect of Ni Doping on Gas Sensing Performance of ZnO Thick Film Resistor

    Directory of Open Access Journals (Sweden)

    M. K. DEORE

    2010-11-01

    Full Text Available This work investigates the use of ZnO-NiO as a H2S metal oxide thick film gas sensor. To find the optimum ratio of NiO to ZnO, two compositions were prepared using different molecular percentages and prepared as a thick film paste. These pastes were then screen-printed onto glass substrates with suitable binder. The final composition of each film was determined using SEM analysis. The films were used to detect CO, CL2, ethanol, Amonia and H2S. For each composition tested, the highest responses where displayed for H2S gas. The Thick film having composition of equal molar ZnO and NiO shows the highest response at operating temp. 350 0C for 100 ppm level. The gas response, selectivity, response and recovery time of the sensor were measured and presented. The role played by NiO species is to improve the gas sensing performance is discussed.

  11. Characterization of ZnO film grown on polycarbonate by atomic layer deposition at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Gyeong Beom; Han, Gwon Deok; Shim, Joon Hyung; Choi, Byoung-Ho, E-mail: bhchoi@korea.ac.kr [School of Mechanical Engineering, Korea University, Seoul 136-707 (Korea, Republic of)

    2015-01-15

    ZnO is an attractive material for use in various technological products such as phosphors, gas sensors, and transparent conductors. Recently, aluminum-doped zinc oxide has received attention as a potential replacement for indium tin oxide, which is one of the transparent conductive oxides used in flat panel displays, organic light-emitting diodes, and organic solar cells. In this study, the characteristics of ZnO films deposited on polycarbonate (PC) substrates by atomic layer deposition (ALD) are investigated for various process temperatures. The growth mechanism of these films was investigated at low process temperatures using x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS). XRD and XPS were used to determine the preferred orientation and chemical composition of the films, respectively. Furthermore, the difference of the deposition mechanisms on an amorphous organic material, i.e., PC substrate and an inorganic material such as silicon was discussed from the viewpoint of the diffusion and deposition of precursors. The structure of the films was also investigated by chemical analysis in order to determine the effect of growth temperature on the films deposited by ALD.

  12. High-dose V+ implantation in ZnO thin film structures

    International Nuclear Information System (INIS)

    Vyatkin, A.F.; Zinenko, V.I.; Agaphonov, Yu.A.; Pustovit, A.N.; Roshchupkin, D.V.; Reuss, F.; Kirchner, C.; Kling, R.; Waag, A.

    2005-01-01

    In the last two decades, diluted magnetic semiconductors have attracted great attention as promising materials for spintronics applications. [K. Sato, H. Katyama-Yoshida, Jpn. J. Phys., Part 2 39 (2000) L555] theoretically predicted that ZnO doped with V, Cr, Fe, Co, and Ni can be ferromagnetic. This has been recently confirmed experimentally for vanadium doped ZnO films which were grown on sapphire substrates, using laser deposition technique [H. Saeki, H.N. Tabata, T. Kawai, Solid State Commun. 120 (2001) 439]. In the present work, high-dose vanadium implantation was used to produce Zn 1-x V x O (x ∼ 0.10) thin film structures (250 nm thick) that had been epitaxially grown on sapphire substrates. Implantation with the dose 2 x 10 16 cm -2 was performed to reach a maximum vanadium concentration of 10 at%. To avoid ZnO film amorphization due to radiation damage accumulation [S.O. Kucheyev, J.S. Williams, C. Jagadish, J. Zou, C. Evans, A.J. Nelson, A.V. Hamza, Phys. Rev. B 67 (2003) 094115], all implants were done at elevated temperatures 300 and 400 deg. C and ion current density 10 μA/cm 2 . X-ray diffraction, SIMS and photoluminescence techniques were exploited to study the implanted samples. No luminescence was observed in the implanted samples after implantation procedures. However, annealing at 800 deg. C for 30 min gave rise to ZnO crystal structure improvement. This implies that healing of implantation induced defects is possible even after heavy-ion bombardment. As a result, the photoluminescence peak at 3.359 eV related to the donorbound exiton was detected

  13. Optical modeling of plasma-deposited ZnO films: Electron scattering at different length scales

    International Nuclear Information System (INIS)

    Knoops, Harm C. M.; Loo, Bas W. H. van de; Smit, Sjoerd; Ponomarev, Mikhail V.; Weber, Jan-Willem; Sharma, Kashish; Kessels, Wilhelmus M. M.; Creatore, Mariadriana

    2015-01-01

    In this work, an optical modeling study on electron scattering mechanisms in plasma-deposited ZnO layers is presented. Because various applications of ZnO films pose a limit on the electron carrier density due to its effect on the film transmittance, higher electron mobility values are generally preferred instead. Hence, insights into the electron scattering contributions affecting the carrier mobility are required. In optical models, the Drude oscillator is adopted to represent the free-electron contribution and the obtained optical mobility can be then correlated with the macroscopic material properties. However, the influence of scattering phenomena on the optical mobility depends on the considered range of photon energy. For example, the grain-boundary scattering is generally not probed by means of optical measurements and the ionized-impurity scattering contribution decreases toward higher photon energies. To understand this frequency dependence and quantify contributions from different scattering phenomena to the mobility, several case studies were analyzed in this work by means of spectroscopic ellipsometry and Fourier transform infrared (IR) spectroscopy. The obtained electrical parameters were compared to the results inferred by Hall measurements. For intrinsic ZnO (i-ZnO), the in-grain mobility was obtained by fitting reflection data with a normal Drude model in the IR range. For Al-doped ZnO (Al:ZnO), besides a normal Drude fit in the IR range, an Extended Drude fit in the UV-vis range could be used to obtain the in-grain mobility. Scattering mechanisms for a thickness series of Al:ZnO films were discerned using the more intuitive parameter “scattering frequency” instead of the parameter “mobility”. The interaction distance concept was introduced to give a physical interpretation to the frequency dependence of the scattering frequency. This physical interpretation furthermore allows the prediction of which Drude models can be used in a specific

  14. Effect of Eosin Y Dye on Electrical Properties of ZnO Film Synthesized by Sol-Gel Technique

    Science.gov (United States)

    Rani, Mamta; Tripathi, S. K.

    2014-02-01

    This paper presents preparation of zinc oxide (ZnO) nanoparticles by the sol-gel technique. ZnO films were prepared by the doctor-blade method, and the resulting films were sensitized with eosin Y (EY) by immersing them in a solution of EY dye in ethanol. The prepared samples were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transmission infrared spectroscopy, and ultraviolet (UV)-visible spectroscopy. The monodispersed ZnO nanocrystals possess a wurtzite hexagonal structure with diameter of ˜7 nm to 17 nm as observed by XRD and TEM analyses. The absorption spectrum of EY-dye-sensitized ZnO (ZnO/EY) film is slightly broadened, with a red-shift in the peak position compared with the absorbance spectrum of the dye in ethanol. Measurements of electrical parameters such as dark conductivity and photoconductivity were carried out at different temperatures. Transient photoconductivity was also studied at different temperatures to investigate the photoconduction mechanism. The photosensitivity of the ZnO/EY film is higher than that of the ZnO film. Hall measurements show n-type behavior for both samples. The visible absorption spectrum and high photosensitivity of the ZnO/EY films support their potential use as photoanode materials in dye-sensitized solar cells and optoelectronic devices.

  15. Tunable field emission characteristics of ZnO nanowires coated with varied thickness of lanthanum boride thin films

    International Nuclear Information System (INIS)

    Zhao, C.X.; Li, Y.F.; Chen, Jun; Deng, S.Z.; Xu, N.S.

    2013-01-01

    Lanthanum boride (LaB x ) thin films with various thicknesses were deposited on ZnO nanowire arrays by electron beam evaporation. Field emission characteristics of ZnO nanowires show close dependence on LaB x coating thickness. The turn-on field increases with increasing LaB x coating thickness from 10 nm to 50 nm. The observed phenomena were explained by a model that the tunneling at ZnO/LaB x interface dominates the emission process. - Highlights: ► Coating thickness dependence of field emission characteristics of ZnO nanowires was observed from LaB x coated ZnO nanowires. ► More stable field emission was observed from ZnO nanowires with LaB x coating. ► A model was proposed that the tunneling at ZnO/LaB x interface dominates the emission process

  16. Influence of different carrier gases on the properties of ZnO films grown by MOCVD

    Directory of Open Access Journals (Sweden)

    Wang, Jinzhong

    2008-08-01

    Full Text Available ZnO films were grown on sapphire (001 substrate by atmospheric MOCVD using diethyl zinc and tertiary butanol precursors. The influence of different carrier gases (H2 and He on the properties was analyzed by their structural (XRD, microstructural (SEM and compositional (SIMS characterization. The intensity of the strongest diffraction peak from ZnO (002 plane was increased by about 2 orders of magnitude when He is used as carrier gas, indicating the significant enhancement in crystallinity. The surface of the samples grown using H2 and He carrier gases was composed of leaf-like and spherical grains respectively. Hydrogen [H] content in the film grown using H2 is higher than that using He, indicating that the [H] was influenced by the H2 carrier gas. Ultraviolet emission dominates the low temperature PL spectra. The emission from ZnO films grown using He show higher optical quality and more emission centers.

    Se depositaron películas de ZnO sobre sustratos de zafiro (001 utilizando dietil zinc y butanol terciario como precursores. La influencia de los diferentes gases portadores (H2 y He sobre las propiedades se estudió mediante la caracterización estructural (XRD, microestructural (SEM y composicional (SIMS. La intensidad del pico de difracción más importante del plano (002 del ZnO aumentó en dos órdenes de magnitud cuando se utiliza He como gas portador indicando un incremento significativo de la cristalinidad. La superficie de las muestras crecidas utilizando H2 y He está formada por granos en forma de hoja y de forma esférica respectivamente. El contenido en hidrógeno (H en la película es mayor cuando se utiliza H2 que cuando se utiliza He, indicando que la cantidad de hidrógeno está influenciada por el H2 del gas portador. La emisión ultravioleta domina el espectro PL de baja temperatura. La emisión de las películas de ZnO utilizando

  17. Screen printed nanosized ZnO thick film

    Indian Academy of Sciences (India)

    Unknown

    The ex- tracted powder was screen printed on glass substrates using ethyl cellulose as binder and turpinol as solvent. ... racterized and a thick film paste is prepared by adding suitable .... UV peak and a broad green emission which is usually.

  18. Impedance measurements of nanoporosity in electrodeposited ZnO films for DSSC

    Energy Technology Data Exchange (ETDEWEB)

    Dupuy, L.; Haller, S.; Rousset, J.; Donsanti, F.; Guillemoles, J.-F.; Lincot, D. [Institute of R and D on Photovoltaic Energy (IRDEP), UMR 7174 EDF-CNRS-Chimie Paristech, 6 quai Watier, 78400 Chatou (France); Decker, F. [Chemistry Department, ' ' Sapienza' ' Universita di Roma, 00185 Roma (Italy)

    2010-05-15

    Porous ZnO/dye hybrid films have been deposited by cathodic electrodeposition, and their active surface area after dye desorption was evaluated by impedance measurements with the semiconducting electrode polarized in accumulation. Surface area ratios have been deduced for a large number of films from imaginary part Z' vs. frequency measurements, having a constant rate over the frequency range from 0.5 Hz to > 50 Hz. The active surface increased by a factor of roughly 150 per every micron of film with respect to the area of a flat ZnO electrode: this linear relationship held from less than 1 {mu}m up to 9 {mu}m thick films. (author)

  19. Photoelectrocatrocatalytic hydrolysis of starch by using sprayed ZnO thin films

    International Nuclear Information System (INIS)

    Sapkal, R. T.; Shinde, S. S.; Rajpure, K.Y.; Bhosale, C. H.

    2013-01-01

    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. (semiconductor materials)

  20. 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.

  1. Improved damp heat stability of Ga-Doped ZnO thin film by pretreatment of the polyethylene terephthalate substrate

    Science.gov (United States)

    Kim, B. B.; Seo, S. G.; Lim, Y. S.; Choi, H.-S.; Seo, W.-S.; Park, H.-H.

    2013-09-01

    A study on the damp heat stability of transparent conducting ZnO thin film grown on a polyethylene terephthalate substrate (PET) is reported. By thermal annealing of the PET substrate at 100°C with Ar flow in a vacuum chamber prior to the sputtering growth of Ga-doped ZnO (GZO) thin film, significantly enhanced damp heat stability was achieved at 60°C with a 90% relative humidity. Electrical and structural characterizations of the GZO thin films were carried out and the effects of the pretreatment on the improved damp heat stability are discussed.

  2. Fabrication of Al doped ZnO films using atmospheric pressure cold plasma

    International Nuclear Information System (INIS)

    Suzaki, Yoshifumi; Miyagawa, Hayato; Yamaguchi, Kenzo; Kim, Yoon-Kee

    2012-01-01

    Under atmospheric pressure, homogeneous non-equilibrium cold plasma was generated stably by high voltage pulsed power (1 kV, 20 kHz, 38 W) excitation of a mixture of He and O 2 gases produced by a dielectric barrier discharge setup. By feeding Bis (2 methoxy‐6-methyl‐3, 5-heptanedione) Zn (Zn-MOPD, C 18 H 3 O 6 Zn) and Tris (2-methoxy‐6‐methy l‐3, 5-heptanedione) Al (Al-MOPD, C 27 H 45 O 9 Al) into this plasma with He carrier gas, transparent flat Al-doped ZnO (ZnO:Al) films about 120–240 nm thick were prepared on glass substrates directly under the slit made into the cathode. Deposition rates of the films were about 20–40 nm/min. The concentration of Al was measured by inductively coupled plasma atomic emission spectroscopy. The composition ratio of Al to Zn was 7.8 mol% when the carrier He gas flow rate of Al-MOPD was 30 cm 3 . The average transmittance of all films was more than 85% in the wavelength range from 400 to 800 nm. When the composition ratio of Al/Zn was between 1.1 and 7.8 mol%, the optical band gap of the film increased from 3.28 to 3.40 eV. The resistivity of ZnO:Al film was 2.96 Ω cm at 1.3 mol% of Al/Zn. In addition, the microstructure of the films was studied by X-ray diffraction measurement and field emission scanning electron microscope observation. It was revealed that doped Al is substituted onto the Zn site of the ZnO crystalline structure in ZnO:Al films. - Highlights: ► An atmospheric pressure cold plasma generator generated stable glow discharge. ► We fabricated Al doped ZnO films on glass substrates using cold plasma. ► Al concentration measured by inductively coupled plasma atomic emission spectroscopy. ► The transmission spectrum and the resistivity of the films were measured. ► The microstructure of the films was studied.

  3. Effect of Ag doping on the properties of ZnO thin films for UV stimulated emission

    Science.gov (United States)

    Razeen, Ahmed S.; Gadallah, A.-S.; El-Nahass, M. M.

    2018-06-01

    Ag doped ZnO thin films have been prepared using sol-gel spin coating method, with different doping concentrations. Structural and morphological properties of the films have been investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Thin films have been optically pumped and stimulated emission has been observed with strong peaks in the UV region. The UV stimulated emission is found to be due to exciton-exciton scattering, and Ag doping promoted this process by increasing the excitons concentrations in the ZnO lattice. Output-input intensity relation and peak emission, FWHM, and quantum efficiency relations with pump intensity have been reported. The threshold for which stimulated emission started has been evaluated to be about 18 MW/cm2 with quantum efficiency of about 58.7%. Mechanisms explaining the role of Ag in enhancement of stimulated emission from ZnO thin films have been proposed.

  4. Negative permittivity of ZnO thin films prepared from aluminum and gallium doped ceramics via pulsed-laser deposition

    DEFF Research Database (Denmark)

    Bodea, M. A.; Sbarcea, G.; Naik, G. V.

    2013-01-01

    Aluminum and gallium doped zinc oxide thin films with negative dielectric permittivity in the near infrared spectral range are grown by pulsed laser deposition. Composite ceramics comprising ZnO and secondary phase Al2O3 or Ga2O3 are employed as targets for laser ablation. Films deposited on glass...

  5. Structural, optical and magnetic properties of nanocrystalline Co-doped ZnO thin films grown by sol-gel

    Energy Technology Data Exchange (ETDEWEB)

    Kayani, Zohra Nazir; Shah, Iqra; Zulfiqar, Bareera; Sabah, Aneeqa [Lahore College for Women Univ., Lahore (Pakistan); Riaz, Saira; Naseem, Shahzad [Univ. of the Punjab, Lahore (Pakistan). Centre of Excellence in Solid State Physics

    2018-04-01

    Cobalt-doped ZnO thin films have been deposited using a sol-gel route by changing the number of coats on the substrate from 6 to 18. This project deals with various film thicknesses by increasing the number of deposited coats. The effect of thickness on structural, magnetic, surface morphology and optical properties of Co-doped ZnO thin film was studied. The crystal structure of the Co-doped ZnO films was investigated by X-ray diffraction. The films have polycrystalline wurtzite hexagonal structures. A Co{sup 2+} ion takes the place of a Zn{sup 2+} ion in the lattice without creating any distortion in its hexagonal wurtzite structure. An examination of the optical transmission spectra showed that the energy band gap of the Co-doped ZnO films increased from 3.87 to 3.97 eV with an increase in the number of coatings on the substrate. Ferromagnetic behaviour was confirmed by measurements using a vibrating sample magnetometer. The surface morphology of thin films was assessed by scanning electron microscope. The grain size on the surface of thin films increased with an increase in the number of coats.

  6. Effect of B doping on optical, electrical properties and defects of ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Caiying [State Key Laboratory of Mechanical Transmission, College of Physics, Chongqing University, Chongqing, 400044 (China); Fang, Liang, E-mail: lfang@cqu.edu.cn [State Key Laboratory of Mechanical Transmission, College of Physics, Chongqing University, Chongqing, 400044 (China); Zhang, Hong; Li, Wanjun [Key Laboratory of Optoelectronic Functional Materials of Chongqing, College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331 (China); Wu, Fang, E-mail: fang01234@163.com [State Key Laboratory of Mechanical Transmission, College of Physics, Chongqing University, Chongqing, 400044 (China); Qin, Guoping [Key Laboratory of Optoelectronic Functional Materials of Chongqing, College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331 (China); Ruan, Haibo, E-mail: rhbcqu@aliyun.com [Chongqing Key Laboratory of Micro/Nano Materials Engineering and Technology, Research Center for Materials Interdisciplinary Sciences, Chongqing University of Arts and Sciences, Chongqing, 402160 (China); Kong, Chunyang, E-mail: kchy@163.com [Key Laboratory of Optoelectronic Functional Materials of Chongqing, College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331 (China)

    2016-08-15

    Boron doped ZnO (BZO) films with B content in the range of 0–6 at.% were deposited on quartz glass substrates by RF magnetron sputtering technique. The effects of B doping content on microstructure, optical and electrical properties of BZO films were systematically investigated by XRD, SEM, AFM, XPS, PL, UV–vis–near infrared spectrophotometer and Hall-effect measurement, respectively. It is found that the crystal quality of ZnO films can be improved as B doping content increases to no larger than 4 at.% and will be deteriorated at higher B doping content. The grain size and surface roughness of the films reduce with the increase of B doping content. The BZO films exhibit tensile stress and the stress increases with B content. The transmittance of the BZO films is revealed to be 90% in the visible region. As the B doping content increases from 0 to 6 at.%, the optical band gap of BZO films enhances from 3.28 to 3.57 eV, which is found to increase linearly with the tensile stress in the films. The lowest resistivity of 1.58 × 10{sup −3} (Ω cm) is obtained at 2 at.% B doping content. XPS and PL analyses demonstrated that B doping can promote the formation of defects of zinc interstitials (Zn{sub i}) and oxygen vacancies (V{sub O}). - Highlights: • The relationship of band gap (E{sub g}) and stress (σ) in BZO is deduced. • XPS and PL illustrate B doping can promote the formation of Zn{sub i} and V{sub O} in BZO. • The lowest resistivity (1.58 × 10{sup −3} Ω cm) is obtained at 2 at.% B content.

  7. Magnetic Properties of Gadolinium-Doped ZnO Films and Nanostructures

    KAUST Repository

    Roqan, Iman S.

    2016-08-29

    The magnetic properties of Gd-doped ZnO films and nanostructures are important to the development of next-generation spintronic devices. Here, we elucidate the significant role played by Gd-oxygen-deficiency defects in mediating/inducing ferromagnetic coupling in in situ Gd-doped ZnO thin films deposited at low oxygen pressure by pulsed laser deposition (PLD). Samples deposited at higher oxygen pressures exhibited diamagnetic responses. Vacuum annealing was used on these diamagnetic samples (grown at a relatively high oxygen pressures) to create oxygen- deficiency defects with the aim of demonstrating reproducibility of room-temperature ferromagnetism (RTFM). Samples annealed at oxygen environment exhibited super‐ paramagnetism and blocking-temperature effects. The samples possessed secondary phases; Gd segregation led to superparamagnetism. Theoretical studies showed a shift of the 4f level of Gd to the conduction band minimum (CBM) in Gd-doped ZnO nanowires, which led to an overlap with the Fermi level, resulting in strong exchange coupling and consequently RTFM.

  8. Photoluminescence properties of ZnO films grown on InP by thermally oxidizing metallic Zn films

    CERN Document Server

    Chen, S J; Zhang, J Y; Lu, Y M; Shen, D Z; Fan, X W

    2003-01-01

    Photoluminescence (PL) properties of ZnO films grown on (001) InP substrates by thermal oxidization of metallic Zn films, in which oxygen vacancies and interstitial Zn ions are compensated by P ions diffusing from (001) InP substrates, are investigated. X-ray diffraction spectra indicate that P ions have diffused into the Zn films and chemically combined with Zn ions to form Zn sub 3 P sub 2. Intense free exciton emission dominates the PL spectra of ZnO films with very weak deep-level emission. Low-temperature PL spectra at 79 K are dominated by neutral-donor bound exciton emission at 3.299 eV (I sub 4) with a linewidth of 17.3 meV and neutral-acceptor bound exciton emission at 3.264 eV. The free exciton emission increases with increasing temperature and eventually dominates the emission spectrum for temperature higher than 170 K. Furthermore, the visible emission around 2.3 eV correlated with oxygen deficiencies and interstitial Zn defects was quenched to a remarkable degree by P diffusing from InP substrate...

  9. Photoluminescence properties of ZnO films grown on InP by thermally oxidizing metallic Zn films

    International Nuclear Information System (INIS)

    Chen, S J; Liu, Y C; Zhang, J Y; Lu, Y M; Shen, D Z; Fan, X W

    2003-01-01

    Photoluminescence (PL) properties of ZnO films grown on (001) InP substrates by thermal oxidization of metallic Zn films, in which oxygen vacancies and interstitial Zn ions are compensated by P ions diffusing from (001) InP substrates, are investigated. X-ray diffraction spectra indicate that P ions have diffused into the Zn films and chemically combined with Zn ions to form Zn 3 P 2 . Intense free exciton emission dominates the PL spectra of ZnO films with very weak deep-level emission. Low-temperature PL spectra at 79 K are dominated by neutral-donor bound exciton emission at 3.299 eV (I 4 ) with a linewidth of 17.3 meV and neutral-acceptor bound exciton emission at 3.264 eV. The free exciton emission increases with increasing temperature and eventually dominates the emission spectrum for temperature higher than 170 K. Furthermore, the visible emission around 2.3 eV correlated with oxygen deficiencies and interstitial Zn defects was quenched to a remarkable degree by P diffusing from InP substrates

  10. Studies on the adsorption of RuN{sub 3} dye on sheet-like nanostructured porous ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Rong; Pan, Jie; Briggs, Evan P.; Thrash, Marvin; Kerr, Lei L. [Department of Paper and Chemical Engineering, Miami University, Oxford, OH 45056 (United States)

    2008-04-15

    The interface between the ZnO and dye directly impacts the dye-sensitized solar cell (DSSC) performance. Nanostructured porous ZnO film was developed by a simple chemical solution process. Scanning electron microscope (SEM) images demonstrated the uniform ZnO films with sheet-like nanostructure. Adsorption studies indicated that the maximum adsorption capacity of RuN{sub 3} dye on the surface of ZnO films was approximately 0.016 mmol RuN{sub 3}/g ZnO films. Adsorption studies were conducted at 25 and 40 C. The results showed that the dye adsorption was significantly influenced by temperatures. Moreover, the problem of the dye aggregation on the ZnO surface was reduced at higher adsorption temperatures. The adsorption chemistry was studied with Raman spectroscopy. (author)

  11. Optical and structural properties of ZnO nanorods grown on graphene oxide and reduced graphene oxide film by hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Alver, U., E-mail: alver@ksu.edu.tr [Department of Physics, Kahramanmaras Sutcu Imam University, K. Maras 46100 (Turkey); Zhou, W.; Belay, A.B. [Nanoscience and Technology Center, University of Central Florida, Orlando, FL 32816 (United States); Florida Solar Energy Center, Cocoa, FL 32922 (United States); Krueger, R. [Nanoscience and Technology Center, University of Central Florida, Orlando, FL 32816 (United States); Davis, K.O.; Hickman, N.S. [Nanoscience and Technology Center, University of Central Florida, Orlando, FL 32816 (United States); Florida Solar Energy Center, Cocoa, FL 32922 (United States)

    2012-01-15

    ZnO nanorods were grown on graphene oxide (GO) and reduced graphene oxide (RGO) films with seed layers by using simple hydrothermal method. The GO films were deposited by spray coating and then annealed at 400 Degree-Sign C in argon atmosphere to obtain RGO films. The optical and structural properties of the ZnO nanorods were systematically studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and ultraviolet-visible spectroscopy. The XRD patterns and SEM images show that without a seed layer, no ZnO nanorod deposition occurs on GO or RGO films. Transmittance of ZnO nanorods grown on RGO films was measured to be approximately 83% at 550 nm. Furthermore, while transmittance of RGO films increases with ZnO nanorod deposition, transmittance of GO decreases.

  12. 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.

  13. Characteristics of sputtered Al-doped ZnO films for transparent electrodes of organic thin-film transistor

    International Nuclear Information System (INIS)

    Park, Yong Seob; Kim, Han-Ki

    2011-01-01

    Aluminum-doped ZnO (AZO) thin-films were deposited with various RF powers at room temperature by radio frequency (RF) magnetron sputtering method. The electrical properties of the AZO film were improved with the increasing RF power. These results can be explained by the improvement of the crystallinity in the AZO film. We fabricated the organic thin-film transistor (OTFT) of the bottom gate structure using pentacene active and poly-4-vinyl phenol gate dielectric layers on the indium tin oxide gate electrode, and estimated the device properties of the OTFTs including drain current-drain voltage (I D -V D ), drain current-gate voltage (I D -V G ), threshold voltage (V T ), on/off ratio and field effect mobility. The AZO film that grown at 160 W RF power exhibited low resistivity (1.54 x 10 -3 Ω.cm), high crystallinity and uniform surface morphology. The pentacene thin-film transistor using the AZO film that's fabricated at 160 W RF power exhibited good device performance such as the mobility of 0.94 cm 2 /V s and the on/off ratio of ∼ 10 5 . Consequently, the performance of the OTFT such as larger field-effect carrier mobility was determined the conductivity of the AZO source/drain (S/D) electrode. AZO films prepared at room temperature by the sputtering method are suitable for the S/D electrodes in the OTFTs.

  14. X-ray diffraction study of thermal stress relaxation in ZnO films deposited by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Conchon, F. [Institut P' , Universite de Poitiers-Ensma-UPR CNRS 3346, 86962 Futuroscope (France); Renault, P.O., E-mail: pierre.olivier.renault@univ-poitiers.f [Institut P' , Universite de Poitiers-Ensma-UPR CNRS 3346, 86962 Futuroscope (France); Le Bourhis, E.; Krauss, C.; Goudeau, P. [Institut P' , Universite de Poitiers-Ensma-UPR CNRS 3346, 86962 Futuroscope (France); Barthel, E.; Grachev, S. Yu.; Sondergard, E. [Lab. Surface du Verre et Interfaces (SVI), UMR 125, 93303 Aubervilliers (France); Rondeau, V.; Gy, R. [Lab. Recherche de Saint-Gobain (SGR), 93303 Aubervilliers (France); Lazzari, R.; Jupille, J. [Institut des Nanosciences de Paris (INSP), UMR 7588, 75015 Paris (France); Brun, N. [Lab. Physique des Solides (LPS), UMR 8502, 91405 Orsay (France)

    2010-12-30

    X-ray diffraction stress analyses have been performed on two different thin films deposited onto silicon substrate: ZnO and ZnO encapsulated into Si{sub 3}N{sub 4} layers. We showed that both as-deposited ZnO films are in a high compressive stress state. In situ X-ray diffraction measurements inside a furnace revealed a relaxation of the as-grown stresses at temperatures which vary with the atmosphere in the furnace and change with Si{sub 3}N{sub 4} encapsulation. The observations show that Si{sub 3}N{sub 4} films lying on both sides of the ZnO film play an important role in the mechanisms responsible for the stress relaxation during heat treatment. The different temperatures observed for relaxation in ambient and argon atmospheres suggest that the thermally activated stress relaxation may be attributed to a variation of the stoichiometry of the ZnO films. The present observations pave the way to fine tuning of the residual stresses through thermal treatment parameters.

  15. Thermal activation of nitrogen acceptors in ZnO thin films grown by MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    Dangbegnon, J.K.; Talla, K.; Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth (South Africa)

    2010-06-15

    Nitrogen doping in ZnO is inhibited by spontaneous formation of compensating defects. Perfect control of the nitrogen doping concentration is required, since a high concentration of nitrogen could induce the formation of donor defects involving nitrogen. In this work, the effect of post-growth annealing in oxygen ambient on ZnO thin films grown by Metalorganic Chemical Vapor Deposition, using NO as both oxidant and nitrogen dopant, is studied. After annealing at 700 C and above, low-temperature photoluminescence shows the appearance of a transition at {proportional_to}3.23 eV which is interpreted as pair emission involving a nitrogen acceptor. A second transition at {proportional_to}3.15 eV is also discussed. This work suggests annealing as a potential means for p-type doping using nitrogen (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. The magnetic ordering in high magnetoresistance Mn-doped ZnO thin films

    KAUST Repository

    Venkatesh, S.

    2016-03-24

    We studied the nature of magnetic ordering in Mn-doped ZnO thin films that exhibited ferromagnetism at 300 K and superparamagnetism at 5 K. We directly inter-related the magnetisation and magnetoresistance by invoking the polaronpercolation theory and variable range of hopping conduction below the metal-to-insulator transition. By obtaining a qualitative agreement between these two models, we attribute the ferromagnetism to the s-d exchange-induced spin splitting that was indicated by large positive magnetoresistance (∼40 %). Low temperature superparamagnetism was attributed to the localization of carriers and non-interacting polaron clusters. This analysis can assist in understanding the presence or absence of ferromagnetism in doped/un-doped ZnO.

  17. The magnetic ordering in high magnetoresistance Mn-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Venkatesh, S.; Baras, A.; Roqan, I. S., E-mail: Iman.roqan@kaust.edu.sa [Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900 (Saudi Arabia); Lee, J.-S. [Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States)

    2016-03-15

    We studied the nature of magnetic ordering in Mn-doped ZnO thin films that exhibited ferromagnetism at 300 K and superparamagnetism at 5 K. We directly inter-related the magnetisation and magnetoresistance by invoking the polaron percolation theory and variable range of hopping conduction below the metal-to-insulator transition. By obtaining a qualitative agreement between these two models, we attribute the ferromagnetism to the s-d exchange-induced spin splitting that was indicated by large positive magnetoresistance (∼40 %). Low temperature superparamagnetism was attributed to the localization of carriers and non-interacting polaron clusters. This analysis can assist in understanding the presence or absence of ferromagnetism in doped/un-doped ZnO.

  18. ZnO buffer layer for metal films on silicon substrates

    Science.gov (United States)

    Ihlefeld, Jon

    2014-09-16

    Dramatic improvements in metallization integrity and electroceramic thin film performance can be achieved by the use of the ZnO buffer layer to minimize interfacial energy between metallization and adhesion layers. In particular, the invention provides a substrate metallization method utilizing a ZnO adhesion layer that has a high work of adhesion, which in turn enables processing under thermal budgets typically reserved for more exotic ceramic, single-crystal, or metal foil substrates. Embodiments of the present invention can be used in a broad range of applications beyond ferroelectric capacitors, including microelectromechanical systems, micro-printed heaters and sensors, and electrochemical energy storage, where integrity of metallized silicon to high temperatures is necessary.

  19. Ultraviolet Stimulated Emission from Sol-Gel Spin Coated ZnO Thin Films

    Directory of Open Access Journals (Sweden)

    Ahmed S. Razeen

    2017-01-01

    Full Text Available Low cost ultraviolet stimulated emission has been generated using optical excitation of ZnO thin films deposited by sol-gel spin coating on n+ As-doped 100 Si-substrate. The number of deposited layers and the heat treatment have been investigated to obtain a film that can generate stimulated emission under optical excitation. The optimum condition for preparation of the film has been presented. X-ray diffraction and scanning electron microscope have been used for structural and morphological investigations. Input-output intensity dependence and spectral width, peak emission wavelength, and the quantum efficiency versus the pump intensity have been presented. A quantum efficiency of about 24.2% has been reported, a power exponent higher than 8 has been obtained in input-output intensity dependence, and a threshold of about 23 Mw/cm2 has been evaluated for the samples. The mechanism by which stimulated emission occurs has been discussed. The results show that sol-gel spin coating is a promising method for generating ultraviolet stimulated emission from ZnO thin films.

  20. Growth-temperature-dependent optical and acetone detection properties of ZnO thin films

    International Nuclear Information System (INIS)

    Shewale, P. S.; Yu, Y. S.

    2015-01-01

    Zinc oxide (ZnO) thin films were prepared onto glass substrates at moderately low growth temperature by two-stage spray pyrolysis technique. The effects of growth temperature on structural, optical and acetone detection properties were investigated with X-ray diffractometry, a UV–visible spectrophotometer, photoluminescence (PL) spectroscopy and a homemade gas sensor testing unit, respectively. All the films are polycrystalline with a hexagonal wurtzite phase and exhibit a preferential orientation along [002] direction. The film crystallinity is gradually enhanced with an increase in growth temperature. The optical measurements show that all the films are physically highly transparent with a transmittance greater than 82% in the visible range. The band gap of the film is observed to exhibit a slight red shift with an increasing growth temperature. The PL studies on the films show UV/violet PL band at ∼ 395 nm. Among all the films investigated, the film deposited at 250 °C demonstrates a maximum sensitivity of 13% towards 20 ppm of acetone vapors at 300 °C operating temperature. (paper)

  1. Influence of lithium doping on the structural and electrical characteristics of ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Johny, T. Anto [Centre for Materials for Electronics Technology (C-MET), (Department of Information Technology, Scientific Society, Ministry of Communication and Information Technology, Govt. of India), Athani - PO, Thrissur, 680 581 Kerala (India); Kumar, Viswanathan, E-mail: vkumar10@yahoo.com [Centre for Materials for Electronics Technology (C-MET), (Department of Information Technology, Scientific Society, Ministry of Communication and Information Technology, Govt. of India), Athani - PO, Thrissur, 680 581 Kerala (India); Imai, Hideyuki; Kanno, Isaku [Micro Engineering, Kyoto University, Kyoto 606-8501 (Japan)

    2012-06-30

    Thin films of undoped and lithium-doped Zinc oxide, (Zn{sub 1-x}Li{sub x})O; x = 0, 0.05, 0.10 and 0.20 were prepared by sol-gel method using spin-coating technique on silicon substrates [(111)Pt/Ti/SiO{sub 2}/Si)]. The influence of lithium doping on the structural, electrical and microstructural characteristics have been investigated by means of X-ray diffraction, leakage current, piezoelectric measurements and scanning electron microscopy. The resistivity of the ZnO film is found to increase markedly with low levels (x {<=} 0.05) of lithium doping thereby enhancing their piezoelectric applications. The transverse piezoelectric coefficient, e{sub 31}{sup Low-Asterisk} has been determined for the thin films having the composition (Zn{sub 0.95}Li{sub 0.05})O, to study their suitability for piezoelectric applications. - Highlights: Black-Right-Pointing-Pointer Preferentially c-axis oriented (Zn{sub 1-x}Li{sub x})O films were spin-coated on glass. Black-Right-Pointing-Pointer (Zn{sub 1-x}Li{sub x})O thin films exhibit dense columnar microstructure. Black-Right-Pointing-Pointer Low levels of lithium doping, increases the electrical resistivity of ZnO thin films. Black-Right-Pointing-Pointer (Zn{sub 1-x}Li{sub x})O thin films show high values of transverse piezoelectric coefficient, e{sup Low-Asterisk }{sub 31}.

  2. Optoelectronic Characterization of Ta-Doped ZnO Thin Films by Pulsed Laser Deposition.

    Science.gov (United States)

    Koo, Horng-Show; Peng, Jo-Chi; Chen, Mi; Chin, Hung-I; Chen, Jaw-Yeh; Wu, Maw-Kuen

    2015-11-01

    Transparent conductive oxide of Ta-doped ZnO (TZO) film with doping amount of 3.0 wt% have been deposited on glass substrates (Corning Eagle XG) at substrate temperatures of 100 to 500 degrees C by the pulsed laser deposition (PLD) technique. The effect of substrate temperature on the structural, optical and electronic characteristics of Ta-doped ZnO (TZO) films with 3.0 wt% dopant of tantalum oxide (Ta2O5) was measured and demonstrated in terms of X-ray diffraction (XRD), ultraviolet-visible spectrometer (UV-Vis), four-probe and Hall-effect measurements. X-ray diffraction pattern shows that TZO films grow in hexagonal crystal structure of wurtzite phase with a preferred orientation of the crystallites along (002) direction and exhibits better physical characteristics of optical transmittance, electrical conductivity, carrier concentration and mobility for the application of window layer in the optoelectronic devices of solar cells, OLEDs and LEDs. The lowest electrical resistivity (ρ) and the highest carrier concentration of the as-deposited film deposited at 300 degrees C are measured as 2.6 x 10(-3) Ω-cm and 3.87 x 10(-20) cm(-3), respectively. The highest optical transmittance of the as-deposited film deposited at 500 degrees C is shown to be 93%, compared with another films deposited below 300 degrees C. It is found that electrical and optical properties of the as-deposited TZO film are greatly dependent on substrate temperature during laser ablation deposition.

  3. Transparent nanocrystalline ZnO films prepared by spin coating

    Energy Technology Data Exchange (ETDEWEB)

    Berber, M. [SusTech GmbH and Co. KG, Petersenstr. 20, 64287 Darmstadt, Hessen (Germany)]. E-mail: mete.berber@sustech.de; Bulto, V. [SusTech GmbH and Co. KG, Petersenstr. 20, 64287 Darmstadt, Hessen (Germany); Kliss, R. [SusTech GmbH and Co. KG, Petersenstr. 20, 64287 Darmstadt, Hessen (Germany); Hahn, H. [SusTech GmbH and Co. KG, Petersenstr. 20, 64287 Darmstadt, Hessen (Germany); Forschungszentrum Karlsruhe, Institute for Nanotechnology, Postfach 3640, 76021 Karlsruhe (Germany); Joint Research Laboratory Nanomaterials, TU Darmstadt, Institute of Materials Science, Petersenstr. 23, 64287 Darmstadt (Germany)

    2005-09-15

    Dispersions of zinc oxide nanoparticles synthesized by the electrochemical deposition under oxidizing conditions process with organic surfactants, were spin coated on glass substrates. After sintering, the microstructure, surface morphology, and electro-optical properties of the transparent nanocrystalline zinc oxide films have been investigated for different coating thicknesses and organic solvents.

  4. Transparent nanocrystalline ZnO films prepared by spin coating

    International Nuclear Information System (INIS)

    Berber, M.; Bulto, V.; Kliss, R.; Hahn, H.

    2005-01-01

    Dispersions of zinc oxide nanoparticles synthesized by the electrochemical deposition under oxidizing conditions process with organic surfactants, were spin coated on glass substrates. After sintering, the microstructure, surface morphology, and electro-optical properties of the transparent nanocrystalline zinc oxide films have been investigated for different coating thicknesses and organic solvents

  5. 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

  6. Fabrication of thin ZnO films with wide-range tuned optical properties by reactive magnetron sputtering

    Science.gov (United States)

    Davydova, A.; Tselikov, G.; Dilone, D.; Rao, K. V.; Kabashin, A. V.; Belova, L.

    2018-02-01

    We report the manufacturing of thin zinc oxide films by reactive magnetron sputtering at room temperature, and examine their structural and optical properties. We show that the partial oxygen pressure in DC mode can have dramatic effect on absorption and refractive index (RI) of the films in a broad spectral range. In particular, the change of the oxygen pressure from 7% to 5% can lead to either conventional crystalline ZnO films having low absorption and characteristic descending dependence of RI from 2.4-2.7 RIU in the visible to 1.8-2 RIU in the near-infrared (1600 nm) range, or to untypical films, composed of ZnO nano-crystals embedded into amorphous matrix, exhibiting unexpectedly high absorption in the visible-infrared region and ascending dependence of RI with values varying from 1.5 RIU in the visible to 4 RIU in the IR (1600 nm), respectively. Untypical optical characteristics in the second case are explained by defects in ZnO structure arising due to under-oxidation of ZnO crystals. We also show that the observed defect-related film structure remains stable even after annealing of films under relatively high temperatures (30 min under 450 °C). We assume that both types of films can be of importance for photovoltaic (as contact or active layers, respectively), as well as for chemical or biological sensing, optoelectronics etc.

  7. Variation of microstructural and optical properties in SILAR grown ZnO thin films by thermal treatment.

    Science.gov (United States)

    Valanarasu, S; Dhanasekaran, V; Chandramohan, R; Kulandaisamy, I; Sakthivelu, A; Mahalingam, T

    2013-08-01

    The influence of thermal treatment on the structural and morphological properties of the ZnO films deposited by double dip Successive ionic layer by adsorption reaction is presented. The effect of annealing temperature and time in air ambient is presented in detail. The deposited films were annealed from 200 to 400 degrees C in air and the structural properties were determined as a function of annealing temperature by XRD. The studies revealed that films were exhibiting preferential orientation along (002) plane. The other structural parameters like the crystallite size (D), micro strain (epsilon), dislocation density (delta) and stacking fault (alpha) of as-deposited and annealed ZnO films were evaluated and reported. The optical properties were also studied and the band gap of the ZnO thins films varied from 3.27 to 3.04 eV with the annealing temperature. SEM studies revealed that the hexagonal shaped grains with uniformly distributed morphology in annealed ZnO thin films. It has been envisaged using EDX analysis that the near stoichiometric composition of the film can be attained by thermal treatment during which microstructural changes do occur.

  8. 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.

  9. Surface structure, optoelectronic properties and charge transport in ZnO nanocrystal/MDMO-PPV multilayer films.

    Science.gov (United States)

    Lian, Qing; Chen, Mu; Mokhtar, Muhamad Z; Wu, Shanglin; Zhu, Mingning; Whittaker, Eric; O'Brien, Paul; Saunders, Brian R

    2018-05-07

    Blends of semiconducting nanocrystals and conjugated polymers continue to attract major research interest because of their potential applications in optoelectronic devices, such as solar cells, photodetectors and light-emitting diodes. In this study we investigate the surface structure, morphological and optoelectronic properties of multilayer films constructed from ZnO nanocrystals (NCs) and poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV). The effects of layer number and ZnO concentration (C ZnO ) used on the multilayer film properties are investigated. An optimised solvent blend enabled well-controlled layers to be sequentially spin coated and the construction of multilayer films containing six ZnO NC (Z) and MDMO-PPV (M) layers (denoted as (ZM) 6 ). Contact angle data showed a strong dependence on C ZnO and indicated distinct differences in the coverage of MDMO-PPV by the ZnO NCs. UV-visible spectroscopy showed that the MDMO-PPV absorption increased linearly with the number of layers in the films and demonstrates highly tuneable light absorption. Photoluminescence spectra showed reversible quenching as well as a surprising red-shift of the MDMO-PPV emission peak. Solar cells were constructed to probe vertical photo-generated charge transport. The measurements showed that (ZM) 6 devices prepared using C ZnO = 14.0 mg mL -1 had a remarkably high open circuit voltage of ∼800 mV. The device power conversion efficiency was similar to that of a control bilayer device prepared using a much thicker MDMO-PPV layer. The results of this study provide insight into the structure-optoelectronic property relationships of new semiconducting multilayer films which should also apply to other semiconducting NC/polymer combinations.

  10. Effect of surface microstructure and wettability on plasma protein adsorption to ZnO thin films prepared at different RF powers

    Energy Technology Data Exchange (ETDEWEB)

    Huang Zhanyun; Chen Min; Chen Dihu [State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-Sen University, Guangzhou 510275 (China); Pan Shirong, E-mail: stscdh@mail.sysu.edu.c [Artificial Heart Lab, the 1st Affiliate Hospital of Sun Yat-Sen University, Guangzhou 510080 (China)

    2010-10-01

    In this paper, the adsorption behavior of plasma proteins on the surface of ZnO thin films prepared by radio frequency (RF) sputtering under different sputtering powers was studied. The microstructures and surface properties of the ZnO thin films were investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible optical absorption spectroscopy and contact angle techniques. The results show that the ZnO thin films have better orientation of the (0 0 2) peak with increasing RF power, especially at around 160 W, and the optical band gap of the ZnO films varies from 3.2 to 3.4 eV. The contact angle test carried out by the sessile drop technique denoted a hydrophobic surface of the ZnO films, and the surface energy and adhesive work of the ZnO thin films decreased with increasing sputtering power. The amounts of human fibrinogen (HFG) and human serum albumin (HSA) adsorbing on the ZnO films and reference samples were determined by using enzyme-linked immunosorbent assay (ELISA). The results show that fewer plasma proteins and a smaller HFG/HSA ratio adsorb on the ZnO thin films' surface.

  11. High Temperature Thermoelectric Properties of ZnO Based Materials

    DEFF Research Database (Denmark)

    Han, Li

    of the dopants and dopant concentrations, a large power factor was obtainable. The sample with the composition of Zn0.9Cd0.1Sc0.01O obtained the highest zT ∼0.3 @1173 K, ~0.24 @1073K, and a good average zT which is better than the state-of-the-art n-type thermoelectric oxide materials. Meanwhile, Sc-doped Zn......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 Zn......O. 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...

  12. Influence of Te and Se doping on ZnO films growth by SILAR method

    Science.gov (United States)

    Güney, Harun; Duman, Ćaǧlar

    2016-04-01

    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.

  13. Influence of Te and Se doping on ZnO films growth by SILAR method

    International Nuclear Information System (INIS)

    Güney, Harun; Duman, Çağlar

    2016-01-01

    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.

  14. 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.

  15. Enhanced stimulated emission in ZnO thin films using microdisk top-down structuring

    Energy Technology Data Exchange (ETDEWEB)

    Nomenyo, K.; Kostcheev, S.; Lérondel, G. [Laboratoire de Nanotechnologie et d' Instrumentation Optique, Institut Charles Delaunay, CNRS UMR 6281, Université de Technologie de Troyes, 12 rue Marie Curie, CS 42060, 10004 Troyes Cedex (France); Gadallah, A.-S. [Laboratoire de Nanotechnologie et d' Instrumentation Optique, Institut Charles Delaunay, CNRS UMR 6281, Université de Technologie de Troyes, 12 rue Marie Curie, CS 42060, 10004 Troyes Cedex (France); Department of Laser Sciences and Interactions, National Institute of Laser Enhanced Sciences, Cairo University, Giza (Egypt); Rogers, D. J. [Nanovation, 8, route de Chevreuse, 78117 Châteaufort (France)

    2014-05-05

    Microdisks were fabricated in zinc oxide (ZnO) thin films using a top-down approach combining electron beam lithography and reactive ion etching. These microdisk structured thin films exhibit a stimulated surface emission between 3 and 7 times higher than that from a reference film depending on the excitation power density. Emission peak narrowing, reduction in lasing threshold and blue-shifting of the emission wavelength were observed along with enhancement in the emitted intensity. Results indicate that this enhancement is due to an increase in the internal quantum efficiency combined with an amplification of the stimulated emission. An analysis in terms of waveguiding is presented in order to explain these effects. These results demonstrate that very significant gains in emission can be obtained through conventional microstructuration without the need for more onerous top-down nanostructuration techniques.

  16. Optical band gap of ZnO thin films deposited by electron beam evaporation

    International Nuclear Information System (INIS)

    Nadeem, M. Y.; Ali, S. L.; Wasiq, M. F.; Rana, A. M.

    2006-01-01

    Optical band gap of ZnO thin films deposited by electron beam evaporation at evaporation rates ranging 5 As/sup -1/ to 15 As /sup -1/ and thickness ranging 1000A to 3000A is presented. Deposited films were annealed at 573K for one and half hour. The variations in the optical band gap were observed and showed decreasing behavior from 3.15 eV, 3.05 eV, from 3.18 eV to 3.10 eV and from 3.19 eV to 3.18 eV for films with respective thickness 1000A, 2000 A, 3000 A on increasing the evaporation rate from 5 As/sup-1/ to As/sup -1/ by keeping thickness constant. (author)

  17. Effects of Annealing Temperature on Properties of Ti-Ga-Doped ZnO Films Deposited on Flexible Substrates.

    Science.gov (United States)

    Chen, Tao-Hsing; Chen, Ting-You

    2015-11-03

    An investigation is performed into the optical, electrical, and microstructural properties of Ti-Ga-doped ZnO films deposited on polyimide (PI) flexible substrates and then annealed at temperatures of 300 °C, 400 °C, and 450 °C, respectively. The X-ray diffraction (XRD) analysis results show that all of the films have a strong (002) Ga doped ZnO (GZO) preferential orientation. As the annealing temperature is increased to 400 °C, the optical transmittance increases and the electrical resistivity decreases. However, as the temperature is further increased to 450 °C, the transmittance reduces and the resistivity increases due to a carbonization of the PI substrate. Finally, the crystallinity of the ZnO film improves with an increasing annealing temperature only up to 400 °C and is accompanied by a smaller crystallite size and a lower surface roughness.

  18. p-type ZnO films with solid-source phosphorus doping by molecular-beam epitaxy

    International Nuclear Information System (INIS)

    Xiu, F.X.; Yang, Z.; Mandalapu, L.J.; Liu, J.L.; Beyermann, W. P.

    2006-01-01

    Phosphorus-doped p-type ZnO films were grown on r-plane sapphire substrates using molecular-beam epitaxy with a solid-source GaP effusion cell. X-ray diffraction spectra and reflection high-energy electron diffraction patterns indicate that high-quality single crystalline (1120) ZnO films were obtained. Hall and resistivity measurements show that the phosphorus-doped ZnO films have high hole concentrations and low resistivities at room temperature. Photoluminescence (PL) measurements at 8 K reveal a dominant acceptor-bound exciton emission with an energy of 3.317 eV. The acceptor energy level of the phosphorus dopant is estimated to be 0.18 eV above the valence band from PL spectra, which is also consistent with the temperature dependence of PL measurements

  19. Doping properties of ZnO thin films for photovoltaic devices grown by URT-IP (ion plating) method

    International Nuclear Information System (INIS)

    Iwata, K.; Sakemi, T.; Yamada, A.; Fons, P.; Awai, K.; Yamamoto, T.; Matsubara, M.; Tampo, H.; Sakurai, K.; Ishizuka, S.; Niki, S.

    2004-01-01

    The Uramoto-gun with Tanaka magnetic field (URT)-ion plating (IP) method is a novel ion plating technique for thin film deposition. This method offers the advantage of low-ion damage, low deposition temperatures, large area deposition and high growth rates. Ga-doped ZnO thin films were grown using the URT-IP method, and the doping properties were evaluated. The opposing goals of low Ga composition and low resistivity are required for industrial applications of transparent conductive oxide (TCO). We have carried out a comparison between the carrier concentration and Ga atomic concentration in Ga-doped ZnO thin films and found the trade-off point for optimal TCO performance. The optimum growth conditions were obtained using a 3% Ga 2 O 3 content ZnO target

  20. X-ray diffraction analysis of thermally-induced stress relaxation in ZnO films deposited by magnetron sputtering on (100) Si substrates

    Energy Technology Data Exchange (ETDEWEB)

    Conchon, F., E-mail: florineconchon@gmail.co [Laboratoire de Physique des Materiaux (PHYMAT) UMR 6630, Universite de Poitiers, 86962 Futuroscope-Chasseneuil (France); Renault, P.O.; Goudeau, P.; Le Bourhis, E. [Laboratoire de Physique des Materiaux (PHYMAT) UMR 6630, Universite de Poitiers, 86962 Futuroscope-Chasseneuil (France); Sondergard, E.; Barthel, E.; Grachev, S. [Laboratoire de Surface du Verre et Interfaces (SVI), UMR 125, 93303 Aubervilliers (France); Gouardes, E.; Rondeau, V.; Gy, R. [Laboratoire de Recherche de Saint-Gobain (SGR), 93303 Aubervilliers (France); Lazzari, R.; Jupille, J. [Institut des Nanosciences de Paris (INSP), UMR 7588, 75015 Paris (France); Brun, N. [Laboratoire de Physique des Solides (LPS), UMR 8502, 91405 Orsay (France)

    2010-07-01

    Residual stresses in sputtered ZnO films on Si are determined and discussed. By means of X-ray diffraction, we show that as-deposited ZnO films are highly compressively stressed. Moreover, a transition of stress is observed as a function of the post-deposition annealing temperature. After an 800 {sup o}C annealing, ZnO films are tensily stressed while ZnO films encapsulated by Si{sub 3}N{sub 4} are stress-free. With the aid of in-situ X-ray diffraction under ambient and argon atmosphere, we argue that this thermally activated stress relaxation may be attributed to a variation of the stoichiometry of the ZnO films.

  1. Preparation and characterization of electrodeposited ZnO and ZnO:Co nanorod films for heterojunction diode applications

    Energy Technology Data Exchange (ETDEWEB)

    Caglar, Yasemin, E-mail: yasemincaglar@anadolu.edu.tr [Anadolu University, Science Faculty, Physics Department, Eskisehir (Turkey); Arslan, Andaç [Eskisehir Osmangazi University, Art and Science Faculty, Chemistry Department, Eskisehir (Turkey); Ilican, Saliha [Anadolu University, Science Faculty, Physics Department, Eskisehir (Turkey); Hür, Evrim [Eskisehir Osmangazi University, Art and Science Faculty, Chemistry Department, Eskisehir (Turkey); Aksoy, Seval; Caglar, Mujdat [Anadolu University, Science Faculty, Physics Department, Eskisehir (Turkey)

    2013-10-15

    Highlights: •Undoped and Co-doped ZnO films were deposited on p-Si by electrodeposition method. •The effects of Co doping on some properties of ZnO films were investigated. •ZnO morphology was converted uniform multi-oriented rods with incorporation of Co. •Co-doped ZnO nanorod films showed a multi-oriented spear-like structure. -- Abstract: Well-aligned undoped and Co-doped nanorod ZnO films were grown by electrochemical deposition onto p-Si substrates from an aqueous route. Aqueous solution of Zn(NO{sub 3}){sub 2}⋅6H{sub 2}O and hexamethylenetetramine (HMT) were prepared using triple distilled water. Two different atomic ratios of Co(NO{sub 3}){sub 2}⋅6H{sub 2}O were used as a dopant element. Electrodepositions were carried out in a conventional three electrode cell for the working electrode (p-Si), reference electrode (Ag/AgCl, sat.) and counter electrode (platin wire). The effects of Co doping on the structural, morphological and electrical properties of ZnO films were investigated. X-ray diffraction (XRD) measurement showed that the undoped ZnO nanorod film was crystallized in the hexagonal wurtzite phase and presented a preferential orientation along the c-axis. Only one peak, corresponding to the (0 0 2) phase, appeared on the diffractograms. The lattice parameters and texture coefficient values were calculated. The nanorods were confirmed by the field emission scanning electron microscopy (FE-SEM) measurements. The FE-SEM image showed that the ZnO nanorods grow uniformly on the substrates, providing a surface with fairly homogeneous roughness. The surface morphology was transformed into uniform multi-oriented rods with incorporation of Co. Co-doped ZnO nanorod films showed a multi-oriented spear-like structure. The diffuse reflectance spectra of the films were measured and the optical band gap values were determined using Kubelka–Munk theory. The van der Pauw method was used to measure the sheet resistance of the films. The sheet resistance

  2. Improvement of stoichiometry in (ZnO)1-x(GaN)x thin films grown by laser ablation

    International Nuclear Information System (INIS)

    Gopalakrishnan, N.; Shin, B.C.; Bhuvana, K.P.; Elanchezhiyan, J.; Balasubramanian, T.

    2008-01-01

    The fabrication of pure and GaN (1 mol%) doped ZnO thin films by KrF excimer laser have been addressed. The fabricated films on Si(1 1 1) substrates have been investigated by X-ray diffraction (XRD), photoluminescence (PL) and atomic force microscopy (AFM) in order to investigate the structural, optical and morphological properties, respectively. The XRD analysis shows that the full width at half maximum (FWHM) of ZnO film is found to be decreased as doped with GaN due to the improvement of the stoichiometery between Zn and O. The PL spectra reveal that the deep level emissions due to native donor defects in pure ZnO are suppressed upon doping with GaN. The images of AFM show that the RMS surface roughness of pure ZnO, 27 nm is reduced to18 nm while doped with 1 mol% GaN. The incorporation of nitrogen in the film is confirmed by glow discharge mass spectroscopy (GDMS). The improved structural, optical and morphological properties of ZnO by GaN dopant due to enhancement of stoichiometry have been discussed in detail

  3. 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.

  4. Study of Microstructural Parameters of Screen Printed ZnO Thick Film Sensors

    Directory of Open Access Journals (Sweden)

    A. V. PATIL

    2010-06-01

    Full Text Available This paper explores the compositional, morphological and structural properties of ZnO thick films prepared by a standard screen printing method and fired between 650 oC to 900 oC for 2 hours in an air atmosphere. The material characterization was done using X-ray energy dispersive analysis (EDX, X-ray diffraction (XRD and a scanning electron microscope (SEM. The deposited films were polycrystalline in nature having the wurtzite (hexagonal structure with a preferred orientation along the (101 plane. The result shows that the wt. % of Zn was found to be 80.39, 82.66 and 83.47 % for firing temperatures of 700, 800 and 900 oC respectively may be due to the release of excess oxygen. The effect of the firing temperature on structural parameters such as the crystallite size, specific surface area, texture coefficient, RMSmicrostrain, dislocation density and stacking fault probability have been studied. The results indicate that grain growth can be increased by increasing the firing temperature which is responsible for decreasing the RMSmicrostrain, stacking fault probability and dislocation density in ZnO thick films. The crystallite size changes from 18.58 nm to 37.23 nm with respect to the increase in the firing temperature.

  5. Intrinsic and spatially nonuniform ferromagnetism in Co-doped ZnO films

    Science.gov (United States)

    Tseng, L. T.; Suter, A.; Wang, Y. R.; Xiang, F. X.; Bian, P.; Ding, X.; Tseng, A.; Hu, H. L.; Fan, H. M.; Zheng, R. K.; Wang, X. L.; Salman, Z.; Prokscha, T.; Suzuki, K.; Liu, R.; Li, S.; Morenzoni, E.; Yi, J. B.

    2017-09-01

    Co doped ZnO films have been deposited by a laser-molecular beam epitaxy system. X-ray diffraction and UV spectra analysis show that Co effectively substitutes the Zn site. Transmission electron microscopy (TEM) and secondary ion mass spectroscopy analysis indicate that there are no clusters. Co dopants are uniformly distributed in ZnO film. Ferromagnetic ordering is observed in all samples deposited under an oxygen partial pressure, PO2=10-3 , 10-5, and 10-7 torr, respectively. However, the magnetization of PO2=10-3 and 10-5 is very small at room temperature. At low temperature, the ferromagnetic ordering is enhanced. Muon spin relaxation (μ SR ) measurements confirm the ferromagnetism in all samples, and the results are consistent with magnetization measurements. From μ SR and TEM analysis, the film deposited under PO2=10-7 torr shows intrinsic ferromagnetism. However, the volume fraction of the ferromagnetism phase is approximately 70%, suggesting that the ferromagnetism is not carrier mediated. Resistivity versus temperature measurements indicate Efros variable range hopping dominates the conductivity. From the above results, we can confirm that a bound magnetic polaron is the origin of the ferromagnetism.

  6. Acceptor-modulated optical enhancements and band-gap narrowing in ZnO thin films

    Science.gov (United States)

    Hassan, Ali; Jin, Yuhua; Irfan, Muhammad; Jiang, Yijian

    2018-03-01

    Fermi-Dirac distribution for doped semiconductors and Burstein-Moss effect have been correlated first time to figure out the conductivity type of ZnO. Hall Effect in the Van der Pauw configuration has been applied to reconcile our theoretical estimations which evince our assumption. Band-gap narrowing has been found in all p-type samples, whereas blue Burstein-Moss shift has been recorded in the n-type films. Atomic Force Microscopic (AFM) analysis shows that both p-type and n-type films have almost same granular-like structure with minor change in average grain size (˜ 6 nm to 10 nm) and surface roughness rms value 3 nm for thickness ˜315 nm which points that grain size and surface roughness did not play any significant role in order to modulate the conductivity type of ZnO. X-ray diffraction (XRD), Energy Dispersive X-ray Spectroscopy (EDS) and X-ray Photoelectron Spectroscopy (XPS) have been employed to perform the structural, chemical and elemental analysis. Hexagonal wurtzite structure has been observed in all samples. The introduction of nitrogen reduces the crystallinity of host lattice. 97% transmittance in the visible range with 1.4 × 107 Ω-1cm-1 optical conductivity have been detected. High absorption value in the ultra-violet (UV) region reveals that NZOs thin films can be used to fabricate next-generation high-performance UV detectors.

  7. Acceptor-modulated optical enhancements and band-gap narrowing in ZnO thin films

    Directory of Open Access Journals (Sweden)

    Ali Hassan

    2018-03-01

    Full Text Available Fermi-Dirac distribution for doped semiconductors and Burstein-Moss effect have been correlated first time to figure out the conductivity type of ZnO. Hall Effect in the Van der Pauw configuration has been applied to reconcile our theoretical estimations which evince our assumption. Band-gap narrowing has been found in all p-type samples, whereas blue Burstein-Moss shift has been recorded in the n-type films. Atomic Force Microscopic (AFM analysis shows that both p-type and n-type films have almost same granular-like structure with minor change in average grain size (∼ 6 nm to 10 nm and surface roughness rms value 3 nm for thickness ∼315 nm which points that grain size and surface roughness did not play any significant role in order to modulate the conductivity type of ZnO. X-ray diffraction (XRD, Energy Dispersive X-ray Spectroscopy (EDS and X-ray Photoelectron Spectroscopy (XPS have been employed to perform the structural, chemical and elemental analysis. Hexagonal wurtzite structure has been observed in all samples. The introduction of nitrogen reduces the crystallinity of host lattice. 97% transmittance in the visible range with 1.4 × 107 Ω-1cm-1 optical conductivity have been detected. High absorption value in the ultra-violet (UV region reveals that NZOs thin films can be used to fabricate next-generation high-performance UV detectors.

  8. Effects of Post Heat Treatments on ZnO Thin-Films Grown on Zn-coated Teflon Substrates

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ikhyun; Nam, Giwoong; Lee, Cheoleon; Kim, Dongwhan; Choi, Hyonkwang; Kim, Yangsoo; Leem, Jae-Young [Inje University, Gimhae (Korea, Republic of); Kim, Jin Soo [Chonbuk National University, Jeonju (Korea, Republic of); Kim, Jong Su [Yeungnam University, Gyeongsan (Korea, Republic of); Son, Jeong-Sik [Kyungwoon University, Gumi (Korea, Republic of)

    2015-06-15

    ZnO thin films were first grown on Zn-coated Teflon substrates using a spin-coating method, with various post-heating temperatures. The structural and optical properties of the ZnO thin films were then investigated using field-effect scanning-electron microscopy, X-ray diffractometry, and photoluminescence (PL) spectroscopy. The surface morphology of these ZnO thin films exhibited dendritic structures. With increasing post-heating temperature, all samples preferentially exhibited preferential c-axis orientation and increased residual tensile stress. All of the films exhibited preferential c-axis orientation, and the residual tensile stress of those increased with increasing post-heating temperature. The near-band-edge emission (NBE) peaks were red-shifted after post-heating treatment at 400 ℃. The intensity of the deep-level emission (DLE) peaks gradually decreased with increasing post- heating temperature. Moreover, the narrowest ‘full width at half maximum’ (FWHM) and the highest intensity ratio of the NBE to the DLE for thin films, were observed after post-heating at 400 ℃. The ZnO thin films fabricated with the 400 ℃ post-heating process provided the highest crystallinity and optical properties.

  9. Effects of Post- Heat Treatment of Nanocrystalline ZnO Thin Films deposited on Zn-Deposited FTO Substrates

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ikhyun; Kim, Younggyu; Nam, Giwoong; Leem, Jae-Young [Inje University, Gimhae (Korea, Republic of)

    2015-10-15

    The effects of heat-treatment temperature on the structural and optical properties of ZnO thin films were investigated with field-effect scanning electron microscopy (SEM), X-ray diffraction analysis, and photoluminescence (PL) measurements. The ZnO thin films were grown on Zn-deposited fluorine-doped tin oxide substrates by sol-gel spin coating. The SEM images of the samples showed that their surfaces had a mountain-chain-like structure. The film annealed at 400 ℃ had the highest degree of alignment along the c-axis, and its residual stress was close to zero. The PL spectra of the ZnO thin films consisted of sharp near-band-edge emissions (NBE) and broad deep-level emissions (DLE) in the visible range. The DLE peaks exhibited a green-to-red shift with an increase in the temperature. The highest INBE/IDLE ratio was observed in the film annealed at 400 ℃. Thus, the optimal temperature for growing high-quality ZnO thin films on Zn-deposited FTO substrates is 400 ℃.

  10. Effect of Mg doping in the gas-sensing performance of RF-sputtered ZnO thin films

    Science.gov (United States)

    Vinoth, E.; Gowrishankar, S.; Gopalakrishnan, N.

    2018-06-01

    Thin films of Mg-free and Mg-doped (3, 10 and 20 mol%) ZnO thin films have been deposited on Si (100) substrates by RF magnetron sputtering for gas-sensing application. Preferential orientation along (002) plane with hexagonal wurtzite structure has been observed in X-ray diffraction analysis. The conductivity, resistivity, and mobility of the deposited films have been measured by Hall effect measurement. The bandgap of the films has been calculated from the UV-Vis-NIR spectroscopy. It has been found that the bandgap was increased from 3.35 to 3.91 eV with Mg content in ZnO due to the radiative recombination of excitons. The change in morphology of the grown films has been investigated by scanning electron microscope. Gas-sensing measurements have been conducted for fabricated films. The sensor response, selectivity, and stability measurement were done for the fabricated films. Though better response was found towards ethanol, methanol, and ammonia for MZ2 (Mg at 10 mol%) film and maximum gas response was observed towards ammonia. The selectivity measurement reveals maximum sensitivity about 42% for ammonia. The low response time of 123 s and recovery time of 152 s towards ammonia were observed for MZ2 (Mg at 10 mol%). Stability of the Mg-doped ZnO thin film confirmed by the continuous sensing measurements for 4 months.

  11. Structural and morphological studies of ZnO: F films

    International Nuclear Information System (INIS)

    Tirado G, S.; Sanchez C, A.; Maldonado, A.

    2004-01-01

    Semiconductor thin films Zn O and F doped, using the chemical spray technique has been pre- pared, starting from pentanedionate and zinc acetate and ammonium fluorine in ethanol and methanol for a solution at 0.25%. The concentration [F]/[Zn] and the substrate temperature have been changed. From the X-rays diffraction and scanning electron microscopy techniques, the electrical, optical and chemical stability properties for the layers were studied. Size, geometry, and the grain orientation, distribution and the roughness effect in the light trapping were discussed. (Author)

  12. Origin of green luminescence in ZnO thin film grown by molecular-beam epitaxy

    International Nuclear Information System (INIS)

    Heo, Y.W.; Norton, D.P.; Pearton, S.J.

    2005-01-01

    The properties of ZnO films grown by molecular-beam epitaxy are reported. The primary focus was on understanding the origin of deep-level luminescence. A shift in deep-level emission from green to yellow is observed with reduced Zn pressure during the growth. Photoluminescence and Hall measurements were employed to study correlations between deep-level/near-band-edge emission and carrier density. With these results, we suggest that the green emission is related to donor-deep acceptor (Zn vacancy V Zn - ) and the yellow to donor-deep acceptor (oxygen vacancy, O i - )

  13. Structural characterization of ZnO thin films grown on various substrates by pulsed laser deposition

    Czech Academy of Sciences Publication Activity Database

    Novotný, Michal; Čížek, J.; Kužel, R.; Bulíř, Jiří; Lančok, Ján; Connolly, J.; McCarthy, E.; Krishnamurthy, S.; Mosnier, J.-P.; Anwand, W.; Brauer, G.

    2012-01-01

    Roč. 45, č. 22 (2012), 1-12 ISSN 0022-3727 R&D Projects: GA ČR(CZ) GAP108/11/0958; GA ČR GP202/09/P324 Institutional research plan: CEZ:AV0Z10100522 Keywords : ZnO thin film * pulsed laser deposition * x-ray diffraction positron implantation spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.528, year: 2012 http://dx.doi.org/10.1088/0022-3727/45/22/225101

  14. The phonon-assisted tunneling mechanism of conduction in ZnO nanowires and films

    International Nuclear Information System (INIS)

    Pipinys, Povilas; Ohlckers, Per

    2010-01-01

    The phonon-assisted tunneling (PhAT) model is applied for an explanation of the conductivity dependence on temperature and temperature-dependent I-V characteristics measured by other investigators for zinc oxide (ZnO) nanowires and films. Our proposed model describes well not only conductivity dependence on temperature measured in a wide temperature range, but also temperature-dependent I-V data using the same set of parameters characterizing the material under investigation. The values of active phonons energy are estimated from a fit of the conductivity dependence to temperature data with the PhAT theory.

  15. Combined effect of oxygen deficient point defects and Ni doping in radio frequency magnetron sputtering deposited ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Saha, B., E-mail: biswajit.physics@gmail.com [Thin Film and Nano Science Laboratory, Department of Physics, Jadavpur University, 700 032 Kolkata (India); Department of Physics, National Institute of Technology Agartala, Jirania 799046, Tripura (India); Das, N.S.; Chattopadhyay, K.K. [Thin Film and Nano Science Laboratory, Department of Physics, Jadavpur University, 700 032 Kolkata (India)

    2014-07-01

    Ni doped ZnO thin films with oxygen deficiency have been synthesized on glass substrates by radio frequency magnetron sputtering technique using argon plasma. The combined effect of point defects generated due to oxygen vacancies and Ni doping on the optical and electrical properties of ZnO thin films has been studied in this work. Ni doping concentrations were varied and the structural, optical and electrical properties of the films were studied as a function of doping concentrations. The films were characterized with X-ray diffractometer, UV–Vis–NIR spectrophotometer, X-ray photoelectron spectroscopy, atomic force microscopy and electrical conductivity measurements. Oxygen deficient point defects (Schottky defects) made the ZnO thin film highly conducting while incorporation of Ni dopant made it more functional regarding their electrical and optical properties. The films were found to have tunable electrical conductivity with Ni doping concentrations. - Highlights: • ZnO thin films prepared by radio frequency magnetron sputtering technique • Synthesis process was stimulated to introduce Schottky-type point defects. • Point defects and external doping of Ni made ZnO thin films more functional. • Point defect induced high electrical conductivity in ZnO thin film. • Significant shift in optical bandgap observed in ZnO with Ni doping concentrations.

  16. Influence of substrate temperature and Zn-precursors on atomic layer deposition of polycrystalline ZnO films on glass

    International Nuclear Information System (INIS)

    Makino, Hisao; Miyake, Aki; Yamada, Takahiro; Yamamoto, Naoki; Yamamoto, Tetsuya

    2009-01-01

    Influence of substrate temperature and Zn-precursors on growth rate, crystal structure, and electrical property of undoped ZnO thin films grown by atomic layer deposition (ALD) have been studied. Differences between dimethylzinc (DMeZn) and diethylzinc (DEtZn) used as Zn-precursors were examined. The ZnO films grown using DMeZn showed higher electrical resistivity compared to that grown using DEtZn. However, the higher resistivity in the case of DMeZn was owing to much amount of residual impurities incorporated during the ALD growth

  17. Synthesis of ZnO nanorods and observation of resistive switching memory in ZnO based polymer nanocomposites

    Science.gov (United States)

    Nair, Manjula G.; Malakar, Meenakshi; Mohapatra, Saumya R.; Chowdhury, Avijit

    2018-05-01

    This research reports the observation of bipolar resistive switching memory in ZnO nanorod based polymer nanocomposites. We synthesized ZnO nanorods by wet-chemical method and characterized them using XRD, UV-VIS spectroscopy and SEM. The synthesized materials have hexagonal ZnO phase with grain size of 24 nm and having strong orientation along (101) direction as observed from XRD. The SEM micrograph confirms the formation of ZnO nanorods with diameter in the range of 10 to 20 nm and length of the order of 1 µm. From optical absorption spectra the band gap is estimated to be 2.42 eV. ZnO nanorods were dispersed in PVDF-HFP polymer matrix to prepare the nanocomposite. This nanocomposite was used as active layer in the devices having sandwich structure of ITO/PVDF-HFP+ZnO nanorods/Al. Bipolar non-volatile memory was observed with ON-OFF resistance ratio of the order of 103 and with a wide voltage window of 2.3V. The switching mechanism could be due to the trapping and de-trapping of electrons by the ZnO nanorods in the nanocomposite during ON and OFF states respectively.

  18. Smart chemical sensors using ZnO semiconducting thin films for freshness detection of foods and beverages

    Science.gov (United States)

    Nanto, Hidehito; Kobayashi, Toshiki; Dougami, Naganori; Habara, Masaaki; Yamamoto, Hajime; Kusano, Eiji; Kinbara, Akira; Douguchi, Yoshiteru

    1998-07-01

    The sensitivity of the chemical sensor, based on the resistance change of Al2O3-doped and SnO2-doped ZnO (ZnO:Al and ZnO:SnO2) thin film, is studied for exposure to various gases. It is found that the ZnO:Al and ZnO:Sn thin film chemical sensor has a high sensitivity and excellent selectivity for amine (TMA and DMA) gas and ethanol gas, respectively. The ZnO:Al (5.0 wt%) thin film chemical sensor which exhibit a high sensitivity for exposure to odors from rotten sea foods, such as salmon, sea bream, oyster, squid and sardine, responds to the freshness change of these sea foods. The ZnO:SnO2 (78 wt%) thin film chemical sensor which exhibit a high sensitivity for exposure to aroma from alcohols, such as wine, Japanese sake, and whisky, responds to the freshness change of these alcohols.

  19. Chemical-bath ZnO buffer layer for CuInS{sub 2} thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ennaoui, A.; Weber, M.; Scheer, R.; Lewerenz, H.J. [Hahn-Meitner-Institut, Abt. Grenzflaechen, Bereich Physikalische Chemie, Glienicker Strasse 100, D-14109 Berlin (Germany)

    1998-07-13

    ZnO buffer layers were grown by a chemical-bath deposition (CBD) in order to improve the interface quality in p-CuInS{sub 2} based solar cells, to improve the light transmission in the blue wavelength region, but also as an alternative to eliminate the toxic cadmium. The process consists of immersion of different substrates (glass, CIS) in a dilute solution of tetraamminezinc II, [Zn(NH{sub 2}){sub 4}]{sup 2+}, complex at 60-95C. During the growth process, a homogeneous growth mechanism which proceeds by the sedimentation of a mixture of ZnO and Zn(OH){sub 2} clusters formed in solution, competes with the heterogeneous growth mechanism. The mechanism consists of specific adsorption of a complex Zn(II) followed by a chemical reaction. The last process of growth results in thin, hard, adherent and specularly reflecting films. The characterization of the deposited CBD-ZnO layers was performed by X-ray diffraction (XRD), optical transmittance, scanning electron microscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The as-deposited films on glass show hexagonal zincite structure with two preferred orientations (1 0 0) and (1 0 1). High optical transmittance up to 80% in the near-infrared and part of the visible region was observed. The low growth rate of the films on CIS suggests an atomic layer-by-layer growth process.The device parameters and performance are compared to heterojunction with a standard CdS buffer layer

  20. Friction and wear behavior of nitrogen-doped ZnO thin films deposited via MOCVD under dry contact

    Directory of Open Access Journals (Sweden)

    U.S. Mbamara

    2016-06-01

    Full Text Available Most researches on doped ZnO thin films are tilted toward their applications in optoelectronics and semiconductor devices. Research on their tribological properties is still unfolding. In this work, nitrogen-doped ZnO thin films were deposited on 304 L stainless steel substrate from a combination of zinc acetate and ammonium acetate precursor by MOCVD technique. Compositional and structural studies of the films were done using Rutherford Backscattering Spectroscopy (RBS and X-ray Diffraction (XRD. The frictional behavior of the thin film coatings was evaluated using a ball-on-flat configuration in reciprocating sliding under dry contact condition. After friction test, the flat and ball counter-face surfaces were examined to assess the wear dimension and failure mechanism. Both friction behavior and wear (in the ball counter-face were observed to be dependent on the crystallinity and thickness of the thin film coatings.

  1. Praseodymium - A Competent Dopant for Luminescent Downshifting and Photocatalysis in ZnO Thin Films

    Science.gov (United States)

    Narayanan, Nripasree; Deepak, N. K.

    2018-05-01

    Highly transparent and conducting Zinc oxide (ZnO) thin films doped with Praseodymium (Pr) were deposited on glass substrates by using the spray pyrolysis method. The X-ray diffraction (XRD) analysis revealed the polycrystallinity of the deposited films with a hexagonal wurtzite structure, whereas the energy-dispersive X-ray spectroscopy (EDX) analysis confirmed the incorporation of Pr in the films. The optical energy gap decreased by Pr doping due to the merging of the conduction band with the impurity bands formed within the forbidden gap. The room temperature photoluminescence spectra of the Pr-doped film showed enhancement of visible emission, suggesting efficient luminescent downshifting. The photocatalytic activity of the Pr-doped films is higher than that of undoped films due to the effective suppression of the rapid recombination of the photo-generated electron-hole pairs. The impurity levels formed within the forbidden gap act as efficient luminescent centers and electron traps, which lead to luminescent downshifting and enhanced photocatalytic activity.

  2. High energy electron irradiation effects on Ga-doped ZnO thin films for optoelectronic space applications

    Science.gov (United States)

    Serrao, Felcy Jyothi; Sandeep, K. M.; Bhat, Shreesha; Dharmaprakash, S. M.

    2018-03-01

    Gallium-doped ZnO (GZO) thin films of thickness 394 nm were prepared by a simple, cost-effective sol-gel spin coating method. The effect of 8 MeV electron beam irradiation with different irradiation doses ranging from 0 to 10 kGy on the structural, optical and electrical properties was investigated. Electron irradiation influences the changes in the structural properties and surface morphology of GZO thin films. X-ray diffraction analysis showed that the polycrystalline nature of the GZO films is unaffected by the high energy electron irradiation. The grain size and the surface roughness were found maximum for the GZO film irradiated with 10 kGy electron dosage. The average transmittance of GZO thin films decreased after electron irradiation. The optical band gap of Ga-doped ZnO films was decreased with the increase in the electron dosage. The electrical resistivity of GZO films decreased from 4.83 × 10-3 to 8.725 × 10-4 Ω cm, when the electron dosage was increased from 0 to 10 kGy. The variation in the optical and electrical properties in the Ga-doped ZnO thin films due to electron beam irradiation in the present study is useful in deciding their compatibility in optoelectronic device applications in electron radiation environment.

  3. Cycling behaviour of sponge-like nanostructured ZnO as thin-film Li-ion battery anodes

    International Nuclear Information System (INIS)

    Garino, Nadia; Lamberti, Andrea; Gazia, Rossana; Chiodoni, Angelica; Gerbaldi, Claudio

    2014-01-01

    Highlights: • Zn is thermally oxidized in ambient air to obtain sponge-like ZnO film. • Polycrystalline, transparent, porous thin film is obtained. • Film exhibits stabile specific capacity (∼300 mAh g −1 ) after prolonged cycling. • Sponge-like ZnO film shows promising prospects as Li-ion battery anode. - Abstract: Single phase wurtzitic porous ZnO thin films are obtained by a simple two-step method, involving the sputtering deposition of a sponge-like metallic Zn layer, followed by a moderately low temperature treatment for the complete zinc oxidation. Thanks to its 3D nanostructuration, the superimposition of small branches able to grow in length almost isotropically and forming a complex topography, sponge-like ZnO can combine the fast transport properties of one dimensional material and the high surface area usually provided by nanocrystalline electrodes. When galvanostatically tested in lithium cell, after the initial decay, it can provide an almost stable specific capacity higher than 50 μAh cm −2 after prolonged cycling at estimated 0.7 C, with very high Coulombic efficiency

  4. Cycling behaviour of sponge-like nanostructured ZnO as thin-film Li-ion battery anodes

    Energy Technology Data Exchange (ETDEWEB)

    Garino, Nadia, E-mail: nadia.garino@iit.it [Center for Space Human Robotics @Polito, Istituto Italiano di Tecnologia, Corso Trento, 21, 10129 Turin (Italy); Lamberti, Andrea; Gazia, Rossana; Chiodoni, Angelica [Center for Space Human Robotics @Polito, Istituto Italiano di Tecnologia, Corso Trento, 21, 10129 Turin (Italy); Gerbaldi, Claudio, E-mail: claudio.gerbaldi@polito.it [Center for Space Human Robotics @Polito, Istituto Italiano di Tecnologia, Corso Trento, 21, 10129 Turin (Italy); GAME Lab, Department of Applied Science and Technology – DISAT, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Turin (Italy)

    2014-12-05

    Highlights: • Zn is thermally oxidized in ambient air to obtain sponge-like ZnO film. • Polycrystalline, transparent, porous thin film is obtained. • Film exhibits stabile specific capacity (∼300 mAh g{sup −1}) after prolonged cycling. • Sponge-like ZnO film shows promising prospects as Li-ion battery anode. - Abstract: Single phase wurtzitic porous ZnO thin films are obtained by a simple two-step method, involving the sputtering deposition of a sponge-like metallic Zn layer, followed by a moderately low temperature treatment for the complete zinc oxidation. Thanks to its 3D nanostructuration, the superimposition of small branches able to grow in length almost isotropically and forming a complex topography, sponge-like ZnO can combine the fast transport properties of one dimensional material and the high surface area usually provided by nanocrystalline electrodes. When galvanostatically tested in lithium cell, after the initial decay, it can provide an almost stable specific capacity higher than 50 μAh cm{sup −2} after prolonged cycling at estimated 0.7 C, with very high Coulombic efficiency.

  5. Fabrication of nanostructured ZnO film as a hole-conducting layer of organic photovoltaic cell

    Science.gov (United States)

    Kim, Hyomin; Kwon, Yiseul; Choe, Youngson

    2013-05-01

    We have investigated the effect of fibrous nanostructured ZnO film as a hole-conducting layer on the performance of polymer photovoltaic cells. By increasing the concentration of zinc acetate dihydrate, the changes of performance characteristics were evaluated. Fibrous nanostructured ZnO film was prepared by sol-gel process and annealed on a hot plate. As the concentration of zinc acetate dihydrate increased, ZnO fibrous nanostructure grew from 300 to 600 nm. The obtained ZnO nanostructured fibrous films have taken the shape of a maze-like structure and were characterized by UV-visible absorption, scanning electron microscopy, and X-ray diffraction techniques. The intensity of absorption bands in the ultraviolet region was increased with increasing precursor concentration. The X-ray diffraction studies show that the ZnO fibrous nanostructures became strongly (002)-oriented with increasing concentration of precursor. The bulk heterojunction photovoltaic cells were fabricated using poly(3-hexylthiophene-2,5-diyl) and indene-C60 bisadduct as active layer, and their electrical properties were investigated. The external quantum efficiency of the fabricated device increased with increasing precursor concentration.

  6. Effect of different sol concentrations on the properties of nanocrystalline ZnO thin films grown on FTO substrates by sol-gel spin-coating

    International Nuclear Information System (INIS)

    Kim, Ikhyun; Kim, Younggyu; Nam, Giwoong; Kim, Dongwan; Park, Minju; Kim, Haeun; Lee, Wookbin; Leem, Jaeyoung; Kim, Jongsu; Kim, Jin Soo

    2014-01-01

    Nanocrystalline ZnO thin films grown on fluorine-doped tinoxide (FTO) substrates were fabricated using the spin-coating method. The structural and the optical properties of the ZnO thin films prepared using different sol concentrations were investigated by using field-emission scanning electron microscopy (FE-SEM), X-ray diffractometry (XRD), photoluminescence (PL) measurements, and ultraviolet-visible (UV-vis) spectrometry. The surface morphology of the ZnO thin films, as observed in the SEM images, exhibited a mountain-chain structure. XRD results indicated that the thin films were preferentially orientated along the direction of the c-axis and that the grain size of the ZnO thin films increased with increasing sol concentration. The PL spectra showed a strong ultraviolet emission peak at 3.22 eV and a broad orange emission peak at 2.0 eV. The intensities of deep-level emission (DLE) gradually increased with increasing sol concentration from 0.4 to 1.0 M. The transmittance spectra of the ZnO thin films showed that the ZnO thin films were transparent (∼85%) in the visible region and exhibited sharp absorption edges at 375 nm. Thus, The Urbach energy of ZnO thin films decreased with increasing sol concentration.

  7. Effect of annealing temperature on the tribological behavior of ZnO films prepared by sol-gel method

    International Nuclear Information System (INIS)

    Lin Liyu; Kim, Dae-Eun

    2009-01-01

    The tribological behavior of zinc oxide (ZnO) films grown on glass and silicon (100) substrates by sol-gel method was investigated. Particularly, the as-coated films were post-annealed at different temperatures in air to investigate the effect of annealing temperature. Crystal structural and surface morphology of the films were measured by X-ray diffraction (XRD) and Atomic Force Microscopy (AFM). XRD patterns and AFM images indicated that the crystallinity and grain size of the films were enhanced and increased, respectively, with temperature. The tribological behavior of films was evaluated by sliding the ZnO films against a Si 3 N 4 ball under 0.5 gf normal load using a reciprocating pin-on-plate tribo-tester. The wear tracks of the films were measured by AFM to quantify the wear resistance of the films. The results showed that the wear resistance of the films could be improved by the annealing process. The wear resistance of the films generally increased with annealing temperature. Specifically, the wear resistance of the films was significantly improved when the annealing temperature was higher than 550 deg. C. The increase in the wear resistance is attributed to the increase in hardness and modulus of the film with annealing temperature

  8. Effect of Sn-doped on microstructural and optical properties of ZnO thin films deposited by sol-gel method

    International Nuclear Information System (INIS)

    Tsay, C.-Y.; Cheng, H.-C.; Tung, Y.-T.; Tuan, W.-H.; Lin, C.-K.

    2008-01-01

    In this study, transparent thin films of Sn-doped ZnO (ZnO:Sn) were deposited onto alkali-free glass substrates by a sol-gel method; the effect of Sn doping on crystallinity, microstructural and optical properties was investigated. The atomic percentages of dopant in ZnO-based sols were Sn/Zn = 0, 1, 2, 3, and 5 at.%. The as-deposited films were pre-heated at 300 deg. C for 10 min and then annealed in air at 500 deg. C for 1 h. The results show that Sn-doped ZnO thin films demonstrate obviously improved surface roughness, enhanced transmittance in the 400-600 nm wavelength range and reduced average crystallite size. Among all of the annealed ZnO-based films in this study, films doped with 2 at.% Sn concentration exhibited the best properties, namely an average transmittance of 90%, an RMS roughness value of 1.92 nm and a resistivity of 9.3 x 10 2 Ω-cm

  9. UV-screening, transparency and water barrier properties of semi refined iota carrageenan packaging film incorporated with ZnO nanoparticles

    Science.gov (United States)

    Khoirunnisa, Assifa Rahma; Joni, I. Made; Panatarani, Camellia; Rochima, Emma; Praseptiangga, Danar

    2018-02-01

    This study aims to develop film for food packaging application with high UV-screening, transparency and water barrier properties. Semi refined iota carrageenan (SRiC) nanocomposite films prepared by addition of zinc oxide (ZnO) nanoparticles as nanofiller using solution casting method. The effect of nanofiller with different concentration (0%, 0.5%, 1.0%, 1.5% w/w carrageenan) on UV-screening, transparency and water barrier properties of films were tested. The water barrier properties of the films were studied by measuring water vapor permeability (WVP) and the optical properties of the films were studied by using UV-Vis spectrophotometer at 280 nm for UV-screening test and at 660 nm for transparency test. WVP value of carrageenan films with addition of ZnO is low compared to a control carrageenan film and the lowest WVP value was found for the film with addition of 1.5% of ZnO. These result indicate that the addition of ZnO had a positive effect on the water barrier properties of the carrageenan matrix. Increase in the concentration of nanofiller leads to an increase in the UV-screening properties. Among all the films, carrageenan film with 1.5% ZnO has the highest UV-screening. The result showed that adding 0.5% and 1.0% of ZnO was insignificantly affect transparency of the films, however the transparency decreased sligthly when 1.5% ZnO was added. In conclusion, incorporating no more than 1.0% of ZnO to the films can obtain films with high UV-screening, transparency and water barrier properties and suitable for food packaging application.

  10. The roles of buffer layer thickness on the properties of the ZnO epitaxial films

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Kun, E-mail: ktang@nju.edu.cn [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Huang, Shimin [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Gu, Shulin, E-mail: slgu@nju.edu.cn [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Zhu, Shunming [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Ye, Jiandong [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Nanjing University Institute of Optoelectronics at Yangzhou, Yangzhou 225009 (China); Xu, Zhonghua; Zheng, Youdou [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China)

    2016-12-01

    Highlights: • The growth mechanism has been revealed for the ZnO buffers with different thickness. • The surface morphology has been determined as the key factor to affect the epitaxial growth. • The relation between the hexagonal pits from buffers and epi-films has been established. • The hexagonal pits formed in the epi-films have been attributed to the V-shaped defects inheriting from the dislocations in the buffers. • The structural and electrical properties of the V-defects have been presented and analyzed. - Abstract: In this article, the authors have investigated the optimization of the buffer thickness for obtaining high-quality ZnO epi-films on sapphire substrates. The growth mechanism of the buffers with different thickness has been clearly revealed, including the initial nucleation and vertical growth, the subsequent lateral growth with small grain coalescence, and the final vertical growth along the existing larger grains. Overall, the quality of the buffer improves with increasing thickness except the deformed surface morphology. However, by a full-scale evaluation of the properties for the epi-layers, the quality of the epi-film is briefly determined by the surface morphology of the buffer, rather than the structural, optical, or electrical properties of it. The best quality epi-layer has been grown on the buffer with a smooth surface and well-coalescent grains. Meanwhile, due to the huge lattice mismatch between sapphire and ZnO, dislocations are inevitably formed during the growth of buffers. More importantly, as the film grows thicker, the dislocations may attracting other smaller dislocations and defects to reduce the total line energy and thus result in the formation of V-shape defects, which are connected with the bottom of the threading dislocations in the buffers. The V-defects appear as deep and large hexagonal pits from top view and they may act as electron traps which would affect the free carrier concentration of the epi-layers.

  11. The roles of buffer layer thickness on the properties of the ZnO epitaxial films

    International Nuclear Information System (INIS)

    Tang, Kun; Huang, Shimin; Gu, Shulin; Zhu, Shunming; Ye, Jiandong; Xu, Zhonghua; Zheng, Youdou

    2016-01-01

    Highlights: • The growth mechanism has been revealed for the ZnO buffers with different thickness. • The surface morphology has been determined as the key factor to affect the epitaxial growth. • The relation between the hexagonal pits from buffers and epi-films has been established. • The hexagonal pits formed in the epi-films have been attributed to the V-shaped defects inheriting from the dislocations in the buffers. • The structural and electrical properties of the V-defects have been presented and analyzed. - Abstract: In this article, the authors have investigated the optimization of the buffer thickness for obtaining high-quality ZnO epi-films on sapphire substrates. The growth mechanism of the buffers with different thickness has been clearly revealed, including the initial nucleation and vertical growth, the subsequent lateral growth with small grain coalescence, and the final vertical growth along the existing larger grains. Overall, the quality of the buffer improves with increasing thickness except the deformed surface morphology. However, by a full-scale evaluation of the properties for the epi-layers, the quality of the epi-film is briefly determined by the surface morphology of the buffer, rather than the structural, optical, or electrical properties of it. The best quality epi-layer has been grown on the buffer with a smooth surface and well-coalescent grains. Meanwhile, due to the huge lattice mismatch between sapphire and ZnO, dislocations are inevitably formed during the growth of buffers. More importantly, as the film grows thicker, the dislocations may attracting other smaller dislocations and defects to reduce the total line energy and thus result in the formation of V-shape defects, which are connected with the bottom of the threading dislocations in the buffers. The V-defects appear as deep and large hexagonal pits from top view and they may act as electron traps which would affect the free carrier concentration of the epi-layers.

  12. Structural and optical properties of ZnO nanostructures electrochemically synthesized on AZO/Ag/AZO-multilayer-film-coated polyethersulfone substrates

    International Nuclear Information System (INIS)

    Oh, Dohyun; Yoo, Chanho; No, Youngsoo; Kim, Suyoun; Kim, Taewhan; Cho, Woonjo; Kim, Jinyoung

    2012-01-01

    ZnO nanostructures were formed on Al-doped ZnO (AZO)/Ag/AZO-multilayer-film-coated flexible polyethersulfone (PES) substrates at low temperature by using an electrochemical deposition method. The resistivity of the AZO/Ag/AZO multilayer films decreased with increasing thickness of the Ag film. X-ray diffraction patterns for the ZnO nanostructures showed that the crystal structure of the ZnO was hexagonal wurtzite and that the orientation was along the c-axis perpendicular to the substrate. Scanning electron microscopy images showed that the ZnO nanostructures grown at current densities of - 1.0 and - 1.5 mA/cm 2 were ZnO nanorods with diameters of 150 nm and ZnO nanoflowers with a planar dimension, respectively. Photoluminescence spectra showed that the band-edge emission peak of the ZnO nanostructures dominantly appeared in the ultraviolet region. These results showed that ZnO nanorods and nanoflowers with high quality were synthesized on AZO/Ag/AZO-multilayer-film-coated PES substrates.

  13. Nanocystalline ZnO films prepared via polymeric precursor method (Pechini)

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, C.; Doria, J.; Paucar, C.; Hernandez, M. [Laboratorio de Materiales Ceramicos y Vitreos, Universidad Nacional de Colombia, Sede Medellin, A.A. 568, Medellin (Colombia); Mosquera, A.; Rodriguez, J.E. [Grupo CYTEMAC, Universidad del Cauca, Calle 5 No 4-70, Popayan (Colombia); Gomez, A. [Departamento de Ingenieria de Materiales, Universidad Nacional de Colombia, sede Medellin, A.A. 568, Medellin (Colombia); Baca, E. [Grupo de Ingenieria de Nuevos Materiales, Universidad del Valle, A.A. 25360 Cali (Colombia); Moran, O., E-mail: omoranc@unal.edu.c [Laboratorio de Materiales Ceramicos y Vitreos, Universidad Nacional de Colombia, Sede Medellin, A.A. 568, Medellin (Colombia)

    2010-09-01

    The polymeric precursor method (Pechini) was employed to prepare high-quality nanocrystalline zinc oxide (ZnO) films. Briefly, the process started off with the preparation of a coating solution by the Pechini process followed by a coating of the glass substrates by a dip-coating technique and subsequent heat-treatment of the as-deposited films up to 550 {sup o}C for 30 min. The Rietveld profile analysis of the X-ray diffraction (XRD) spectra revealed the wuerzite structure as expected for ZnO with a P6{sub 3}mc symmetry. No additional peaks were observed that would correspond to any secondary crystalline phase. The average crystallites size was 20 nm as calculated by Sherrer's equation. UV-vis spectroscopy showed sharp ultraviolet absorption edges at {approx}380 nm. The absorption edge analysis yielded optical band gap energy of 3.24 eV with electronic transition of the direct transition type. The Fourier transform infrared (FTIR) analysis showed asymmetric and symmetric stretching modes of the carboxyl group (C=O). Scanning electron microscope (SEM) analysis revealed a crack-free surface morphology indicating that coating of the amorphous glass substrates was homogeneous on large surface areas. The temperature dependent conductivity featured a typical semiconducting-like behavior with resistivity approaching 3x10{sup -1} {Omega} cm at 220 K.

  14. ZnO transparent conductive oxide for thin film silicon solar cells

    Science.gov (United States)

    Söderström, T.; Dominé, D.; Feltrin, A.; Despeisse, M.; Meillaud, F.; Bugnon, G.; Boccard, M.; Cuony, P.; Haug, F.-J.; Faÿ, S.; Nicolay, S.; Ballif, C.

    2010-03-01

    There is general agreement that the future production of electric energy has to be renewable and sustainable in the long term. Photovoltaic (PV) is booming with more than 7GW produced in 2008 and will therefore play an important role in the future electricity supply mix. Currently, crystalline silicon (c-Si) dominates the market with a share of about 90%. Reducing the cost per watt peak and energy pay back time of PV was the major concern of the last decade and remains the main challenge today. For that, thin film silicon solar cells has a strong potential because it allies the strength of c-Si (i.e. durability, abundancy, non toxicity) together with reduced material usage, lower temperature processes and monolithic interconnection. One of the technological key points is the transparent conductive oxide (TCO) used for front contact, barrier layer or intermediate reflector. In this paper, we report on the versatility of ZnO grown by low pressure chemical vapor deposition (ZnO LP-CVD) and its application in thin film silicon solar cells. In particular, we focus on the transparency, the morphology of the textured surface and its effects on the light in-coupling for micromorph tandem cells in both the substrate (n-i-p) and superstrate (p-i-n) configurations. The stabilized efficiencies achieved in Neuchâtel are 11.2% and 9.8% for p-i-n (without ARC) and n-i-p (plastic substrate), respectively.

  15. Preparation of a Non-Polar ZnO Film on a Single-Crystal NdGaO3 Substrate by the RF Sputtering Method

    Science.gov (United States)

    Kashiwaba, Y.; Tanaka, Y.; Sakuma, M.; Abe, T.; Imai, Y.; Kawasaki, K.; Nakagawa, A.; Niikura, I.; Kashiwaba, Y.; Osada, H.

    2018-04-01

    Preparation of non-polar ZnO ( 11\\overline{2} 0 ) films on single-crystal NdGaO3 (NGO) (001) substrates was successfully achieved by the radio frequency (RF) sputtering method. Orientation, deposition rate, and surface roughness of ZnO films strongly depend on the working pressure. Characteristics of ZnO films deposited on single-crystal NGO (001) substrates were compared with those of ZnO films deposited on single-crystal sapphire ( 01\\overline{1} 2 ) substrates. An x-ray diffraction peak of the ZnO ( 11\\overline{2} 0 ) plane was observed on ZnO films deposited on single-crystal NGO (001) substrates under working pressure of less than 0.5 Pa. On the other hand, uniaxially oriented ZnO ( 11\\overline{2} 0 ) films on single-crystal sapphire ( 01\\overline{1} 2 ) substrates were observed under working pressure of 0.1 Pa. The mechanism by which the diffraction angle of the ZnO ( 11\\overline{2} 0 ) plane on single-crystal NGO (001) substrates was shifted is discussed on the basis of anisotropic stress of lattice mismatch. The deposition rate of ZnO films decreased with an increase in working pressure, and the deposition rate on single-crystal NGO (001) substrates was larger than that on single-crystal sapphire ( 01\\overline{1} 2 ) substrates. Root mean square (RMS) roughness of ZnO films increased with an increase in working pressure, and RMS roughness of ZnO films on single-crystal NGO (001) substrates was smaller than that of ZnO films on single-crystal sapphire ( 01\\overline{1} 2 ) substrates even though the film thickness on single-crystal NGO (001) substrates was greater than that on sapphire substrates. It is thought that a single-crystal NGO (001) substrate is useful for deposition of non-polar ZnO ( 11\\overline{2} 0 ) films.

  16. Functionalized carbon nanotubes in ZnO thin films for photoinactivation of bacteria

    International Nuclear Information System (INIS)

    Akhavan, O.; Azimirad, R.; Safa, S.

    2011-01-01

    Highlights: → Unfunctionalized and functionalized MWCNT/ZnO thin films were synthesized by sol-gel method. → Zn-O-C carbonaceous bonds formed in the functionalized MWCNT/ZnO thin films. → The functionalized MWCNT/ZnO had stronger photoinactivation of the bacteria than the unfunctionalize type. → 10 wt% functionalized MWCNT content had the optimum antibacterial property. - Abstract: Two types of unfunctionalized and functionalized multi-wall carbon nanotubes (MWCNTs) were prepared to be applied in fabrication of MWCNT-ZnO nanocomposite thin films with various MWCNT contents. X-ray photoelectron spectroscopy indicated formation of functional groups on surface of the functionalized MWCNTs in the MWCNT-ZnO nanocomposite. Formation of the effective carbonaceous bonds between the ZnO and the MWCNTs was also investigated through photoinactivation of Escherichia coli bacteria on surface of the both unfunctionalized and functionalized MWCNT-ZnO nanocomposites. The functionalized MWCNT-ZnO nanocomposites showed significantly stronger photoinactivation of the bacteria than the unfunctionalized ones, for all of the various MWCNT contents (from 2 to 30 wt%). While the functionalized MWCNT-ZnO nanocomposites with the optimum MWCNT content of 10 wt% inactivated whole of the bacteria after 10 min UV-visible light irradiation, the unfunctionalized ones could inactivate only 63% of the bacteria under the same conditions. The significant enhancement of the photoinactivation of the bacteria onto the surface of the functionalized MWCNT-ZnO nanocomposites was assigned to charge transfer through Zn-O-C bands formed between the Zn atoms of the ZnO film and oxygen atoms of the carboxylic functional groups of the functionalized MWCNTs.

  17. High-energy electron beam irradiation of Al-doped ZnO thin films deposited at room temperature

    International Nuclear Information System (INIS)

    Yun, Eui-Jung; Jung, Jin-Woo; Hwang, Jong-Ha; Lee, Byung-Cheol; Jung, Myung-Hee

    2011-01-01

    In this research, we demonstrated the effects of high-energy electron beam irradiation (HEEBI) on the optical and structural properties of Al-doped ZnO (AZO) films grown on transparent corning glass substrates at room temperature (RT) by using a radio-frequency magnetron sputtering technique. The AZO thin films were treated with HEEBI in air at RT at an electron beam energy of 0.8 MeV and doses of 1 x 10 14 - 1 x 10 16 electrons/cm 2 . The photoluminescence (PL) measurements revealed that the dominant peak at 2.77 eV was a blue emission originating from donor-like defects, oxygen vacancies (V o ), suggesting that the n-type conductivity was preserved in HEEBI-treated films. On the basis of PL, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy results, we suggest that the density of V o donor defects is decreased due to in-diffusion of oxygen from the ambient into the films after HEEBI treatment at low doses up to 10 15 electrons/cm 2 while the opposite phenomenon can occur with further increase in the dose. We also found from the XRD analysis that the worse crystallinity with a smaller grain size was observed in HEEBI-treated AZO films at a higher dose, corresponding to a higher oxygen fraction in the films. We believe that our results will contribute to developing high-quality AZO-based materials and devices for space applications.

  18. Plasmonic enhancement of UV emission from ZnO thin films induced by Al nano-concave arrays

    International Nuclear Information System (INIS)

    Norek, Małgorzata; Łuka, Grzegorz; Włodarski, Maksymilian

    2016-01-01

    Highlights: • Al nano-concave arrays with different interpore distance (D c ) were prepared. • PL of ZnO thin films deposited directly on the Al nano-concaves were studied. • The effect of 10 nm Al 2 O 3 spacer on PL emission from ZnO thin films was analyzed. • Plasmonic enhancement of the PL emission was dependent on the D c and the spacer. • The highest 9-fold enhancement was obtained for the Al/ZnO sample with D c ∼333 nm. - Abstract: Surface plasmons (SPs) supported by Al nano-concave arrays with increasing interpore distance (D c ) were used to enhance the ultraviolet light emission from ZnO thin films. Two sets of samples were prepared: in the first set the thin ZnO films were deposited directly on Al nanoconcaves (the Al/ZnO samples) and in the second set a 10 nm − Al 2 O 3 spacer was placed between the textured Al and the ZnO films (the Al/Al 2 O 3 -ALD/ZnO samples). In the Al/ZnO samples the enhancement was limited by a nonradiative energy dissipation due to the Ohmic loss in the Al metal. However, for the ZnO layer deposited directly on Al nanopits synthesized at 150 V (D c = 333 ± 18 nm), the largest 9-fold enhancement was obtained by achieving the best energy fit between the near band-edge (NBE) emission from ZnO and the λ (0,1) SPP resonance mode. In the Al/Al 2 O 3 -ALD/ZnO samples the amplification of the UV emission was smaller than in the Al/ZnO samples due to a big energy mismatch between the NBE emission and the λ (0,1) plasmonic mode. The results obtained in this work indicate that better tuning of the NBE − λ (0,1) SPP resonance mode coupling is possible through a proper modification of geometrical parameters in the Al/Al 2 O 3 -ALD/ZnO system such as Al nano-concave spacing and the thickness of the corresponding layer. This approach will reduce the negative influence of the non-radiative plasmonic modes and most likely will lead to further enhancement of the SP-modulated UV emission from ZnO thin films.

  19. Plasmonic enhancement of UV emission from ZnO thin films induced by Al nano-concave arrays

    Energy Technology Data Exchange (ETDEWEB)

    Norek, Małgorzata, E-mail: mnorek@wat.edu.pl [Department of Advanced Materials and Technologies, Faculty of Advanced Technologies and Chemistry, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland); Łuka, Grzegorz [Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warsaw (Poland); Włodarski, Maksymilian [Institute of Optoelectronics, Military University of Technology, Str. Kaliskiego 2, 00-908 Warszawa (Poland)

    2016-10-30

    Highlights: • Al nano-concave arrays with different interpore distance (D{sub c}) were prepared. • PL of ZnO thin films deposited directly on the Al nano-concaves were studied. • The effect of 10 nm Al{sub 2}O{sub 3} spacer on PL emission from ZnO thin films was analyzed. • Plasmonic enhancement of the PL emission was dependent on the D{sub c} and the spacer. • The highest 9-fold enhancement was obtained for the Al/ZnO sample with D{sub c} ∼333 nm. - Abstract: Surface plasmons (SPs) supported by Al nano-concave arrays with increasing interpore distance (D{sub c}) were used to enhance the ultraviolet light emission from ZnO thin films. Two sets of samples were prepared: in the first set the thin ZnO films were deposited directly on Al nanoconcaves (the Al/ZnO samples) and in the second set a 10 nm − Al{sub 2}O{sub 3} spacer was placed between the textured Al and the ZnO films (the Al/Al{sub 2}O{sub 3}-ALD/ZnO samples). In the Al/ZnO samples the enhancement was limited by a nonradiative energy dissipation due to the Ohmic loss in the Al metal. However, for the ZnO layer deposited directly on Al nanopits synthesized at 150 V (D{sub c} = 333 ± 18 nm), the largest 9-fold enhancement was obtained by achieving the best energy fit between the near band-edge (NBE) emission from ZnO and the λ{sub (0,1)} SPP resonance mode. In the Al/Al{sub 2}O{sub 3}-ALD/ZnO samples the amplification of the UV emission was smaller than in the Al/ZnO samples due to a big energy mismatch between the NBE emission and the λ{sub (0,1)} plasmonic mode. The results obtained in this work indicate that better tuning of the NBE − λ{sub (0,1)} SPP resonance mode coupling is possible through a proper modification of geometrical parameters in the Al/Al{sub 2}O{sub 3}-ALD/ZnO system such as Al nano-concave spacing and the thickness of the corresponding layer. This approach will reduce the negative influence of the non-radiative plasmonic modes and most likely will lead to further

  20. Composite structure of ZnO films coated with reduced graphene oxide: structural, electrical and electrochemical properties

    Science.gov (United States)

    Shuai, Weiqiang; Hu, Yuehui; Chen, Yichuan; Hu, Keyan; Zhang, Xiaohua; Zhu, Wenjun; Tong, Fan; Lao, Zixuan

    2018-02-01

    ZnO films coated with reduced graphene oxide (RGO-ZnO) were prepared by a simple chemical approach. The graphene oxide (GO) films transferred onto ZnO films by spin coating were reduced to RGO films by two steps (exposed to hydrazine vapor for 12 h and annealed at 600 °C). The crystal structures, electrical and photoluminescence properties of RGO-ZnO films on quartz substrates were systematically studied. The SEM images illustrated that RGO layers have successfully been coated on the ZnO films very tightly. The PL properties of RGO-ZnO were studied. PL spectra show two sharp peaks at 390 nm and a broad visible emission around 490 nm. The resistivity of RGO-ZnO films was measured by a Hall measurement system, RGO as nanofiller considerably decrease the resistivity of ZnO films. An electrode was fabricated, using RGO-ZnO films deposited on Si substrate as active materials, for super capacitor application. By comparison of different results, we conclude that the RGO-ZnO composite material couples possess the properties of super capacitor. Project supported by the National Natural Science Foundation of China (Nos. 61464005, 51562015), the Natural Science Foundation of Jiangxi Province (Nos. 20143ACB21004, 20151BAB212008, 20171BAB216015), the Jiangxi Province Foreign Cooperation Projects, China (No. 20151BDH80031), the Leader Training Object Project of Major Disciplines Academic and Technical of Jiangxi Province (No. 20123BCB22002), and the Key Technology R & D Program of the Jiangxi Provine of Science and Technology (No. 20171BBE50053).

  1. Influence of Ag thickness of aluminum-doped ZnO/Ag/aluminum-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Hung-Wei, E-mail: hwwu@mail.ksu.edu.tw [Department of Computer and Communication, Kun Shan University, No. 949, Dawan Rd., Yongkang Dist., Tainan City 710, Taiwan (China); Yang, Ru-Yuan [Graduate Institute of Materials Engineering, National Pingtung University of Science and Technology, 1, Shuefu Rd., Neipu, Pingtung City 912, Taiwan (China); Hsiung, Chin-Min; Chu, Chien-Hsun [Department of Mechanical Engineering, National Pingtung University of Science and Technology, 1, Shuefu Rd., Neipu, Pingtung City 912, Taiwan (China)

    2012-10-01

    Highly conducting aluminum-doped ZnO (30 nm)/Ag (5-15 nm)/aluminum-doped ZnO (30 nm) multilayer thin films were deposited on glass substrate by rf magnetron sputtering (for top/bottom aluminum-doped ZnO films) and e-beam evaporation (for Ag film). The transmittance is more than 70% for wavelengths above 400 nm with the Ag layer thickness of 10 nm. The resistivity is 3.71 Multiplication-Sign 10{sup -4} {Omega}-cm, which can be decreased to 3.8 Multiplication-Sign 10{sup -5} {Omega}-cm with the increase of the Ag layer thickness to 15 nm. The Haacke figure of merit has been calculated for the films with the best value being 8 Multiplication-Sign 10{sup -3} {Omega}{sup -1}. It was shown that the multilayer thin films have potential for applications in optoelectronics. - Highlights: Black-Right-Pointing-Pointer High-quality Al-doped ZnO (AZO)/Ag/AZO Transparent Conducting Oxide films. Black-Right-Pointing-Pointer AZO films (30 nm) made by RF sputtering; E-beam evaporation for Ag film (5-15 nm). Black-Right-Pointing-Pointer Influence of Ag thickness on optical and electrical properties were analyzed. Black-Right-Pointing-Pointer High quality multilayer film with optimal intermediate Ag layer thickness of 10 nm. Black-Right-Pointing-Pointer 3.71 Multiplication-Sign 10{sup -4} {Omega}-cm resistivity, 91.89% transmittance at 470 nm obtained and reproducible.

  2. Microstructure and characterization of Al-doped ZnO films prepared by RF power sputtering on Al and ZnO targets

    Energy Technology Data Exchange (ETDEWEB)

    Tseng, Chun-An [Department of Mechanical Engineering, National Central University, Taiwan (China); Lin, Jing-Chie, E-mail: jclincom@cc.ncu.edu.tw [Department of Mechanical Engineering, National Central University, Taiwan (China); Institute of Material Science and Engineering, National Central University, Taiwan (China); Chang, Yu-Fong [Department of Mechanical Engineering, National Central University, Taiwan (China); Chyou, San-Der [Power Research Institute, Taiwan Power Company, Taiwan (China); Peng, Kun-Cheng [Department of Materials Science and Engineering, Mingchi University of Technology, Taiwan (China)

    2012-06-01

    Al-doped zinc oxide (AZO) transparent conductive films were prepared on a glass substrate using a magnetron sputtering system with a pure zinc oxide (ZnO) target and a pure Al target sputtered using radio frequency (RF) power. The RF power was set at 100 W for the ZnO target and varied from 20 to 150 W for the Al target. The morphology of the thin films was examined by field-emission scanning electron microscope (FE-SEM), and their composition was analyzed by the equipped energy-dispersive X-ray spectroscopy (EDS). The cross section of the films determined through FE-SEM indicated that their thickness was around 650 nm. EDS analysis revealed that the Al-dopant concentration of the AZO films increased in the following order: 0.85 at.% (20 W) < 1.60 at.% (40 W) < 3.52 at.% (100 W) < 4.34 at.% (150 W). Analysis of the films using X-ray diffractometer (XRD) indicated that all films had a wurtzite structure with a texture of (0 0 2). High-resolution transmission electron microscopy (HRTEM) revealed a number of defects in the films, such as stacking faults and dislocations. Ultraviolet photoelectron spectroscopy (UPS) was used to estimate the optical energy gap (E{sub g}) for the AZO thin films. The energy gap increases from 3.39 to 3.58 eV as the RF power applied to the Al target increase. The electrical resistivity of the films decreased from 3.43 Multiplication-Sign 10{sup -2} {Omega} cm to 3.29 Multiplication-Sign 10{sup -3} {Omega} cm as the RF power increased from 20 to 150 W when a four-point probe was used to investigate. Atomic force microscope (AFM) revealed that the surface roughness of the films increased with increasing RF power. The average optical transmittance of the films was determined by UV-visible spectrometer. The films are suitable for use as transparent conductive oxide films in the optoelectronic industry. A decrease in the electrical resistivity of the film with increasing Al-dopant concentration was ascribed to an increase in the carrier

  3. Characterization of a new transparent-conducting material of ZnO doped ITO thin films

    Science.gov (United States)

    Ali, H. M.

    2005-11-01

    Thin films of indium tin oxide (ITO) doped with zinc oxide have the remarkable properties of being conductive yet still highly transparent in the visible and near-IR spectral ranges. The Electron beam deposi- tion technique is one of the simplest and least expensive ways of preparing. High-quality ITO thin films have been deposited on glass substrates by Electron beam evaporation technique. The effect of doping and substrate deposition temperature was found to have a significant effect on the structure, electrical and optical properties of ZnO doped ITO films. The average optical transmittance has been increased with in- creasing the substrate temperature. The maximum value of transmittance is greater than 84% in the visible region and 85% in the NIR region obtained for film with Zn/ITO = 0.13 at substrate temperature 200 °C. The dielectric constant, average excitation energy for electronic transitions (E o), the dispersion energy (E d), the long wavelength refractive index (n ), average oscillator wave length ( o) and oscillator strength S o for the thin films were determined and presented in this work.

  4. Microstructural and electrical characteristics of rare earth oxides doped ZnO varistor films

    Science.gov (Uni