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Sample records for based zno film

  1. ZnO film based surface acoustic wave micro-pump

    International Nuclear Information System (INIS)

    In this study, a micro-pump unit based on surface acoustic wave (SAW) on piezoelectric ZnO film is designed and fabricated as a micro-fluidic device. It employs a mechanical wave, which is generated electrically using an aluminum interdigital transducer (IDT), and propagates on the surface of the ZnO film. The ZnO film was used in this study because it has a high electromechanical coefficient and an excellent bonding with various substrate materials, in particular silicon. The sputtering parameters for ZnO film deposition have been optimized, and the ZnO films with different thickness from 1 micron to 5.5 microns were prepared. The film properties have been characterized using different methods, such as scanning electron microscopy, X-ray diffraction and atomic force microscopy. Aluminum IDT with a finger width and spacing of 8 microns was patterned on the ZnO film using a lift-off process. The frequency generated was measured using a network analyzer, and it varies from 130 MHz to 180 MHz as a function of film thickness. A signal generator was used to generate the frequency with a power amplifier to amplify the signal, which was then applied to aluminum IDT to generate the surface acoustic wave. If a liquid droplet exists on the surface carrying the acoustic wave, the energy and the momentum of the SAW will be coupled into the fluid, causing the liquid to vibrate and move on film surface. The strength of this movement is determined by the applied voltage and frequency. The volume of the liquid drop loaded on the SAW device in this study is of several hundreds of nanoliters. The movement of the liquid inside the droplet and also on the ZnO film surface can be demonstrated. The performance of ZnO SAW device was characterized as a function of film thickness

  2. Ti doped ZnO thin film based UV photodetector: Fabrication and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Shewale, P.S.; Lee, N.K.; Lee, S.H.; Kang, K.Y. [Convergence of IT Devices Institute, Dong-Eui University, Busan 614-714 (Korea, Republic of); Yu, Y.S., E-mail: ysyu@deu.ac.kr [Convergence of IT Devices Institute, Dong-Eui University, Busan 614-714 (Korea, Republic of); Department of Radiological Science, Dong-Eui University, Busan 614-714 (Korea, Republic of)

    2015-03-05

    Highlights: • UV photoconductive undoped and Ti doped ZnO films were grown by spray pyrolysis. • Ti doping effects on physical and UV detection properties of films were studied. • Samples are polycrystalline with a hexagonal wurtzite crystal structure. • Ti doping increases the optical transmittance and band gap of ZnO film. • Ti doping improves the responsivity of ZnO film based MSM UV photodetector. - Abstract: This paper presents the synthesis of undoped and 2 wt.% titanium (Ti) doped zinc oxide (ZnO) thin films onto glass substrates by chemical spray pyrolysis technique. Both films are deposited at 375 °C substrate temperature. The influence of Ti doping on structural, morphological, optical and UV detection properties of ZnO film was studied. Both films revealed to be of polycrystalline nature with a hexagonal wurtzite structure; and the ZnO film crystallinity improved on Ti doping. Surface morphological observations agreed well with structural results. The Ti incorporation in ZnO thin films were confirmed by an energy dispersive X-ray spectroscopic analysis (EDX). The Ti doping increased the optical transmittance (∼96% at 550) and band gap (∼3.2927 eV) of ZnO thin film. Further, the metal–semiconductor–metal (MSM) planar ultraviolet photodetectors (UV PDs) were fabricated from deposition of tin (Sn) contacts onto undoped and Ti doped ZnO films using e-beam evaporation technique. To investigate UV photodetection properties, the MSM devices were subjected to current–voltage (I–V) characteristics measurements of forward and reverse bias in dark and UV light conditions. The photocurrent and responsivity were measured as a function of optical power density and applied voltage, respectively. The reproducibility of the UV detection performance of MSM devices was ensured by constantly switching UV light on and off at regular time intervals. The Ti doped ZnO film based UV PD demonstrates highest responsivity of about 0.051 A/W upon 2 mW/cm{sup 2

  3. 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.

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

    Science.gov (United States)

    Rahmanian, Reza; Mozaffari, Sayed Ahmad; 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 SnO2 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 8.0-110.0mg dL(-1) with the limit of detection as 5.0mg dL(-1). PMID:26354280

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

    International Nuclear Information System (INIS)

    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 SnO2 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

  6. 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

  7. High-performance metal–semiconductor–metal UV photodetector based on spray deposited ZnO thin films

    International Nuclear Information System (INIS)

    Highlights: • ZnO based MSM UV photodetector by economical chemical spray pyrolysis technique. • Effect of substrate temperature on properties of ZnO based MSM UV photodetector. • Photoresponse mechanism by optical switching property of ZnO thin film photodetectors. - Abstract: Zinc oxide (ZnO) based metal–semiconductor–metal (MSM) ultraviolet photodetectors at different substrate temperatures were fabricated on glass substrates by economical chemical spray pyrolysis technique and its UV photoresponsivity was measured at room temperature. The samples were characterized with respect to their structural, morphological, and optical properties using various methods such as X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–Vis spectroscopy, transmittance, reflectance etc. The synthesized ZnO thin films were c-axis oriented with hexagonal crystal structure as confirmed from XRD. All deposited films were specular and show high transmittance (∼85%) in visible region with steep fall off at 375 nm. The photoconductive MSM UV photodetector showed relatively high photocurrent (1.3 mA) and fast switching. ZnO thin films exhibited relatively high photoresponsivity (788 A/W) with cut of wavelength ∼375 nm signifying their application as UV detector

  8. Investigation of ZnO thin films deposited on ferromagnetic metallic buffer layer by molecular beam epitaxy toward realization of ZnO-based magnetic tunneling junctions

    International Nuclear Information System (INIS)

    Deposition of ZnO thin films on a ferromagnetic metallic buffer layer (Co3Pt) by molecular beam epitaxy technique was investigated for realization of ZnO-based magnetic tunneling junctions with good quality hexagonal ZnO films as tunnel barriers. For substrate temperature of 600 °C, ZnO films exhibited low oxygen defects and high electrical resistivity of 130 Ω cm. This value exceeded that of hexagonal ZnO films grown by sputtering technique, which are used as tunnel barriers in ZnO-MTJs. Also, the effect of oxygen flow during deposition on epitaxial growth conditions and Co3Pt surface oxidation was discussed.

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

    International Nuclear Information System (INIS)

    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 ZrO2 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

  11. Mechanical and structural characterization of atomic layer deposition-based ZnO films

    International Nuclear Information System (INIS)

    Zinc oxide thin films were deposited by atomic layer deposition (ALD). The structural and mechanical properties of the thin films were investigated by x-ray diffraction, transmission electron microscopy, atomic force microscopy, and nanoindentation. Diethyl zinc was used as the chemical precursor for zinc and water vapor was used as the oxidation agent. The samples were deposited at 150 °C and at a pressure of 2.1 × 10−1 Torr in the ALD reactor. A growth rate of 2 Å per cycle was calculated in the ALD process window. The Nano Indenter XP was used in conjunction with the continuous stiffness method in depth control mode in order to measure and to analyze the mechanical properties of hardness and modulus of ALD ZnO thin film samples. For comparison, we benchmarked the mechanical properties of single crystal bulk ZnO samples against those of our ALD ZnO thin films

  12. Mechanical and structural characterization of atomic layer deposition-based ZnO films

    Science.gov (United States)

    Tapily, K.; Gu, D.; Baumgart, H.; Namkoong, G.; Stegall, D.; Elmustafa, A. A.

    2011-11-01

    Zinc oxide thin films were deposited by atomic layer deposition (ALD). The structural and mechanical properties of the thin films were investigated by x-ray diffraction, transmission electron microscopy, atomic force microscopy, and nanoindentation. Diethyl zinc was used as the chemical precursor for zinc and water vapor was used as the oxidation agent. The samples were deposited at 150 °C and at a pressure of 2.1 × 10-1 Torr in the ALD reactor. A growth rate of 2 Å per cycle was calculated in the ALD process window. The Nano Indenter XP was used in conjunction with the continuous stiffness method in depth control mode in order to measure and to analyze the mechanical properties of hardness and modulus of ALD ZnO thin film samples. For comparison, we benchmarked the mechanical properties of single crystal bulk ZnO samples against those of our ALD ZnO thin films.

  13. Towards solution-processed ambipolar hybrid thin-film transistors based on ZnO nanoparticles and P3HT polymer

    Science.gov (United States)

    Diallo, Abdou Karim; Gaceur, Meriem; Berton, Nicolas; Margeat, Olivier; Ackermann, Jörg; Videlot-Ackermann, Christine

    2013-06-01

    Solution-processed n-channel oxide semiconductor thin-film transistors (TFTs) were fabricated using zinc oxide (ZnO) nanoparticles. Polycrystalline fused-ZnO nanoparticle films were produced by spin-coating ZnO nanosphere dispersions following by a subsequent heat treatment. The solution-processable semiconductor ink based on ZnO was prepared by dispersing the synthesized ZnO nanospheres in isopropanol mixed with ethanolamine to various concentrations from 20 to 80 mg/mL. Such concentration dependence on morphology and microstructure of thin films was studied on spin-coated ZnO films by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Spin-coated ZnO films involved as active layers in transistor configuration delivered an almost ideal output characteristic (Id-Vd) with an electron mobility up to 3 × 10-2 cm2/V s. As a p-channel semiconductor, a poly(3-hexylthiophene) (P3HT) solution-processable ink was deposited by spin-coating on top of closely packed ZnO nanoparticles-based films to form an uniform overlying layer. A hybrid (inorganic-organic) interface was formed by the direct contact between ZnO and P3HT leading to carrier redistribution. Such solution-processed hybrid thin-film transistors delivered in air well balanced electron and hole mobilities as 3.9 × 10-5 and 2 × 10-5 cm2/V s, respectively.

  14. 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.

  15. Ultrasonic Energy Transference Based on an MEMS ZnO Film Array

    International Nuclear Information System (INIS)

    An ultrasonic energy transference system with a ZnO square piezoelectric thin-film array (SPTFA) structure is presented. The design principle of the system is analyzed, and a device with the SPTFA structure is successfully fabricated based on MEMS processes. The characteristics of the energy transference system are investigated in detail. The experimental results reveal that the resonant frequency of the system is 13 MHz, the maximum voltage of the receiving end reaches 10.87 V when the amplitude of excitation voltage is 10 V, at that time the output power of system is 5.377 mW, and power density is 2.581 mW/cm2. The light emitting diode is lit successfully by the system in a distance of 3 mm

  16. UV photodetectors based on 3D periodic Au-decorated nanocone ZnO films

    Science.gov (United States)

    Fan, Haowen; Sun, Mengwei; Ma, Pengsha; Yin, Min; Lu, Linfeng; Xue, Xinzhong; Zhu, Xufei; Li, Dongdong; Ma, Jing

    2016-09-01

    Thermal nanoimprinting technology was employed to fabricate 3D periodic nanocone ZnO films with different height/pitch values for photodetectors to optimize their light capturing property. The photocurrents of patterned film photodetectors increase with the height/pitch values. The patterned ZnO–Au hybrid film further boosts the ultraviolet (UV) response. Due to the co-contribution of the light trapping of 3D periodic structures and the driving force of the Schottky barrier in the Au/ZnO interface, the patterned ZnO–Au hybrid films with height/pitch of 40 nm/866 nm exhibit the best UV photoresponse (I on/I off = 779.927), which is 3.8 times higher than its film counterpart (I on/I off = 164.1).

  17. 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.

  18. Green emission in carbon doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Tseng, L. T.; Yi, J. B., E-mail: jiabao.yi@unsw.edu.au; Zhang, X. Y.; Xing, G. Z.; Luo, X.; Li, S. [School of Materials Science and Engineering, University of New South Wales, Kensington, NSW, 2052 (Australia); Fan, H. M. [School of Chemical Engineering, Northwest University, Xi' an 710069 (China); Herng, T. S.; Ding, J. [Department of Materials Science and Engineering, National University of Singapore, 119260 (Singapore); Ionescu, M. [Australian Nuclear Science and Technology Organization, (ANSTO), New Illawarra Road, Lucas Heights, NSW 2234 (Australia)

    2014-06-15

    The emission behavior of C-doped ZnO films, which were prepared by implantation of carbon into ZnO films, is investigated. Orange/red emission is observed for the films with the thickness of 60–100 nm. However, the film with thickness of 200 nm shows strong green emission. Further investigations by annealing bulk ZnO single crystals under different environments, i.e. Ar, Zn or C vapor, indicated that the complex defects based on Zn interstitials are responsible for the strong green emission. The existence of complex defects was confirmed by electron spin resonance (ESR) and low temperature photoluminescence (PL) measurement.

  19. Green emission in carbon doped ZnO films

    Directory of Open Access Journals (Sweden)

    L. T. Tseng

    2014-06-01

    Full Text Available The emission behavior of C-doped ZnO films, which were prepared by implantation of carbon into ZnO films, is investigated. Orange/red emission is observed for the films with the thickness of 60–100 nm. However, the film with thickness of 200 nm shows strong green emission. Further investigations by annealing bulk ZnO single crystals under different environments, i.e. Ar, Zn or C vapor, indicated that the complex defects based on Zn interstitials are responsible for the strong green emission. The existence of complex defects was confirmed by electron spin resonance (ESR and low temperature photoluminescence (PL measurement.

  20. Flexible pH sensors based on polysilicon thin film transistors and ZnO nanowalls

    Science.gov (United States)

    Maiolo, L.; Mirabella, S.; Maita, F.; Alberti, A.; Minotti, A.; Strano, V.; Pecora, A.; Shacham-Diamand, Y.; Fortunato, G.

    2014-09-01

    A fully flexible pH sensor using nanoporous ZnO on extended gate thin film transistor (EGTFT) fabricated on polymeric substrate is demonstrated. The sensor adopts the Low Temperature Polycrystalline Silicon (LTPS) TFT technology for the active device, since it allows excellent electrical characteristics and good stability and opens the way towards the possibility of exploiting CMOS architectures in the future. The nanoporous ZnO sensitive film, consisting of very thin (20 nm) crystalline ZnO walls with a large surface-to-volume ratio, was chemically deposited at 90 °C, allowing simple process integration with conventional TFT micro-fabrication processes compatible with wide range of polymeric substrates. The pH sensor showed a near-ideal Nernstian response (˜59 mV/pH), indicating an ideality factor α ˜ 1 according to the conventional site binding model. The present results can pave the way to advanced flexible sensing systems, where sensors and local signal conditioning circuits will be integrated on the same flexible substrate.

  1. 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.

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

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    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.

  3. Nanostructured porous ZnO film with enhanced photocatalytic activity

    International Nuclear Information System (INIS)

    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.

  4. Electrodeposited nanoporous ZnO films exhibiting enhanced performance in dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Electrodeposition of nanoporous ZnO films and their applications to dye-sensitized solar cells (DSSCs) were investigated in the aim of developing cost-effective alternative synthetic methods and improving the ZnO-based DSSCs performance. ZnO films were grown by cathodic electrodeposition from an aqueous zinc nitrate solution containing polyvinylpyrrolidone (PVP) surfactant. PVP concentration had strong effects on the grain sizes and surface morphologies of ZnO films. Nanoporous ZnO film with grain size of 20-40 nm was obtained in the electrolyte containing 4 g/L PVP. The X-ray diffraction pattern showed that nanoporous ZnO films had a hexagonal wurtzite structure. Optical properties of such films were studied and the results indicated that the films had a band gap of 3.3 eV. DSSCs were fabricated from nanoporous ZnO films and the cell performance could be greatly improved with the increase of ZnO film thickness. The highest solar-to-electric energy conversion efficiency of 5.08% was obtained by using the electrodeposited double-layer ZnO films (8 μm thick nanoporous ZnO films on a 200 nm thick compact nanocrystalline ZnO film). The performance of such cell surpassed levels attained in previous studies on ZnO film-based DSSCs and was among the highest for DSSCs containing electrodeposited film components

  5. An economic approach to fabricate photo sensor based on nanostructured ZnO thin films

    Science.gov (United States)

    Huse, Nanasaheb; Upadhye, Deepak; Sharma, Ramphal

    2016-05-01

    Nanostructural ZnO Thin Films have been synthesized by simple and economic Chemical Bath Deposition technique onto glass substrate with bath temperature at 60°C for 1 hour. Structural, Optical, Electrical and topographical properties of the prepared Thin Films were investigated by GIXRD, I-V Measurement System, UV-Visible Spectrophotometer and AFM respectively. Calculated lattice parameters are in good agreement with the standard JCPDS card (36-1451) values, exhibits Hexagonal Wurtzite crystal structure. I-V Measurement curve has shown ohmic nature in dark condition and responds to light illumination which reveals Photo sensor properties. After illumination of 60W light, decrease in resistance was observed from 110.9 KΩ to 104.4 KΩ. The change in current and calculated Photo sensitivity was found to be 3.51 µA and 6.3% respectively. Optical band gap was found to be 3.24 eV. AFM images revealed uniform deposition over entire glass substrate with 32.27 nm average roughness of the film.

  6. Low operating temperature of oxygen gas sensor based on undoped and Cr-doped ZnO films

    International Nuclear Information System (INIS)

    Undoped and doped ZnO with 1 at.% (atomic percentage) chromium (Cr) was synthesized by RF reactive co-sputtering for oxygen gas sensing applications. The prepared films showed a highly c-oriented phase with a dominant (0 0 2) peak at a Bragg angle of around 34.2o. The operating temperature of the prepared ZnO sensor was around 350 deg. C and shifted to around 250 deg. C for the doped ZnO sensor which is lower than that of previously reported work. The sensitivity of the sensor toward oxygen gas was enhanced by doping ZnO with 1 at.% Cr. Good stability and repeatability of the sensor were demonstrated when tested under different concentration of oxygen atmosphere.

  7. Mechanisms of lighting enhancement of Al nanoclusters-embedded Al-doped ZnO film in GaN-based light-emitting diodes

    International Nuclear Information System (INIS)

    Aluminum (Al)-doped ZnO (AZO) films with embedded Al nanoclusters were proposed and utilized to enhance the light output power and maximum operation current of GaN-based light-emitting diodes (LEDs). The AZO films were sputtered using ZnO and Al targets in a magnetron cosputtering system. With Al dc power of 7 W and ZnO 100 W ac power, the electron concentration of 4.1x1020 cm-3, electron mobility of 16.2 cm2/V s, and resistivity of 7.2x10-4 Ω cm were obtained for the deposited AZO film annealed at 600 deg. C for 1 min in a N2 ambient. As verified by a high resolution transmission electron microscopy, the deposited AZO films with embedded Al nanoclusters were clearly observed. A 35% increase in light output power of the GaN-based LEDs with Al nanoclusters-embedded AZO films was realized compared with the conventional LEDs operated at 500 mA. It was verified experimentally that the various characteristics of GaN-based LEDs including the antireflection, light scattering, current spreading, and the light extraction efficiency in light emission could be significantly enhanced with the use of Al nanoclusters-embedded AZO films.

  8. Growth of a-axis ZnO films on the defective substrate with different O/Zn ratios: A reactive force field based molecular dynamics study

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Y.L. [Institute of Materials Physics and Chemistry, School of Sciences, Northeastern University, Shenyang 110819 (China); Shahzad, M. Babar [Institute of Materials Physics and Chemistry, School of Sciences, Northeastern University, Shenyang 110819 (China); Institute of Metals Research, Chinese Academy of Sciences, Shenyang 110016 (China); Qi, Y., E-mail: qiyang@imp.neu.edu.cn [Institute of Materials Physics and Chemistry, School of Sciences, Northeastern University, Shenyang 110819 (China)

    2015-04-15

    Highlights: • The O/Zn effect on the non-polar a-axis film growth is studied at the atomic scale. • The optimized film quality is achieved through a series of ReaxFF based MD study. • A film growth mode (singular atom → cluster → chains → continue film) is revealed. • The transformed way of the defective substrate to the perfect stacking is revealed. - Abstract: The understanding of the growth process and formation mechanism of non-polar ZnO films in atomic-scale is crucial in adjusting and controlling the film deposition conditions. Using the advanced reactive force field based molecular dynamics method, we theoretically studied the effect of O/Zn ratios (8/10–10/8) on the quality of ZnO films. The comprehensive investigation of energy and temperature fluctuation profile, radial distribution function, the sputtering and injecting phenomenon, and layer coverage indicated that the film grown under stoichiometric conditions possesses the optimized quality. Furthermore, the auto-transformation ability of the substrate from defective to perfect stacking was presented and discussed by comparing to the perfect structure. The instant film growth configurations, atomic layer snapshots, and the interfacial morphology evolution were provided step-by-step to reveal the defect type and initial film nucleation and growth mechanism.

  9. ZnO nanolasers on graphene films

    Science.gov (United States)

    Baek, Hyeonjun; Park, Jun Beom; Park, Jong-woo; Hyun, Jerome K.; Yoon, Hosang; Oh, Hongseok; Yoon, Jiyoung

    2016-06-01

    We grew and characterized zinc oxide (ZnO) nanolasers on graphene films. By using graphene as a growth medium, we were able to prepare position-controlled and vertically aligned ZnO nanotube lasers. The ZnO nanolasers grown on graphene films showed good optical characteristics, evidenced by a low lasing threshold. Furthermore, the nanolaser/graphene system was easily lifted off the original substrate and transferred onto foreign substrates. The lasing performance was observed to be significantly enhanced by depositing a layer of silver on the back of the graphene film during this transfer process, which was quantitatively investigated using finite-difference time-domain simulations. Due to the wide selection of substrates enabled by the use of graphene films, our results suggest promising strategies for preparing practical nanolasers with improved performance.

  10. PMMA–SiO{sub 2} hybrid films as gate dielectric for ZnO based thin-film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Morales-Acosta, M.D. [Centro de Investigación y de Estudios Avanzados del IPN, Unidad Querétaro, Apdo. Postal 1-798, Querétaro, Qro. 76001 (Mexico); Quevedo-López, M.A. [Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, TX 75083 (United States); Ramírez-Bon, R., E-mail: rrbon@qro.cinvestav.mx [Centro de Investigación y de Estudios Avanzados del IPN, Unidad Querétaro, Apdo. Postal 1-798, Querétaro, Qro. 76001 (Mexico)

    2014-08-01

    In this paper we report a low temperature sol–gel deposition process of PMMA–SiO{sub 2} hybrid films, with variable dielectric properties depending on the composition of the precursor solution, for applications to gate dielectric layers in field-effect thin film transistors (FE-TFT). The hybrid layers were processed by a modified sol–gel route using as precursors Tetraethyl orthosilicate (TEOS) and Methyl methacrylate (MMA), and 3-(Trimethoxysilyl)propyl methacrylate (TMSPM) as the coupling agent. Three types of hybrid films were processed with molar ratios of the precursors in the initial solution 1.0: 0.25, 0.50, 0.75: 1.0 for TEOS: TMSPM: MMA, respectively. The hybrid films were deposited by spin coating of the hybrid precursor solutions onto p-type Si (100) substrates and heat-treated at 90 °C for 24 h. The chemical bonding in the hybrid films was analyzed by Fourier Transform Infrared Spectroscopy to confirm their hybrid nature. The refractive index of the hybrid films as a function of the TMSPM coupling agent concentration, were determined from a simultaneous analysis of optical reflectance and spectroscopic ellipsometry experimental data. The PMMA–SiO{sub 2} hybrid films were studied as dielectric films using metal-insulator-metal structures. Capacitance–Voltage (C–V) and current–voltage (I–V) electrical methods were used to extract the dielectric properties of the different hybrid layers. The three types of hybrid films were tested as gate dielectric layers in thin film transistors with structure ZnO/PMMA–SiO{sub 2}/p-Si with a common bottom gate and patterned Al source/drain contacts, with different channel lengths. We analyzed the output electrical responses of the ZnO-based TFTs to determine their performance parameters as a function of channel length and hybrid gate dielectric layer. - Highlights: • PMMA–SiO{sub 2} hybrid films as dielectric material synthesized by sol–gel process at low temperature. • PMMA–SiO{sub 2

  11. PMMA–SiO2 hybrid films as gate dielectric for ZnO based thin-film transistors

    International Nuclear Information System (INIS)

    In this paper we report a low temperature sol–gel deposition process of PMMA–SiO2 hybrid films, with variable dielectric properties depending on the composition of the precursor solution, for applications to gate dielectric layers in field-effect thin film transistors (FE-TFT). The hybrid layers were processed by a modified sol–gel route using as precursors Tetraethyl orthosilicate (TEOS) and Methyl methacrylate (MMA), and 3-(Trimethoxysilyl)propyl methacrylate (TMSPM) as the coupling agent. Three types of hybrid films were processed with molar ratios of the precursors in the initial solution 1.0: 0.25, 0.50, 0.75: 1.0 for TEOS: TMSPM: MMA, respectively. The hybrid films were deposited by spin coating of the hybrid precursor solutions onto p-type Si (100) substrates and heat-treated at 90 °C for 24 h. The chemical bonding in the hybrid films was analyzed by Fourier Transform Infrared Spectroscopy to confirm their hybrid nature. The refractive index of the hybrid films as a function of the TMSPM coupling agent concentration, were determined from a simultaneous analysis of optical reflectance and spectroscopic ellipsometry experimental data. The PMMA–SiO2 hybrid films were studied as dielectric films using metal-insulator-metal structures. Capacitance–Voltage (C–V) and current–voltage (I–V) electrical methods were used to extract the dielectric properties of the different hybrid layers. The three types of hybrid films were tested as gate dielectric layers in thin film transistors with structure ZnO/PMMA–SiO2/p-Si with a common bottom gate and patterned Al source/drain contacts, with different channel lengths. We analyzed the output electrical responses of the ZnO-based TFTs to determine their performance parameters as a function of channel length and hybrid gate dielectric layer. - Highlights: • PMMA–SiO2 hybrid films as dielectric material synthesized by sol–gel process at low temperature. • PMMA–SiO2 films implemented for the first

  12. A MEMS based acetone sensor incorporating ZnO nanowires synthesized by wet oxidation of Zn film

    International Nuclear Information System (INIS)

    In this work, we report a simple and efficient method for synthesis of ZnO nanowires by thermal oxidation of Zn film and their integration with MEMS technologies to fabricate a sensor for acetone vapour detection. ZnO nanowires were prepared by thermal oxidation of sputter deposited Zn film. The nanostructured ZnO was characterized by x-ray diffraction, a scanning electron microscope and room temperature photoluminescence measurements. The ZnO nanowires synthesis process was integrated with MEMS technologies to obtain a sensor for volatile organic compounds, incorporating an on-chip Ni microheater and an interdigited electrode structure. To reduce the heat loss from the on-chip microheater, the sensor was made on a thin silicon diaphragm obtained via a modified reactive ion etching process. This resulted in considerable power saving during sensor operation. For this, a three-mask process was used. The performance of the microheater was simulated on COMSOL and validated experimentally. The sensor has been tested for acetone vapour sensing and the operating parameters were optimized. The sensor has the ability to detect acetone vapour at 5 parts per million (ppm) concentrations when operated at 100 °C. The sensor consumed only 36 mW power and showed a high-sensitivity value of 26.3% for 100 ppm of acetone vapour. (paper)

  13. A MEMS based acetone sensor incorporating ZnO nanowires synthesized by wet oxidation of Zn film

    Science.gov (United States)

    Behera, Bhagaban; Chandra, Sudhir

    2015-01-01

    In this work, we report a simple and efficient method for synthesis of ZnO nanowires by thermal oxidation of Zn film and their integration with MEMS technologies to fabricate a sensor for acetone vapour detection. ZnO nanowires were prepared by thermal oxidation of sputter deposited Zn film. The nanostructured ZnO was characterized by x-ray diffraction, a scanning electron microscope and room temperature photoluminescence measurements. The ZnO nanowires synthesis process was integrated with MEMS technologies to obtain a sensor for volatile organic compounds, incorporating an on-chip Ni microheater and an interdigited electrode structure. To reduce the heat loss from the on-chip microheater, the sensor was made on a thin silicon diaphragm obtained via a modified reactive ion etching process. This resulted in considerable power saving during sensor operation. For this, a three-mask process was used. The performance of the microheater was simulated on COMSOL and validated experimentally. The sensor has been tested for acetone vapour sensing and the operating parameters were optimized. The sensor has the ability to detect acetone vapour at 5 parts per million (ppm) concentrations when operated at 100 °C. The sensor consumed only 36 mW power and showed a high-sensitivity value of 26.3% for 100 ppm of acetone vapour.

  14. Microstructural characterization, optical and photocatalytic properties of bilayered CuO and ZnO based thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sáenz-Trevizo, A.; Amézaga-Madrid, P.; Pizá-Ruiz, P.; Solís-Canto, O.; Ornelas-Gutiérrez, C.; Pérez-García, S.; Miki-Yoshida, M., E-mail: mario.miki@cimav.edu.mx

    2014-12-05

    Highlights: • High quality bilayered Zn–Cu oxide thin films were deposited by aerosol assisted CVD. • Detailed microstructural characterization was performed by XRD and electron microscopy. • Absorbance of bilayered films shows a shift of absorption edge toward visible region. • Optical band gap or nearly 3.2 and 2 eV was determined for ZnO and Cu oxide. • High photocatalytic activity around 90% was obtained for bilayered samples. - Abstract: In this work, it is presented the synthesis, microstructural characterization and photocatalytic properties of bilayered CuO–ZnO/ZnO thin films onto borosilicate glass and fused silica substrates. The films were deposited by aerosol assisted chemical vapor deposition, using an experimental setup reported elsewhere. Deposition conditions were optimized to get high quality films; i.e. they were structurally uniform, highly transparent, non-light scattering, homogeneous, and well adhered to the substrate. Different Cu/Zn atomic ratios were tried for the upper layer. The microstructure of the films was characterized by grazing incidence X-ray diffraction (GIXRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy. GIXRD results indicate the presence of ZnO Wurzite and Cu oxide phases. Results of SEM and HRTEM analysis of the cross sectional microstructure showed that the films were composed of compact and dense layers with no visible evidence of an interfacial boundary or porosity. Optical absorbance of the bilayered films showed a clear shift of the absorption toward the visible range. Optical band gap was determined roughly at 3.2 and 2 eV for ZnO and Cu oxide, respectively. Photocatalytic activity of the samples, for the degradation of a 10{sup −5} mol dm{sup −3} solution of methylene blue (MB), was determined after 120 and 240 min of irradiation with an UV-A source. Around 90% of MB degradation was reached by bilayered films with

  15. 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.

  16. Growth of ZnO and GaN Films

    Science.gov (United States)

    Chang, J.; Hong, S.-K.; Matsumoto, K.; Tokunaga, H.; Tachibana, A.; Lee, S. W.; Cho, M.-W.

    . Zinc oxide (ZnO) and gallium nitride (GaN) are wide bandgap semi conductors applicable to light emitting diodes (LEDs) and laser diodes (LDs) with wavelengths ranging from ultraviolet to blue light. Now ZnO and GaN are key ma terials for optoelectronic device applications and their applications are being rapidly expanded to lots of other technology including electronics, biotechnology, nanotech-nology, and fusion technology among all these. As a fundamental starting point for the development of this new technique, epitaxy of ZnO and GaN films is one of the most important key technology. Hence, development of the growth technique for high quality epitaxial films is highly necessary. Among the various kinds of epi taxy technique for semiconductor films developed so far, physical vapor deposition (PVD)-based epitaxy technique has been revealed to be the appropriate way for the high quality ZnO film and related alloy growths, while chemical vapor deposition (CVD)-based epitaxy technique has been proved to be the best method for the high quality GaN film and related alloy growths.

  17. 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

  18. Improvement in the negative bias temperature stability of ZnO based thin film transistors by Hf and Sn doping

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Woong-Sun; Moon, Yeon-Keon; Kim, Kyung-Taek; Shin, Sae-Young [Department of Materials Science and Engineering, Hanyang University, 17 Haengdang-dong, Seoungdong-ku, Seoul 133-791 (Korea, Republic of); Ahn, Byung Du; Lee, Je-Hun [Samsung Electronics Co., Ltd., LCD Business, San 24 Nongseo-dong, Giheung-gu, Yongin, Gyonggi-do 446-711 (Korea, Republic of); Park, Jong-Wan, E-mail: jwpark@hanyang.ac.kr [Department of Materials Science and Engineering, Hanyang University, 17 Haengdang-dong, Seoungdong-ku, Seoul 133-791 (Korea, Republic of)

    2011-08-01

    We assessed the performance of ZnO TFTs using Si{sub 3}N{sub 4} gate dielectrics after various treatments. A remarkable improvement in the transfer characteristics was obtained for the O{sub 2} plasma treated ZnO TFT and SiO{sub 2} interlayer deposited ZnO TFT. Also, we developed amorphous hafnium-zinc-tin oxide (HZTO) thin film transistors (TFTs) and investigated the influence of hafnium (Hf) doping on the electrical characteristics of the hafnium-zinc oxide (HZO) thin film transistors. Doping with Hf can decrease the carrier concentration, which may result from a decrease of the field effect mobility, and reduce oxygen vacancy related defects in the interfacial layer. Adding tin (Sn) can suppress the growth of a crystalline phase in the HZTO films. The HZTO TFTs exhibited good electrical properties with a field effect mobility of 14.33 cm{sup 2}/Vs, a subthreshold swing of 0.97 V/decade, and a high I{sub ON/OFF} ratio of over 10{sup 9}.

  19. ZnO homojunction ultraviolet photodetector based on p-type dual-doped film and n-type nanorods

    Science.gov (United States)

    Duan, Li; Wang, Pei; Zhang, Wenxue; Yu, Xiaochen; Fan, Jibin; Wei, Feng

    2015-01-01

    ZnO:(Ag,N)/ZnO p-n homojunction was fabricated by depositing a ZnO:(Ag,N) film on vertically aligned ZnO nanorods (NRs). The homojunction is able to work as a self-powered device due to the photovoltaic effect, and the ZnO NRs play an important role in the photovoltaic conversion process. Current-voltage (I-V) characteristic shows a turn-on voltage of ∼3 V and a rectification ratio of 1.3 × 102 at 5 V. Spectral responsivity exhibits an UV-to-visible rejection ratio of 1 × 102. The photocurrent rise and decay times are 7 and 45 ms, respectively. These results indicate the ZnO:(Ag,N)/ZnO homojunction is an attractive candidate for high-performance self-powered UV photodetectors.

  20. Synthesis and characterization of ZnO thin films

    Science.gov (United States)

    Anilkumar T., S.; Girija M., L.; Venkatesh, J.

    2016-05-01

    Zinc oxide (ZnO) Thin films were deposited on glass substrate using Spin coating method. Zinc acetate dehydrate, Carbinol and Mono-ethanolamine were used as the precursor, solvent and stabilizer respectively to prepare ZnO Thin-films. The molar ratio of Monoethanolamine to Zinc acetate was maintained as approximately 1. The thickness of the films was determined by Interference technique. The optical properties of the films were studied by UV Vis-Spectrophotometer. From transmittance and absorbance curve, the energy band gap of ZnO is found out. Electrical Conductivity measurements of ZnO are carried out by two probe method and Activation energy for the electrical conductivity of ZnO are found out. The crystal structure and orientation of the films were analyzed by XRD. The XRD patterns show that the ZnO films are polycrystalline with wurtzite hexagonal structure.

  1. The annealing induced extraordinary properties of SI based ZNO film grown by RF sputtering

    CERN Document Server

    Li, Jing; Wu, Suntao

    2007-01-01

    Pb(Zr0.52Ti0.48)O3 (PZT) thin films were in situ deposited by pulsed laser deposition (PLD) on Pt/Ti/SiO2/Si substrates using a template layer derived by sol-gel method. A 0.1-$\\mu$m-thick PZT layer with (111) or (100)-preferred orientation was first deposited onto Pt/Ti/SiO2/Si substrates using the sol-gel method, and than a PZT layer with thickness of 1$\\mu$m was in situ deposited by PLD on the above-mentioned PZT layer. The crystalline phases and the preferred orientations of the PZT films were investigated by X-ray diffraction analysis. Surface and cross-sectional morphologies were observed by scanning electron microscopy and transmission electron microscopy. The electrical properties of the films were evaluated by measuring their P-E hysteresis loops and dielectric constants. The preferred orientation of the films can be controlled using the template layer derived by the sol-gel method. The deposition temperature required to obtain the perovskite phase in this process is approximately 460 degrees C, and ...

  2. Surface Engineering of ZnO Thin Film for High Efficiency Planar Perovskite Solar Cells

    OpenAIRE

    Zong-Liang Tseng; Chien-Hung Chiang; Chun-Guey Wu

    2015-01-01

    Sputtering made ZnO thin film was used as an electron-transport layer in a regular planar perovskite solar cell based on high quality CH3NH3PbI3 absorber prepared with a two-step spin-coating. An efficiency up to 15.9% under AM 1.5G irradiation is achieved for the cell based on ZnO film fabricated under Ar working gas. The atmosphere of the sputtering chamber can tune the surface electronic properties (band structure) of the resulting ZnO thin film and therefore the photovoltaic performance o...

  3. 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.

  4. Photo-Patternable ZnO Thin Films Based on Cross-Linked Zinc Acrylate for Organic/Inorganic Hybrid Complementary Inverters.

    Science.gov (United States)

    Jeong, Yong Jin; An, Tae Kyu; Yun, Dong-Jin; Kim, Lae Ho; Park, Seonuk; Kim, Yebyeol; Nam, Sooji; Lee, Keun Hyung; Kim, Se Hyun; Jang, Jaeyoung; Park, Chan Eon

    2016-03-01

    Complementary inverters consisting of p-type organic and n-type metal oxide semiconductors have received considerable attention as key elements for realizing low-cost and large-area future electronics. Solution-processed ZnO thin-film transistors (TFTs) have great potential for use in hybrid complementary inverters as n-type load transistors because of the low cost of their fabrication process and natural abundance of active materials. The integration of a single ZnO TFT into an inverter requires the development of a simple patterning method as an alternative to conventional time-consuming and complicated photolithography techniques. In this study, we used a photocurable polymer precursor, zinc acrylate (or zinc diacrylate, ZDA), to conveniently fabricate photopatternable ZnO thin films for use as the active layers of n-type ZnO TFTs. UV-irradiated ZDA thin films became insoluble in developing solvent as the acrylate moiety photo-cross-linked; therefore, we were able to successfully photopattern solution-processed ZDA thin films using UV light. We studied the effects of addition of a tiny amount of indium dopant on the transistor characteristics of the photopatterned ZnO thin films and demonstrated low-voltage operation of the ZnO TFTs within ±3 V by utilizing Al2O3/TiO2 laminate thin films or ion-gels as gate dielectrics. By combining the ZnO TFTs with p-type pentacene TFTs, we successfully fabricated organic/inorganic hybrid complementary inverters using solution-processed and photopatterned ZnO TFTs. PMID:26840992

  5. Memristor memory element based on ZnO thin film structures

    Science.gov (United States)

    Poghosyan, A. R.; Elbakyan, E. Y.; Guo, R.; Hovsepyan, R. K.

    2015-08-01

    The memristor element for random access memory (resistance random access memory - ReRAM) was developed and investigated. The developed structure consists of a Schottky diode (1D) based on Pt/ZnO:Ga/ZnO/Pt heterostructure and a memristor (1R) based on Pt/ZnO:Ga/ZnO/ZnO:Li/Pt heterostructure. Thus the unipolar memristor memory element of 1D1R type was obtained. The heterostructures were produced by the electron-beam vacuum deposition method. The laboratory samples of the memory elements were prepared and their characteristics were studied. The proposed device has a high stability and withstands 1000 switching cycles without derating.

  6. 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.

  7. 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.

  8. 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

  9. Study on pulsed laser ablation and deposition of ZnO thin films by L-MBE

    Institute of Scientific and Technical Information of China (English)

    HE YongNing; ZHANG JingWen; YANG XiaoDong; XU QingAn; ZHU ChangChun; HOU Xun

    2007-01-01

    ZnO, as a wide-band gap semiconductor, has recently become a new research focus in the field of ultraviolet optoelectronic semiconductors. Laser molecular beam epitaxy (L-MBE) is quite useful for the unit cell layer-by-layer epitaxial growth of zinc oxide thin films from the sintered ceramic target. The ZnO ceramic target with high purity was ablated by KrF laser pulses in an ultra high vacuum to deposit ZnO thin film during the process of L-MBE. It is found that the deposition rate of ZnO thin film by L-MBE is much lower than that by conventional pulsed laser deposition (PLD). Based on the experimental phenomena in the ZnO thin film growth process and the thermal-controlling mechanism of the nanosecond (ns) pulsed laser ablation of ZnO ceramic target, the suggested effective ablating time during the pulse duration can explain the very low deposition rate of the ZnO film by L-MBE. The unique dynamic mechanism for growing ZnO thin film is analyzed. Both the high energy of the deposition species and the low growth rate of the film are really beneficial for the L-MBE growth of the ZnO thin film with high crystallinity at low temperature.

  10. Photosensitivity of nanocrystalline ZnO films grown by PLD

    Energy Technology Data Exchange (ETDEWEB)

    Ayouchi, R.; Bentes, L.; Casteleiro, C. [Departamento de Fisica, Instituto Superior Tecnico, Av. Rovisco Pais 1, P-1049-001 Lisboa (Portugal); Conde, O. [Departamento de Fisica, Faculdade de Ciencias da Universidade de Lisboa, P-1749-016 Lisboa (Portugal); Marques, C.P.; Alves, E. [Instituto Tecnologico e Nuclear, ITN, P-2686-953 Sacavem (Portugal); Moutinho, A.M.C.; Marques, H.P.; Teodoro, O. [CeFiTec, Departamento de Fisica, Universidade Nova de Lisboa, P-2829-516 Caparica (Portugal); Schwarz, R. [Departamento de Fisica, Instituto Superior Tecnico, Av. Rovisco Pais 1, P-1049-001 Lisboa (Portugal)], E-mail: rschwarz@fisica.ist.utl.pt

    2009-03-15

    We have studied the properties of ZnO thin films grown by laser ablation of ZnO targets on (0 0 0 1) sapphire (Al{sub 2}O{sub 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 {theta}-2{theta} 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.

  11. Synthesis and luminescence properties of electrodeposited ZnO films

    OpenAIRE

    Manzano, Cristina V.; Alegre, Daniel; Caballero-Calero, Olga; Alén, Benito; Martín-González, Marisol S.

    2011-01-01

    Zinc oxide (ZnO) films have been grown on gold (111) by electrodeposition using two different OH− sources, nitrate and peroxide, in order to obtain a comparative study between them. The morphology, structural and optical characterization of the films were investigated depending on the solution used (nitrate and peroxide) and the applied potential. Scanning electron microscopy pictures show different morphologies in each case. X-ray diffraction confirms that the films are pure ZnO oriented alo...

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

    OpenAIRE

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

    2013-01-01

    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 ultra-violet 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 flu...

  13. Nucleant layer effect on nanocolumnar ZnO films grown by electrodeposition

    OpenAIRE

    Reyes Tolosa, María Dolores; Damonte, Laura Cristina; Brine, Hicham; Bolink, Henk J.; Hernández Fenollosa, María De Los Ángeles

    2013-01-01

    Different ZnO nanostructured films were electrochemically grown, using an aqueous solution based on ZnCl2, on three types of transparent conductive oxides grow on commercial ITO (In2O3:Sn)-covered glass substrates: (1) ZnO prepared by spin coating, (2) ZnO prepared by direct current magnetron sputtering, and (3) commercial ITO-covered glass substrates. Although thin, these primary oxide layers play an important role on the properties of the nanostructured films grown on top of ...

  14. Photoelectrochemistry of semiconductor ZnO particulate films

    International Nuclear Information System (INIS)

    This paper reports on thin films of ZnO semiconductor that have been prepared on electrode surfaces by coating them with quantized ZnO colloids. The photoelectrochemical properties of semiconductor particulate films have been evaluated with both steady-state and laser pulse excitations. The ZnO film behaves like an n-type semiconductor with a flatband potential of -0.6 V vs. SCE. The incident-photon conversion efficiency at 320 nm is 15%. The generation of photovoltage at these electrodes has been time-resolved with coulostatic laser-flash-photolysis experiments

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

    International Nuclear Information System (INIS)

    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

  16. Study on pulsed laser ablation and deposition of ZnO thin films by L-MBE

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    ZnO,as a wide-band gap semiconductor,has recently become a new research fo-cus in the field of ultraviolet optoelectronic semiconductors. Laser molecular beam epitaxy(L-MBE) is quite useful for the unit cell layer-by-layer epitaxial growth of zinc oxide thin films from the sintered ceramic target. The ZnO ceramic target with high purity was ablated by KrF laser pulses in an ultra high vacuum to deposit ZnO thin film during the process of L-MBE. It is found that the deposition rate of ZnO thin film by L-MBE is much lower than that by conventional pulsed laser deposition(PLD) . Based on the experimental phenomena in the ZnO thin film growth process and the thermal-controlling mechanism of the nanosecond(ns) pulsed laser abla-tion of ZnO ceramic target,the suggested effective ablating time during the pulse duration can explain the very low deposition rate of the ZnO film by L-MBE. The unique dynamic mechanism for growing ZnO thin film is analyzed. Both the high energy of the deposition species and the low growth rate of the film are really beneficial for the L-MBE growth of the ZnO thin film with high crystallinity at low temperature.

  17. 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.

  18. 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

  19. Modulation of ZnO film thickness and formation of water-hyacinth nanostructure

    Science.gov (United States)

    Gunasekaran, Ezhilarasan; Shankar, Prabakaran; Mani, Ganesh Kumar; Bosco Balaguru Rayappan, John

    2014-08-01

    The influence of precursor medium was investigated on the structural, morphological, optical and electrical properties of spray pyrolysis deposited nanostructured ZnO thin films. Three batches of ZnO thin films were deposited on glass substrates using three different solvents (water, water-ethanol [ratio of 1:1] and ethanol) based precursor solution of zinc nitrate hexahydrate. The substrate temperature was fixed at 523 K. The variation in film thickness from 150 to 875 nm was observed as the effect of changing solvent medium. X-ray diffraction (XRD) data confirmed the formation of polycrystalline ZnO thin films with hexagonal wurtzite crystallite structure and the estimated crystallite size was found to be ranging from 31 to 55 nm. Scanning electron micrographs revealed the formation of water-hyacinth shaped nanostructures when water-ethanol mixture was used as the solvent medium. Interestingly, UV-vis spectrophotometer revealed the formation of ZnO film with twin optical band gap of 3.15 eV and 3.56 eV when ethanol was used as the solvent medium. The modulation of film thickness and grain size by solvent medium has strongly influenced the electrical conductivity of ZnO thin films. The homogenous nano-spherical grains with uniform grain boundaries showed a good response towards 100 ppm of ammonia at room temperature.

  20. ZnO Thin Film Ga s Sensor for CO

    International Nuclear Information System (INIS)

    ZnO thin films were deposited onto corning glass substrates by rf magnetron sputtering system using ZnO targets. Films were deposited under rf power of 80 W at various deposition time. The distance between the target and substrate was held at 45 cm. A mixed Ar and O2 gas was introduced into the chamber at 4x10-2 Torr. The structure of the deposited ZnO films was investigated by Scanning electron miscroscopy. The gas sensing properties were evaluated at various operation temperatures by measuring the changes of resistance of the sensor in air and in CO gas respectively using the gas sensing characterization system. The grain size was increased as the film thickness was increased during deposition. The sensor with 233 nm film thickness exhibited the highest sensitivity for CO gas.

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

    Directory of Open Access Journals (Sweden)

    Yunus E. Kesim

    2014-07-01

    Full Text Available 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.

  2. Effect of substrate temperature on properties of multilayer thin film based on ZnO and Mo-doped indium oxide

    International Nuclear Information System (INIS)

    Zinc oxide/molybdenum-doped indium oxide/zinc oxide (ZnO/IMO/ZnO) multilayer thin films are grown using pulsed laser deposition technique. The effect of substrate temperature on structural, optical, and electrical properties of multilayer films is studied. It is observed that films grown at high substrate temperature are oriented along (0 0 2) and (2 2 2) direction for ZnO and IMO respectively. The crystallinity of these films increases with increase in substrate temperature. It is also seen that conductivity, carrier concentration, and mobility increase with increase in temperature. The multilayer film grown at 500 deg. C has low resistivity (7.67 x 10-5 Ω cm), high carrier concentration (3.90 x 1020 cm-3), and high mobility (209 cm2/Vs).

  3. RBS and XRD study on preparation of Fe and N codoped ZnO film

    International Nuclear Information System (INIS)

    Background: ZnO-based diluted magnetic semiconductors (DMSs) have attracted much attention for their potential applications in spintronics, which utilizes both the spin degree of freedom and electronic charge. After Dietl et al. theoretically predicted that ZnO doped with 5 at% Mn might exhibit room temperature ferromagnetism, most studies were focused on this system. The other transition metal such as Fe doped ZnO DMSs were rarely studied, especially, Fe and N codoped ZnO system. The thermal oxidation method, a very simple method, was used to prepare the ZnO: (Fe, N) films. First, Zn3N2: Fe films were grown by radio frequency (RF) reactive magnetron sputtering on quartz substrates and then annealed in oxygen atmosphere at different temperatures for 2 h. Purpose: This paper attempted to study annealing behavior and structural evolvement of Zn3N2: Fe at the different annealing temperature. Methods: Rutherford backscattering spectrometry (RBS) was a very powerful tool to study the growth of thin film. Therefore in this paper RBS combining with X-ray diffraction (XRD) was used to study the preparation of the ZnO: (Fe, N) films. Results: The results showed that the as-grown sample was Zn3N2: Fe film. After annealed at 300℃, Zn3N2: Fe in the surface had transformed to ZnO: (Fe, N) and the film under the surface was not oxidated. After annealed above 400℃, the Zn3N2: Fe film had entirely transformed to the polycrystalline ZnO: (Fe, N) film. Annealed at 500℃, the film started to diffuse into the substrate and at 600℃-700℃, the diffusion was very obvious. Conclusions: RBS combining with XRD can effectively study the preparation of the ZnO: (Fe, N) films. Within the range of the sensitivity, no precipitates such as Fe cluster or Fe3O4, Fe2O3 and FeO were observed by XRD. From SQUID, the maximum of the saturation magnetic moment (Ms) at room temperature appeared at 500℃. (authors)

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

    OpenAIRE

    Bohari Noor Aini; Shafiquzzaman Siddiquee; Kamaruzaman Ampon; Kenneth Francis Rodrigues; Saallah Suryani

    2015-01-01

    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 t...

  5. Orientation fluctuation trend of Pt and ZnO layers in film bulk acoustic resonator

    International Nuclear Information System (INIS)

    ZnO-based film bulk acoustic resonator (FBAR) was fabricated with many ZnO/Pt layers by magnetron sputtering. All the layers are good crystallized and highly textured. By crystallographic test, the orientation fluctuation of Pt layer increases with increasing film thickness or stack layers, whereas that of ZnO layer decreases slightly. It is consistent with ZnO grain c-axis tilting observed using transmission electron microscopy. Due to these good quality layers, the device has a high resonate frequency of 3.94 GHz

  6. Ozone-assisted atomic layer deposited ZnO thin films for multifunctional device applications

    International Nuclear Information System (INIS)

    We demonstrate the growth temperature dependence of film thickness and surface roughness of ZnO films grown by atomic layer deposition using ozone as an oxidizer. The significantly low growth rate of the film using O3 precursor is attributed to the recombinative surface loss of O3. The variation of the spatial uniformity inferred from the surface roughness of the ZnO films and the O3 concentration was explained by a transition from reaction- to recombination-limited growth. We have fabricated a metal–oxide–semiconductor device, consisting of an insulating ZnO layer using an O3 source, between metallic and semiconducting Al : ZnO layers. The device demonstrates a remarkable resistive switching behaviour. The electrochemical migration of oxygen vacancies, which is created in the vicinity of the interface of ZnO semiconductor–ZnO insulator, drives the resistive switching behaviour. This significant result produced on the all-oxide-based device fabricated by atomic layer deposited ZnO can have significant impact for multifunctional applications. (paper)

  7. Surface modification of ZnO film by hydrogen peroxide solution

    Science.gov (United States)

    Tsai, Chia-Hung; Wang, Wei-Chin; Jenq, Feng-Lin; Liu, Chien-Chih; Hung, Chen-I.; Houng, Mau-Phon

    2008-09-01

    The effect of hydrogen peroxide (H2O2) treatment on the microstructure and luminescent properties of ZnO thin films has been investigated. Governed by high-resolution transmission electron microscopy and selected-area electron diffraction patterns, the oxygen radicals dissociated from H2O2 solution at room temperature and substantially changed the polycrystalline ZnO film into an insulator. In addition, the photoluminescence spectra showed that H2O2 solution had nearly no effect on the intensity of ultraviolet emission, whereas it significantly enhanced the intensity of deep-level emission. These observations strongly reveal the fact that the oxygen radicals penetrating into a ZnO film are reasonably speculated to occupy the interstitial sites to form oxygen interstitials Oi or fill the Zn vacancies to form antisite oxygen OZn defects. Because of these extra defects involved, an enhancement of the green light luminescence is significantly promoted in our ZnO samples after handling with H2O2 solution. Based on the characteristics mentioned above, our hydrogen peroxide solution treated ZnO film has the potential for applying to the light-emitting diode with metal-insulator-semiconductor structure.

  8. Resistive switching characteristics and conduction mechanisms of nonvolatile memory devices based on Ga and Sn co-doped ZnO films

    International Nuclear Information System (INIS)

    Nonvolatile memory devices were fabricated utilizing Ga and Sn co-doped ZnO (GZTO) films formed by using a solution process method. X-ray diffraction patterns showed that the crystallinity of the annealed GZTO films was an amorphous phase. X-ray photoelectron spectroscopy spectra of the GZTO films depicted Zn−O, Ga−O, and Sn−O bonds. Current–voltage measurements on the Al/GZTO/indium-tin-oxide (ITO) devices at 300 K showed bipolar resistive switching behaviors. The resistances at both the low resistance state (LRS) and high resistance state (HRS) measured at 0.5 V for the devices maintain almost constant without any damage and breakdown above 130 s, indicative of the memory stability of the devices. A difference in the resistance between the HRS and the LRS was more than 1 order of the magnitude. The conduction mechanisms of the HRS in the set process for the Al/GZTO/ITO devices were dominated by a space-charge-limited current model. - Highlights: • Nonvolatile memory devices were fabricated utilizing Ga and Sn co-doped ZnO (GZTO) films. • X-ray diffraction patterns showed that the annealed GZTO films were an amorphous phase. • Current–voltage measurements on the devices showed bipolar resistive switching behaviors. • One order magnitude difference in resistance between low and high resistance states (HRS) • Space charge limited conduction is the dominant conduction mechanisms of the HRS

  9. Resistive switching characteristics and conduction mechanisms of nonvolatile memory devices based on Ga and Sn co-doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Dohyun; Yun, Dong Yeol; Lee, Nam Hyun; Kim, Tae Whan, E-mail: twk@hanyang.ac.kr

    2015-07-31

    Nonvolatile memory devices were fabricated utilizing Ga and Sn co-doped ZnO (GZTO) films formed by using a solution process method. X-ray diffraction patterns showed that the crystallinity of the annealed GZTO films was an amorphous phase. X-ray photoelectron spectroscopy spectra of the GZTO films depicted Zn−O, Ga−O, and Sn−O bonds. Current–voltage measurements on the Al/GZTO/indium-tin-oxide (ITO) devices at 300 K showed bipolar resistive switching behaviors. The resistances at both the low resistance state (LRS) and high resistance state (HRS) measured at 0.5 V for the devices maintain almost constant without any damage and breakdown above 130 s, indicative of the memory stability of the devices. A difference in the resistance between the HRS and the LRS was more than 1 order of the magnitude. The conduction mechanisms of the HRS in the set process for the Al/GZTO/ITO devices were dominated by a space-charge-limited current model. - Highlights: • Nonvolatile memory devices were fabricated utilizing Ga and Sn co-doped ZnO (GZTO) films. • X-ray diffraction patterns showed that the annealed GZTO films were an amorphous phase. • Current–voltage measurements on the devices showed bipolar resistive switching behaviors. • One order magnitude difference in resistance between low and high resistance states (HRS) • Space charge limited conduction is the dominant conduction mechanisms of the HRS.

  10. 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.

  11. Preparation of highly textured surface ZnO thin films

    International Nuclear Information System (INIS)

    In order to investigate the influence of the deposition technique upon the surface morphology of ZnO thin films we have employed two methods, which are the spray pyrolysis and magnetron sputtering. The surface morphology of ZnO thin films is a crucial parameter for controlling the reflection losses reduction when the coating is used as a transparent front layer in solar cells. The morphology of the surface was characterized by optical microscopy and profilometry. The results indicate that spray technique enables the elaboration of films with a highly rough surface, however sputtering technique yields to smoother films. This difference originates from the different deposition processes involved in both techniques. A vertical r.m.s. (root mean square) roughness in the order of 200 nm was measured in sprayed film; however only 40 nm r.m.s. vertical roughness is reported in sputtered one. The surface morphology in sprayed films causes the incident light diffraction; consequently the reflection is reduced up to zero. Therefore we show that ZnO thin films deposited with spray method is a potential candidate for use as a front transparent layer in solar cells

  12. Ethanedithiol Treatment of Solution-Processed ZnO Thin Films: Controlling the Intragap States of Electron Transporting Interlayers for Efficient and Stable Inverted Organic Photovoltaics

    OpenAIRE

    Bai, Sai; Jin, Yizheng; Liang, Xiaoyong; Ye, Zhizhen; Wu, Zhongwei; Sun, Baoquan; Ma, Zaifei; Tang, Zheng; Wang, Jianpu; Wuerfel, Uli; Gao, Feng; Zhang, Fengling

    2015-01-01

    The surface defects of solution-processed ZnO films lead to various intragap states. When the solution-processed ZnO films are used as electron transport interlayers (ETLs) in inverted organic solar cells, the intragap states act as interfacial recombination centers for photogenerated charges and thereby degrade the device performance. Here, a simple passivation method based on ethanedithiol (EDT) treatment is demonstrated, which effectively removes the surface defects of the ZnO nanocrystal ...

  13. 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.

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

    International Nuclear Information System (INIS)

    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

  15. Structural and electrical properties of electric field assisted spray deposited pea structured ZnO film

    Science.gov (United States)

    Chaturvedi, Neha; Swami, Sanjay Kumar; Dutta, Viresh

    2016-05-01

    Spray deposition of ZnO film was carried out. The uneven growth of ZnO nanostructures is resulted for spray deposited ZnO film. Application of DC voltage (1000V) during spray deposition provides formation of pea like structures with uniform coverage over the substrate. Electric field assisted spray deposition provides increased crystallinity with reduced resistivity and improved mobility of the ZnO film as compared to spray deposited ZnO film without electric field. This with large area deposition makes the process more efficient than other techniques.

  16. 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.

  17. Effects of doping concentration on properties of Mn-doped ZnO thin films

    Institute of Scientific and Technical Information of China (English)

    Gao Li; Zhang Jian-Min

    2009-01-01

    This paper reports that the radio frequency magnetron sputtering is used to fabricate ZnO and Mn-doped ZnO thin films on glass substrates at 500 ℃. The Mn-doped ZnO thin films present wurtzite structure of ZnO and have a smoother surface, better conductivity but no ferromagnetism. The x-ray photoelectron spectroscopy results show that the binding energy of Mn_(2p3/2) increases with increasing Mn content slightly, and the state of Mn in the Mn-doped ZnO thin films is divalent. The chemisorbed oxygen in the Mn-doped ZnO thin films increases with increasing Mn doping concentration. The photoluminescence spectra of ZnO and Mn-doped ZnO thin films have a similar ultraviolet emission. The yellow green emissions of 4 wt. % and 10 wt. % Mn-doped thin films are quenched, whereas the yellow green emission occurs because of abundant oxygen vacancies in the Mn-doped ZnO thin films after 20 wt. % Mn doping. Compared with pure ZnO thin film, the bandgap of the Mn-doped ZnO thin films increases with increasing Mn content.

  18. 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.

  19. Atomic layer deposition of ZnO thin films and dot structures

    International Nuclear Information System (INIS)

    Successful growth of thin films and quantum dots of ZnO by atomic layer deposition (ALD) is reported. Properties of ZnO films produced by four different ALD-procedures and by oxidation of ALD-grown ZnS films are discussed. The use of thin ZnO films as buffer layers for GaN deposition is also shortly described. (author)

  20. Photoconductive ZnO films with embedded quantum dot or ruthenium dye sensitizers

    Directory of Open Access Journals (Sweden)

    Michael A. White

    2013-09-01

    Full Text Available We report a new type of solution-processed photoconductive film based on embedding photosensitizers (semiconductor nanocrystals or ruthenium dye molecules within conductive ZnO sol-gel matrices. Mixing photosensitizers directly with sol-gel precursors prior to film deposition yields highly colored ZnO films containing well-dispersed sensitizers. These films show internal photoconductivity quantum efficiencies up to ∼50% and photoresponses over 100 mA/W with visible photoexcitation, competitive with other more complex photodetectors reported recently. This simple motif is attractive for the development of robust sensitized-oxide photodetectors and for fundamental studies of photoinduced charge separation from a variety of molecular or quantum dot sensitizers into conductive oxides.

  1. Effects of annealing on properties of ZnO thin films prepared by electrochemical deposition in chloride medium

    International Nuclear Information System (INIS)

    The development of cost-effective and low-temperature synthesis techniques for the growth of high-quality zinc oxide thin films is paramount for fabrication of ZnO-based optoelectronic devices, especially ultraviolet (UV)-light-emitting diodes, lasers and detectors. We demonstrate that the properties, especially UV emission, observed at room temperature, of electrodeposited ZnO thin films from chloride medium (at 70 deg. C) on fluor-doped tin oxide (FTO) substrates is strongly influenced by the post-growth thermal annealing treatments. X-ray diffraction (XRD) measurements show that the films have preferably grown along (0 0 2) direction. Thermal annealing in the temperature range of 150-400 deg. C in air has been carried out for these ZnO thin films. The as-grown films contain chlorine which is partially removed after annealing at 400 deg. C. Morphological changes upon annealing are discussed in the light of compositional changes observed in the ZnO crystals that constitute the film. The optical quality of ZnO thin films was improved after post-deposition thermal treatment at 150 deg. C and 400 deg. C in our experiments due to the reducing of defects levels and of chlorine content. The transmission and absorption spectra become steeper and the optical bandgap red shifted to the single-crystal value. These findings demonstrate that electrodeposition have potential for the growth of high-quality ZnO thin films with reduced defects for device applications.

  2. Residual and intentional n-type doping of ZnO thin films grown by metal-organic vapor phase epitaxy on sapphire and ZnO substrates

    Science.gov (United States)

    Brochen, Stéphane; Lafossas, Matthieu; Robin, Ivan-Christophe; Ferret, Pierre; Gemain, Frédérique; Pernot, Julien; Feuillet, Guy

    2014-03-01

    ZnO epilayers usually exhibit high n-type residual doping which is one of the reasons behind the difficulties to dope this material p-type. In this work, we aimed at determining the nature of the involved impurities and their potential role as dopant in ZnO thin films grown by metalorganic vapor phase epitaxy (MOVPE) on sapphire and ZnO substrates. In both cases, secondary ion mass spectroscopy (SIMS) measurements give evidence for a strong diffusion of impurities from the substrate to the epilayer, especially for silicon and aluminum. In the case of samples grown on sapphire substrates, aluminum follows Fick's diffusion law on a wide growth temperature range (800-1000°C). Thus, the saturation solubility and the diffusion coefficient of aluminum in ZnO single crystals have been determined. Furthermore, the comparison between SIMS impurity and effective dopant concentrations determined by capacitance-voltage measurements highlights, on one hand a substitutional mechanism for aluminum diffusion, and on the other hand that silicon acts as a donor in ZnO and not as an amphoteric impurity. In addition, photoluminescence spectra exhibit excitonic recombinations at the same energy for aluminum and silicon, indicating that silicon behaves as an hydrogenic donor in ZnO. Based on these experimental observations, ZnO thin films with a controlled n-type doping in the 1016-1019cm-3 range have been carried out. These results show that MOVPE growth is fully compatible with the achievement of highly Al-doped n-type thin films, but also with the growth of materials with low residual doping, which is a crucial parameter to address ZnO p-type doping issues.

  3. Effects of Annealing Temperature on Structural and Optical Properties of ZnO Thin Films

    Science.gov (United States)

    Xu, Jian-Ping; Shi, Shao-Bo; Li, Lan; Zhang, Xiao-Song; Wang, Ya-Xin; Chen, Xi-Ming

    2010-04-01

    The effects of annealing temperature on the structural and optical properties of ZnO films grown on Si (100) substrates by sol-gel spin-coating are investigated. The structural and optical properties are characterized by x-ray diffraction, scanning electron microscopy and photoluminescence spectra. X-ray diffraction analysis shows the crystal quality of ZnO films becomes better after annealing at high temperature. The grain size increases with the temperature increasing. It is found that the tensile stress in the plane of ZnO films first increases and then decreases with the annealing temperature increasing, reaching the maximum value of 1.8 GPa at 700°C. PL spectra of ZnO films annealed at various temperatures consists of a near band edge emission around 380 nm and visible emissions due to the electronic defects, which are related to deep level emissions, such as oxide antisite (OZn), interstitial oxygen (Oi), interstitial zinc (Zni) and zinc vacancy (V-Zn), which are generated during annealing process. The evolution of defects is analyzed by PL spectra based on the energy of the electronic transitions.

  4. Electrical and photovoltaic properties of ZnO/Si heterostructures with ZnO films grown by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Pietruszka, R., E-mail: pietruszka@ifpan.edu.pl [Institute of Physics, Polish Academy of Sciences, Warsaw (Poland); Luka, G.; Witkowski, B.S.; Kopalko, K. [Institute of Physics, Polish Academy of Sciences, Warsaw (Poland); Zielony, E.; Bieganski, P.; Placzek-Popko, E. [Institute of Physics, Wroclaw University of Technology, Wroclaw (Poland); Godlewski, M. [Institute of Physics, Polish Academy of Sciences, Warsaw (Poland); Department of Mathematics and Natural Sciences College of Science, Cardinal Stefan Wyszynski University, Warsaw (Poland)

    2014-07-31

    We report on the properties of photovoltaic (PV) structures based on thin films of n-type zinc oxide grown by atomic layer deposition method on a cheap silicon substrate. Thin films of ZnO are used as n-type partner to p-type Si (110) and, when doped with Al, as a transparent electrode. PV structures with different thicknesses of ZnO layers (from 600 nm to 1600 nm) were deposited to determine the optimal performance of PV structures. The best response we obtained for the structure with ZnO layer thickness of 800 nm. The so-obtained PV structures show 6% efficiency. - Highlights: • Zinc oxide thin films grown by atomic layer deposition for solar cells application • Optimization of ZnO properties for an efficient photovoltaic response • Evaluation of electrical and photovoltaic performance of fabricated photovoltaic devices.

  5. Correlation of film morphology and defect content with the charge-carrier transport in thin-film transistors based on ZnO nanoparticles

    International Nuclear Information System (INIS)

    The correlation of defect content and film morphology with the charge-carrier transport in field-effect devices based on zinc oxide nanoparticles was investigated. Changes in the defect content and the morphology were realized by annealing and sintering of the nanoparticle thin films. Temperature-dependent electrical measurements reveal that the carrier transport is thermally activated for both the unsintered and sintered thin films. Reduced energetic barrier heights between the particles have been determined after sintering. Additionally, the energetic barrier heights between the particles can be reduced by increasing the drain-to-source voltage and the gate-to-source voltage. The changes in the barrier height are discussed with respect to information obtained by scanning electron microscopy and photoluminescence measurements. It is found that a reduction of surface states and a lower roughness at the interface between the particle layer and the gate dielectric lead to lower barrier heights. Both surface termination and layer morphology at the interface affect the barrier height and thus are the main criteria for mobility improvement and device optimization

  6. Correlation of film morphology and defect content with the charge-carrier transport in thin-film transistors based on ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Polster, S. [Chair of Electron Devices, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Cauerstrasse 6, 91058 Erlangen (Germany); Jank, M. P. M. [Fraunhofer Institute for Integrated Systems and Device Technology, Schottkystrasse 10, 91058 Erlangen (Germany); Frey, L. [Chair of Electron Devices, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Cauerstrasse 6, 91058 Erlangen (Germany); Fraunhofer Institute for Integrated Systems and Device Technology, Schottkystrasse 10, 91058 Erlangen (Germany)

    2016-01-14

    The correlation of defect content and film morphology with the charge-carrier transport in field-effect devices based on zinc oxide nanoparticles was investigated. Changes in the defect content and the morphology were realized by annealing and sintering of the nanoparticle thin films. Temperature-dependent electrical measurements reveal that the carrier transport is thermally activated for both the unsintered and sintered thin films. Reduced energetic barrier heights between the particles have been determined after sintering. Additionally, the energetic barrier heights between the particles can be reduced by increasing the drain-to-source voltage and the gate-to-source voltage. The changes in the barrier height are discussed with respect to information obtained by scanning electron microscopy and photoluminescence measurements. It is found that a reduction of surface states and a lower roughness at the interface between the particle layer and the gate dielectric lead to lower barrier heights. Both surface termination and layer morphology at the interface affect the barrier height and thus are the main criteria for mobility improvement and device optimization.

  7. Comparative study on the properties of ZnO nanowires and nanocrystalline thin films

    OpenAIRE

    Broitman, Esteban; Bojorge, C; Elhordoy, F; Kent, V.; Zanini Gadioli, G; Marotti, R.; Canepa, H; Dalchiele, E. A.

    2012-01-01

    The microstructural, morphological, optical and water-adsorption properties of nanocrystalline ZnO thin films and ZnO nanowires were studied and compared. The ZnO thin films were obtained by a sol–gel process, while the ZnO nanowires were electrochemically grown onto a ZnO sol–gel spin-coated seed layer. Thin films and nanowire samples were deposited onto crystalline quartz substrates covered by an Au electrode, able to be used in a quartz crystal microbalance. X-ray diffraction measurements ...

  8. 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.

  9. Room temperature magnetic properties of Fe and C implanted ZnO films

    International Nuclear Information System (INIS)

    ZnO films prepared by radio frequency magnetron sputtering were singly or sequentially implanted with 120 keV Fe ions at a fluence of 5 x 1016 ions/cm2 and 20 keV C ions at a fluence of 3 x 1015 ions/cm2. Magnetic and optical properties as well as structures of the films have been investigated using various techniques. Magnetic measurements show that the as-deposited ZnO film presents room temperature ferromagnetism. Single Fe or C ion implantation has no contribution to enhancement in the film magnetism, while magnetic moment increases distinctly in the Fe and C ions sequentially implanted film. Results from structural measurements reveal that Fe nanoparticles are formed in the Fe singly implanted ZnO film. The post C implantation induces dissolution of Fe nanoparticles and promotes Fe atoms to substitute Zn atoms in the lattice. Based on the structural results, the effect of magnetic enhancement has been tentatively interpreted.

  10. Plasmonic assisted enhanced photoresponse of metal nanoparticle loaded ZnO thin film ultraviolet photodetectors

    International Nuclear Information System (INIS)

    An ultraviolet (UV) photodetector exhibiting enhanced response characteristics has been realized successfully after integrating various metal nanoparticles (NPs) such as silver (Ag), gold (Au) and platinum (Pt) with sol–gel derived ZnO thin film (NPs–ZnO). The metal NP based photodetector (Ag, Au, Pt-NPs–ZnO) exhibits a relatively high photoresponse in comparison to the bare ZnO based UV photodetector and gives a maximum value of about 4.27 × 103. The combined effect of the lowering of dark current due to the formation of a Schottky barrier at the interface of the metal NPs with the ZnO thin film and the photocurrent upon UV illumination due to the plasmonic effect of loaded NPs results in an enhanced photoresponse of the prepared metal NP–ZnO photodetector. The trapping of incident UV radiation mainly through the enhanced optical absorption by loaded metal NPs due to the plasmonic effect and subsequent coupling of harvesting photons into underlying optical modes of the surface of photoconducting ZnO thin films lead to a significant increase in photocurrent. The observed results provide an indication that the plasmonic assisted UV response of the novel metal NP–ZnO photodetector might provide a breakthrough for the development of next generation photodetectors. (paper)

  11. Laser nanostructuring of ZnO thin films

    Science.gov (United States)

    Nedyalkov, N.; Koleva, M.; Nikov, R.; Atanasov, P.; Nakajima, Y.; Takami, A.; Shibata, A.; Terakawa, M.

    2016-06-01

    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.

  12. Pattern Recognition Based Discrimination of Ethanol Concentration Using ZnO Thick-Film Gas Sensor for the Detection and Warning of Drunken Driving

    OpenAIRE

    AMBARISH G. MOHAPATRA,; BIRANCHI N. RATH

    2011-01-01

    DUI (Driving under the influence) is a synonymous term that represents the criminal offense of operating a motor vehicle while being under the influence of alcohol. Semiconductor oxides such as SnO2, TiO2, and ZnO have been more successfully employed as sensing materials compare to organic semiconductors for the detection of ethanol gas concentration. This work investigates the fabrication and characterization of the thickfilm gas sensor based on Zinc Oxide on an Alumina substrate. The sensor...

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

    International Nuclear Information System (INIS)

    Zinc oxide (ZnO) thin films on c-sapphire substrates were synthesized by spin-coating aqueous polymeric precursors. The effects of annealing at 1000 °C on crystallinity, surface morphology, and optical properties of ZnO thin films, with varying thicknesses, were studied. Single-layered ZnO thin films are polycrystalline with wurtzite structure and preferentially oriented along the (002) plane. X-ray diffraction pattern also reveals the presence of spinel zinc aluminate (ZnAl2O4) peaks. ZnO films have highly faceted granular morphology. Multilayered ZnO films, annealed twice at 1000 °C, do not exhibit any ZnO peaks but only ZnAl2O4 peaks. Moreover, the surface morphology was smooth with ridges. These films do not exhibit the band gap or ultra-violet emission photoluminescence characteristics of ZnO. On annealing, there is an interfacial reaction between ZnO and sapphire resulting in ZnAl2O4. - Highlights: • Multilayer polymeric precursor derived ZnO film is annealed at 1000 °C on c-sapphire. • X-Ray diffraction (XRD) pattern of ZnO film annealed at 1000 °C shows ZnO peaks. • XRD pattern of ZnO films twice-annealed at 1000 °C shows only ZnAl2O4 peaks. • Optical characterization of the multilayered films does not show ZnAl2O4 peaks. • On annealing twice at 1000 °C, ZnO reacts with the c-sapphire to form ZnAl2O4

  14. Optical characterization of ZnO thin films deposited by RF magnetron sputtering method

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    This study investigated the process parameter effects on the structural and optical properties of ZnO thin film using radio frequency (RF) magnetron sputtering on amorphous glass substrates. The process parameters included RF power and working pressure. Results show that RF power was increased to promote the crystalline quality and decrease ZnO thin film defects. However, when the working pressure was increased to 3 Pa the ZnO thin film crystalline quality became worse. At a 200 W RF power and 1 Pa working pressure, the ZnO thin film with an optical band gap energy of 3.225 eV was obtained.

  15. All spray pyrolysis deposited CdS sensitized ZnO films for quantum dot-sensitized solar cells

    International Nuclear Information System (INIS)

    Graphical abstract: Display Omitted Research highlights: → Solar cells based on CdS quantum dot sensitized ZnO photoanode are fabricated. → Both ZnO and CdS are prepared using ultrasonic spray pyrolysis technique. → Good contact is formed between CdS and ZnO to facilitate the electron transfer. → As-prepared cell achieves maximally a power conversion efficiency of 1.54%. - Abstract: Sensitized-type solar cells based on ZnO photoanode and CdS quantum dots (QDs) as sensitizers have been fabricated. Both ZnO films and CdS QDs are prepared using ultrasonic spray pyrolysis (USP) deposition technique. This method allows a facile and rapid deposition and integration between CdS QDs and ZnO films without the need for post thermal treatment. The photovoltaic performances of the cells are investigated. The results show that the performance of the cell based on all USP deposited CdS sensitized ZnO photoanode achieves maximally a short circuit current density of 6.99 mA cm-2 and a power conversion efficiency of 1.54%.

  16. Characterization of photovoltage evolution of ZnO films using a scanning Kelvin probe system

    International Nuclear Information System (INIS)

    Work function (WF) and surface photovoltage evolution of films can be measured using the Kelvin probe technique, and further analysis of the photoelectronic behavior can provide information on the energy level structure. In this paper, a theoretical analysis to measure surface photovoltage using Kelvin probe technique is presented. Based on this analysis, the surface photovoltage and its time-resolved evolution process as well as the energy level structure of ZnO films are determined using a scanning Kelvin probe. The present study therefore provides a simple and practical methodology for the characterization of the electronic behavior of films.

  17. 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.

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

    International Nuclear Information System (INIS)

    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.

  19. Studies on Crystal Orientation of ZnO Film on Sapphire Using High-throughout X-ray Diffraction

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The orientation of the nano-columnar ZnO films grown on sapphire using the technique of metal-organic chemical vapor deposition (MOCVD) exhibits deviation because of the mismatch between the crystal lattices of the films and the sapphire substrate. A high-throughout X-ray diffraction method was employed to determine the crystal orientation of the ZnO films at a time scale of the order of minutes based on the general area detection diffraction system (GADDS). This rapid, effective, and ready method, adapted for characterizing the orientation of the nano-columnar crystals is used to directly explain the results of observation of the X-ray diffraction images, by the measurements of the orientations of the crystal columns of the ZnO films along c-axis and in parallel to ab plane.

  20. Analysis of Li-related defects in ZnO thin films influenced by annealing ambient

    Indian Academy of Sciences (India)

    Bing Wang; Lidan Tang

    2014-02-01

    Li-doped ZnO thin films were grown on quartz substrates by radio frequency magnetron sputtering and in situ annealing under O2 or Ar ambient. Li-related defects in ZnO films strongly depend on the annealing ambient. AFM and XRD indicated that ZnO films possessed a good crystallinity with -axis orientation, uniform thickness and dense surface. Electrical and optical properties demonstrated that, an amount of LiZn defect had existed in ZnO annealed under O2 ambient and an amount of Lii(o) defect had existed in ZnO annealed under Ar ambient. First-principle calculations were performed to calculate formation energies of Li-doped ZnO in order to explain the formation mechanism of Li-related defects in ZnO.

  1. 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. PMID:26399539

  2. Thickness dependent magnetic transitions in pristine MgO and ZnO sputtered thin films

    Directory of Open Access Journals (Sweden)

    Mukes Kapilashrami

    2010-09-01

    Full Text Available We report a systematic study of the thickness dependency of room temperature ferromagnetism in pristine MgO (~100–500 nm and ZnO (~100–1000 nm thin films deposited by reactive magnetron sputtering technique under the respective identical controlled optimum oxygen ambience. As far as we know this is the first such report on ferromagnetic pure MgO thin films, a result which should be of significance in understanding the functional aspects of magnetic tunnelling characteristics in devices using MgO dielectrics. From the magnetic characterization we observe a distinct variation in the saturation magnetization (MS with increasing film thickness. In the case of MgO thin films MS values vary in the range 0.04–1.58 emu/g (i.e. 0.0012–0.046 μB/unit cell with increasing film thickness showing the highest MS value for the 170 nm thick film. Above this thickness MS is found to decrease and eventually above 420 nm the films show a paramagnetic behaviour followed by the well known diamagnetic property for the bulk (>500 nm. It is obvious that since initially the MS values increase with thickness, there has to be a maximum before the films become diamagnetic at some finite thickness. We also note that the MS values observed for MgO are the highest (more than twice the value observed for ZnO to be reported for such a defect induced ferromagnetism in a pristine oxide. The origin of ferromagnetic order in both the oxides appears to arise from the respective cat-ion vacancies. The discovery of film thickness dependent ferromagnetic order should be very useful in developing multifunctional devices based on the technologically important materials MgO and ZnO.

  3. Microfluidic pumps employing surface acoustic waves generated in ZnO thin films

    International Nuclear Information System (INIS)

    ZnO thin film based surface acoustic wave (SAW) devices have been utilized to fabricate microfluidic pumps. The SAW devices were fabricated on nanocrystalline ZnO piezoelectric thin films deposited on Si substrates using rf magnetron sputtering and use a Sezawa wave mode for effective droplet motion. The as-deposited ZnO surface is hydrophilic, with a water contact angle of ∼75 deg., which prevents droplet pumping. Therefore, the ZnO surface was coated using a self-assembled monolayer of octadecyltrichlorosilane which forms a hydrophobic surface with a water contact angle of ∼110 deg. Liquid droplets between 0.5 and 1 μl in volume were successfully pumped on the hydrophobic ZnO surface at velocities up to 1 cm s-1. Under acoustic pressure, the water droplet on an hydrophilic surface becomes deformed, and the asymmetry in the contact angle at the trailing and leading edges allow the force acting upon the droplet to be calculated. These forces, which increase with input voltage above a threshold level, are found to be in the range of ∼100 μN. A pulsed rf signal has also been used to demonstrate precision manipulation of the liquid droplets. Furthermore, a SAW device structure is demonstrated in which the ZnO piezoelectric only exists under the input and output transducers. This structure still permits pumping, while avoiding direct contact between the piezoelectric material and the fluid. This is of particular importance for biological laboratory-on-a-chip applications

  4. Structure and haemocompatibility of ZnO films deposited by radio frequency sputtering

    International Nuclear Information System (INIS)

    ZnO films were first deposited on silicon and glass substrates using radio frequency sputtering and then annealed in air at different temperatures from 300 to 700 deg. C. The microstructures, surface energy and optical properties of ZnO films were examined by x-ray diffraction, Raman spectroscopy, contact angle test and UV-visible optical absorption spectroscopy, respectively. Results show that a perfectly oriented ZnO (0 0 2) thin film is obtained in all ZnO samples. Raman spectroscopy, in combination with those derived by UV-visible optical absorption spectroscopy, provides us with an accurate description of ZnO nature, revealing that, after annealing, ZnO films exhibit better crystallinity and narrower optical energy gap. The contact angle test denotes that the adhesive work and polar component of the surface energy of ZnO films increase steadily with the annealing temperature, which leads to more active interaction between annealed ZnO films and blood plasma. The platelet adhesion experiment shows that there are fewer platelets adhered to the surface of ZnO films compared to the polyurethane (PU) used in clinical application, suggesting ZnO's better compatibility with blood. As the annealing temperature increases, the number of platelets adhered to ZnO films increases correspondingly, which we believe is due to the narrower optical energy gap. Therefore, the appropriate surface properties and the wide optical energy gap of ZnO thin films are believed to be the main factors responsible for the excellent haemocompatibility.

  5. Performance improvement of ZnO film by room-temperature oxygen plasma pretreatment

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ping; XIA Yi-ben; WANG Lin-jun; LIU Jian-min; XU Run; PENG Hong-yan; SHI Wei-min

    2006-01-01

    The room-temperature oxygen plasma treatment before depositing ZnO films on nanocrystalline diamond substrates was studied. The nanocrystalline diamond substrates were pretreated in oxygen plasma at 50 W for 30 min at room temperature and then ZnO films were sputtered on diamond substrates at 400 W. The X-ray diffraction (XRD) patterns show that the c-axis orientation of ZnO film increases evidently after oxygen plasma pretreatment. The AFM and SEM measurements also show that the high c-axis orientation of ZnO film and the average surface roughness is less than 5 nm. The resistivity of ZnO films increases nearly two orders of magnitude to 1.04×108 Ω·cm. As a result,room-temperature oxygen plasma pretreatment is indeed a simple and effective way to improve the performance of ZnO film used in SAW devices by ameliorating the combination between diamond film and ZnO film and also complementing the absence of oxygen atoms in ZnO film.

  6. Physical Property Evaluation of ZnO Thin Film Fabricated by Low-Temperature Process for Flexible Transparent TFT.

    Science.gov (United States)

    Khafe, Adie Bin Mohd; Watanabe, Hiraku; Yamauchi, Hiroshi; Kuniyoshi, Shigekazu; Iizuka, Masaaki; Sakai, Masatoshi; Kudo, Kazuhiro

    2016-04-01

    The usual silicon-based display back planes require fairly high process temperature and thus the development of a low temperature process is needed on flexible plastic substrates. A new type of flexible organic light emitting transistor (OLET) had been proposed and investigated in the previous work. By using ultraviolet/ozone (UV/O3) assisted thermal treatments on wet processed zinc oxide field effect transistor (ZnO-FET), through low-process temperature, ZnO-FETs were fabricated which succeeded to achieve target drain current value and mobility. In this study, physical property evaluation of ZnO was conducted in term of their crystallinity, the increase composition of ZnO formed inside the thin film and the decrease of the carbon impurities originated from aqueous solution of the ZnO itself. The X-ray diffraction (XRD) evaluation showed UV/03 assisted thermal treatment has no obvious effect towards crystallinity of ZnO in the range of low process temperature. Moreover, through X-ray photoelectron spectroscopy (XPS) evaluation and Fourier transform infrared (FT-IR) spectroscopy evaluation, more carbon impurities disappeared from the ZnO thin film and the increase of composition amount of ZnO, when the thin film was subjected to UV/O3 assisted thermal treatment. Therefore, UV/O3 assisted thermal treatment contributed in carbon impurities elimination and accelerate ZnO formation in ZnO thin film, which led to the improvement in the electrical property of ZnO-FET in the low-process temperature. PMID:27451599

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

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Linhua, E-mail: congyu3256@tom.com [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Optics and Photonic Technology Laboratory, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Zheng, Gaige; Zhao, Lilong; Pei, Shixin [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Optics and Photonic Technology Laboratory, Nanjing University of Information Science and Technology, Nanjing 210044 (China)

    2015-02-15

    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{sup +} ion (Ag{sub Zn}) while the Ag in the ZnO thin films without a post-annealing mainly exists in the form of simple substance (Ag{sup 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.

  8. 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 ...

  9. Optimization of (002)-Oriented ZnO Film Synthesis in Sol-Gel Process and Film Photoluminescence Property

    Institute of Scientific and Technical Information of China (English)

    YAN Jun-Feng; ZHAO Li-Li; ZHANG Zhi-Yong

    2008-01-01

    By orthogonal design theory, technological parameters of the (002)-oriented ZnO film prepared in sol-gel process are optimized. A set of technological parameters for growing highly (002)-oriented ZnO film is obtained. As a result, it is proven that the Zn2+ concentration is the most important factor to grow a highly (O02)-oriented ZnO film. We take an appropriate Zn2+ concentration 0.35 mol/L for the aimed film, of which photoluminescence property is better than those of the films derived from other Zn2+ concentrations precursor solution. The Zn2+ concentration either larger or smaller than 0.35 mol/L leads to the (002)-oriented degree decrease of films. By employing an atom force microscope, a hexagonal atom arrangement, which indicates that the film site detected is a ZnO single crystal, is observed in the surface of the highly (002)-oriented film.

  10. Recent advances in the transparent conducting ZnO for thin-film Si solar cells

    Science.gov (United States)

    Moon, Taeho; Shin, Gwang Su; Park, Byungwoo

    2015-11-01

    The key challenge for solar-cell development lies in the improvement of power-conversion efficiency and the reduction of fabrication cost. For thin-film Si solar cells, researches have been especially focused on the light trapping for the breakthrough in the saturated efficiencies. The ZnO-based transparent conducting oxides (TCOs) have therefore received strong attention because of their excellent light-scattering capability by the texture-etched surface and cost effectiveness through in-house fabrication. Here, we have highlighted our recent studies on the transparent conducting ZnO for thin-film Si solar cells. From the electrical properties and their degradation mechanisms, bilayer deposition and organic-acid texturing approaches for enhancing the light trapping, and finally the relation between textured ZnO and electrical cell performances are sequentially introduced in this review article. [Figure not available: see fulltext.

  11. Dye-sensitized solar cells using ZnO nanotips and Ga-doped ZnO films

    Science.gov (United States)

    Chen, Hanhong; Du Pasquier, Aurelien; Saraf, Gaurav; Zhong, Jian; Lu, Yicheng

    2008-04-01

    Ga-doped ZnO (GZO) transparent conducting films and well-aligned ZnO nanotips were sequentially grown on a glass substrate using metal-organic chemical vapor deposition (MOCVD). The morphology control of ZnO from dense films to nanotips was realized through temperature-modulated growth. The ZnO nanotips/GZO structure was sensitized with dye N719 to form photoelectrochemical cells. It is found that the power conversion efficiency linearly increases with the length of ZnO nanotips. For the 1.0 cm2 dye-sensitized solar cell built from 4.8 µm ZnO nanotips, a peak incident photo-to-current conversion efficiency of 79% (at ~530 nm) and a power conversion efficiency of 0.77% under the illumination of one sun-simulated sunlight were achieved. UV light harvesting directly by ZnO was observed. The I-V characteristics of the cells were analyzed using a one-diode equivalent circuit model.

  12. Defects Induced Room Temperature Ferromagnetism in ZnO Thin Films

    OpenAIRE

    Xiao Zhang; , Wei Zhang; Xinghua Zhang; Xuewen Xu; Fanbin Meng; Tang, C.C.

    2014-01-01

    Polycrystalline ZnO thin films are prepared by the co-sputtering method under different oxygen partial pressures. Films deposited in pure argon gas exhibit ferromagnetism, whereas other films deposited under different oxygen partial pressures are diamagnetism. XPS results show the presence of Zn interstitial and oxygen vacancy in all of samples. Further analysis indicates that Zn interstitial may play an important role in triggering magnetic order on the undoped ZnO thin films by inducing an ...

  13. Effect of Rapid Thermal Annealing Ambient on Photoluminescence of ZnO Films

    Institute of Scientific and Technical Information of China (English)

    XU Xiao-Yan; MA Xiang-Yang; JIN Lu; YANG De-Ren

    2012-01-01

    The effects of rapid thermal annealing (RTA) ambient on photoluminescence (PL) of sputtered ZnO films are investigated.The RTA at 800℃ under either oxygen (O2) or argon (Ar) ambient can remarkably enhance the PL of the ZnO films due to the improved crystallinities of the ZnO films.It is somewhat unexpected that the ZnO film which received the RTA under O2 ambient exhibits weaker near-band-edge (NBE) PL than that which received the RTA under Ar ambient.It is supposed that a certain amount of negatively charged oxygen species exist on the surface of the ZnO film that received the RTA under O2 ambient,leading to a build-in electric field.This in turn reduces the recombination probability of photo-generated electrons and holes,resulting in the suppressed NBE PL.

  14. Properties of ZnO thin films grown on Si substrates by photo-assisted MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    Li Xiangping [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Qianjin Street 2699, Changchun 130012 (China)], E-mail: lxp2897871@126.com; Zhang Baolin [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Qianjin Street 2699, Changchun 130012 (China)], E-mail: zbl@jlu.edu.cn; Zhu Huichao [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Qianjin Street 2699, Changchun 130012 (China); Dong Xin [State Key Laboratory for Materials Modification by Laser, Ion, and Electron Beams and Department of Physics, Dalian University of Technology, Dalian 116024 (China); Xia Xiaochuan [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Qianjin Street 2699, Changchun 130012 (China); Cui Yongguo [State Key Laboratory for Materials Modification by Laser, Ion, and Electron Beams and Department of Physics, Dalian University of Technology, Dalian 116024 (China); Huang Keke [State Key Laboratory of Inorganic Synthesis and Preparation Chemistry, Jilin University, Qianjin Street 2699, Changchun 130012 (China); Du Guotong [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Qianjin Street 2699, Changchun 130012 (China); State Key Laboratory for Materials Modification by Laser, Ion, and Electron Beams and Department of Physics, Dalian University of Technology, Dalian 116024 (China)

    2008-01-30

    ZnO thin films were grown on (1 0 0) p-Si substrates by Photo-assisted Metal Organic Chemical Vapor Deposition (PA-MOCVD) using diethylzinc (DEZn) and O{sub 2} as source materials and tungsten-halogen lamp as a light source. The effects of tungsten-halogen lamp irradiation on the surface morphology, structural and optical properties of the deposited ZnO films have been investigated by means of atomic force microscope (AFM), X-ray diffraction and photoluminescence (PL) spectra measurements. Compared with the samples without irradiation, the several characteristics of ZnO films with irradiation are improved, including an improvement in the crystallinity of c-axis orientation, an increase in the grain size and an improvement in optical quality of ZnO films. These results indicated that light irradiation played an important role in the growth of ZnO films by PA-MOCVD.

  15. Properties of ZnO thin films grown on Si substrates by photo-assisted MOCVD

    International Nuclear Information System (INIS)

    ZnO thin films were grown on (1 0 0) p-Si substrates by Photo-assisted Metal Organic Chemical Vapor Deposition (PA-MOCVD) using diethylzinc (DEZn) and O2 as source materials and tungsten-halogen lamp as a light source. The effects of tungsten-halogen lamp irradiation on the surface morphology, structural and optical properties of the deposited ZnO films have been investigated by means of atomic force microscope (AFM), X-ray diffraction and photoluminescence (PL) spectra measurements. Compared with the samples without irradiation, the several characteristics of ZnO films with irradiation are improved, including an improvement in the crystallinity of c-axis orientation, an increase in the grain size and an improvement in optical quality of ZnO films. These results indicated that light irradiation played an important role in the growth of ZnO films by PA-MOCVD

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

    International Nuclear Information System (INIS)

    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)

  17. Room-temperature anomalous Hall effect and magnetroresistance in (Ga, Co)-codoped ZnO diluted magnetic semiconductor films

    Institute of Scientific and Technical Information of China (English)

    Liu Xue-Chao; Chen Zhi-Zhan; Shi Er-Wei; Liao Da-Qian; Zhou Ke-Jin

    2011-01-01

    This paper reports that the (Ga, Co)-codoped ZnO thin films have been grown by inductively coupled plasma enhanced physical vapour deposition. Room-temperature ferromagnetism is observed for the as-grown thin films. The x-ray absorption fine structure characterization reveals that Co2+ and Ga3+ ions substitute for Zn2+ ions in the ZnO lattice and exclude the possibility of extrinsic ferromagnetism origin. The ferromagnetic (Ga, Co)-codoped ZnO thin films exhibit carrier concentration dependent anomalous Hall effect and positive magnetoresistance at room temperature. The mechanism of anomalous Hall effect and magneto-transport in ferromagnetic ZnO-based diluted magnetic semiconductors is discussed.

  18. Room temperature ferromagnetism in Tb doped ZnO nanocrystalline films

    International Nuclear Information System (INIS)

    Nanocrystalline Tb doped ZnO films have been prepared by ion-beam sputtering technology. Magnetic property shows that the films are ferromagnetic and the Curie Temperature (Tc) is over room temperature. Structure property investigation indicates that no secondary phase is found in all the films, which suggests that the ferromagnetism is caused by the incorporation of Tb into ZnO lattice. The saturation magnetization of the films are about 0.38 μb/Tb. Electrical property investigation proves that the carriers of the films are strongly localized, which suggests that the ferromagnetism in the film may be caused by the defects in the films. - Highlights: → Room temperature ferromagnetism was found in nanocrystalline Tb doped ZnO films. → No secondary phase existed in the film. → Carriers in the films were highly localized. → Ferromagnetism may be related to the defects in the films.

  19. Elaboration and characterization of Al doped ZnO nanorod thin films annealed in hydrogen

    International Nuclear Information System (INIS)

    Research highlights: → High transparent and conductive Al doped ZnO nanorod thin films were synthesized using sol-gel spin-coating method. → Al doped ZnO nanorod thin films can be got by annealing in hydrogen rather than in air. → Crystal orientation of Al doped ZnO thin film has been raised. → Resistivity of films has been remarkably reduced by annealing in hydrogen. - Abstract: ZnO thin films doped with Al concentrations of 1.0, 2.0, 3.0, 4.0, 5.0 at% were prepared by a sol-gel spin-coating method on glass substrates and respectively annealed at 550 deg. C for 2 h in hydrogen and air. The X-ray diffraction and selected-area electron diffraction results confirm that the Al doped ZnO thin films are of wurtzite hexagonal ZnO. The scanning electron microscope results indicate that the Al doped ZnO nanorod thin films can be got by annealing in hydrogen rather than in air. The optical properties reveal that the Al doped ZnO thin films have obviously enhanced transmittance in the visible region. The electrical properties show that the resistivity of 1.0 at% Al doped ZnO thin films has been remarkably reduced from 0.73 Ω m by annealing in air to 3.2 x 10-5 Ω m by annealing in hydrogen. It is originated that the Al doped ZnO nanorod thin films annealed in hydrogen increased in electron concentration and mobility due to the elimination of adsorbed oxygen species, and multicoordinated hydrogen.

  20. Superhydrophobic surfaces based on dandelion-like ZnO microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Pan Qinmin [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China)], E-mail: panqm@hit.edu.cn; Cheng Yuexiang [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China)

    2009-01-01

    This study presents a simple method to fabricate superhydrophobic surface based on ZnO nanoneedles. ZnO nanoneedles had been constructed on zinc layers by immersing in an aqueous NH{sub 4}OH solution at 80 deg. C. The ZnO films were characterized by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The ZnO films exhibited excellent superhydrophilicity (contact angle for water was 0 deg.), while they changed wettability to superhydrophobicity with a water contact angle greater than 150 deg. after further chemical modification with n-dodecanoic acid. The procedure reported here only needs readily available reagents and laboratory equipments, which can be applied to various substrates of any size and shape.

  1. Superhydrophobic surfaces based on dandelion-like ZnO microspheres

    Science.gov (United States)

    Pan, Qinmin; Cheng, Yuexiang

    2009-01-01

    This study presents a simple method to fabricate superhydrophobic surface based on ZnO nanoneedles. ZnO nanoneedles had been constructed on zinc layers by immersing in an aqueous NH 4OH solution at 80 °C. The ZnO films were characterized by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The ZnO films exhibited excellent superhydrophilicity (contact angle for water was 0°), while they changed wettability to superhydrophobicity with a water contact angle greater than 150° after further chemical modification with n-dodecanoic acid. The procedure reported here only needs readily available reagents and laboratory equipments, which can be applied to various substrates of any size and shape.

  2. Superhydrophobic surfaces based on dandelion-like ZnO microspheres

    International Nuclear Information System (INIS)

    This study presents a simple method to fabricate superhydrophobic surface based on ZnO nanoneedles. ZnO nanoneedles had been constructed on zinc layers by immersing in an aqueous NH4OH solution at 80 deg. C. The ZnO films were characterized by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The ZnO films exhibited excellent superhydrophilicity (contact angle for water was 0 deg.), while they changed wettability to superhydrophobicity with a water contact angle greater than 150 deg. after further chemical modification with n-dodecanoic acid. The procedure reported here only needs readily available reagents and laboratory equipments, which can be applied to various substrates of any size and shape.

  3. ZnO thin films prepared by surfatron produced discharge

    Czech Academy of Sciences Publication Activity Database

    Olejníček, Jiří; Šmíd, Jiří; Čada, Martin; Kment, Š.; Churpita, Olexandr; Kšírová, Petra; Brunclíková, Michaela; Adámek, Petr; Kohout, Michal; Valvoda, V.; Chvostová, Dagmar; Zlámal, M.; Hubička, Zdeněk

    2014-01-01

    Roč. 230, Jul (2014), s. 119-124. ISSN 0920-5861 R&D Projects: GA TA ČR TA01011740; GA MŠk LH12045; GA ČR GAP108/12/1941; GA ČR(CZ) GAP205/11/0386 Grant ostatní: GACR(CZ) GP13-29241P Institutional support: RVO:68378271 Keywords : ZnO * surfatron * thin films * Langmuir probe * plasma density Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.893, year: 2014

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

    Energy Technology Data Exchange (ETDEWEB)

    Amezaga-Madrid, P.; Antunez-Flores, W.; Ledezma-Sillas, J.E.; Murillo-Ramirez, J.G.; Solis-Canto, O.; Vega-Becerra, O.E.; Martinez-Sanchez, R. [Centro de Investigacion en Materiales Avanzados S.C. and Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes 120, Chihuahua, Chih., C.P. 31109 (Mexico); Miki-Yoshida, M., E-mail: mario.miki@cimav.edu.mx [Centro de Investigacion en Materiales Avanzados S.C. and Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes 120, Chihuahua, Chih., C.P. 31109 (Mexico)

    2011-06-15

    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{sub 2}, SnO{sub 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.

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

    International Nuclear Information System (INIS)

    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, TiO2, SnO2) 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.

  6. Amorphous grain boundary layers in the ferromagnetic nanograined ZnO films

    International Nuclear Information System (INIS)

    Pure ZnO thin films were obtained by the wet chemistry (“liquid ceramics”) method from the butanoate precursors. Films consist of dense equiaxial nanograins and reveal ferromagnetic behaviour. The structure of the ZnO films was studied by the high-resolution transmission electron microscopy. The intergranular regions in the nanograined ZnO films obtained by the “liquid ceramics” method are amorphous. It looks like fine areas of the second amorphous phase which wets (covers) some of the ZnO/ZnO grain boundaries. Most probably these amorphous intergranular regions contain the defects which are responsible for the ferromagnetic behaviour.

  7. ZnO thin films with (Li,Ni)-codoping

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Senthil; Rao, M.S. Ramachandra [Materials Science Research Centre, Indian Institute of Technology Madras, Chennai (India); Althammer, Matthias; Venkateshvaran, Deepak; Karrer-Mueller, Eva; Goennenwein, Sebastian T.B.; Opel, Matthias; Gross, Rudolf [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Garching (Germany)

    2011-07-01

    The wide bandgap II-VI semiconductor ZnO is controversially discussed with regard to both dilute magnetic doping and stable p-type conductivity. Following a recent report [APL 96, 232504 (2010)], we investigated (Li,Ni)-codoping to establish ferromagnetism together with p-type conduction. Using laser-MBE, we deposited thin films from stoichiometric targets with compositions Zn{sub 0.98-x}Li{sub x}Ni{sub 0.02}O (x=0, 0.02, 0.05, 0.09). High-resolution x-ray diffraction reveals excellent structural quality and nearly perfect in-plane orientation. Magnetization measurements show an ''S''-shaped behavior in M(H) at room temperature and a clear difference after field cooling or zero-field cooling in M(T) which is reminiscent of superparamagnetism. The saturation magnetic moment is around 0.7 {mu}{sub B} per Ni and, hence, very close to the bulk value of Ni metal (0.6 {mu}{sub B}). From thermopower measurements, we obtained negative Seebeck coefficients between -400 {mu} V/K and -900 {mu} V/K, with smaller absolute values corresponding to lower Li concentrations. In summary, we could not confirm p-type conductivity or ferromagnetism in (Li,Ni)-substituted ZnO thin films.

  8. Effect of energetic electron beam treatment on transparent conductive ZnO thin films

    International Nuclear Information System (INIS)

    Undoped and Al-doped ZnO thin films were prepared by a sol–gel spin coating method. The films were exposed to the electron beam at different energies to improve their electrical properties by modifying their film crystallinity. For both the undoped and Al-doped ZnO thin films, the carrier concentration significantly increased and the resistivity decreased after the introduction of the energetic electron beam. Since band gap widening of the undoped and Al-doped ZnO thin films was also observed with exposure to the electron beam, the behaviors and tendencies can be explained by the Burstein–Moss effect. The effects of the electron beam on ZnO thin film properties, including band gap widening, increasing carrier concentration, and significantly decreased resistivity, were similar to the effects of Al doping in ZnO. Finally, by combining electron beam treatment and Al doping of ZnO thin films prepared by a sol–gel method, the resistivity of the sol–gel synthesized ZnO thin film decreased from 5.8 × 102 Ω cm to 8.2 × 10−2 Ω cm. According to the Monte Carlo simulation of electron penetration in the ZnO thin film, the penetration depth increased with electron beam energy, which induced lattice heating and atomic rearrangement by electronic excitation in a collision cascade. - Highlights: • Electron beam treatment on ZnO thin films by sol–gel spin coating synthesis • Improvement of crystallinity and increase in the optical band gap energy • Decrease in the resistivity with the increase in the carrier concentration • Increase in the electron penetration depth with beam energy

  9. Nanocrystalline ZnO thin film for photocatalytic purification of water

    International Nuclear Information System (INIS)

    ZnO thin film was prepared via evaporation of Zn metal on a glass sheet following by calcination (oxidation) process. The influences of calcination parameters such as temperature and time on the surface morphology and phase structure of ZnO films were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The analysis of XRD patterns indicated that the growth of ZnO nano-structure was controlled by calcination time and temperature. Optimum ZnO nano-fibers can be formed uniformly after 2 h of oxidation at 550 deg. C. Nanostructured ZnO catalyst exhibited a significantly greater superiority for the photodegradation of 2,4,6-Trichlorophenol (TCP) as a model pollutant in water over photolysis via irradiation with UV of 254 nm wavelength. The role of ZnO catalyst is discussed and the chemical composition of degradation products and intermediates are identified.

  10. Surface phonon polariton characteristics of wurtzite ZnO thin film grown on silicon substrate

    Energy Technology Data Exchange (ETDEWEB)

    Ng, Sha Shiong; Ooi, Poh Kok; Lee, Sai Cheong; Abdullah, Mat Johar; Hassan, Zainuriah; Hassan, Haslan Abu [Nano-Optoelectronics Research and Technology Laboratory, School of Physics, Universiti Sains Malaysia, 11800 Penang (Malaysia)

    2012-05-15

    In this work, p-polarized far infrared attenuated total reflection (ATR) with Otto configuration technique is employed to study the surface phonon polariton (SPP) characteristics of wurtzite ZnO thin film grown on Si(111) substrate. One prominent dip corresponding to the leaky SPP mode of the ZnO is detected at 532 cm{sup -1}. The obtained result is in good agreement with the calculated ATR spectrum simulated based on the transfer matrix formulation. The origin of the observed dip is verified with the surface polariton dispersion curves based on a three anisotropic layer model (air-ZnO-Si). The results also reveal that the real SPP and the interface phonon polariton modes for this studied structure are barely observable experimentally. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Piezoelectric film electro-deposition for optical fiber sensor with ZnO coating

    Institute of Scientific and Technical Information of China (English)

    Li Zhou; Ping Gu; Ya Zhou

    2008-01-01

    The piezoelectric film electro-deposition for optical fiber sensor with ZnO coating is studied. The zinc oxide plating film is made on the copper surface directly by cathodic electro-deposition in the Zn(NO3)2 single salt aqueous solution systems. The influences of main experimental conditions on the properties of ZnO thin film in the electro-deposition processes are analyzed and a stable, practical and economic technique is obtained.

  12. Photocatalytic activity of ZnO films with micro-grid structure

    Institute of Scientific and Technical Information of China (English)

    Chunzhi LI; Wenwen WANG; Junying ZHANG; Hailing ZHU; Weiwei ZHANG; Tianmin WANG

    2009-01-01

    A layer of zinc oxide (ZnO) micro-grid was deposited on the surface of ZnO film using the DC reactive magnetron sputtering method and the micro-sphere lithography technique on glass substrates. Samples of this layer were characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM), atomic force micro-scopy (AFM), and ultraviolet-visible light spectroscopy.X-ray diffraction showed the high crystallinity of ZnO film and the regular arrangement of the micro-grid. The micro-grid ZnO has a lower specular reflection and a higher diffuse reflection, allowing incident light to reflect two or three times to enhance the usage of light. Photocatalytic degradation experiments on methylene blue using both ZnO micro-grid and ordinary film showed that the ZnO micro-grid has better photocatalytic properties than ordinary film. The ZnO micro-grid enhanced the photo-catalytic efficiency of ZnO film by 28% with a degradation time of 300 min.

  13. Thermal stability of conductive and transparent V-doped ZnO thin films

    International Nuclear Information System (INIS)

    The thermal stability of electrical, optical and structural properties of vanadium-doped zinc oxide (VZO) thin films has been investigated after heat treatments up to 550 °C in N2 and O2 atmospheres. ZnO and VZO films were prepared by RF magnetron sputtering on quartz substrates at 200 °C. It was found that the resistivity of VZO films remains low at about 5 × 10−4 Ω cm when heat treated at temperature up to 450 °C in both N2 and O2 atmospheres, while resistivity of the ZnO film increased remarkably due to the compensation of oxygen vacancies in O2 heat treatments over 400 °C. Optical transmittance of the as-grown VZO film in the visible range (400–1100 nm) was 20–30% and improved up to about 80% when heat treated at temperature up to 500 °C in N2 and O2 atmospheres. Decreased c-axis lattice constant in the VZO film was larger in N2 heat treatments than in O2 heat treatments. Based on these experimental results, we made the hypothesis that V-O bonds similar to vanadium trioxide in the as-grown VZO film changed to those similar to vanadium pentoxide after heat treatments over 500 °C. - Highlight: • Vanadium-doped zinc oxide (VZO) deposited on quartz by RF magnetron sputtering • VZO films were heat-treated up to 550 °C in N2 and O2 atmospheres. • Resistivity of the VZO films remains low at 450 °C in both N2 and O2 atmospheres. • Heat treatment over 500 °C results in change of dominant charge number of V in VZO

  14. Fabrication and characterization of ZnO nanowires by wet oxidation of Zn thin film deposited on Teflon substrate

    Science.gov (United States)

    Farhat, O. F.; Halim, M. M.; Abdullah, M. J.; Ali, M. K. M.; Ahmed, Naser M.; Bououdina, M.

    2015-10-01

    In this study, ZnO nanowires (NWs) were successfully grown for the first time on to Teflon substrate by a wet oxidation of a Zn thin film coated by RF sputtering technique. The sputtered Zn thin film was oxidized at 100 °C for 5 h under water-vapour using a horizontal furnace. This oxidation process transformed Zn thin film into ZnO with wire-like nanostructure. XRD analysis confirms the formation of single nanocrystalline ZnO phase having a low compressive strain. FESEM observations reveal high density of ZnO NWs with diameter ranging from 34 to 52 nm and length about 2.231 μm, which are well distributed in different direction. A flexible ZnO NWs-based metal-semiconductor-metal UV photodetector was fabricated. Photo-response and sensitivity measurements under low power illumination (375 nm, 1.5 mW/cm2) showed a high sensitivity of 2050%, which can be considered a relatively fast response and baseline recovery for UV detection.

  15. Effect of annealing in hydrogen atmosphere on ZnO films for field emission display

    Science.gov (United States)

    Zulkifli, Zurita; Sharma, Subash; Shinde, Sachin; Kalita, Golap; Tanemura, M.

    2015-11-01

    Surface morphology, crystallinity, conductivity and optical transmittance of ZnO films can be modified by annealing process. Hydrogen is one of the popular annealing gases as well as nitrogen, argon, oxygen and air which are commonly used for thin film cleaning or the removal of native oxide. In general, annealing is done at high temperatures (> 600degC) to improve the film properties. From a view point of environment, however, lower annealing temperature is preferable. In this work, low annealing process was challenged to understand the effect of annealing temperature on properties of ZnO thin films and nanostructured film grown on glass substrates for transparent field emission device applications. The annealing temperature employed was 100, 200 and 450°C at 100 sccm hydrogen flow rate. ZnO thin films were deposited by RF magnetron sputtering. The ZnO thin films were characterized by X-ray diffraction analysis (XRD), Atomic Force Microscopy (AFM), UV-VIS and Raman spectroscopy. The sheet resistances reduced about 15 kohm/sq at low annealing temperature. By contrast, the optical transmittance did not show any significant changes after annealing. The FE current density increased after the ZnO nanostructures film was annealed in 100°C. The results obtained could motivate a surface treatment for flexible ZnO thin film since the substrate is always suffered by heat.

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

    OpenAIRE

    Gurpreet Kaur; Anirban Mitra; K.L. Yadav

    2015-01-01

    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...

  17. PIXE, SR-XRD and EXAFS analysis of Cu-doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, B., E-mail: binzhang@fudan.edu.cn; Yang, C.; Wang, J.Z.; Shi, L.Q., E-mail: lqshi@fudan.edu.cn; Cheng, H.S.

    2014-08-01

    Cu-doped ZnO films were prepared by rf magnetron sputtering on sapphire substrate at different atmosphere. Microstructure of these films and Cu occupation sites were investigated using PIXE, SR-XRD and EXAFS. Only 2.9 at.% Cu, no other magnetic impurities (e.g., Fe, Co and Ni) were detected. The ZnO:Cu films possessed the wurtzite ZnO structures and no precipitates (e.g., CuO and Cu{sub 2}O or Cu cluster) were found. Cu atoms were incorporated into ZnO crystal lattice by occupying Zn atomic sites.

  18. Electrical properties of ZnO thin films grown by MOCVD

    International Nuclear Information System (INIS)

    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

  19. Optical and structural properties of Sr-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Linhua, E-mail: congyu3256@tom.com [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Optics and Photonic Technology Laboratory, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Xiao, Shaorong; Zhang, Chengyi; Zheng, Gaige; Su, Jing; Zhao, Lilong; Wang, Junfeng [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Optics and Photonic Technology Laboratory, Nanjing University of Information Science and Technology, Nanjing 210044 (China)

    2014-12-15

    ZnO thin film is a widely studied optoelectronic material at present. Doping is an important method to adjust its structural, optical, electrical and magnetic properties. A lot of doped ZnO thin films especially those doped with Al, Ga, Co have been extensively investigated. However, the Sr-doped ZnO thin films are still few reported up to now. In this work, the Sr-doped ZnO thin films have been deposited by sol–gel method. Their structural and optical properties have been analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–visible spectrophotometry and photoluminescence (PL), respectively. The results show that the appropriate Sr-doping levels can improve the crystalline quality and ultraviolet emission performance of ZnO thin films and suppress their visible emissions. This probably results from the decrease of point defects such as oxygen vacancy etc. due to the Sr-doping. What is more, it is also found that there exists a saturation value of Sr-doping concentration in ZnO thin films deposited using our prepared sol system, which is because the dopant Strontium chloride is slightly soluble in ethanol. - Graphical abstract: The figure shows the XRD patterns of the Sr-doped ZnO thin films with different doping levels. All the diffraction peaks correspond to the diffraction from wurtzite ZnO planes and no secondary phases are detected from the XRD patterns. Compared with the pure ZnO thin film, the intensity of the (002) peak located at ∼34.4° is enhanced and the FWHM is decreased when the Sr-doped level is below 7%. This means Sr-doping improves the crystalline quality of ZnO thin films to some extent. - Highlights: • Sr-doped ZnO thin films have been prepared by sol–gel method and deeply studied. • The crystalline quality of ZnO thin film is improved to some extent by Sr-doping. • All the films exhibit high transmittance in the visible range. • With an appropriate Sr-doping level, the visible emissions are suppressed and

  20. Improved electron emission characteristics of ZnO nano-gap with Pd films

    International Nuclear Information System (INIS)

    The properties of the surface-conduction electron-emitter display (SED) are mainly decided by the surface-conduction electron emitters (SCEs). Pd is mostly used to fabricate the surface-conduction electron emitters, which are normally obtained by generating a nano-scale gap from PdO conductive film. ZnO is a potential material for electron emission and the research work has proved that ZnO film can act as the electron-emitter material. In this study, we propose to use the ZnO-Pd two-layer film as the conductive film. Both the multi-layer device electrode film and conductive film were deposited by a magnetron sputter, and SCEs are formed by the electro-forming process as used in SED. The results revealed that the Pd film on ZnO film surface increases the electron emission efficiency from 0.36 per mille to 3.85 per mille.

  1. ZnO film for application in surface acoustic wave device

    International Nuclear Information System (INIS)

    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 SiO2layer, in name of reflection signal amplitude and phase velocity of Rayleigh wave

  2. SR-XRD and EXAFS study on microstructure of Mn doped ZnO films

    International Nuclear Information System (INIS)

    Mn-doped ZnO films were prepared by radio frequency magnetron sputtering on sapphire substrate at different temperatures. They contained Mn of 5 at.%, without any magnetic impurities of Fe, Co and Ni, as were revealed by proton induced X-ray emission (PIXE). Synchrotron radiation X-ray diffraction (SR-XRD) showed that the ZnO: Mn films possessed the wurtzite ZnO structure. No precipitates such as Mn cluster or MnO, MnO2, Mn2O3, and Mn3O4 were observed by SR-XRD and fluorescence extended X-ray absorption fine structure spectra (EXAFS) in ZnO: Mn films. EXAFS analysis also showed that Mn atoms were incorporated into ZnO crystal lattice by occupying the sites of zinc atoms. (authors)

  3. Electrical and optical properties of ZnO films grown by molecular beam epitaxy

    International Nuclear Information System (INIS)

    Zinc oxide (ZnO) films have been grown on sapphire by molecular beam epitaxy (MBE), and it is found that the grain size of the ZnO films increased with increasing the growth temperature. Photoluminescence (PL) study shows that the intensity ratio of near-band-edge emission to deep-level-related emission (NBE/DL) of the ZnO is significantly enhanced with increasing the growth temperature, and the dependence of the carrier mobility on the growth temperature shows very similar trend, which implies that there is a community factor that determines the optical and electrical properties of ZnO, and this factor is suggested to be the grain boundary. The results obtained in this paper reveal that by reducing the grain boundaries, ZnO films with high optical and electrical properties may be acquired.

  4. Microwave annealing effects on ZnO films deposited by atomic layer deposition

    Institute of Scientific and Technical Information of China (English)

    Zhao Shirui; Dong Yabin; Yu Mingyan; Guo Xiaolong; Xu Xinwei; Jing Yupeng; Xia Yang

    2014-01-01

    Zinc oxide thin films deposited on glass substrate at 150 ℃ by atomic layer deposition were annealed by the microwave method at temperatures below 500 ℃.The microwave annealing effects on the structural and luminescent properties of ZnO films have been investigated by X-ray diffraction and photoluminescence.The results show that the MWA process can increase the crystal quality of ZnO thin films with a lower annealing temperature than RTA and relatively decrease the green luminescence of ZnO films.The observed changes have demonstrated that MWA is a viable technique for improving the crystalline quality of ZnO thin film on glass.

  5. 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}.

  6. Growth of phosphorus doped ZnO thin films by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Vaithianathan, Veeramuthu; Lee, Byung-Teak; Kim, Sang Sub [Photonic and Electronic Thin Film Laboratory, Department of Materials Science and Engineering Chonnam National University, 300 Yongbong-dong, Gwangju 500-757 (Korea)

    2004-09-01

    Undoped and phosphorus doped (1 and 3 mol%) ZnO (P-doped ZnO) films were grown on sapphire substrates by a pulsed laser deposition technique and then the phosphorus doping effect was investigated. Results of X-ray diffraction and scanning electron microscopy revealed that the phosphorus doping did not noticeably affect the microstructure and crystallinity of the undoped ZnO film. In the as-grown state, both of the P-doped ZnO films showed n-type conductivity rather with slightly more electron concentrations than that of the undoped ZnO film. For the 3 mol% P-doped ZnO film a significant decrease in the carrier concentration was observed at particular annealing temperatures ({>=}800 C), still showing n-type conductivity. In contrast, in the case of 1 mol% P-doping, the variation in the carrier concentration was not significant under any annealing temperature. Our results suggest that a careful adjustment both of annealing temperature and of phosphorus doping content is required to control the electrical properties including the carrier concentration, resistivity and mobility in ZnO films. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Morphological, physical, antimicrobial and release properties of ZnO nanoparticles-loaded bacterial cellulose films.

    Science.gov (United States)

    Shahmohammadi Jebel, Fereshteh; Almasi, Hadi

    2016-09-20

    Bacterial cellulose (BC) monolayer and multilayer films, incorporating 5wt.% ZnO nanoparticles (NPs) have been obtained. Ultrasound (US) irradiation (40kHz) was applied during ZnO-BC nanocomposites preparation. X-ray diffraction (XRD) patterns showed that ZnO NPs were crystallized in their pure phase. SEM scanning electron microscopy (SEM) results indicated that US treatment causes to decrease ZnO particle size, forming a stable hybrid nanostructure and evenly distributed ZnO NPs coated BC nanofibers. ZnO NPs enhanced the mechanical properties and diminished water vapor permeability and moisture absorption of BC films. Antibacterial activity of ZnO-BC films against Staphylococcus aureus was more than Escherichia coli. The antibacterial activity was enhanced with the utilization of US irradiation. The ZnO release was influenced by films composition; the multilayer and US treated films being promising in order to achieve controlled release of ZnO. Results suggest that ZnO-BC films may be used as controlled release antimicrobial food active packaging. PMID:27261725

  8. Assembly of ordered ZnO porous thin films by cooperative assembly method using polystyrene spheres and ultrafine ZnO particles

    International Nuclear Information System (INIS)

    Ordered ZnO porous thin films were fabricated by cooperative assembly method using polystyrene sphere (PS) and ultrafine ZnO particles, in which ultrafine ZnO particles were directly assembled in the voids of PS while the template was being assembled by capillary forces. The influence of experimental parameters, such as evaporation temperature, ZnO concentration and the concentration ratio of PS/ZnO on morphology of the porous structure was mainly studied. The results showed that an ordered porous structure could be obtained by this method. X-ray diffraction (XRD) spectra indicated the porous ZnO thin film was wurtzite structure. The transmissivity decreased with the decrease of wavelength, but still kept above 80% beyond the wavelength of 550 nm. Optical band gap of the ZnO thin film was 3.13 eV

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

    International Nuclear Information System (INIS)

    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

  10. Influence of optical properties of ZnO thin-films deposited by spray pyrolysis and RF magnetron sputtering on the output performance of silicon solar cell

    International Nuclear Information System (INIS)

    ZnO thin-films were deposited by spray pyrolysis and RF magnetron sputtering techniques. The optical reflection of these thin-films is measured using UV-Vis spectrophotometer. The measured optical reflection data is used in PC-1D simulation software to study the output performance of commercial silicon wafer-based solar cell. As far as optical performance is concerned it could be demonstrated that the sprayed ZnO thin-film under laboratory conditions show equivalent performance compared to sputtered ZnO thin-film. The influence of optical properties of 65 nm thick zinc oxide thin-films deposited by vacuum and non-vacuum techniques on quantum efficiency and IV characteristics of commercial silicon-wafer based solar cell is studied and reported here.

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

    International Nuclear Information System (INIS)

    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.

  12. Nanoporous characteristics of sol-gel-derived ZnO thin film

    Institute of Scientific and Technical Information of China (English)

    Anees A. Ansari; M. A. M. Khan; M. Alhoshan; S. A. Alrokayan; M. S. Alsalhi

    2012-01-01

    Sol-gel-derived nanoporous ZnO film has been successfully deposited on glass substrate at 200 ℃ and subsequently annealed at different temperatures of 300,400 and 600 ℃.Atomic force micrographs demonstrated that the film was crack-free,and that granular nanoparticles were homogenously distributed on the film surface.The average grain size of the nanoparticles and RMS roughness of the scanned surface area was 10 nm and 13.6nm,respectively,which is due to the high porosity of the film.Photoluminescence (PL) spectra of the nanoporous ZnO film at room temperature show a diffused band,which might be due to an increased amount of oxygen vacancies on the lattice surface.The observed results of the nanoporous ZnO film indicates a promising applicationin the development of electrochemical biosensors due to the porosity of film enhancing the higher loading of biomacromolecules (enzyme and proteins).

  13. Simple way for preparation of ZnO films by surfactant mediated spray pyrolysis

    International Nuclear Information System (INIS)

    Highlights: ► ZnO was prepared by surfactant mediated spray pyrolysis. ► The film surface morphology can be enhanced by PVA addition. ► The PVA improves significant the photocatalytic activity of ZnO. ► The zinc acetate precursor is preferred for film preparation than nitrate one. - Abstract: Nanocrystalline porous ZnO films are deposited onto alumina foil substrates by polyvinyl alcohol (PVA) modified spray pyrolysis. Water and ethanol–water mixture were used for preparation of the sols. The effect of polyvinyl alcohol on the morphological and photocatalytical properties of ZnO films was studied. It was found that the polyvinyl alcohol plays important role in formation of porous films structure with ganglia like morphology. Relatively compact granular morphology was observed for the ZnO samples, grown without organic surfactant. The X-ray diffraction patterns revealed the formation of phase-pure ZnO thin films. The FTIR spectra and DTA-TG analyses of the precursor mixtures: Zn(CH3COOH)2·2H2O and Zn(NO3)2·6H20 with PVA revealed that ZnO is formed before the final decomposition of the polymer at 350 °C. It was observed that both: the acetate precursor and the organic surfactant could enhance significantly the photocatalytic properties of the ZnO films. The films obtained from sols, containing PVA showed better photocatalytic decolorization of Malachite Green dye, than the films, deposited from unmodified sols.

  14. Synthesis, structural and optical characterization of undoped, N-doped ZnO and co-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Pathak, Trilok Kumar, E-mail: tpathak01@gmail.com; Kumar, R.; Purohit, L. P., E-mail: proflppurohitphys@gmail.com [Semiconductor Research Lab., Department of Physics, Gurukula Kangri University, Haridwar (India)

    2015-05-15

    ZnO, N-doped ZnO and Al-N co-doped ZnO thin films were deposited on ITO coated corning glass by spin coater using sol-gel method. The films were annealed in air at 450°C for one hour. The crystallographic structure and morphology of the films were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM) respectively. The X-ray diffraction results confirm that the thin films are of wurtzite hexagonal with a very small distortion. The optical properties were investigated by transmission spectra of different films using spectrophotometer (Shimadzu UV-VIS-NIR 3600). The results indicate that the N doped ZnO thin films have obviously enhanced transmittance in visible region. Moreover, the thickness of the films has strong influences on the optical constants.

  15. Investigation of sol-gel yttrium doped ZnO thin films: structural and optical properties

    Science.gov (United States)

    Ivanova, T.; Harizanova, A.; Koutzarova, T.; Vertruyen, B.

    2016-02-01

    Nanostructured metal oxide films are extensively studied due to their numerous applications such as optoelectronic devices, sensors. In this work, we report the Y-Zn-O nanostructured films prepared by sol-gel technology from sols with different concentration of yttrium precursor, followed by post-annealing treatment. The Y doped ZnO thin films have been deposited on Si and quartz substrates by spin coating method, then treated at temperatures ranging from 300-800oC. XRD analysis reveals modification of the film structure and phases in the doped ZnO films.

  16. 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.

  17. 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.

  18. Low pressure chemical vapour deposition of ZnO layers for thin-film solar cells. Temperature-induced morphological changes

    Energy Technology Data Exchange (ETDEWEB)

    Fay, S.; Kroll, U.; Bucher, C.; Vallat-Sauvain, E.; Shah, A. [Institut de Microtechnique IMT, Thin-film Silicon and Photovoltaics Laboratory, Rue A.-L. Breguet 2, 2000 Neuchatel (Switzerland)

    2005-03-31

    Zinc oxide (ZnO) is now often used as a transparent conductive oxide for contacts in thin-film silicon solar cells. This paper presents a study of ZnO material deposited by the low-pressure chemical vapour deposition technique, in a pressure range below the pressures usually applied for the deposition of this kind of material. A temperature series has been deposited, showing a morphological transition around 150{sup o}C. ZnO samples deposited with temperatures just higher than this transition are constituted of large grains highly oriented along a single crystallographic orientation. These 'monocrystals' lead to low resistivity values, showing a clear correlation between the size of the surface grains and the electrical performance of corresponding films. Additionally, these large grains also yield ZnO layers with high transparency and high light-scattering power, specially suitable for solar cell technology based on thin-film silicon.

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

    International Nuclear Information System (INIS)

    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.

  20. Structural, electronic and magnetic properties of Er implanted ZnO thin films

    International Nuclear Information System (INIS)

    We report the structural, electronic and magnetic properties of Er implanted and annealed ZnO thin films. The effect of annealing in oxygen-deficient and oxygen-rich conditions was investigated. Rutherford backscattering spectrometry results revealed that the Er atoms are located at the implantation depth of around 13 nm, and annealing conditions had no adverse effect on the Er concentration in the layer. Raman spectroscopy results showed peak related to E2(high) mode of ZnO indicating enhanced crystalline quality of the Er implanted and annealed ZnO films. X-ray absorption near edge spectroscopy results demonstrated pre-edge features in O K-edge which are attributed to the structural defects in the films. Room temperature magnetic ordering was observed in Er implanted and annealed films, and is mainly assigned to the intrinsic defects in ZnO

  1. Structural, electronic and magnetic properties of Er implanted ZnO thin films

    Science.gov (United States)

    Murmu, P. P.; Kennedy, J.; Ruck, B. J.; Leveneur, J.

    2015-09-01

    We report the structural, electronic and magnetic properties of Er implanted and annealed ZnO thin films. The effect of annealing in oxygen-deficient and oxygen-rich conditions was investigated. Rutherford backscattering spectrometry results revealed that the Er atoms are located at the implantation depth of around 13 nm, and annealing conditions had no adverse effect on the Er concentration in the layer. Raman spectroscopy results showed peak related to E2(high) mode of ZnO indicating enhanced crystalline quality of the Er implanted and annealed ZnO films. X-ray absorption near edge spectroscopy results demonstrated pre-edge features in O K-edge which are attributed to the structural defects in the films. Room temperature magnetic ordering was observed in Er implanted and annealed films, and is mainly assigned to the intrinsic defects in ZnO.

  2. Structural, electronic and magnetic properties of Er implanted ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Murmu, P.P. [National Isotope Centre, GNS Science, PO Box 31312, Lower Hutt 5010 (New Zealand); The MacDiarmid Institute for Advanced Materials and Nanotechnology, PO Box 600, Wellington 6140 (New Zealand); Kennedy, J., E-mail: J.Kennedy@gns.cri.nz [National Isotope Centre, GNS Science, PO Box 31312, Lower Hutt 5010 (New Zealand); The MacDiarmid Institute for Advanced Materials and Nanotechnology, PO Box 600, Wellington 6140 (New Zealand); Ruck, B.J. [The MacDiarmid Institute for Advanced Materials and Nanotechnology, PO Box 600, Wellington 6140 (New Zealand); Leveneur, J. [National Isotope Centre, GNS Science, PO Box 31312, Lower Hutt 5010 (New Zealand)

    2015-09-15

    We report the structural, electronic and magnetic properties of Er implanted and annealed ZnO thin films. The effect of annealing in oxygen-deficient and oxygen-rich conditions was investigated. Rutherford backscattering spectrometry results revealed that the Er atoms are located at the implantation depth of around 13 nm, and annealing conditions had no adverse effect on the Er concentration in the layer. Raman spectroscopy results showed peak related to E{sub 2}(high) mode of ZnO indicating enhanced crystalline quality of the Er implanted and annealed ZnO films. X-ray absorption near edge spectroscopy results demonstrated pre-edge features in O K-edge which are attributed to the structural defects in the films. Room temperature magnetic ordering was observed in Er implanted and annealed films, and is mainly assigned to the intrinsic defects in ZnO.

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

    International Nuclear Information System (INIS)

    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 JSC = 10.62 mA/cm2, open-circuit voltage VOC = 0.93 V and fill factor = 64%).

  4. Effects of Homo-buffer Layer on Properties of Sputter-deposited ZnO Films

    Institute of Scientific and Technical Information of China (English)

    Jian Huang; Linjun Wang; Run Xu; Weimin Shi; Yiben Xia

    2009-01-01

    Two-step growth regimes were applied to realize a homoepitaxial growth of ZnO films on freestanding diamond substrates by radio-frequency (RF) reactive magnetron sputtering method. ZnO buffer layers were deposited on freestanding diamond substrates at a low sputtering power of 50 W, and then ZnO main layers were prepared on this buffer layer at a high sputtering power of 150 W. For comparison, a sample was also deposited directly on freestanding diamond substrate at a power of 150 W. The effects of ZnO buffer layers on the structural, optical, electrical and morphological properties of the ZnO main layer were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, semiconductor characterization system and atomic force microscopy (AFM) respectively. The experimental results suggested that homo-buffer layer was helpful to improve the crystalline quality of ZnO/diamond heteroepitaxial films.

  5. 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...

  6. Preparation of ZnO Thin Films on Free-Standing Diamond Substrates

    International Nuclear Information System (INIS)

    Highly c-axis-oriented ZnO films were deposited successfully on the nucleation sides of free-standing diamond (FD) films by the direct current (DC) magnetron sputtering method. The effect of the sputtering parameters, such as power, gas pressure and sputtering plasma composition of Ar-to-O2, on the properties of ZnO thin films was investigated in detail. X-ray diffraction (XRD) measurements showed that, at a sputtering power of 200 W, gas pressure of 0.5 Pa and an Ar-to-O2 composition of 1:1, a higher intensity of the (002) diffraction peak and a narrower full width at half maximum (FWHM) were detected which meant high c-axis orientation and high quality of the ZnO films. To improve the quality of the ZnO film, a thin ZnO layer was pre-grown as a homo-buffer layer. XRD measurements showed that this buffer layer had a beneficial effect on the structural and morphological properties of the post-grown ZnO film. (low temperature plasma)

  7. Optical properties of Ti-doped ZnO films synthesized via magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Chen Haixia, E-mail: chxia8154@163.com [School of Science, Xi' an Shiyou University, Xi' an, Shaanxi 710065 (China); Ding Jijun [Electronic Materials Research Laboratory, Key Laboratory of Ministry of Education, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China); Shi Feng [Department of Renewable Energy Engineering, Oregon Institute of Technology, Klamath Falls, OR 97601 (United States); Li Yingfeng [Department of Electrical and Computer Engineering, Texas A and M University, College Station, TX 77843 (United States); Guo Wenge [School of Science, Xi' an Shiyou University, Xi' an, Shaanxi 710065 (China)

    2012-09-05

    Highlights: Black-Right-Pointing-Pointer Via magnetron sputtering technique, Ti-doped ZnO films were prepared. Black-Right-Pointing-Pointer Optical properties in Ti-doped ZnO films were systematically investigated. Black-Right-Pointing-Pointer A metallic conduction behavior was observed at higher sputtering power. Black-Right-Pointing-Pointer The shift mechanism of blue emission is discussed in detail. - Abstract: Undoped and Ti-doped ZnO films were deposited using magnetron sputtering at various sputtering power. The crystal structures, surface morphology and optical properties in ZnO films were systematically investigated via X-ray diffraction (XRD), atomic force microscopy (AFM), Jasco V-570 UV/VIS/NIR and ultraviolet visible (UV-Vis) spectrophotometer. The results indicated that Ti-doped ZnO polycrystalline films with a hexagonal wurzite structure formed. Ti-doped ZnO films show more uniform and denser columnar structures with the increase of sputtering power, and a metallic conduction behavior was observed when sputtering powers is increased to 150 and 200 W. One main blue emission peak located at 445 nm was observed. However, blue emission centered at 445 nm continually blue shifted to 438 nm as sputtering power further increased. The shift mechanism of blue emission at different deposited conditions is discussed in detail.

  8. Optical properties of Ti-doped ZnO films synthesized via magnetron sputtering

    International Nuclear Information System (INIS)

    Highlights: ► Via magnetron sputtering technique, Ti-doped ZnO films were prepared. ► Optical properties in Ti-doped ZnO films were systematically investigated. ► A metallic conduction behavior was observed at higher sputtering power. ► The shift mechanism of blue emission is discussed in detail. - Abstract: Undoped and Ti-doped ZnO films were deposited using magnetron sputtering at various sputtering power. The crystal structures, surface morphology and optical properties in ZnO films were systematically investigated via X-ray diffraction (XRD), atomic force microscopy (AFM), Jasco V-570 UV/VIS/NIR and ultraviolet visible (UV–Vis) spectrophotometer. The results indicated that Ti-doped ZnO polycrystalline films with a hexagonal wurzite structure formed. Ti-doped ZnO films show more uniform and denser columnar structures with the increase of sputtering power, and a metallic conduction behavior was observed when sputtering powers is increased to 150 and 200 W. One main blue emission peak located at 445 nm was observed. However, blue emission centered at 445 nm continually blue shifted to 438 nm as sputtering power further increased. The shift mechanism of blue emission at different deposited conditions is discussed in detail.

  9. Study on Ni-doped ZnO films as gas sensors

    Energy Technology Data Exchange (ETDEWEB)

    Rambu, A.P., E-mail: alicia.rambu@uaic.ro [Alexandru Ioan Cuza University of Iasi, Faculty of Physics, 11 Carol I Blvd., 700506 Iasi (Romania); Ursu, L. [Petru Poni Institute of Macromolecular Chemistry, Grigore Ghica Vodă, 41 A, 700487 Iasi (Romania); Iftimie, N. [National Institute of Research and Development for Technical Physics, 47 Mangeron Blvd., 700050 Iasi (Romania); Nica, V.; Dobromir, M.; Iacomi, F. [Alexandru Ioan Cuza University of Iasi, Faculty of Physics, 11 Carol I Blvd., 700506 Iasi (Romania)

    2013-09-01

    Ni doped ZnO films were obtained by spin coating, using zinc acetate and nickel acetate as starting materials and N,N-dimethylformamide as solvent. The X-ray diffraction (XRD) analysis indicates that, spin coated films posses a polycrystalline structure. Ni doped ZnO films are single phase and no trace of nickel metal or binary zinc nickel phases are observed. The values of some structural parameters (crystallite size, surface roughness) are varying with the variation of Ni concentration. The sensitivity of Ni:ZnO films, at three different gasses (ammonia, liquefied petroleum gas and ethanol) was investigated. Obtained results indicate that our films are most sensitive to ammonia, the operating temperature was found to be 190 °C and the response time is 35 s. The gas sensitivity was found to depend on the Ni concentration in ZnO films.

  10. ZnO thin film synthesis by reactive radio frequency magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Şenay, Volkan, E-mail: vsenay@bayburt.edu.tr [Bayburt University, Primary Science Education Department, Bayburt, 69000 (Turkey); Pat, Suat; Korkmaz, Şadan; Aydoğmuş, Tuna; Elmas, Saliha; Özen, Soner; Ekem, Naci [Eskisehir Osmangazi University, Physics Department, Eskisehir, 26480 (Turkey); Balbağ, M. Zafer [Eskisehir Osmangazi University, Education Faculty, Eskisehir, 26480 (Turkey)

    2014-11-01

    Highlights: • Band gaps of the layer are affected by the film thickness. • Nano structured ZnO deposited. • Spectral dependence of reflectance of deposited ZnO thin films. - Abstract: In this study, ZnO thin films were deposited on glass substrates by reactive RF magnetron sputtering method at argon–oxygen gas mixing (1:1) atmosphere. Some properties of the synthesized films were investigated by interferometry, UV–vis spectrophotometer, atomic force microscopy, and tensiometer. Tauc method was adopted to estimate the optical band gaps. The band gaps of the deposited films were affected by film thickness. We concluded that the surface composition plays a substantial role in the values of the band gaps. Nanocrystalline structures were detected in all produced samples.

  11. Modification of Photoluminescence Properties of ZnO Island Films by Localized Surface Plasmons

    Science.gov (United States)

    Zhang, Yang; Li, Xue-Hong; Peng, Cheng-Xiao

    2012-10-01

    The modification of localised surface plasmons of photoluminescence properties of ZnO is studied. It is found that the ultraviolet emission is drastically enhanced, and the visible emission related to the defects is almost completely suppressed, after an Au layer of nanoparticles is deposited on the surface of ZnO island films. This pronounced change in PL spectra is attributed to the efficient electron transfer via the coupling of localised surface plasmons at the interface between the Au nanoparticle layer and ZnO films.

  12. Electrodeposited ZnO thin film as an efficient alternative blocking layer for TiCl4 pre-treatment in TiO2-based dye sensitized solar cells

    Science.gov (United States)

    Kouhestanian, E.; Mozaffari, S. A.; Ranjbar, M.; SalarAmoli, H.; Armanmehr, M. H.

    2016-08-01

    Recently, ZnO nanostructures have received considerable attention in fabrication of dye sensitized solar cell (DSSC) photoanodes due to their unique transport properties. In the present study, a chronoamperometric method was performed to fabricate the ZnO nanostructures as an appropriate alternative of TiCl4 pre-treatment to reduce the recombination reactions, while retaining the TiO2-based DSSC performance. The effect of polyvinyl alcohol (PVA) on ZnO electrodeposition to control the growth and crystallization of ZnO nanostructures was investigated. ZnO/TiO2 based-DSSCs were fabricated using N719 ruthenium dye and all photovoltaic parameters were characterized. Incident photon to current efficiency (IPCE), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and VOC decay techniques were employed for studying the cell properties which is resulted in a significant enhancement in cell performance.

  13. Influence of preparation methods on photoluminescence properties of ZnO films on quartz glass

    Institute of Scientific and Technical Information of China (English)

    ZHAO Lei; LIAN Jian-she; LIU Yu-hua; JIANG Qing

    2008-01-01

    The influence of preparation methods on the photoluminescence properties of ZnO film was studied. Two methods were applied to fabricate ZnO films in a conventional pulsed laser deposition apparatus. One is high temperature (500-700 ℃) oxidation of the metallic zinc film that is obtained by pulsed laser deposition. The other is pulse laser ablation of Zn target in oxygen atmosphere at low temperature (100-250 ℃). The photoluminescence property was detected by PL spectrum. The room temperature PL spectra of the ZnO films obtained by oxidation method show single violet luminescence emission centered at 424 nm (or 2.90 eV) without any accompanied deep-level emission and UV emission. The violet emission is attributed to interstitial zinc in the films. Nanostructure ZnO film with c-axis (002) orientation is obtained by pulsed laser deposition. The ZnO film deposited at 200 ℃ shows single strong ultraviolet emission. The excellent UV emission is attributed to the good crystalline quality of the film and low intrinsic defects at such low temperature.

  14. Second harmonic generation in ZnO thin films fabricated by metalorganic chemical vapor deposition

    Science.gov (United States)

    Liu, C. Y.; Zhang, B. P.; Binh, N. T.; Segawa, Y.

    2004-07-01

    Second harmonic generation (SHG) from ZnO thin films fabricated by metalorganic chemical vapor deposition (MOCVD) technique was carried out. By comparing the second harmonic signal generated in a series of ZnO films with different deposition temperatures, we conclude that a significant part of second harmonic signal is generated at the film deposited with appropriate temperature. The second-order susceptibility tensor χ(2)zzz=9.2 pm/V was deduced for a film deposited at 250 °C.

  15. Room temperature ferromagnetism of Ni, (Ni, Li), (Ni, N)-doped ZnO thin films

    Institute of Scientific and Technical Information of China (English)

    AU; ChakTong

    2010-01-01

    Ni-doped ZnO thin films (Ni concentration up to 10 mol%) were generated on Si (100) substrates by a sol-gel technique. The films showed wurtzite structure and no other phase was found. The chemical state of Ni was found to be bivalent by X-ray photoelectron spectroscopy. The results of magnetic measurements at room temperature indicated that the films were ferromagnetic, and magnetic moment decreased with rise of Ni concentration. The magnetization of Ni (10 mol%)-doped ZnO film annealed in nitrogen was lower than that annealed in argon, suggesting that the density of defects had an effect on ferromagnetism.

  16. Low switching voltage ZnO quantum dots doped polymer-dispersed liquid crystal film.

    Science.gov (United States)

    Hsu, Chuan-Chun; Chen, Yi-Xuan; Li, Hui-Wen; Hsu, Jy-Shan

    2016-04-01

    This paper investigates the effects of ZnO nanoparticles (NPs) on the switching voltages of polymer dispersed liquid crystal (PDLC) films. The threshold and driving electric fields of PDLC film doped with 2.44 wt% ZnO NPs were 0.13 and 0.31 V/μm, respectively, with a contrast ratio of 26. The results of field emission scanning electron microscopy show that the size of the droplets in doped PDLC films increases with the doping concentration. The development of ZnO-doped PDLC films with low driving voltages greatly broadens the applicability of these devices. PMID:27137000

  17. Ultraviolet Sensing by Al-doped ZnO Thin Films

    International Nuclear Information System (INIS)

    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)

  18. Fabrication of superhydrophobic surface of hierarchical ZnO thin films by using stearic acid

    Science.gov (United States)

    Wang, Yanfen; Li, Benxia; Xu, Chuyang

    2012-01-01

    Flower-like hierarchical ZnO microspheres were successfully synthesized by a simple, template-free, and low-temperature aqueous solution route. The morphology and microstructure of the ZnO microspheres were examined by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The bionic films with hydrophobicity were fabricated by the hierarchical ZnO microspheres modified by stearic acid. It was found that the hydrophobicity of the thin films was very sensitive to the added amount of stearic acid. The thin films modified with 8% stearic acid took on strong superhydrophobicity with a water contact angle (CA) almost to be 178° and weak adhersion. The remarkable superhydrophobicity could be attributed to the synergistic effect of micro/nano hierarchical structure of ZnO and low surface energy of stearic acid.

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

    International Nuclear Information System (INIS)

    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

  20. ZnO thin films fabricated by chemical bath deposition, used as buffer layer in organic solar cells

    International Nuclear Information System (INIS)

    ZnO thin films synthetized by chemical bath deposition are used as buffer layer between the anode and the organic electron donor in organic solar cells. Films deposited from zinc nitrate solutions are annealed in room air at 300 deg. C for half an hour. The X-ray diffraction and microanalysis studies show that ZnO polycrystalline thin films are obtained. The solar cells used are based on the couple copper phthalocyanine as electron donor and (N,N-diheptyl-3,4,9,10-perylenetetracarboxylicdiimide-PTCDI-C7) as electron acceptor. It is shown that the presence of the ZnO buffer layer improves the energy conversion efficiency of the cells. Such improvement could be attributed to a better energy level alignment at the anode/electron donor interface. The anode roughness induced by the ZnO buffer layer can also transform the planar interface organic electron donor/electron acceptor into roughen topography. This increases the interface area, where carrier separation takes place, which improves solar cells performances.

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

    International Nuclear Information System (INIS)

    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)

  2. Cytotoxic evaluation of nanostructured zinc oxide (ZnO) thin films and leachates.

    Science.gov (United States)

    Petrochenko, Peter E; Zhang, Qin; Bayati, Reza; Skoog, Shelby A; Phillips, K Scott; Kumar, Girish; Narayan, Roger J; Goering, Peter L

    2014-09-01

    Nanostructured ZnO films have potential use as coatings on medical devices and food packaging due to their antimicrobial and UV-protection properties. However, their influence on mammalian cells during clinical use is not fully understood. This study investigated the potential cytotoxicity of ZnO thin films in RAW 264.7 macrophages. ZnO thin films (∼96nm thick with a 50nm grain) were deposited onto silicon wafers using pulsed laser deposition. Cells grown directly on ZnO thin film coatings exhibited less toxicity than cells exposed to extracts of the coatings. Cells on ZnO thin films exhibited a 43% and 68% decrease in cell viability using the MTT and 7-AAD/Annexin V flow cytometry assays, respectively, after a 24-h exposure as compared to controls. Undiluted 100% 24- and 48-h extracts decreased viability by 89%, increased cell death by LDH release to 76% 24h after treatment, and increased ROS after 5-24h of exposure. In contrast, no cytotoxicity or ROS were observed for 25% and 50% extracts, indicating a tolerable concentration. Roughly 24 and 34μg/m(2) Zn leached off the surfaces after 24 and 48h of incubation, respectively. ZnO coatings may produce gradual ion release which becomes toxic after a certain level and should be evaluated using both direct exposure and extraction methods. PMID:24878115

  3. Reactive Radiofrequency Sputtering-Deposited Nanocrystalline ZnO Thin-Film Transistors

    International Nuclear Information System (INIS)

    The structural and electrical properties of ZnO films deposited by reactive radiofrequency sputtering with a metallic zinc target are systematically investigated. While the as-deposited ZnO film is in a poly-crystalline structure when the partial pressure of oxygen (pO2) is low, the grain size abruptly decreases to a few nanometers as pO2 increases to a critical value, and then becomes almost unchanged with a further increase in pO2. In addition, the resistivity of the ZnO films shows a non-monotonic dependence on pO2, including an abrupt transition of about seven orders of magnitude at the critical pO2. Thin-film transistors (TFTs) with the nanocrystalline ZnO films as channel layers have an on/off current ratio of more than 107, an off-current in the order of pA, a threshold voltage of about 4.5 V, and a carrier mobility of about 2cm2/(V·s). The results show that radiofrequency sputtered ZnO with a zinc target is a promising candidate for high-performance ZnO TFTs. (cross-disciplinary physics and related areas of science and technology)

  4. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Yu-Min, E-mail: ymhu@nuk.edu.tw; Kuang, Chein-Hsiun; Han, Tai-Chun; Yu, Chin-Chung [Department of Applied Physics, National University of Kaohsiung, Kaohsiung 811, Taiwan (China); Li, Sih-Sian [Institute of Electro-Optical Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China)

    2015-05-07

    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{sup 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{sup 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.

  6. Influence of Oxygen Partial Pressure on the Fermi Level of ZnO Films Investigated by Kelvin Probe Force Microscopy

    International Nuclear Information System (INIS)

    The influence of oxygen partial pressure on the Fermi level of ZnO films prepared by pulsed laser deposition is investigated. The contact potential difference of the ZnO films fabricated under various oxygen partial pressures is studied systematically using Kelvin probe force microscopy. The Fermi level shifted by 0.35 eV as oxygen partial pressure increased. This indicates a significant change in the electronic structure and energy balance in ZnO films. This fact provides a consistent explanation that the changes in carrier concentration, resistivity and mobility of ZnO films are attributed to oxygen vacancy induced shift of the Fermi level

  7. Influence of Oxygen Partial Pressure on the Fermi Level of ZnO Films Investigated by Kelvin Probe Force Microscopy

    Science.gov (United States)

    Su, Ting; Zhang, Hai-Feng

    2012-12-01

    The influence of oxygen partial pressure on the Fermi level of ZnO films prepared by pulsed laser deposition is investigated. The contact potential difference of the ZnO films fabricated under various oxygen partial pressures is studied systematically using Kelvin probe force microscopy. The Fermi level shifted by 0.35 eV as oxygen partial pressure increased. This indicates a significant change in the electronic structure and energy balance in ZnO films. This fact provides a consistent explanation that the changes in carrier concentration, resistivity and mobility of ZnO films are attributed to oxygen vacancy induced shift of the Fermi level.

  8. Effects of Mn doping on electrical properties of ZnO thin films

    Science.gov (United States)

    Motevalizadeh, Leili; Shohany, Boshra Ghanbari; Abrishami, Majid Ebrahimizadeh

    2016-01-01

    In this paper, we have investigated the effect of Mn doping on the electrical properties of ZnO thin films. ZnO thin films with different amounts of Mn concentrations (0, 5, 10 and 15 mol.%) were prepared by spray pyrolysis technique. The crystal structure was examined by X-ray diffraction (XRD) analysis. XRD patterns showed that all the samples were crystallized in wurtzite structure while a decrease in crystallinity and switch in preferential orientations were observed in Mn-doped thin films comparing to undoped ZnO. The element composition of all thin films was detected by energy dispersive X-ray (EDX). The surface morphology of the films was investigated using field emission scanning electron microscope (FESEM) and optical properties were studied using UV-vis spectroscopy. UV-vis study revealed that the band gap blueshifts with the increase in Mn content and Eg increases with the increase in Mn concentration. The resistivity and activation energy were measured at room temperature and ranging from 373 K to 573 K. Comparing to undoped ZnO thin film, the resistivity of Mn-doped ZnO films increased because of different parameters such as increasing barrier height energy and reducing the oxygen deficiency.

  9. Random lasing of ZnO thin films grown by pulsed-laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Cachoncinlle, C., E-mail: christophe.cachoncinlle@univ-orleans.fr [GREMI, UMR 7344 CNRS—Université Orléans, 45067 Orléans Cedex 2 (France); Hebert, C.; Perrière, J. [Sorbonne Universités, UPMC Université Paris 06, UMR 7588, INSP, 75005 Paris (France); CNRS, UMR 7588, INSP, 75005 Paris (France); Nistor, M. [NILPRP, L 22 PO Box. MG-36, 77125 Bucharest—Magurele (Romania); Petit, A.; Millon, E. [GREMI, UMR 7344 CNRS—Université Orléans, 45067 Orléans Cedex 2 (France)

    2015-05-01

    Highlights: • Random lasing at RT in nanocrystalline ZnO PLD thin film (<100 nm). • Low optical pumping threshold (<30 kW cm{sup −2}) for UV random lasing. • Random lasing interpreted by the electron-hole plasma (EHP) model. - Abstract: Low-dimensional semiconductor structures on nanometer scale are of great interest because of their strong potential applications in nanotechnologies. We report here optical and structural properties on UV lasing in ZnO thin films. The ZnO films, 110 nm thick, were prepared using pulsed-laser deposition on c-cut sapphire substrates at 500 °C under 10{sup −2} oxygen pressure. The ZnO films are nearly stoichiometric, dense and display the wurtzite phase. The films are highly textured along the ZnO c-axis and are constituted of nanocrystallites. According to Hall measurements these films are conductive (0.11 Ω cm). Photoluminescence measurements reveals a so-called random lasing in the range 390 to 410 nm, when illuminating at 355 nm with a tripled frequency pulsed Nd-YAG laser. Such random lasing is obtained at rather low optical pumping, 45 kW cm{sup −2}, a value lower than those classically reported for pulsed-laser deposition thin films.

  10. Random lasing of ZnO thin films grown by pulsed-laser deposition

    International Nuclear Information System (INIS)

    Highlights: • Random lasing at RT in nanocrystalline ZnO PLD thin film (<100 nm). • Low optical pumping threshold (<30 kW cm−2) for UV random lasing. • Random lasing interpreted by the electron-hole plasma (EHP) model. - Abstract: Low-dimensional semiconductor structures on nanometer scale are of great interest because of their strong potential applications in nanotechnologies. We report here optical and structural properties on UV lasing in ZnO thin films. The ZnO films, 110 nm thick, were prepared using pulsed-laser deposition on c-cut sapphire substrates at 500 °C under 10−2 oxygen pressure. The ZnO films are nearly stoichiometric, dense and display the wurtzite phase. The films are highly textured along the ZnO c-axis and are constituted of nanocrystallites. According to Hall measurements these films are conductive (0.11 Ω cm). Photoluminescence measurements reveals a so-called random lasing in the range 390 to 410 nm, when illuminating at 355 nm with a tripled frequency pulsed Nd-YAG laser. Such random lasing is obtained at rather low optical pumping, 45 kW cm−2, a value lower than those classically reported for pulsed-laser deposition thin films

  11. Preparation of ZnO films with variable electric field-assisted atomic layer deposition technique

    International Nuclear Information System (INIS)

    The ZnO films have been prepared by a variable electric field-assisted atomic layer deposition method (ALD). By applying electric fields during the precursor pulses, we can modulate both the crystal orientation and structure of the obtained ZnO films. The ZnO films with c-axis preferred orientation and the least oxygen vacancy defect were obtained when the holder electric polarities were positive and negative during the DEZn and H2O pulse, respectively. It is supported that when electric field was applied in the chamber, the torque may lead to the precursor molecular alignments along the electric field direction, which could affect the film growth process and then influence their structures and properties. This variable electric field-assisted ALD approach would provide an efficient protocol for the growth of semiconductor films with designed properties.

  12. Studies of structural evolution and sensing properties of ZnO nanocrystalline films

    International Nuclear Information System (INIS)

    ZnO nanocrystalline films have been prepared on Si(1 0 0) substrate using direct current (D.C) magnetron sputtering technique at room temperature. The thickness of nanocrystalline films almost linearly increased with deposition duration and the sizes of crystalline grains almost kept unchanged. After deposition, thermal annealing was performed at 800 deg. C in atmosphere for 2 h in order to improve the qualities of ZnO thin films. Scanning electron microscope (SEM) images showed the surface roughness of the films less than 45 nm. X-ray diffraction (XRD) patterns revealed the slight evolution of the crystal structures. Raman scattering spectra confirmed the data obtained from X-ray diffraction measurements. With these ZnO nanocrystalline films, prototypic gas sensors were fabricated. Both sensitivity and response of the sensors to different gases (H2 and CH4) were investigated. A quick response of time, less than 1 second to CH4 gas sensor has been achieved.

  13. Laser-assisted sol-gel growth and characteristics of ZnO thin films

    International Nuclear Information System (INIS)

    ZnO thin films were grown on Si(100) substrates by a sol-gel method assisted by laser beam irradiation with a 325 nm He-Cd laser. In contrast to conventional sol-gel ZnO thin films, the surface morphology of the laser-assisted sol-gel thin films was much smoother, and the residual stress in the films was relaxed by laser irradiation. The luminescent properties of the films were also enhanced by laser irradiation, especially, by irradiation during the deposition and post-heat treatment stages. The incident laser beam is thought to play several roles, such as annihilating defects by accelerating crystallization during heat treatment, enhancing the surface migration of atoms and molecules, and relaxing the ZnO matrix structure during crystallization.

  14. High electron mobility ZnO film for high-performance inverted polymer solar cells

    International Nuclear Information System (INIS)

    High-quality ZnO films (ZnO-MS) are prepared via magnetron sputtering deposition with a high mobility of about 2 cm2/(V·s) and are used as electron transport layer for inverted polymer solar cells (PSCs) with polymer poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′] dithiophene-co-3-fluorothieno[3,4-b]thiophene-2-carboxylate]:[6,6]-phenyl C71-butyric acid methyl ester as the active layer. A significant improvement of JSC, about 20% enhancement in contrast to the devices built on sol-gel derived ZnO film (ZnO-Sol), is found in the ZnO-MS based device. High performance ZnO-MS based PSCs exhibit power conversion efficiency (PCE) up to 8.55%, which is much better than the device based on ZnO-Sol (PCE = 7.78%). Further research on cathode materials is promising to achieve higher performance

  15. High electron mobility ZnO film for high-performance inverted polymer solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Peiwen; Chen, Shan-Ci; Zheng, Qingdong; Huang, Feng, E-mail: fhuang@fjirsm.ac.cn; Ding, Kai [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou Fujian, 350002 (China)

    2015-04-20

    High-quality ZnO films (ZnO-MS) are prepared via magnetron sputtering deposition with a high mobility of about 2 cm{sup 2}/(V·s) and are used as electron transport layer for inverted polymer solar cells (PSCs) with polymer poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′] dithiophene-co-3-fluorothieno[3,4-b]thiophene-2-carboxylate]:[6,6]-phenyl C71-butyric acid methyl ester as the active layer. A significant improvement of J{sub SC}, about 20% enhancement in contrast to the devices built on sol-gel derived ZnO film (ZnO-Sol), is found in the ZnO-MS based device. High performance ZnO-MS based PSCs exhibit power conversion efficiency (PCE) up to 8.55%, which is much better than the device based on ZnO-Sol (PCE = 7.78%). Further research on cathode materials is promising to achieve higher performance.

  16. Experiment and prediction on thermal conductivity of Al2O3/ZnO nano thin film interface structure

    Indian Academy of Sciences (India)

    Ping Yang; Liqiang Zhang; Haiying Yang; Dongjing Liu; Xialong Li

    2014-05-01

    We predict that there is a critical value of Al2O3/ZnO nano thin interface thickness based on two assumptions according to an interesting phenomenon, which the thermal conductivity (TC) trend of Al2O3/ZnO nano thin interface is consistent with that of relevant single nano thin interface when the nano thin interface thickness is > 300 nm; however, TC of Al2O3/ZnO nano thin interface is higher than that of relevant single nano thin interface when the thin films thickness is < 10 nm. This prediction may build a basis for the understanding of interface between two different oxide materials. It implies an idea for new generation of semiconductor devices manufacturing.

  17. A greener electrodeposition recipe for ZnO films in terawatt photovoltaics

    International Nuclear Information System (INIS)

    Electrodeposition of ZnO can be performed in an aqueous solution using a greener recipe, where the solution can be reused for multiple deposition runs. The solution in this greener recipe has only one function, i.e. to provide electrical conductivity for the deposition reactions. A Zn sheet serves as the anode, which dissolves during the deposition as the Zn source. O2 is bubbled into the solution and reduced to OH− ions as the O source. This recipe minimizes concentration changes in the solution as deposition proceeds, making the solution reusable. An initial Zn2+ concentration of a few mM in the solution is required, not to serve as a Zn source but to facilitate the deposition and prevent precipitation of ZnO in the solution. Multiple deposition runs for ZnO films in the same solution have been demonstrated. X-ray diffraction, optical transmittance and absorption spectra reveal that all the ZnO films have similar structural and optical properties. They all display high transmittance of ∼ 80% and low absorbance of ∼ 10%. - Highlights: ► A new ZnO electrodeposition recipe is developed where the solution is reusable. ► Waste solutions from ZnO electrodeposition are reduced by over four fold. ► ZnO films from the same solution show high transmittance and low absorbance.

  18. Degenerate interface layers in epitaxial scandium-doped ZnO thin films

    International Nuclear Information System (INIS)

    Scandium is a donor in ZnO, in contradiction to all heavier 3d-elements. Although the Sc3+ ion fits exactly the size of Zn2+, the conductivity of epitaxial Sc-doped ZnO thin films is dominated by a degenerated interface layer with pronounced Sc accumulation in the concentration depth profile. Electron paramagnetic resonance clearly excludes the isovalent oxidation state Sc2+ in ZnO, in agreement with the low resistivity of homoepitaxial ZnO:Sc of 1.3 × 10-2 Ω cm and high Hall mobility of 139 cm2 V-1 s-1 at 300 K. Employing the two-layer Hall model of Look and Molnar, a maximum Hall mobility of the volume part of the ZnO:Sc layer of 650 cm2 V-1 s-1 at 95 K was extracted. Thermal activation energies of the donors are 28 and 43 meV for a homoepitaxial ZnO:0.1% Sc film. Homoepitaxial ZnO films with 0.1 and 1 at% Sc on c-plane ZnO are almost phase pure and in-plane lattice matched with perpendicular compressive strain up to 1%. Heteroepitaxial ZnO:Sc on a-plane sapphire shows secondary XRD peaks, pointing to a limited solubility of Sc in ZnO.

  19. Effect of oxygen content on the structural and optical properties of ZnO films grown by atmospheric pressure MOCVD

    Institute of Scientific and Technical Information of China (English)

    Sajjad Hussain; Yaqoob Khan; Volodymyr Khranovskyy; Riaz Muhammad; Rositza Yakimova

    2013-01-01

    Atmospheric pressure MOCVD was used to deposit ZnO layers on sapphire and homoepitaxial template under different oxygen flow rates. Oxygen content affects the lattice constant value and texture coefficient of the films as evidenced by the y-2y peaks position and their intensity. Films deposited at lower oxygen flow rate possess higher value of strain and stresses. ZnO films deposited at high oxygen flow rates show intense UV emissions while samples prepared under oxygen deficient conditions exhibited defect related emission along with UV luminescence. The results are compared to the ZnO films deposited homoepitaxially on annealed ZnO samples. The data obtained suggest that ZnO stoichiometry is responsible for the structural and optical quality of ZnO films.

  20. Growth of controllable ZnO film by atomic layer deposition technique via inductively coupled plasma treatment

    International Nuclear Information System (INIS)

    An inductively coupled plasma technique (ICP), namely, remote-plasma treatment was introduced to ionize the water molecules as the precursor for the deposition of ZnO film via the atomic layer deposition processes. Compared with the H2O gas as the precursor for the ALD growth, the ionized water molecules can provide a lesser energy to uniformly stabilize oxidization processes, resulting in a better film quality with a higher resistivity owing to less formation of intrinsic defects at a lower growth temperature. The relationship between resistivity and formation mechanisms have been discussed and investigated through analyses of atomic force microscopy, photonluminescence, and absorption spectra, respectively. Findings indicate that the steric hindrance of the ligands plays an important rule for the ALD-ZnO film sample with the ICP treatment while the limited number of bonding sites will be dominant for the ALD-ZnO film without the ICP treatment owing to decreasing of the reactive sites via the ligand-exchange reaction during the dissociation process. Finally, the enhanced aspect-ratio into the anodic aluminum oxide with the better improved uniform coating of ZnO layer after the ICP treatment was demonstrated, providing an important information for a promising application in electronics based on ZnO ALD films.

  1. 7-Octenyltrichrolosilane/trimethyaluminum hybrid dielectrics fabricated by molecular-atomic layer deposition on ZnO thin film transistors

    Science.gov (United States)

    Huang, Jie; Lee, Mingun; Lucero, Antonio T.; Cheng, Lanxia; Ha, Min-Woo; Kim, Jiyoung

    2016-06-01

    We demonstrate the fabrication of 7-octenytrichlorosilane (7-OTS)/trimethylaluminum (TMA) organic–inorganic hybrid films using molecular-atomic layer deposition (MALD). The properties of 7-OTS/TMA hybrid films are extensively investigated using transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), and electrical measurements. Our results suggest that uniform and smooth amorphous hybrid thin films with excellent insulating properties are obtained using the MALD process. Films have a relatively high dielectric constant of approximately 5.0 and low leakage current density. We fabricate zinc oxide (ZnO) based thin film transistors (TFTs) using 7-OTS/TMA hybrid material as a back gate dielectric with the top ZnO channel layer deposited in-situ via MALD. The ZnO TFTs exhibit a field effect mobility of approximately 0.43 cm2 V‑1 s‑1, a threshold voltage of approximately 1 V, and an on/off ratio of approximately 103 under low voltage operation (from ‑3 to 9 V). This work demonstrates an organic–inorganic hybrid gate dielectric material potentially useful in flexible electronics application.

  2. ZnO nanoparticles induced effects on nanomechanical behavior and cell viability of chitosan films

    Energy Technology Data Exchange (ETDEWEB)

    Jayasuriya, Ambalangodage C., E-mail: a.jayasuriya@utoledo.edu [Department of Orthopaedic Surgery, University of Toledo, Toledo, OH 43614 (United States); Aryaei, Ashkan; Jayatissa, Ahalapitiya H. [Departments of Mechanical Engineering, University of Toledo, Toledo, OH 43606 (United States)

    2013-10-15

    The aim of this paper is to develop novel chitosan–zinc oxide nanocomposite films for biomedical applications. The films were fabricated with 1, 5, 10 and 15% w/w of zinc oxide (ZnO) nanoparticles (NPs) incorporated with chitosan (CS) using a simple method. The prepared nanocomposite films were characterized using atomic force microscopy, Raman and X-ray diffraction studies. In addition, nano and micro mechanical properties were measured. It was found that the microhardness, nanohardness and its corresponding elastic modulus increased with the increase of ZnO NP percentage in the CS films. However, the ductility of films decreased as the percentage of ZnO NPs increased. Cell attachment and cytotoxicity of the prepared films at days two and five were evaluated in vitro using osteoblasts (OBs). It was observed that OB viability decreased in films with higher than 5% ZnO NPs. This result suggests that although ZnO NPs can improve the mechanical properties of pure CS films, only a low percentage of ZnO NPs can be applied for biomedical and bioengineering applications because of the cytotoxicity effects of these particles. Highlights: • Chitosan–zinc oxide nanocomposite films were fabricated using a simple method. • Material characterization methods showed that adding zinc oxide up to 15% does not change the crystal structure of chitosan. • Zinc oxide nanoparticles improve nano and micro mechanical properties of chitosan films. • Adding more than 5% w/w zinc oxide nanoparticles demonstrates cytotoxicity on osteoblast cells.

  3. Thin ZnO nanocomposite poly(styrene-acrylic acid) films on Si and SiO2 surfaces

    International Nuclear Information System (INIS)

    The properties and formation of self-assembled ZnO nanoclusters using polystyrene-based diblock copolymers are reported. The polystyrene-polyacrylic acid copolymer consisting of a majority block (polystyrene) and a minority block (polyacrylic acid) with a block number average molecular weight ratio of 16,500/4500 and a block repeat unit ratio of 159/63 was used in order to obtain self-assembly due to microphase separation with spherical morphology. The self-assembly of the inorganic nanoparticles was achieved at room temperature in the liquid phase using a ZnCl2 precursor dopant attached to the minority block, and both dry and wet chemical processing techniques compatible with semiconductor manufacturing were developed in order to convert the ZnCl2 precursor into ZnO. The polymer films were applied by standard spin-on photolithographic techniques on Si wafers with and without thermally grown SiO2 surface films. A study by X-ray photoelectron spectroscopy (XPS) confirmed the conversion of the ZnCl2 dopant precursor into ZnO within the copolymer matrix, and atomic force microscopy (AFM) showed the spherical morphology of the resultant ZnO nanoclusters. Conversion of the precursor into ZnO was achieved both by a wet chemical treatment and by developing a new dry chemical treatment process based on ozone exposure. The study showed that the dry treatment has better stability and shorter conversion exposure times on the Si surfaces than the wet treatment approach, resulting in lateral size distribution between 250 and 350 nm and height distribution between 80 and 130 nm for the ZnO nanoclusters

  4. Temperature effect on the electrical, structural and optical properties of N-doped ZnO films by plasma-free metal organic chemical vapor deposition

    International Nuclear Information System (INIS)

    N-doped p-type ZnO films were grown by plasma-free metal-organic chemical vapor deposition (MOCVD). The effect of substrate temperature on the electrical, optical, and structural properties of the N-doped ZnO films was investigated by Hall-effect, photoluminescence, X-ray diffraction measurements. The electrical properties of the films were extremely sensitive to the substrate temperature and the conduction type could be reversed in a narrow range from 380 deg. C to 420 deg. C. Based on X-ray photoelectron spectroscopy, a high compensation effect in the N-doped ZnO films grown by plasma-free MOCVD was suggested to explain the temperature-dependent phenomenon.

  5. Characterization of ZnO thin films grown on various substrates by RF magnetron sputtering

    International Nuclear Information System (INIS)

    In this study we investigated properties of ZnO thin films deposited on both oxygen-containing substrates and a substrate without oxygen content at various O2/Ar reactant gas ratios. Deposition of ZnO on indium-tin oxide (ITO) resulted in the best crystallinity, whereas the least degree of crystallization was observed from ZnO deposited on glass. All the films were found to have compressive stress, which was relieved by annealing in O2 environment. ZnO films deposited on glass revealed p-type conductivity when prepared at O2/Ar ratio of 0.25 whereas those on SiNx yielded p-type conductivity when prepared at O2/Ar ratio of 4. In addition, shallower oxygen interstitial seemed to be found from films with better crystallinity. The largest shift in binding energy of Zn2p3/2 was observed from ZnO prepared on glass at O2/Ar ratio of 0.25, whereas that of O1s was obtained from ZnO deposited on SiNx at O2/Ar ratio of 4. A model was proposed in terms of O2 diffusion and hydrogen desorption in order to account for the observed property variations depending on substrates and O2/Ar ratios.

  6. Optical Properties of Cu-Doped ZnO Films Prepared by Cu Solution Coating.

    Science.gov (United States)

    Allabergenov, Bunyod; Chung, Seok-Hwan; Kim, Sungjin; Choi, Byeongdae

    2015-10-01

    This work demonstrates the fabrication of Cu-doped ZnO films by Cu solution coating method. Cu ink was spin coated on ZnO thin films prepared by e-beam deposition. After curing and annealing at high temperatures, structural, morphological and optical properties of the films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and spectrofluorometer, respectively. The XRD results showed that ZnO films formed polycrystalline with a hexagonal wurtzite structure, and the grain size increased with increasing the annealing temperature from 500 to 850 °C. The changes in lattice parameters were caused by grain size, strain, and residual stress. Morphological analysis have revealed that the Cu-doped ZnO film after annealing at 500 °C has flat surface with uniformly distributed grain size, which became porous after higher temperature annealing process. Energy dispersive spectroscopy (EDS) and photoluminescence spectras have shown the presence of Zn, Cu, and O elements, and combined violet, blue, green and weak red emissions between 350 and 650 nm in the ZnO films, respectively. PMID:26726392

  7. 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.

  8. High quality ZnO film prepared on ITO substrate for H2 sensing application

    International Nuclear Information System (INIS)

    In this paper, we report the temperature effect on the properties of ZnO films prepared on ITO coated glass substrate by a spray pyrolysis technique. XRD studies revealed the polycrystalline hexagonal wurtzite ZnO structure. The promoting effect of ITO on the crystal quality of ZnO film is reflected in the film prepared at 350 °C. The red-shift in the PL peak with increase in temperature was confirmed from the decrease in the optical band gap of the film, contributed partially by the size effect and partially by the strain relaxation of ZnO crystallites. Highly compact and porous morphology of the films with large RMS roughness favored the surface reactivity with H2 gas. The large response of ZnO/ITO sensor at low operating temperature, with fast response and recovery was attributed to the microstructure of the ITO underlayer. - Highlights: • Preferred (0 0 2) orientation of ZnO improved with substrate temperature. • Intense red-shift was observed with less violet emission. • SEM revealed highly compact morphology of the films with large RMS roughness. • High sensitivity of ZnO/ITO towards H2 at lower operating temperature

  9. Investigation of physical properties of screen printed nanosized ZnO films for optoelectronic applications

    Science.gov (United States)

    Zargar, Rayees Ahmad; Arora, Manju; Khurram Hafiz, Aurangzeb

    2015-04-01

    Nanosized ZnO particles derived from chemical co-precipitation route were used for casting ZnO films by screen printing method followed by sintering at two different temperatures. The variation in structural, optical and electrical properties of these films with temperature have been investigated by XRD, SEM, FTIR, Raman, UV-VIS, EPR and four probe analytical techniques. XRD patterns of these films exhibit polycrystalline nature with hexagonal wurtzite structure and SEM images reveal the smooth, dense and without any cracks/damage porous surface morphology. Infrared transmission spectra shows peaks pertaining to Zn-O stretching modes and their multiphonon modes. While Raman spectra exhibited strong peaks of E2 (high) phonon and overtone of surface phonon mode at 429 cm-1 and 1144 cm-1 respectively with weak components of LO and TO branches. The direct band gap energy of these films showed narrowing of band gap from 3.21 eV to 3.12 eV on increasing sintering temperature from 500 °C to 600 °C. DC conductivity measurements confirmed semiconducting behaviour and showed lowering of activation energy. EPR spectra showed single narrow line resonance signal of g-value ~ 1.9469 due to oxygen vacancies which are produced during synthesis of ZnO nanoparticles by sol-gel process. These studies revealed that on increasing sintering temperature the crystallinity of the film improves with reduction in lattice deformations in these screen printed ZnO films.

  10. High Temperature Thermoelectric Properties of ZnO Based Materials

    DEFF Research Database (Denmark)

    Han, Li

    This thesis investigated the high temperature thermoelectric properties of ZnO based materials. The investigation first focused on the doping mechanisms of Al-doped ZnO, and then the influence of spark plasma sintering conditions on the thermoelectric properties of Al, Ga-dually doped ZnO. Follow......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...... temperatures. Clear correlations between the initial crystallographic phase of the dopants and the thermoelectric properties of the resulting Al-doped ZnO were observed. For Al, Ga-dually doped ZnO, the spark plasma sintering conditions together with the microstructural evolution and thermoelectric properties...... of the samples were investigated in detail. A proposed solid-state-reaction model suggested that a sintering temperature above 1223K would be preferable in order to achieve phase equilibrium in the samples. The sintering mechanism of the ZnO particles and microstructural evolutions at different...

  11. Dye-Sensitized Nanocrystalline ZnO Solar Cells Based on Ruthenium(II Phendione Complexes

    Directory of Open Access Journals (Sweden)

    Hashem Shahroosvand

    2011-01-01

    Full Text Available The metal complexes (RuII (phen2(phendione(PF62(1, [RuII (phen(bpy(phendione(PF62 (2, and (RuII (bpy2(phendione(PF62 (3 (phen = 1,10-phenanthroline, bpy = 2,2′-bipyridine and phendione = 1,10-phenanthroline-5,6-dione have been synthesized as photo sensitizers for ZnO semiconductor in solar cells. FT-IR and absorption spectra showed the favorable interfacial binding between the dye-molecules and ZnO surface. The surface analysis and size of adsorbed dye on nanostructure ZnO were further examined with AFM and SEM. The AFM images clearly show both, the outgrowth of the complexes which are adsorbed on ZnO thin film and the depression of ZnO thin film. We have studied photovoltaic properties of dye-sensitized nanocrystalline semiconductor solar cells based on Ru phendione complexes, which gave power conversion efficiency of (η of 1.54% under the standard AM 1.5 irradiation (100 mW cm−2 with a short-circuit photocurrent density (sc of 3.42 mA cm−2, an open-circuit photovoltage (oc of 0.622 V, and a fill factor (ff of 0.72. Monochromatic incident photon to current conversion efficiency was 38% at 485 nm.

  12. Preparation and Photovoltaic Properties of Dye Sensitized Solar Cells Using ZnO Nanorods Stacking Films on AZO Substrate as Photoanode.

    Science.gov (United States)

    Xu, Yang; Wang, Xina; Liu, Rong; Wang, Hao

    2016-04-01

    Three-dimensional stacking of ZnO nanorods on conducting aluminum-doped ZnO (AZO) glass were studied as efficient photoanodes of dye sensitized solar cells (DSSCs). By changing hydrothermal growth time and cycle times, the thickness of ZnO nanorods stacking films varied from 30 µm to 64 µm, and its influence on the energetic conversion efficiency of the DSSCs based on the stacking films photoanodes was investigated. The loading density of N719 on the surface of ZnO nanorods was studied to increase the efficiency of the cells. Annealing experiments showed that the AZO substrates remained good conductors until heated above 350 °C. A photoelectric conversion efficiency as high as ~2.0% together with ISC of ~9.5 mA/cm2, VOC of ~0.5 V and FF of ~41.4% was achieved for the DSSC using 50 µm-thick film stacking by ZnO nanorods as photoanode and N719 as sensitizer under illumination of AM1.5G solar light (power density of 100 mW/cm2). A charge separation and transfer mechanism was proposed for the ZnO nanorods stacking electrode-based DSSCs. PMID:27451677

  13. Investigations of ZnO thin films deposited by a reactive pulsed laser ablation

    Institute of Scientific and Technical Information of China (English)

    Y.; C.; SOO; H.; KANDEL; M.; A.; THOMAS; C.; P.; DAGHLIAN

    2009-01-01

    Highly transparent ZnO thin films were deposited at different substrate temperatures by pulsed laser deposition in an oxygen atmosphere. The thin films were characterized by various techniques including X-ray diffraction, scanning electron microscopy, optical absorption, and photoluminescence. We demonstrated that oriented wurtzite ZnO thin films could be deposited at room temperature using a high purity zinc target. Variable temperature photoluminescence revealed new characteristics in the band edge emission. The underlying mechanism for the observed phenomena was also discussed.

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

    International Nuclear Information System (INIS)

    The present study describes the first detailed evaluation of the rise and the decay time of scintillation phenomenon in In3+- and Ga3+-doped ZnO thin films with different dopant concentrations. In3+-(25, 55, and 141 ppm) and Ga3+-(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 In3+ and Ga3+ in the films. However, the scintillation light yield under 241Am α-ray excitation reduced when concentration of In3+ and Ga3+ in the ZnO films was high. (author)

  15. Optical Properties of MEH-PPV Thin Films Containing ZnO Nanoparticles

    International Nuclear Information System (INIS)

    Thin films of poly [2-methoxy-5(2'-ethyl hexyloxy)-phenylene vinylene](MEH-PPV) containing different weight percent of ZnO nanoparticles were deposited by spin coating from THF solutions and their optical properties were investigated. Optical characterization of the nanocomposite thin films were performed by Ultraviolet-Visible Spectrophotometer (UV-Vis) and Photoluminescence Spectrometer while the thickness of the thin films was measured by using Surface Profiler. The UV-Vis absorption spectra of MEH-PPV: ZnO films showed a small red shift as compared with pure MEH-PPV. Similarly, a small red shift was found in PL emission spectra with increasing the content of ZnO nanoparticles.

  16. Role of Ni doping on transport properties of ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Dar, Tanveer Ahmad, E-mail: tanveerphysics@gmail.com; Agrawal, Arpana; Sen, Pratima [Laser Bhawan, School Of Physics, Devi Ahilaya University Takshashila Campus Khandwa Road Indore, Indore-452001 (India)

    2015-06-24

    Nickel doped (Ni=0.05) and undoped Zinc Oxide (ZnO) thin films have been prepared by Pulsed laser deposition (PLD) technique. The structural analysis of the films was done by X-ray diffraction (XRD) studies which reveal absence of any secondary phase in the prepared samples. UV transmission spectra show that Ni doping reduces the transparency of the films. X-ray Photoelectron spectroscopy (XPS) also shows the presence of metallic Ni along with +2 oxidation state in the sample. Low temperature magneto transport properties of the ZnO and NiZnO films are also discussed in view of Khosla fisher model. Ni doping in ZnO results in decrease in magnitude of negative MR.

  17. MICROSTRUCTURE AND PROPERTIES OF ANNEALED ZnO THIN FILMS DEPOSITED BY MAGNETRON SPUTTERING

    Institute of Scientific and Technical Information of China (English)

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

    2005-01-01

    ZnO thin films were deposited on a glass substrate by dc (direct current) and rf (radio frequency) magnetron sputtering. Post-deposition annealing was performed in different atmospheres and at different temperatures. The correlation of the annealing conditions with the microstructure and properties of the ZnO films were investigated by ultraviolet-visible spectroscopy, X-ray diffraction, conductivity measurement and scanning electron microscopy. Only the strong 002peak could be observed by X-ray diffraction. The post-deposition annealing of ZnO films was found to alter the film's microstructure and properties, including crystallinity, porosity, grain size, internal stress level and resistivity. It was also found that after annealing, the conductivity of poorly conductive samples often improved. However, annealing does not improve the conductivity of samples with high conductivity prior to annealing. The resistivity of as-grown films annealing on the conductivity of ZnO, it is believed that annealing may alter the presence and distribution of oxygen defects, reduce the lattice stress, cause diffusion, grain coarsening and recrystallization. Annealing will reduce the density of grain boundaries in less dense films,which may decrease the resistivity of the films. On the other hand, annealing may also increase the porosity of thin films, leading to an increase in resistivity.

  18. Sol-gel-deposited ZnO thin films: A review

    International Nuclear Information System (INIS)

    During the last years, ZnO thin films have been studied extensively due to their potential applications in e.g. piezoelectric and optoelectronic devices or photovoltaic cells. Ordered c-axis orientation of ZnO crystallites is desirable for applications where crystallographic anisotropy is a prerequisite such as for short-wavelength semiconductor diode lasers (SDLs), and piezoelectric surface acoustic wave or acousto-optic devices. Many works were dedicated to c-axis oriented ZnO thin films elaboration and the study of their properties, including physical and chemical methods. For instance, sol-gel processes are particularly well adapted to produce ZnO films in a simple, low-cost and highly controlled way. This review summarizes the main chemical routes used in the sol-gel synthesis of undoped ZnO thin films and highlights the chemical and physical parameters influencing their structural properties. In this process, the ZnO films synthesis includes three principal steps: (i) solution preparation, (ii) coating and (iii) heat treatment. For the first step, the particle formation is discussed including nucleation and growth, particle size, morphology and colloids stability. These three steps involve several parameters such as: (i) nature and concentration of precursor, solvent and additive, and solution aging time, for the chemical system, (ii) coating method, thickness and substrate for the coating step, and (iii) pre-and post-heat treatment for the last step. The influence of these steps and synthesis parameters on ZnO thin films orientation is discussed.

  19. Ultrafast dynamics of ZnO and ZnO-BaTiO3 thin films

    Energy Technology Data Exchange (ETDEWEB)

    Acharya, Snigdhatanu; Chouthe, Sumedha; Seifert, Gerhard [Institute of Physics, Martin-Luther-University, Halle-Wittenberg, Von-Danckelmann Platz 3, D-06120, Halle (Germany); Boentgen, Tammo; Schmidt-Grund, Ruediger; Grundmann, Marius [Institute for Experimental Physics-II, University of Leipzig, Linnestrasse 5, D-04103 Leipzig (Germany)

    2011-07-01

    Femtosecond pump-probe spectroscopy was performed at room temperature on ZnO thin film and a double layer thin film structure of BaTiO{sub 3}/ZnO, to investigate coupling between the layers via the charge carrier dynamics. Frequency-doubled Ti:Sa laser pulses (150 fs, 400 nm) were used as pump; induced transmission changes were probed by supercontinuum (320-600 nm) fs pulses. For ZnO, two photon absorption as well as direct excitation to the trap states close to the conduction band edge leads to transfer of carriers to the conduction band. The displaced carriers relax rapidly to the bottom of conduction band, and bleaching at 375 nm attributed to population of discrete exciton A is observed. Further increase in the density at exciton levels lead to a stimulated emission at 390 nm due to exciton-exciton scattering. Changes in refractive index induced by pump-pulse generates interferometric transmission changes between 400-600 nm. Similar contributions to the transient spectra are observed in BaTiO{sub 3}/ZnO. BaTiO{sub 3} does not show any femtosecond response. Difference in the dynamical behaviour of the contributions in ZnO and BaTiO{sub 3}/ZnO gives an indication of coupling between ZnO and BaTiO{sub 3}.

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

    International Nuclear Information System (INIS)

    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

  1. 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.

  2. 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.

  3. Effect of ZnO films on CdTe solar cells

    International Nuclear Information System (INIS)

    The ZnO high resistivity transparent (HRT) layers were prepared by DC magnetron sputtering on the 1 mm borosilicate glass with 150 nm ITO coating. The structural, optical and electrical properties of the as-deposited films were investigated by XRD, UV/Vis spectroscopy and four-probe technology. The interface characters of the ITO/ZnO and ZnO/CdS systems were studied by ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS) depth profiling tests. The results show that ZnO has good optical and electrical properties. The insertion of the ZnO films decreases the energy barrier between ITO and CdS films. The energy conversion efficiency and quantum efficiency were found to be 12.77% (8.9%) and > 90% (79%) with or (without) ZnO films of CdTe solar cells. Furthermore, the effect of thickness, mobility and carrier density of ZnO films on CdTe solar cells was analyzed by AMPD-1D. (semiconductor materials)

  4. Influence of annealing temperature on ZnO thin films grown by dual ion beam sputtering

    Indian Academy of Sciences (India)

    Sushil Kumar Pandey; Saurabh Kumar Pandey; Vishnu Awasthi; Ashish Kumar; Uday P Deshpande; Mukul Gupta; Shaibal Mukherjee

    2014-08-01

    We have investigated the influence of in situ annealing on the optical, electrical, structural and morphological properties of ZnO thin films prepared on -type Si(100) substrates by dual ion beam sputtering deposition (DIBSD) system. X-ray diffraction (XRD) measurements showed that all ZnO films have (002) preferred orientation. Full-width at half-maximum (FWHM) of XRD from the (002) crystal plane was observed to reach to a minimum value of 0.139° from ZnO film, annealed at 600 °C. Photoluminescence (PL) measurements demonstrated sharp near-band-edge emission (NBE) at ∼ 380 nm along with broad deep level emissions (DLEs) at room temperature. Moreover, when the annealing temperature was increased from 400 to 600 °C, the ratio of NBE peak intensity to DLE peak intensity initially increased, however, it reduced at further increase in annealing temperature. In electrical characterization as well, when annealing temperature was increased from 400 to 600 °C, room temperature electron mobility enhanced from 6.534 to 13.326 cm2/V s, and then reduced with subsequent increase in temperature. Therefore, 600 °C annealing temperature produced good-quality ZnO film, suitable for optoelectronic devices fabrication. X-ray photoelectron spectroscopy (XPS) study revealed the presence of oxygen interstitials and vacancies point defects in ZnO film annealed at 400 °C.

  5. Nitrogen doping in pulsed laser deposited ZnO thin films using dense plasma focus

    International Nuclear Information System (INIS)

    Pulsed laser deposition synthesized ZnO thin films, grown at 400 deg. C substrate temperature in different oxygen gas pressures, were irradiated with 6 shots of pulsed nitrogen ions obtained from 2.94 kJ dense plasma focus to achieve the nitrogen doping in ZnO. Structural, compositional and optical properties of as-deposited and nitrogen ion irradiated ZnO thin films were investigated to confirm the successful doping of nitrogen in irradiated samples. Spectral changes have been seen in the nitrogen irradiated ZnO thin film samples from the low temperature PL measurements. Free electron to acceptor emissions can be observed from the irradiated samples, which hints towards the successful nitrogen doping in films. Compositional analysis by X-ray photoelectron spectroscopy and corresponding shifts in binding energy core peaks of oxygen and nitrogen confirmed the successful use of plasma focus device as a novel source for nitrogen ion doping in ZnO thin films.

  6. 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.

  7. Laser induced photoconductivity in sol–gel derived Al doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Eskandari, F.; Ranjbar, M., E-mail: ranjbar@cc.iut.ac.ir; Kameli, P.; Salamati, H.

    2015-11-15

    In this paper Al doped ZnO (AZO) thin films with 0, 3, 6 and 12 at. % Al concentration were prepared by sol–gel method on glass substrates. The deposited films were annealed at different temperatures of 300, 350, 400, 450 and 500 °C for 1 h in air. X-ray diffraction (XRD) showed wurtzite crystalline structure for the films annealed above 400 °C. The films were subsequently irradiated by beams of excimer (KrF, λ = 248 nm) laser. The evolution of crystal structure, surface morphology and optical properties were studied using XRD, filed emission scanning electron microscope (FE-SEM) and UV–Vis spectrophotometer, respectively. Real-time measurement of electrical conductivity during laser irradiation showed a transient or persistent photoconductivity effect. The effect of laser energy on this photoconductivity was also investigated. Based on the observed photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS), the observed photoconductivity effect was described. - Highlights: • AZO (0–12 at. % Al) films were prepared by sol–gel method and annealed at different temperatures. • Excimer laser (λ = 248 nm) irradiation leads to improvement of crystalline structure. • Average optical transmission doesn't change and optical gap decreases by irradiation. • Photoconductivity was investigated by real-time measurement of electrical resistance. • Sample of 6% Al annealed at 450–500 °C showed the best photoconductivity effect.

  8. 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

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

    International Nuclear Information System (INIS)

    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 (SnO2) 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

  10. Quantum corrections to low temperature electrical conductivity in Dy doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ajimsha, R.S., E-mail: ajimsha@gmail.com; Das, Amit K.; Joshi, M.P.; Kukreja, L.M.

    2015-08-31

    We have grown thin films of Dy doped ZnO (Dy:ZnO) on sapphire substrate using pulsed laser deposition with Dy concentration varying from 0.05 at.% to 1.8 at.%. These as grown Dy:ZnO thin films were characterized using low temperature four probe electrical measurements (in the range ~ 300 K to 4 K). All the Dy:ZnO thin films showed metal like behavior with a transition from positive to negative temperature coefficient of resistivity (TCR) and again to positive TCR with an increase of Dy concentration. This anomaly in conduction mechanism was investigated by considering quantum corrections to classical Boltzmann conductivity. All the Dy:ZnO thin films also exhibited negative magneto-resistance that supported for a significant contribution of weak localization in quantum corrections to conductivity. - Highlights: • Dy doped ZnO films were grown on sapphire substrate using pulsed laser deposition. • All the Dy doped ZnO films show metal like behavior according to Mott's criteria. • All the Dy doped ZnO thin films exhibited negative magneto-resistance. • Observation of weak localization leading to Quantum corrections to conductivity.

  11. Structural properties of ZnO films grown by picosecond pulsed-laser deposition

    International Nuclear Information System (INIS)

    Highlights: ► Textured and epitaxial ZnO films grown by picosecond pulsed-laser deposition. ► Epitaxial relationships evidenced on c-cut and r-cut sapphire substrates. ► Nanocrystallised ZnO films obtained with a growth rate 10 times greater than in nanosecond PLD. - Abstract: Zinc oxide thin films have been grown on c-cut (0 0 0 1) and r-cut (11¯02) sapphire substrates by pulsed-laser deposition using a Nd:YAG laser operating at 355 nm in picosecond regime (pulse duration: 42 ps). The composition and the structural properties of the films have been investigated by scanning electron microscopy, Rutherford backscattering spectroscopy and X-ray diffraction according to different substrate temperatures. The RBS spectra show a Zn/O ratio close to 1.1 with a constant in-depth oxygen concentration. The XRD diagrams in Bragg–Brentano geometry display a preferred orientation depending on the used substrate. The large width of XRD peaks is indicative of a small coherence length. In addition, according to the pole figures recorded in asymmetric configuration, epitaxial relationships between substrate and film are evidenced. An increase in the substrate temperature leads to a film crystalline quality improvement. The results are discussed regarding the well-known properties of ZnO films obtained by nanosecond and femtosecond PLD.

  12. Electrical and optical properties of Ti doped ZnO films grown on glass substrate by atomic layer deposition

    International Nuclear Information System (INIS)

    Highlights: • Ti doped ZnO films were prepared on Corning XG glass substrate by ALD. • The electrical properties and optical properties were systematically investigated. • An optimized Ti doped ZnO films had low resistivity and excellent optical transmittance. - Abstract: Titanium doped zinc oxide (Ti doped ZnO) films were prepared by atomic layer deposition methods at a deposition temperature of 200 °C. The Ti content in Ti doped ZnO films was varied from 5.08 at.% to 15.02 at.%. X-ray diffraction results indicated that the crystallinity of the Ti doped ZnO films had degraded with increasing Ti content. Transmission electron microscopy was used to investigate the microstructural evolution of the Ti doped ZnO films, showing that both the grain size and crystallinity reduced with increasing Ti content. The electrical resistivity of the Ti doped ZnO films showed a minimum value of 1.6 × 10−3 Ω cm with the Ti content of 6.20 at.%. Furthermore, the Ti doped ZnO films exhibited excellent transmittance

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

    International Nuclear Information System (INIS)

    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

  14. 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.

  15. Mechanical, structural and thermal properties of Ag-Cu and ZnO reinforced polylactide nanocomposite films.

    Science.gov (United States)

    Ahmed, Jasim; Arfat, Yasir Ali; Castro-Aguirre, Edgar; Auras, Rafael

    2016-05-01

    Plasticized polylactic acid (PLA) based nanocomposite films were prepared by incorporating polyethylene glycol (PEG) and two selected nanoparticles (NPs) [silver-copper (Ag-Cu) alloy (<100nm) and zinc oxide (ZnO) (<50 and <100nm)] through solvent casting method. Incorporation of Ag-Cu alloy into the PLA/PEG matrix increased the glass transition temperature (Tg) significantly. The crystallinity of the nanocomposites (NCs) was significantly influenced by NP incorporation as evidenced from differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis. The PLA nanocomposite reinforced with NPs exhibited much higher tensile strength than that of PLA/PEG blend. Melt rheology of NCs exhibited a shear-thinning behavior. The mechanical property drastically reduced with a loading of NPs, which is associated with degradation of PLA. SEM micrographs exhibited that both Ag-Cu alloy and ZnO NPs were dispersed well in the PLA film matrix. PMID:26893045

  16. Diffusion of phosphorus and arsenic using ampoule-tube method on undoped ZnO thin films and electrical and optical properties of P-type ZnO thin films

    Science.gov (United States)

    So, Soon-Jin; Park, Choon-Bae

    2005-12-01

    To investigate ZnO thin films, which are in the spotlight of next generation short wavelength LEDs and semiconductor lasers, the ZnO thin films were deposited using RF sputtering system in this study. The substrate temperature and work pressure were set at 300 °C and 5.2 mTorr, respectively, in the sputtering process of ZnO thin films and ZnO 5N was used as the purity target. The thickness of ZnO thin films was about 2.1 μm at the time of SEM analysis after the sputtering process. Phosphorus (P) and arsenic (As) were diffused in an ampoule tube of below 5×10 -7 Torr into the undoped ZnO thin films sputtered by RF magnetron sputtering system. The doping sources of phosphorus and arsenic were Zn 3P 2 and ZnAs 2. The diffusion of these elements was performed at the temperatures of 500, 600, and 700 °C for 3 h. Diffusion process of the conductive ZnO thin films, which have n-type and p-type properties, has been discovered. The ZnO thin films in this study showed not only very high carrier concentration of above 10 17/cm 3 but also low resistivity of below 2.0×10 -2 Ω cm.

  17. 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.

  18. Sn doping effects on the electro-optical properties of sol gel derived transparent ZnO films

    International Nuclear Information System (INIS)

    Undoped and tin (Sn) doped ZnO films have been deposited by sol gel spin coating method. The Sn/Zn nominal volume ratio was 1, 3 and 5% in the solution. The effect of Sn incorporation on structural and electro-optical properties of ZnO films was investigated. All the films have polycrystalline structure, with a preferential growth along the ZnO (002) plane. The crystallite size was calculated using a well-known Scherrer's formula and found to be in the range of 26-16 nm. X-ray diffraction patterns of the films showed that Sn incorporation leads to substantial changes in the structural characteristics of ZnO films. The SEM measurements showed that the surface morphology of the films was affected from the Sn incorporation. The highest average optical transmittance value in the visible region was belonging to the undoped ZnO film. The optical band gap and Urbach energy values of these films were determined. The absorption edge shifted to the lower energy depending on the Sn dopant. The shift of absorption edge is associated with shrinkage effect. The electrical conductivity of the ZnO film enhanced with the Sn dopant. From the temperature dependence of conductivity measurements, the activation energy of ZnO film increased with Sn incorporation.

  19. 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.

  20. Chitosan/poly (vinyl alcohol) films containing ZnO nanoparticles and plasticizers

    Energy Technology Data Exchange (ETDEWEB)

    Vicentini, Denice S. [Mechanical Engineering Department, Federal University of Santa Catarina, University Campus, 88040-900 Florianopolis, Santa Catarina (Brazil); Smania, Arthur [Microbiology and Parasitology Department, Federal University of Santa Catarina, University Campus, 88040-900 Florianopolis, Santa Catarina (Brazil); Laranjeira, Mauro C.M., E-mail: mauro@qmc.ufsc.br [Mechanical Engineering Department, Federal University of Santa Catarina, University Campus, 88040-900 Florianopolis, Santa Catarina (Brazil); Chemistry Department, QUITECH, Federal University of Santa Catarina, University Campus, 88040-900 Florianopolis, Santa Catarina (Brazil)

    2010-05-10

    In this study ZnO nanoparticles were prepared by the Pechini method from a polyester by reacting citric acid with ethylene glycol in which the metal ions are dissolved, and incorporated into blend films of chitosan (CS) and poly (vinyl alcohol) (PVA) with different concentrations of polyoxyethylene sorbitan monooleate, Tween 80 (T80). These films were characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), swelling degree, degradation of films in Hank's solution and the mechanical properties. Besides these characterizations, the antibacterial activity of the films was tested, and the films containing ZnO nanoparticles showed antibacterial activity toward the bacterial species Staphylococcus aureus. The observed antibacterial activity in the composite films prepared in this work suggests that they may be used as hydrophilic wound and burn dressings.

  1. Chitosan/poly (vinyl alcohol) films containing ZnO nanoparticles and plasticizers

    International Nuclear Information System (INIS)

    In this study ZnO nanoparticles were prepared by the Pechini method from a polyester by reacting citric acid with ethylene glycol in which the metal ions are dissolved, and incorporated into blend films of chitosan (CS) and poly (vinyl alcohol) (PVA) with different concentrations of polyoxyethylene sorbitan monooleate, Tween 80 (T80). These films were characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), swelling degree, degradation of films in Hank's solution and the mechanical properties. Besides these characterizations, the antibacterial activity of the films was tested, and the films containing ZnO nanoparticles showed antibacterial activity toward the bacterial species Staphylococcus aureus. The observed antibacterial activity in the composite films prepared in this work suggests that they may be used as hydrophilic wound and burn dressings.

  2. Metal-semiconductor transition in undoped ZnO films deposited by spray pyrolysis

    International Nuclear Information System (INIS)

    ZnO films were deposited on glass substrate by using spray pyrolysis method. Films were deposited at different solution molarities 0.02 and 0.1 M. The films are highly transparent in the visible range of the electromagnetic spectrum with a transmission reaching up values to 90%. Band gaps were calculated as 3.24 and 3.28 eV with the help of transmission spectrums. When the solution molarity of the sprayed solution is increased from 0.02 to 0.1 M, carrier concentrations of the films increase from 1.6x1019 cm-3 to 5.1x1019 cm-3. Temperature-dependent conductivity measurements of these conducting and transparent films also showed, for the first time, a metal-semiconductor transition (MST). The deposited ZnO films show metallic conductivity above ∼420 K and semiconducting behavior at temperatures below it

  3. Pulsed laser deposition of piezoelectric ZnO thin films for bulk acoustic wave devices

    Energy Technology Data Exchange (ETDEWEB)

    Serhane, Rafik, E-mail: rserhane@cdta.dz [Centre for Development of Advanced Technologies, Cité 20 Août 1956, Baba Hassen, BP: 17, DZ-16303 Algiers (Algeria); Abdelli-Messaci, Samira; Lafane, Slimane; Khales, Hammouche; Aouimeur, Walid [Centre for Development of Advanced Technologies, Cité 20 Août 1956, Baba Hassen, BP: 17, DZ-16303 Algiers (Algeria); Hassein-Bey, Abdelkadder [Centre for Development of Advanced Technologies, Cité 20 Août 1956, Baba Hassen, BP: 17, DZ-16303 Algiers (Algeria); Micro and Nano Physics Group, Faculty of Sciences, University Saad Dahlab of Blida (USDB), BP. 270, DZ-09000 Blida (Algeria); Boutkedjirt, Tarek [Equipe de Recherche Physique des Ultrasons, Faculté de Physique, Université des Sciences et de la Technologie Houari Boumediene (USTHB), BP 32, El-Alia, Bab-Ezzouar, DZ-16111 Algiers (Algeria)

    2014-01-01

    Piezoelectric properties of ZnO thin films have been investigated for micro-electro-mechanical systems (MEMS). Wurtzite ZnO structure was prepared on different substrates (Si (1 0 0), Pt (1 1 1)/Ti/SiO{sub 2}/Si and Al (1 1 1)/SiO{sub 2}/Si) at different substrate temperatures (from 100 to 500 °C) by a pulsed laser deposition (PLD) technique. X-ray diffraction (XRD) characterization showed that the ZnO films were highly c-axis (0 0 2) oriented, which is of interest for various piezoelectric applications. Scanning electron microscopy (SEM) showed evidence of honeycomb-like structure on the surface and columnar structure on the cross-section. In the case of ZnO on Al, ZnO exhibited an amorphous phase at the ZnO/Al interface. The XRD measurements indicated that the substrate temperature of 300 °C was the optimum condition to obtain high quality (strongest (0 0 2) peak with the biggest associated grain size) of crystalline ZnO on Pt and on Al and that 400 °C was the optimum one on Si. ZnO on Al exhibits smallest rocking curve width than on Pt, leading to better crystalline quality. The ZnO films were used in bulk acoustic wave (BAW) transducer. Electrical measurements of the input impedance and S-Parameters showed evidence of piezoelectric response. The electromechanical coupling coefficient was evaluated as K{sub eff}{sup 2}=5.09%, with a quality factor Q{sub r} = 1001.4.

  4. Pulsed laser deposition of piezoelectric ZnO thin films for bulk acoustic wave devices

    International Nuclear Information System (INIS)

    Piezoelectric properties of ZnO thin films have been investigated for micro-electro-mechanical systems (MEMS). Wurtzite ZnO structure was prepared on different substrates (Si (1 0 0), Pt (1 1 1)/Ti/SiO2/Si and Al (1 1 1)/SiO2/Si) at different substrate temperatures (from 100 to 500 °C) by a pulsed laser deposition (PLD) technique. X-ray diffraction (XRD) characterization showed that the ZnO films were highly c-axis (0 0 2) oriented, which is of interest for various piezoelectric applications. Scanning electron microscopy (SEM) showed evidence of honeycomb-like structure on the surface and columnar structure on the cross-section. In the case of ZnO on Al, ZnO exhibited an amorphous phase at the ZnO/Al interface. The XRD measurements indicated that the substrate temperature of 300 °C was the optimum condition to obtain high quality (strongest (0 0 2) peak with the biggest associated grain size) of crystalline ZnO on Pt and on Al and that 400 °C was the optimum one on Si. ZnO on Al exhibits smallest rocking curve width than on Pt, leading to better crystalline quality. The ZnO films were used in bulk acoustic wave (BAW) transducer. Electrical measurements of the input impedance and S-Parameters showed evidence of piezoelectric response. The electromechanical coupling coefficient was evaluated as Keff2=5.09%, with a quality factor Qr = 1001.4.

  5. Effect of substrate temperature on structural and optical properties of spray deposited ZnO thin films

    Directory of Open Access Journals (Sweden)

    Larbah Y.

    2015-09-01

    Full Text Available Undoped ZnO thin films have been prepared on glass substrates at different substrate temperatures by spray pyrolysis method. The effect of temperature on the structural, morphological and optical properties of n-type ZnO films was studied. The X-ray diffraction (XRD results confirmed that the ZnO thin films were polycrystalline with wurtzite structure. Scanning electron microscopy (SEM measurements showed that the surface morphology of the films changed with temperature. The studies demonstrated that the ZnO film had a transmission of about 85 % and energy gap of 3.28 eV at 450 °C. The RBS measurements revealed that ZnO layers with a thickness up to 200 nm had a good stoichiometry.

  6. ZnSe and ZnO film growth by pulsed-laser deposition

    Science.gov (United States)

    Ryu, Y. R.; Zhu, S.; Han, S. W.; White, H. W.; Miceli, P. F.; Chandrasekhar, H. R.

    1998-05-01

    ZnSe and ZnO films have been deposited on (001) GaAs substrates under different pressures by pulsed-laser deposition (PLD) with a 193 nm laser beam. The ambient pressures were changed from 8×10 -6 to 5×10 -2 Torr with high-purity argon gas for ZnSe and oxygen gas for ZnO. X-ray diffraction (XRD) measurement was performed on these samples. The FWHM's of X-ray theta-rocking curves for the (004) peaks of ZnSe films were less than 0.5°. X-ray data show that high-quality ZnO films can be also synthesized by PLD.

  7. Production of high-quality ZnO films by the two-step annealing method

    Science.gov (United States)

    Ye, J. D.; Gu, S. L.; Zhu, S. M.; Qin, F.; Liu, S. M.; Liu, W.; Zhou, X.; Hu, L. Q.; Zhang, R.; Shi, Y.; Zheng, Y. D.

    2004-11-01

    In this study, a two-step annealing method is advanced to produce high-quality ZnO films with excellent structural, electrical, and optical properties. The effects of oxygen and nitrogen annealing on the properties of undoped ZnO films are reversible to each other and are attributed to the creation and annihilation of extrinsic trap states of antisite oxygen OZn and oxygen vacancies VO, which result from the chemisorption and desorption of oxygen, respectively. Moreover, annealing in nitrogen causes slight nitrogen incorporation, subsequently increasing the resistivity and inducing compressive stress in the film. The key to this two-step method is to keep the chemisorption and desorption of oxygen in equilibrium. Due to the similarity of annealing ambient with the growth condition, this process can be transplanted and employed in the in situ preparation of high-quality ZnO epilayers.

  8. Preparation and gas-sensing property of parallel-aligned ZnO nanofibrous films

    Indian Academy of Sciences (India)

    Zikui Bai; Weilin Xu; Changsheng Xie; Mingchao Dong; Shunping Zhang; Jie Xu; Shili Xiao

    2013-08-01

    Parallel-aligned zinc oxide (ZnO) nanofibrous films fabricated by using electrospinning technique were used in gas sensors for the detection of ethanol and formaldehyde. The morphologies and crystal structures of the films were characterized by field-emission scanning electron microscopy (FE–SEM) and X-ray diffraction (XRD), respectively. FE–SEM results showed that ZnO nanofibres had an approximate diameter of 100–300 nm and consisted of hexagonal wurtzite structure ZnO nanocrystals with a primary particle diameter of 20–50 nm. The results of resistance–temperature characteristics and responses to ethanol and formaldehyde indicated that the parallelaligned ZnO nanofibrous film had a low activation energy (0.246 eV), a low optimum operating temperature and a high response. The response and recovery had a high rate in the initial stage and a low rate in the later stage. The parallel-aligned ZnO nanofibrous film had excellent potential application for formaldehyde sensor.

  9. Heteroepitaxial growth of nonpolar Cu-doped ZnO thin film on MnS-buffered (100) Si substrate

    Science.gov (United States)

    Nakamura, Tatsuru; Nguyen, Nam; Nagata, Takahiro; Takahashi, Kenichiro; Ri, Sung-Gi; Ishibashi, Keiji; Suzuki, Setsu; Chikyow, Toyohiro

    2015-06-01

    The preparation of nonpolar ZnO and Cu-doped ZnO thin films on Si substrates was studied for the application to the fabrication of green-light-emitting diodes. The use of rocksalt MnS and wurtzite AlN as buffer layers is a key technology for achieving the heteroepitaxial growth of nonpolar ZnO thin film on a (100) Si substrate. X-ray diffraction and photoluminescence measurements revealed that deposition under a high oxygen partial pressure (∼1 Torr) can enhance the nonpolar crystallization of undoped ZnO, and can simultaneously suppress the formation of defects such as oxygen vacancies. These techniques can be also applied to the growth of Cu-doped ZnO. A room-temperature photoluminescence study revealed that nonpolar [11\\bar{2}0]-oriented Cu-doped ZnO film exhibits enhanced green emission owing to the doped Cu ions.

  10. Near-infrared optical constants and optical polarization properties of ZnO thin films

    International Nuclear Information System (INIS)

    The optical characteristics of ZnO thin films deposited on Si (111) and quartz at temperature < 50 °C using reactive RF sputtering deposition were examined within the near-infrared (NIR) region. From the X-ray diffraction observations, it was found that the films show a polycrystalline structure. X-ray photoelectron spectroscopy analysis shows the chemical bonding states of zinc and oxygen in the surface of the films and confirms the formation of Zn–O bonds. The field emission scanning electron microscopy and the atomic force microscopy images of the films shown an almost uniform distribution and the surfaces are smooth with grains of the order of 40–60 nm. The average surface roughness was in the range of 3.15–24.33 nm. Over a wavelength range 700–2500 nm, the optical constants of the films were obtained by analysis of the measured ellipsometric spectra using the Cauchy–Urbach model. Refractive indices and extinction coefficients of the ZnO films were determined to be in the range n = 1.65–1.73 and κ = 0.0060–0.029, respectively. Also, the s- and p-polarized optical properties (transmittance and reflectance) of the films have been measured at different angles of incidence in the UV–Vis–NIR spectral range. In addition, calculations have been carried out in order to determine the optical absorptance by using the conservation of energy. The films reveal a high transmittance (85%–95%), low reflectance (5%–15%), and very low absorptance (< 1%) at normal incidence. This means that the sputtered polycrystalline ZnO films could be good candidates for antireflection (AR) optical coatings. - Highlights: • The ZnO films exhibited a polycrystalline structure. • The as-deposited ZnO films are homogeneous and continuous. • The Cauchy–Urbach model can represent sufficiently the films in the NIR range. • The films reveal a high transmittance, low reflectance and very low absorptance. • Polycrystalline ZnO films could be good candidates for

  11. Epitaxial ZnO films grown on ZnO-buffered c-plane sapphire substrates by hydrothermal method

    International Nuclear Information System (INIS)

    ZnO films are hydrothermally grown on ZnO-buffered c-plane sapphire substrates at a low temperature of 70 deg. C. A radio-frequency (RF) reactive magnetron sputtering has been used to grow the ZnO buffer layers. X-ray diffraction, scanning electron microscopy, and room temperature photoluminescence are carried out to characterize the structure, morphology and optical property of the films. It is found that the films are stress-free. The epitaxial relationship between the ZnO film and the c-plane sapphire substrate is found to be ZnO (0 0 0 1)||Al2O3 (0 0 0 1) in the surface normal and ZnO[101-bar 0]||Al2O3[112-bar 0] in plane. Sapphire treatment, as such acid etching, nitridation, and oxidation are found to influence the nucleation of the film growth, and the buffer layers determine the crystalline quality of the ZnO films. The maximum PL quantum efficiency of ZnO films grown with hydrothermal method is found to be about 80% of single-crystal ZnO.

  12. Fabrication and Characterization of High-Crystalline Nanoporous ZnO Thin Films by Modified Thermal Evaporation System

    Science.gov (United States)

    Islam, M. S.; Hossain, M. F.; Razzak, S. M. A.; Haque, M. M.; Saha, D. K.

    2016-05-01

    The aim of this work is to fabricate high-crystalline nanoporous zinc oxide (ZnO) thin films by a modified thermal evaporation system. First, zinc thin films have been deposited on bare glass substrate by the modified thermal evaporation system with pressure of 0.05mbar, source-substrate distance of 3cm and source temperature 700∘C. Then, high-crystalline ZnO thin film is obtained by annealing at 500∘C for 2h in atmosphere. The prepared ZnO films are characterized with various deposition times of 10min and 20min. The structural property was investigated by X-ray diffractometer (XRD). The optical bandgap and absorbance/transmittance of these films are examined by ultraviolet/visible spectrophotometer. The surface morphological property has been observed by scanning electron microscope (SEM). ZnO films have showed uniform nanoporous surface with high-crystalline hexagonal wurtzite structure. The ZnO films prepared with 20min has excitation absorption-edge at 369nm, which is blueshifted with respect to the bulk absorption-edge appearing at 380nm. The gap energy of ZnO film is decreased from 3.14eV to 3.09eV with increase of the deposition time, which can enhance the excitation of ZnO films by the near visible light, and is suitable for the application of photocatalyst of waste water cleaning and polluted air purification.

  13. Selective Purcell enhancement of defect emission in ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Haglund, Jr, Richard F [ORNL

    2012-01-01

    A zinc interstitial defect present but unobservable in ZnO thin films annealed at 500 C in oxygen or in atmosphere was selectively detected by interaction of the film with an Ag surface-plasmon polariton. The time-dependent differential reflectivity of the ZnO near the ZnO/MgO interface exhibited a subpicosecond decay followed by a several nanosecond recovery, consistent with the Purcell-enhanced Zn interstitial luminescence seen in Ag-ZnO heterostructures. Heterostructures annealed at other temperatures showed significantly greater band-edge photoluminescence and no evidence of the Zn interstitial defect.

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

    International Nuclear Information System (INIS)

    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

  15. 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.

  16. Hydrogen-incorporated ZnO nanowire films: stable and high electrical conductivity

    International Nuclear Information System (INIS)

    Post-growth hydrogen annealing treatment of highly oriented ZnO nanowire (NW) films (ZnO : H) results in high electrical conductivity (3.7 × 103 S m−1) and fully suppressed defect emission at room temperature. The formation of hydrogen-related vacancy complexes is responsible for the suppression of vacancies ( Vo+ and Vo2+), leading to a reduction in defect-based emission. ZnO : H NW films show five orders larger stable electrical conductance with a four-fold increment in carrier mobility (7–28 cm2 V−1 s−1). As compared with pristine NWs, the carrier concentration in ZnO : H NW films increases from 1015 to 1019 cm−3, which is in the range of commercial transparent conducting oxides. X-ray photoelectron spectroscopy and secondary ion mass spectrometry analyses reveal stable OH bond formation, which strongly supports the prediction of H doping. These films offer a promising conducting oxide platform for photovoltaic applications. (paper)

  17. 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.

  18. Controlling the processable ZnO and polythiophene interface for dye-sensitized thin film organic solar cells

    International Nuclear Information System (INIS)

    Dye-sensitized thin film hybrid solar cells (DS thin film solar cell) were fabricated by one-pot process using solution processable zinc oxide (ZnO) precursor as electron acceptor, ester-functionalized polythiophene copolymer as donor and a squaraine dye. Incorporation of slight amount of ester functionality (6%) in the regioregular poly-3-hexylthiophene (P3HT) main chain leads to enhancement in the photoconversion efficiency of the ester functionalized polymer (P3HT-E) from 0.8% to about 1% (AM1.5, 100 mw/cm2). Photocurrent associated with both of the P3HT-E (400–650 nm) and the squaraine dye (650–750 nm) were observed in incident photon to current efficiency curve of the DS thin film solar cell. This proves that the ZnO/dye/P3HT-E interface could be fabricated by one-pot coating process from ternary mixture based on a ZnO precursor. - Highlights: • Single step and one pot fabrication of dye-sensitized polymer-ZnO hybrid solar cells. • In situ generation of ZnO using its diethyl zinc precursor. • Enhanced photovoltaic performance by introduction of ester functionalized polymers. • Demonstration of far-red photon harvesting by polymer-dye-ZnO ternary blend

  19. Screen printed nanosized ZnO thick film

    Indian Academy of Sciences (India)

    Bindu Krishnan; V P N Nampoori

    2005-06-01

    Nanosized ZnO was prepared by polyol synthesis. Fluorescence spectrum of the ZnO colloid at varying pump intensities was studied. The powder was extracted and characterized by XRD and BET. The extracted powder was screen printed on glass substrates using ethyl cellulose as binder and turpinol as solvent. Coherent back scattering studies were performed on the screen printed sample which showed evidence of weak localization. The screen printed pattern showed strong UV emission.

  20. Enhanced photovoltaic performance of dye sensitized solar cells using one dimensional ZnO nanorod decorated porous TiO{sub 2} film electrode

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Long; Ma, Qing-lan [School of Mathematic and Physics, Changzhou University, Jiangsu 213164 (China); Cai, Yungao [Department of Science and Technology, Baoshan University, Yunnan 678000 (China); Huang, Yuan Ming, E-mail: dongshanisland@126.com [School of Mathematic and Physics, Changzhou University, Jiangsu 213164 (China)

    2014-02-15

    A low cost and effective working electrode with one dimensional ZnO nanorod grown on the porous TiO{sub 2} film is used to improve the power conversion efficiency of dye sensitized solar cells. The one dimensional ZnO nanorod is introduced into the porous TiO{sub 2} film by a simple and facile hydrothermal route, and the obtained composite film is characterized using the field-emission scan electron microscopy, X-ray diffractometer and photoluminescence spectroscopy. The photocurrent–voltage curves of fabricated dye sensitized solar cells are measured by a solar cell measurement system. Compared with the bare porous TiO{sub 2} film based dye sensitized solar cell, it is found that the power conversion efficiency of dye sensitized solar cell with ZnO nanorod decorated TiO{sub 2} porous film was improved by more than triple. It is mainly believed that the improved power conversion efficiency of dye sensitized solar cell is ascribed to the increased dye adsorption amount and formation of energy barrier between ZnO nanorod and porous TiO{sub 2} film.

  1. Enhanced photovoltaic performance of dye sensitized solar cells using one dimensional ZnO nanorod decorated porous TiO2 film electrode

    International Nuclear Information System (INIS)

    A low cost and effective working electrode with one dimensional ZnO nanorod grown on the porous TiO2 film is used to improve the power conversion efficiency of dye sensitized solar cells. The one dimensional ZnO nanorod is introduced into the porous TiO2 film by a simple and facile hydrothermal route, and the obtained composite film is characterized using the field-emission scan electron microscopy, X-ray diffractometer and photoluminescence spectroscopy. The photocurrent–voltage curves of fabricated dye sensitized solar cells are measured by a solar cell measurement system. Compared with the bare porous TiO2 film based dye sensitized solar cell, it is found that the power conversion efficiency of dye sensitized solar cell with ZnO nanorod decorated TiO2 porous film was improved by more than triple. It is mainly believed that the improved power conversion efficiency of dye sensitized solar cell is ascribed to the increased dye adsorption amount and formation of energy barrier between ZnO nanorod and porous TiO2 film.

  2. Influence of high-pressure hydrogen treatment on structural and electrical properties of ZnO thin films

    International Nuclear Information System (INIS)

    ZnO thin films were treated by high-pressure hydrogen (H2). Scanning electron microscope (SEM) images show that the surface morphology of ZnO films has been changed significantly by H2 treatment. X-ray diffraction patterns show that the Zn(OH)2 phases formed after H2 treatment. The X-ray photoelectron spectroscopy results indicate that H atoms were doped into the surface of ZnO by forming H-O-Zn bond. The phenomenon shows that it is easy to form O-H bond in ZnO rather than H interstitial atom under high-pressure hydrogen circumstance.

  3. Preparation and characterization of nanostructured ZnO thin films for photoelectrochemical splitting of water

    Indian Academy of Sciences (India)

    Monika Gupta; Vidhika Sharma; Jaya Shrivastava; Anjana Solanki; A P Singh; V R Satsangi; S Dass; Rohit Shrivastav

    2009-02-01

    Nanostructured zinc oxide thin films (ZnO) were prepared on conducting glass support (SnO2: F overlayer) via sol–gel starting from colloidal solution of zinc acetate 2-hydrate in ethanol and 2-methoxy ethanol. Films were obtained by spin coating at 1500 rpm under room conditions (temperature, 28–35°C) and were subsequently sintered in air at three different temperatures (400, 500 and 600°C). The evolution of oxide coatings under thermal treatment was studied by glancing incidence X-ray diffraction and scanning electron microscopy. Average particle size, resistivity and bandgap energy were also determined. Photoelectrochemical properties of thin films and their suitability for splitting of water were investigated. Study suggests that thin films of ZnO, sintered at 600°C are better for photoconversion than the films sintered at 400 or 500°C. Plausible explanations have been provided.

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

    International Nuclear Information System (INIS)

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

  5. Superhydrophilic zinc oxide film prepared by controlling ZnO microrods growth and its attractive recyclable photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Kai, E-mail: daikai940@chnu.edu.cn [College of Physics and Electronic Information, Huaibei Normal University, Huaibei, 235000 (China); Chen, Zheng [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, 215123 (China); Lu, Luhua, E-mail: lhlu@whut.edu.cn [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, 215123 (China); State Key Lab of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Zhu, Guangping; Liu, Zhongliang; Liu, Qinzhuang [College of Physics and Electronic Information, Huaibei Normal University, Huaibei, 235000 (China)

    2013-07-31

    Superhydrophilic functional materials have been found to be of great value for a variety of practical applications in recent years. In this paper, zinc oxide (ZnO) microrod films have been directly synthesized on a large-area zinc substrate via a simple solution method. Morphological and structural observation and crystallinity of the grown products were carried out using scanning electron microscopy, X-ray diffraction, energy dispersive spectrometer, transmission electron microscopy, ultraviolet (UV)–vis diffuse reflectance spectroscopy and photoluminescence (PL) spectroscopy. The influence of reaction time on the size and shapes of the as-prepared ZnO samples was studied. It was found that superhydrophilic ZnO films at reaction time of 20 h were made up of uniform pure ZnO microrods with 600 nm in average diameter and 6 μm in length. Room-temperature PL spectra of the ZnO products showed a UV emission and a broad green band. Photocatalytic performance and sample stability were studied. Under UV light irradiation over 95% of methylene blue was degraded by ZnO microrod films in 4 h, ZnO microrod film can be easily separated from the solution, and no observable performance degradation was observed after 5 cycles. - Highlights: • Superhydrophilic ZnO microrod films were successfully synthesized. • ZnO microrods are single crystalline with the hexagonal wurtzite structure. • ZnO microrod films can be easily separated from the solution. • Superhydrophilic ZnO microrod films can be reused.

  6. Superhydrophilic zinc oxide film prepared by controlling ZnO microrods growth and its attractive recyclable photocatalytic performance

    International Nuclear Information System (INIS)

    Superhydrophilic functional materials have been found to be of great value for a variety of practical applications in recent years. In this paper, zinc oxide (ZnO) microrod films have been directly synthesized on a large-area zinc substrate via a simple solution method. Morphological and structural observation and crystallinity of the grown products were carried out using scanning electron microscopy, X-ray diffraction, energy dispersive spectrometer, transmission electron microscopy, ultraviolet (UV)–vis diffuse reflectance spectroscopy and photoluminescence (PL) spectroscopy. The influence of reaction time on the size and shapes of the as-prepared ZnO samples was studied. It was found that superhydrophilic ZnO films at reaction time of 20 h were made up of uniform pure ZnO microrods with 600 nm in average diameter and 6 μm in length. Room-temperature PL spectra of the ZnO products showed a UV emission and a broad green band. Photocatalytic performance and sample stability were studied. Under UV light irradiation over 95% of methylene blue was degraded by ZnO microrod films in 4 h, ZnO microrod film can be easily separated from the solution, and no observable performance degradation was observed after 5 cycles. - Highlights: • Superhydrophilic ZnO microrod films were successfully synthesized. • ZnO microrods are single crystalline with the hexagonal wurtzite structure. • ZnO microrod films can be easily separated from the solution. • Superhydrophilic ZnO microrod films can be reused

  7. Characteristics of laser-annealed ZnO thin film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jun-Je; Bak, Jun-Yong; Lee, Jong-Hoon [Department of Nano Semiconductor, Korea Maritime University, Busan 606-791 (Korea, Republic of); Kim, Hong Seung, E-mail: hongseung@hhu.ac.k [Department of Nano Semiconductor, Korea Maritime University, Busan 606-791 (Korea, Republic of); Jang, Nak-Won [Department of Electrical Engineering, Korea Maritime University, Busan 609-791 (Korea, Republic of); Yun, Young [Department of Radio Communication Engineering, Korea Maritime University, Busan 606-791 (Korea, Republic of); Lee, Won-Jae [Department of Nano Technology, Dong Eui University, Busan 614-714 (Korea, Republic of)

    2010-03-31

    We investigated the effects of laser annealing on ZnO thin film transistors (TFTs). ZnO layers were deposited on a bottom-gate patterned Si substrate by radio-frequency sputtering at room temperature. Laser annealing of the ZnO films reduced the full width at half maximum of the ZnO (002) diffraction peak from 0.49{sup o} to 0.1{sup o}. It reveals that the crystalline quality is improved by annealing effect. A SiO{sub 2} formed in low temperature was used as the gate dielectric. Unannealed ZnO-TFTs were operated in enhancement mode with a threshold voltage of 21.6 V. They had a field-effect mobility of 0.004 cm{sup 2}/Vs and an on/off current ratio of 134. Laser annealing of the ZnO-TFTs by 200 laser pulses reduced their threshold voltage to 0.6 V and increased their field-effect mobility to 5.08 cm{sup 2}/Vs. The increase of mobility is originated from the crystallization enhancement of ZnO films after laser annealing.

  8. Effect of ZnO films on CdTe solar cells

    Institute of Scientific and Technical Information of China (English)

    Liu Tingliang; He Xulin; Zhang Jingquan; Feng Lianghuan; Wu Lili; Li Wei; Zeng Guanggen; Li Bing

    2012-01-01

    The ZnO high resistivity transparent (HRT) layers were prepared by DC magnetron sputtering on the 1mm borosilicate glass with 150 nm 1TO coating.The structural,optical and electrical properties of the as-deposited films were investigated by XRD,UV/Vis spectroscopy and four-probe technology.The interface characters of the ITO/ZnO and ZnO/CdS systems were studied by ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS) depth profiling tests.The results show that ZnO has good optical and electrical properties.The insertion of the ZnO films decreases the energy barrier between ITO and CdS films.The energy conversion efficiency and quantum efficiency were found to be 12.77% (8.9%) and > 90% (79%) with or (without)ZnO films of CdTe solar cells.Furthermore,the effect of thickness,mobility and carrier density of ZnO films on CdTe solar cells was analyzed by AMPD-1D.

  9. Influence of process parameters on band gap of AI-doped ZnO film

    Institute of Scientific and Technical Information of China (English)

    Diqiu HUANG; Xiangbin ZENG; Yajuan ZHENG; Xiaojin WANG; Yanyan YANG

    2013-01-01

    This paper presents the influence of process parameters, such as argon (Ar) flow rate, sputtering power and substrate temperature on the band gap of Al-doped ZnO film, Al-doped ZnO thin films were fabricated by radio frequency (RF) magnetron sputtering technology and deposited on polyimide and glass substrates. Under different Ar flow rates varied from 30 to 70 sccm, the band gap of thin films were changed from 3.56 to 3.67 eV. As sputtering power ranged from 125 to 200 W, the band gap was varied from 3.28 to 3.82 eV; the band gap was between 3.41 and 3.88 eV as substrate temperature increases from 150℃ to 300℃. Furthermore, the correlation between carrier concentration and band gap was investigated by HALL. These results demonstrate that the band gap of the Al-doped ZnO thin film can be adjusted by changing the Ar flow rate, sputtering power and substrate temperature, which can improve the performance of semiconductor devices related to Al-doped ZnO thin film.

  10. Formation of Al-doped ZnO thin films on glass by sol-gel process and characterization

    Science.gov (United States)

    Shahid, M. U.; Deen, K. M.; Ahmad, A.; Akram, M. A.; Aslam, M.; Akhtar, W.

    2016-02-01

    In this study, pure ZnO and Al-doped ZnO thin films were developed on glass by sol-gel process followed by drying and annealing in air at 170 and 400 °C, respectively. The surface morphology and structural characteristics were determined through scanning electron microscopy, atomic force microscopy and X-ray diffraction. The Fourier transform infrared spectroscopy validated the formation of Al-doped ZnO film on glass substrate. It was evaluated that 1 at% aluminum (Al) doping in ZnO film showed low electrical resistivity and higher charge carrier concentration due to uniformly dispersed regular shape crystallites as compared to pure ZnO and 2 at% `Al'-doped thin films.

  11. Manufacturing of patterned ZnO films with application for photoinitiated decolorization of malachite green in aqueous solutions

    Indian Academy of Sciences (India)

    Nina V Kaneva; Georgi G Yordanov; Ceco D Dushkin

    2010-04-01

    Patterned thin films, ZnO, are successfully prepared on glass substrates by the sol–gel method using dip-coating technique. The films, formed of ZnO nanocrystallites with hexagonal crystal structure, are characterized by means of scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. The as obtained ZnO films are studied with respect to photo-initiated bleaching of malachite green in aqueous solutions. The bleaching process is investigated at various initial concentrations of malachite green in the aqueous solutions by using ZnO films of different thicknesses. The obtained results are promising for the development of ZnO photocatalysts by the sol–gel method.

  12. Pulsed laser deposited cobalt-doped ZnO thin film

    Science.gov (United States)

    Wang, Li; Su, Xue-qiong; Lu, Yi; Chen, Jiang-bo

    2013-09-01

    To realize the room-temperature ferromagnetism (RTFM) in diluted magnetic semiconductors (DMS), we prepared a series of Cobalt-doped ZnO thin films using pulsed laser deposition (PLD) at deposition temperatures 500°C under oxygen pressure from 2.5×10-4 Pa to 15 Pa. To elucidate the physical origin of RTFM, Co 2p spectra of cobalt-doped ZnO thin films was measured by X-ray photoelectron spectroscopy (XPS). The magnetic properties of films were measured by an alternating gradient magnetometer (AGM), and the electrical properties were detected by a Hall Effect instrument using the Van der Pauw method. XPS analysis shows that the Co2+ exists and Co clusters and elemental content change greatly in samples under various deposition oxygen pressures. Not only the valence state and elemental content but also the electrical and magnetic properties were changed. In the case of oxygen pressure 10 Pa, an improvement of saturation magnetic moment about one order of magnitude over other oxygen pressure experiments, and the film exhibits ferromagnetism with a curie temperature above room temperature. It was found that the value of carrier concentration in the Co-doped ZnO film under oxygen pressure 10Pa increases about one order of magnitude than the values of other samples under different oxygen pressure. Combining XPS with AGM measurements, we found that the ferromagnetic signals in cobalt-doped ZnO thin film deposited at 500 °C under oxygen pressure 10 Pa only appear with the detectable Co2+ spectra from incompletely oxidized Co metal or Co cluster. So oxygen pressure 10 Pa can be thought the best condition to obtain room-temperature dilute magnetic semiconductor about cobalt-doped ZnO thin films.

  13. Electrical properties of ZnO thin films grown on a-plane sapphire substrates using catalytically generated high-energy H2O

    International Nuclear Information System (INIS)

    The electrical properties of zinc oxide (ZnO) epitaxial films grown by chemical vapor deposition (CVD) using high-energy H2O generated by H2–O2 reactions on Pt nanoparticles were evaluated. High-energy ZnO precursors formed by the reaction between dimethylzinc gas molecules and H2O molecules were supplied to the substrate surface. The ZnO epitaxial films were grown directly on a-plane sapphire (a-Al2O3) substrates at 773 K without any buffer layer. The electron mobility (μH) at room temperature increased from 30 to 190 cm2V−1 s−1 with increasing film thickness from 100 nm to 2800 nm. The μH increased significantly with decreasing temperature to approximately 100–150 K, but it decreased at temperatures less than 100 K for films thicker than 500 nm. The μH of the ZnO film (189 cm2V−1 s−1) at 290 K increased to 660 cm2V−1 s−1 at 100 K. In contrast, μH hardly changed with temperature for films thinner than 500 nm. According to a two-layer Hall-effect model, the μH and electron concentration of the upper layer were corrected based on the above results, assuming that the degenerate layer had a thickness of 100 nm. - Highlights: • ZnO films were grown by CVD using reaction of high-energy H2O and dimethylzinc gas. • Films were grown on a-plane sapphire substrates at 773 K. • ZnO film at 2.8 µm thick exhibited a large electron mobility of 189 cm2/Vs at room temperature. • From the crystallinity and the electrical properties for various film thicknesses, the structure of the ZnO films was estimated. • The electron mobility and electron concentration of the upper layer were corrected according to a two-layer Hall-effect model

  14. Vibration optimization of ZnO thin film bulk acoustic resonator with ring electrodes

    Science.gov (United States)

    Zhao, Zinan; Qian, Zhenghua; Wang, Bin

    2016-04-01

    A rectangular ZnO thin film bulk acoustic resonator with ring electrodes is presented in this paper to demonstrate the existence of a nearly uniform displacement distribution at the central part of this typical resonator. The variational formulation based on two-dimensional scalar differential equations provides a theoretical foundation for the Ritz method adopted in our analysis. The resonant frequencies and vibration distributions for the thickness-extensional modes of this ring electrode resonator are obtained. The structural parameters are optimized to achieve a more uniform displacement distribution and therefore a uniform mass sensitivity, which guarantee the high accuracy and repeatable measurement for sensor detection in an air or a liquid environment. These results provide a fundamental reference for the design and optimization of the high quality sensor.

  15. ZnO thin film transistor immunosensor with high sensitivity and selectivity

    Science.gov (United States)

    Reyes, Pavel Ivanoff; Ku, Chieh-Jen; Duan, Ziqing; Lu, Yicheng; Solanki, Aniruddh; Lee, Ki-Bum

    2011-04-01

    A zinc oxide thin film transistor-based immunosensor (ZnO-bioTFT) is presented. The back-gate TFT has an on-off ratio of 108 and a threshold voltage of 4.25 V. The ZnO channel surface is biofunctionalized with primary monoclonal antibodies that selectively bind with epidermal growth factor receptor (EGFR). Detection of the antibody-antigen reaction is achieved through channel carrier modulation via pseudo double-gating field effect caused by the biochemical reaction. The sensitivity of 10 fM detection of pure EGFR proteins is achieved. The ZnO-bioTFT immunosensor also enables selectively detecting 10 fM of EGFR in a 5 mg/ml goat serum solution containing various other proteins.

  16. Enhanced the photocatalytic activity of Ni-doped ZnO thin films: Morphological, optical and XPS analysis

    Science.gov (United States)

    Abdel-wahab, M. Sh.; Jilani, Asim; Yahia, I. S.; Al-Ghamdi, Attieh A.

    2016-06-01

    Pure and Ni-doped ZnO thin films with different concentration of Ni (3.5 wt%, 5 wt%, 7 wt%) were prepared by DC/RF magnetron sputtering technique. The X-rays diffraction pattern showed the polycrystalline nature of pure and Ni-doped ZnO thin films. The surface morphology of pure and Ni doped ZnO thin films were investigated through atomic force microscope, which indicated the increase in the grain dimension and surface roughness with increasing the Ni doping. The UV-Visible transmission spectra showed the decrease in the transmittance of doped ZnO thin films with the incorporation of Ni dopants. The surface and chemical state analysis of pure and Ni doped ZnO thin films were investigated by X-rays photoelectron spectroscopy (XPS). The photocatalytic activities were evaluated by an aqueous solution of methyl green dye. The tungsten lamp of 500 W was used as a source of visible light for photocatalytic study. The degradation results showed that the Ni-doped ZnO thin films exhibit highly enhanced photocatalytic activity as compared to the pure ZnO thin films. The enhanced photocatalytic activities of Ni-doped ZnO thin films were attributed to the enhanced surface area (surface defects), surface roughness and decreasing the band gap of Ni-doped ZnO thin films. Our work supports the applications of thin film metal oxides in waste water treatment.

  17. Effect of hydrogen doping in ZnO thin films by pulsed DC magnetron sputtering

    International Nuclear Information System (INIS)

    This study examined the role of hydrogen impurities in highly oriented ZnO thin films. Hydrogen intentionally incorporated was found to play an important role as a donor in n-type conduction, improving the free carrier concentration. The increase in the conductivity of ZnO thin films was attributed to the two centers assigned to isolated hydrogen atoms in the anti-bonding sites as well as bond-centered interstitial hydrogen located between the Zn-O bonds and Zn vacancy passivated by one or two hydrogen atoms. Micro Raman spectroscopy showed two additional modes at approximately 501 and 573 cm-1. These two peaks were attributed to damage to the crystal lattice, which could be explained by the optical-phonon branch at the zone boundary and host lattice defects, such as vacancy clusters, respectively.

  18. Structural, optical and magnetic properties of pulsed laser deposited Co-doped ZnO films

    International Nuclear Information System (INIS)

    Zn1−xCoxO films with different Co concentrations (with x=0.00, 0.10, 0.15, and 0.30) were grown by pulsed laser deposition (PLD) technique. The structural and optical properties of the films were investigated by grazing incidence X-ray diffraction (GIXRD), Raman spectroscopy and photoluminescence (PL). The magnetic properties were measured by conventional magnetometry using a SQUID and simulated by ab-initio calculations using Korring–Khon–Rostoker (KKR) method combined with coherent potential approximation (CPA). The effect of Co-doping on the GIXRD and Raman peaks positions, shape and intensity is discussed. PL studies demonstrate that Co-doping induces a decrease of the bandgap energy and quenching of the UV emission. They also suggest the presence of Zn interstitials when x≥0.15. The 10% Co-doped ZnO film shows ferromagnetism at 390 K with a spontaneous magnetic moment ≈4×10−5 emu and coercive field ≈0.17 kOe. The origin of ferromagnetism is explained based on the calculations using KKR method. - Highlights: • Zn1−xCoxO films (x=0.00, 0.10, 0.15, and 0.30) were grown by (PLD) technique. • Zn0.9Co0.1O film shows ferromagnetism above room temperature. • The origin of ferromagnetism behavior is attributed to the p-d hybridization. • Co-doping induces a decrease of the bandgap energy of the films

  19. Structural, optical and magnetic properties of pulsed laser deposited Co-doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Karzazi, O., E-mail: ouiame_karzazi@hotmail.fr [Centre of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal); LPS, Physics Department, Faculty of Sciences, BP 1796, Fes (Morocco); Sekhar, K.C. [Centre of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal); El Amiri, A. [LPTA, Université Hassan II-Casablanca, Faculté des Sciences, B.P. 5366, Maârif (Morocco); Hlil, E.K. [Institut Néel, CNRS, Université J. Fourier, BP 166, 38042 Grenoble (France); Conde, O. [Departamento de Física, Faculdade de Ciências, Universidade de Lisboa and CeFEMA, Campo Grande, 1749-016 Lisboa (Portugal); Levichev, S. [Research Institute for Chemistry, Nizhni Novgorod State University, 603950 Nizhni Novgorod (Russian Federation); Agostinho Moreira, J. [IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Departamento de Física e Astronomia, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre 687, 4169-007, Porto (Portugal); Chahboun, A. [Centre of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal); FST Tanger, Physics Department, BP 416, Tangier (Morocco); Almeida, A. [IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Departamento de Física e Astronomia, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre 687, 4169-007, Porto (Portugal); Gomes, M.J.M. [Centre of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal)

    2015-12-01

    Zn{sub 1−x}Co{sub x}O films with different Co concentrations (with x=0.00, 0.10, 0.15, and 0.30) were grown by pulsed laser deposition (PLD) technique. The structural and optical properties of the films were investigated by grazing incidence X-ray diffraction (GIXRD), Raman spectroscopy and photoluminescence (PL). The magnetic properties were measured by conventional magnetometry using a SQUID and simulated by ab-initio calculations using Korring–Khon–Rostoker (KKR) method combined with coherent potential approximation (CPA). The effect of Co-doping on the GIXRD and Raman peaks positions, shape and intensity is discussed. PL studies demonstrate that Co-doping induces a decrease of the bandgap energy and quenching of the UV emission. They also suggest the presence of Zn interstitials when x≥0.15. The 10% Co-doped ZnO film shows ferromagnetism at 390 K with a spontaneous magnetic moment ≈4×10{sup −5} emu and coercive field ≈0.17 kOe. The origin of ferromagnetism is explained based on the calculations using KKR method. - Highlights: • Zn{sub 1−x}Co{sub x}O films (x=0.00, 0.10, 0.15, and 0.30) were grown by (PLD) technique. • Zn{sub 0.9}Co{sub 0.1}O film shows ferromagnetism above room temperature. • The origin of ferromagnetism behavior is attributed to the p-d hybridization. • Co-doping induces a decrease of the bandgap energy of the films.

  20. Environmental stability of solution processed Al-doped ZnO naoparticulate thin films using surface modification technique

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • AZO nanoparticulate films were deposited using ultrasonic spray deposition. • Functionalization of solution processed AZO thin films was carried out. • Contact angles and QNM AFM results confirmed the existence of molecular layers. • Environmental stability of AZO films greatly increased with surface modification. - Abstract: The environmental stability of solution processed Al-doped ZnO (AZO) thin films was enhanced by functionalizing the film surface with a thin self-assembled molecular layer. Functionalization of AZO films was performed using two types of molecules having identical 12-carbon alkyl chain termination but different functional groups: dodecanethiol (DDT) and dodecanoic acid (DDA). Surface modified AZO films were examined using electrical resistivity measurements, contact angle measurements and quantitative nanomechanical property mapping atomic force microscopy. The hydrophobic layer inhibits the penetration of oxygen and water into the AZO's grain boundaries thus significantly increasing the environmental stability over unmodified AZO. Surface modified AZO films using DDT exhibited lower electrical resistivity compared to DDA functionalized AZO films. Our study demonstrates a new approach for improving the physical properties of oxide based nanoparticulate films for device applications

  1. Environmental stability of solution processed Al-doped ZnO naoparticulate thin films using surface modification technique

    Energy Technology Data Exchange (ETDEWEB)

    Vunnam, Swathi, E-mail: swathivunnam@gmail.com [Program of Nanoscience and Nanoengineering, South Dakota School of Mines and Technology, Rapid City, SD 57701 (United States); Ankireddy, Krishnamraju; Kellar, Jon [Program of Materials Engineering and Science, South Dakota School of Mines and Technology, Rapid City, SD 57701 (United States); Cross, William, E-mail: William.Cross@sdsmt.edu [Program of Materials Engineering and Science, South Dakota School of Mines and Technology, Rapid City, SD 57701 (United States)

    2014-12-15

    Graphical abstract: - Highlights: • AZO nanoparticulate films were deposited using ultrasonic spray deposition. • Functionalization of solution processed AZO thin films was carried out. • Contact angles and QNM AFM results confirmed the existence of molecular layers. • Environmental stability of AZO films greatly increased with surface modification. - Abstract: The environmental stability of solution processed Al-doped ZnO (AZO) thin films was enhanced by functionalizing the film surface with a thin self-assembled molecular layer. Functionalization of AZO films was performed using two types of molecules having identical 12-carbon alkyl chain termination but different functional groups: dodecanethiol (DDT) and dodecanoic acid (DDA). Surface modified AZO films were examined using electrical resistivity measurements, contact angle measurements and quantitative nanomechanical property mapping atomic force microscopy. The hydrophobic layer inhibits the penetration of oxygen and water into the AZO's grain boundaries thus significantly increasing the environmental stability over unmodified AZO. Surface modified AZO films using DDT exhibited lower electrical resistivity compared to DDA functionalized AZO films. Our study demonstrates a new approach for improving the physical properties of oxide based nanoparticulate films for device applications.

  2. Optical and electrical studies of ZnO thin films heavily implanted with silver ions

    International Nuclear Information System (INIS)

    Thin films of zinc oxide (ZnO) with the thickness of 200 nm have been deposited on quartz substrates by using ion-beam sputtering technique. Then Ag+ ions with the energy of 30 keV have been implanted into as-deposited ZnO films to the fluences in the range of (0.25-1.00)×1017 ions/cm2 to form ZnO:Ag composite layers with different concentrations of the silver impurity. The analysis of the microstructure has shown that the thickness of the ZnO film decreases, and the Ag dopant concentration tends to the saturation with increasing Ag implantation fluence. The ZnO:Ag composite layers reveal the optical selective absorption at the wavelength of the surface plasmon resonance that is typical for silver nanoparticles dispersed in the ZnO matrix. The red shift of the plasmon resonance peak from 480 to 500 nm is observed with the increase in the implantation fluence to 0.75×1017 Ag ions/cm2. Then the absorption peak position starts the backward motion, and the absorption intensity decreases with the subsequent increase in the implantation fluence. The non-monotonic dependence of the absorption peak position on the implantation fluence has been analyzed within of Maxwell Garnet theory and taking into account the strong sputtering of ZnO films during implantation. The ZnO:Ag composite layers exhibit the p-type conductivity indicating that a part of Ag+ ions is in the form of acceptor impurities implanted into the ZnO lattice

  3. Role of evaporation time on the structural and optical properties of ZnO films deposited by thermal evaporator

    Science.gov (United States)

    Khan, Ijaz Ahmad; Noor, Mamoona; Rehman, Aatiqa; Farid, Amjad; Shahid, M. Attique Khan; Shafiq, M.

    2015-12-01

    Zinc oxide films are deposited on Si substrates by thermal evaporator for different evaporation times (ET). XRD pattern shows the development of different diffraction peaks related to Zn, ZnO and Zn2SiO4 phases which confirms the deposition of composite film. The orientation transformation is observed with increasing ET. The maximum peak intensity of ZnO (1 0 1) plane is observed at 3 h ET. The dislocation density observed in ZnO (1 0 1) plane varies from 1.53 × 10-3 nm-2 to 8.94 × 10-3 nm-2. The lattice parameters of ZnO are found to be a = 3.243 Å and c = 5.197 Å. FTIR analysis confirms the formation of ZnO films. SEM microstructures exhibit the formation nano-wires, nano-bars, nano-strips and nano-needles. The optical energy band gap of ZnO films deposited for various ET varies from 3.98 eV to 4.06 eV. Results show that the peak intensity of ZnO (1 0 1) plane, orientation transformation and the presence of Si content are responsible to increase the energy band gap of ZnO films.

  4. Homoepitaxy of ZnO and MgZnO Films at 90 °C

    Energy Technology Data Exchange (ETDEWEB)

    Ehrentraut, Dirk [WPI-AIMR World Premier International Research Center—Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-85 (Japan); Goh, Gregory K.L., E-mail: g-goh@imre.a-star.edu.sg [IMRE Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research, 3 Research Link, Singapore 117602 (Singapore); Fujii, Katsushi [CIR Center for Interdisciplinary Research (CIR), Tohoku University, 6-3 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8578 (Japan); Ooi, Chin Chun; Quang, Le Hong [IMRE Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research, 3 Research Link, Singapore 117602 (Singapore); Fukuda, Tsuguo [WPI-AIMR World Premier International Research Center—Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-85 (Japan); Kano, Masataka [Daishinku Corporation Daishinku Corp., 2082 Maesaka, Kurodasho-cho, Nishiwaki, Hyogo 679-0303 (Japan); Zhang, Yuantao; Matsuoka, Takashi [IMR Institute for Materials Research (IMR), Tohoku University 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

    2014-06-01

    The aqueous synthesis of uniform single crystalline homoepitaxial zinc oxide, ZnO, and magnesium zinc oxide, Mg{sub x}Zn{sub 1−x}O, films under very low temperature conditions at T=90 °C and ambient pressure has been explored. A maximum Mg content of 1 mol% was recorded by energy dispersive spectroscopy. The growth on the polar (0 0 0 1) and (0 0 0 1¯) faces resulted in films that are strongly different in their structural and optical quality as evidenced by high-resolution X-ray diffraction, secondary electron microscopy, and photoluminescence. This is a result of the chemistry and temperature of the solution dictating the stability range of growth-governing metastable species. The use of trisodium citrate, Na{sub 3}C{sub 6}H{sub 5}O{sub 7}, yielded coalesced, mirror-like homoepitaxial films whereas adding magnesium nitrate hexahydrate, Mg(NO{sub 3}){sub 2}·6H{sub 2}O, favors the growth of films with pronounced faceting. - Graphical abstract: Homoepitaxial ZnO films grown from aqueous solution below boiling point of water on a ZnO substrate with off-orientation reveal parallel grooves that are characterized by (1 0 1{sup ¯} 1) facets. Adding trisodium citrate yields closed, single-crystalline ZnO films, which can further be functionalized. Alloying with MgO yields MgZnO films with low Mg content only. - Highlights: • A simple method to synthesize uniform single crystalline homoepitaxial ZnO and MgZnO films. • ZnO growth on (0 0 0 1) and (0 0 0 1{sup ¯}) face resulted in films that are strongly different in their structural and optical quality. • Single crystalline MgZnO film was fabricated under mild conditions (90 °C and ambient pressure). • Mg incorporation of nearly 1 mol% was obtained while maintaining single phase wurtzite structure.

  5. Growth and optical characteristics of high-quality ZnO thin films on graphene layers

    Directory of Open Access Journals (Sweden)

    Suk In Park

    2015-01-01

    Full Text Available We report the growth of high-quality, smooth, and flat ZnO thin films on graphene layers and their photoluminescence (PL characteristics. For the growth of high-quality ZnO thin films on graphene layers, ZnO nanowalls were grown using metal-organic vapor-phase epitaxy on oxygen-plasma treated graphene layers as an intermediate layer. PL measurements were conducted at low temperatures to examine strong near-band-edge emission peaks. The full-width-at-half-maximum value of the dominant PL emission peak was as narrow as 4 meV at T = 11 K, comparable to that of the best-quality films reported previously. Furthermore, the stimulated emission of ZnO thin films on the graphene layers was observed at the low excitation energy of 180 kW/cm2 at room temperature. Their structural and optical characteristics were investigated using X-ray diffraction, transmission electron microscopy, and PL spectroscopy.

  6. Growth and optical characteristics of high-quality ZnO thin films on graphene layers

    Energy Technology Data Exchange (ETDEWEB)

    Park, Suk In; Tchoe, Youngbin; Baek, Hyeonjun; Hyun, Jerome K.; Yi, Gyu-Chul, E-mail: njkim36@gmail.com, E-mail: gcyi@snu.ac.kr [Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 151-747 (Korea, Republic of); Heo, Jaehyuk [Advanced Development Team, LED Business, Samsung Electronics Co., Ltd., San#24 Nongseo-Dong, Giheung-Gu, Yongin-City, Gyeonggi-Do 446–711 (Korea, Republic of); Jo, Janghyun; Kim, Miyoung [Department of Materials Science and Engineering, Seoul National University, Seoul 151–744 (Korea, Republic of); Kim, Nam-Jung, E-mail: njkim36@gmail.com, E-mail: gcyi@snu.ac.kr [Department of Physics and Chemistry, Korea Military Academy, Seoul (Korea, Republic of)

    2015-01-01

    We report the growth of high-quality, smooth, and flat ZnO thin films on graphene layers and their photoluminescence (PL) characteristics. For the growth of high-quality ZnO thin films on graphene layers, ZnO nanowalls were grown using metal-organic vapor-phase epitaxy on oxygen-plasma treated graphene layers as an intermediate layer. PL measurements were conducted at low temperatures to examine strong near-band-edge emission peaks. The full-width-at-half-maximum value of the dominant PL emission peak was as narrow as 4 meV at T = 11 K, comparable to that of the best-quality films reported previously. Furthermore, the stimulated emission of ZnO thin films on the graphene layers was observed at the low excitation energy of 180 kW/cm{sup 2} at room temperature. Their structural and optical characteristics were investigated using X-ray diffraction, transmission electron microscopy, and PL spectroscopy.

  7. Ultrafast Surface-Plasmon Enhancement of Exciton and Defect Luminescence in ZnO Thin Films

    Directory of Open Access Journals (Sweden)

    Haglund R. F.

    2013-03-01

    Full Text Available Femtosecond pump-probe and photoluminescence measurements in transmission and reflection show that ultraviolet band-edge and visible defect luminescence in ZnO films can be selectively enhanced by coupling to Ag surface-plasmon polaritons or localized surface plasmon resonances.

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

    Indian Academy of Sciences (India)

    L M Kukreja; A K Das; P Misra

    2009-06-01

    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 characteristics of these films were studied in the top-bottom configuration using current–voltage measurements at room temperature. Reliable and repeated switching of the resistance of ZnO thin films was obtained between two well defined states of high and low resistance with a narrow dispersion and small switching voltages. Resistance ratios of the high resistance state to low resistance state were found to be in the range of 2–5 orders of magnitude up to 20 test cycles. The conduction mechanism was found to be dominated by the Ohmic behaviour in low resistance states, while Poole–Frenkel emission was found to dominate in high resistance state. The achieved characteristics of the resistive switching in ZnO thin films seem to be promising for nonvolatile memory applications.

  9. Microstructural and Mechanical Studies of PVA Doped with ZnO and WO3 Composites Films

    Directory of Open Access Journals (Sweden)

    N. B. Rithin Kumar

    2014-01-01

    Full Text Available Polymer composites of ZnO and WO3 nanoparticles doped polyvinyl alcohol (PVA matrix have been prepared using solvent casting method. The microstructural properties of prepared films were studied using FTIR, XRD, SEM, and EDAX techniques. In the doped PVA, many irregular shifts in the FTIR spectra have been observed and these shifts in bands can be understood on the basis of intra/intermolecular hydrogen bonding with the adjacent OH group of PVA. The chemical composition, phase homogeneity, and morphology of the polymer composites of the polymer film were studied using EDAX and SEM. These data indicate that the distribution of nanosized ZnO and WO3 dopants is uniform and confirm the presence of ZnO and WO3 in the film. The crystal structure and crystallinity of polymer composites were studied by XRD. It was found that the change in structural repositioning and crystallinity of the composites takes place due to the interaction of dopants and also due to complex formation. The mechanical studies of doped polymer films were carried out using universal testing machine (UTM at room temperature, indicating that the addition of the ZnO and WO3 with weight percentage concentration equal to 14% increases the tensile strength and Young’s modulus.

  10. Origins of conductivity improvement in fluoride-enhanced silicon doping of ZnO films.

    Science.gov (United States)

    Rashidi, Nazanin; Vai, Alex T; Kuznetsov, Vladimir L; Dilworth, Jonathan R; Edwards, Peter P

    2015-06-01

    Fluoride in spray pyrolysis precursor solutions for silicon-doped zinc oxide (SiZO) transparent conductor thin films significantly improves their electrical conductivity by enhancing silicon doping efficiency and not, as previously assumed, by fluoride doping. Containing only earth-abundant elements, SiZO thus prepared rivals the best solution-processed indium-doped ZnO in performance. PMID:25879727

  11. 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

  12. Homoepitaxial growth of ZnO thin film by pulsed laser deposition (PLD)

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, Matthias; Wenckstern, Holger von; Hanisch, Christian; Hochmuth, Holger; Lorenz, Michael; Schmidt, Heidemarie; Grundmann, Marius [Universitaet Leipzig, Semiconductor Physics Group, Institut fuer ExperimentellePhysik II, Leipzig (Germany)

    2007-07-01

    In this work ZnO thin films have been deposited homoepitaxially by PLD on ZnO single crystals grown by the hydrothermal method (purchased from CrysTec GmbH). These wafers have first been investigated by atomic force microscopy (AFM) and were found to show significant surface roughness in the as-received state. Therefore a thermal annealing method has been applied to the wafers prior to thin film growth, in order to improve the surface properties. An overview of the changes during annealing will be presented along with information on the optimal conditions for thermal annealing. Structural, morphological, optical and electrical properties of the thin films grown homoepitaxially on these optimized wafers will be discussed with respect to the growth conditions. Comparisons to properties of thin films grown heteroepitaxially on sapphire (Al{sub 2}O{sub 3}) and SCAM (ScAlM{sub g}O{sub 4}) will be provided.

  13. Structural, electrical and optical properties of Ga-doped ZnO films on PET substrate

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Byeong-Guk; Kim, Jeong-Yeon; Lee, Seok-Jin [Department of Electronic Engineering, Chungju National University, 72 Daehak-ro, Chungju, Chungbuk 380-702 (Korea, Republic of); Park, Jae-Hwan, E-mail: pjh@cjnu.ac.kr [Department of Electronic Engineering, Chungju National University, 72 Daehak-ro, Chungju, Chungbuk 380-702 (Korea, Republic of); Lim, Dong-Gun [Department of Electronic Engineering, Chungju National University, 72 Daehak-ro, Chungju, Chungbuk 380-702 (Korea, Republic of); Park, Mun-Gi [Process Development Team 3, LG Display Co. Ltd., 1007, Deogeun-ri, Wollong-myeon, Paju Gyeonggi-do, 413-811 (Korea, Republic of)

    2010-11-15

    The effects of O{sub 2} plasma pretreatment on the properties of Ga-doped ZnO films on PET substrate were studied. Ga-doped ZnO films were fabricated by RF magnetron sputtering process. To improve surface energy and adhesion of PET substrate, O{sub 2} plasma pretreatment process was used prior to GZO sputtering. With increasing O{sub 2} plasma treatment time, the contact angle decreases and the RMS surface roughness increases significantly. The transmittance of GZO films on PET substrate in a wavelength of 550 nm was 70-84%. With appropriate O{sub 2} plasma treatment, the resistivity of GZO films on PET substrate was 3.4 x 10{sup -3} {Omega} cm.

  14. Structural, electrical and optical properties of Ga-doped ZnO films on PET substrate

    International Nuclear Information System (INIS)

    The effects of O2 plasma pretreatment on the properties of Ga-doped ZnO films on PET substrate were studied. Ga-doped ZnO films were fabricated by RF magnetron sputtering process. To improve surface energy and adhesion of PET substrate, O2 plasma pretreatment process was used prior to GZO sputtering. With increasing O2 plasma treatment time, the contact angle decreases and the RMS surface roughness increases significantly. The transmittance of GZO films on PET substrate in a wavelength of 550 nm was 70-84%. With appropriate O2 plasma treatment, the resistivity of GZO films on PET substrate was 3.4 x 10-3 Ω cm.

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

    Science.gov (United States)

    Raghu, P.; Naveen, C. S.; Shailaja, J.; Mahesh, H. M.

    2016-05-01

    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.

  16. Study of deposition parameters for the fabrication of ZnO thin films using femtosecond laser

    Science.gov (United States)

    Hashmi, Jaweria Zartaj; Siraj, Khurram; Latif, Anwar; Murray, Mathew; Jose, Gin

    2016-08-01

    Femtosecond (fs) pulsed laser deposition (fs-PLD) of ZnO thin film on borosilicate glass substrates is reported in this work. The effect of important fs-PLD parameters such as target-substrate distance, laser pulse energy and substrate temperature on structure, morphology, optical transparency and luminescence of as-deposited films is discussed. XRD analysis reveals that all the films grown using the laser energy range 120-230 μJ are polycrystalline when they are deposited at room temperature in a ~10-5 Torr vacuum. Introducing 0.7 mTorr oxygen pressure, the films show preferred c-axis growth and transform into a single-crystal-like film when the substrate temperature is increased to 100 °C. The scanning electron micrographs show the presence of small nano-size grains at 25 °C, which grow in size to the regular hexagonal shape particles at 100 °C. Optical transmission of the ZnO film is found to increase with an increase in crystal quality. Maximum transmittance of 95 % in the wavelength range 400-1400 nm is achieved for films deposited at 100 °C employing a laser pulse energy of 180 μJ. The luminescence spectra show a strong UV emission band peaked at 377 nm close to the ZnO band gap. The shallow donor defects increase at higher pulse energies and higher substrate temperatures, which give rise to violet-blue luminescence. The results indicate that nano-crystalline ZnO thin films with high crystalline quality and optical transparency can be fabricated by using pulses from fs lasers.

  17. The Electrical Properties of Co-Doped ZnO Thin Films

    International Nuclear Information System (INIS)

    Codoped ZnO thin films were prepared on silicon (111) substrates by cosputtering of aluminium rods and zinc target using DC magnetron sputtering followed by heat treatment at 400 deg. C for 1 hour at different ratios of oxygen and nitrogen gas. Results indicate that gas ratios influenced the film conduction properties, which had the lowest resistivity of 7.985x10-3 cm-3 and highest carrier concentration of 6.89x1021 cm-3.

  18. Photoelectrochemical characterization of dye-modified ZnO hybrid thin films prepared by electrochemical deposition

    OpenAIRE

    Nonomura, Kazuteru

    2006-01-01

    Dye-sensitized electrodeposited ZnO thin films were studied in their photoelectrochemical characteristics. Such electrodes can be applied for dye-sensitized solar cells. The main analysis techniques were wavelength- dependent photocurrent measurements to obtain the incident photon to current conversion efficiency (IPCE) of the films as well as time- and frequency- resolved measurements of the photocurrent (IMPS) and photovoltage (IMVS) to characterize in detail individual steps of photoelectr...

  19. Ferromagnetic behaviour of Fe-doped ZnO nanograined films

    Directory of Open Access Journals (Sweden)

    Boris B. Straumal

    2013-06-01

    Full Text Available The influence of the grain boundary (GB specific area sGB on the appearance of ferromagnetism in Fe-doped ZnO has been analysed. A review of numerous research contributions from the literature on the origin of the ferromagnetic behaviour of Fe-doped ZnO is given. An empirical correlation has been found that the value of the specific grain boundary area sGB is the main factor controlling such behaviour. The Fe-doped ZnO becomes ferromagnetic only if it contains enough GBs, i.e., if sGB is higher than a certain threshold value sth = 5 × 104 m2/m3. It corresponds to the effective grain size of about 40 μm assuming a full, dense material and equiaxial grains. Magnetic properties of ZnO dense nanograined thin films doped with iron (0 to 40 atom % have been investigated. The films were deposited by using the wet chemistry “liquid ceramics” method. The samples demonstrate ferromagnetic behaviour with Js up to 0.10 emu/g (0.025 μB/f.u.ZnO and coercivity Hc ≈ 0.03 T. Saturation magnetisation depends nonmonotonically on the Fe concentration. The dependence on Fe content can be explained by the changes in the structure and contiguity of a ferromagnetic “grain boundary foam” responsible for the magnetic properties of pure and doped ZnO.

  20. 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)

    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 Al2O3 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 Al2O3 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 Al2O3 • 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

  1. Indium-doped ZnO thin films deposited by the sol-gel technique

    International Nuclear Information System (INIS)

    Conducting and transparent indium-doped ZnO thin films were deposited on sodocalcic glass substrates by the sol-gel technique. Zinc acetate and indium chloride were used as precursor materials. The electrical resistivity, structure, morphology and optical transmittance of the films were analyzed as a function of the film thickness and the post-deposition annealing treatments in vacuum, oxygen or argon. The obtained films exhibited a (002) preferential growth in all the cases. Surface morphology studies showed that an increase in the films' thickness causes an increase in the grain size. Films with 0.18 μm thickness, prepared under optimal deposition conditions followed by an annealing treatment in vacuum showed electrical resistivity of 1.3 x 10-2 Ωcm and optical transmittance higher than 85%. These results make ZnO:In thin films an attractive material for transparent electrodes in thin film solar cells

  2. A comparison of ZnO films deposited on indium tin oxide and soda lime glass under identical conditions

    International Nuclear Information System (INIS)

    ZnO films have been grown via a vapour phase transport (VPT) on soda lime glass (SLG) and indium-tin oxide (ITO) coated glass. ZnO film on ITO had traces of Zn and C which gives them a dark appearance while that appears yellowish-white on SLG. X-ray photoelectron spectroscopy studies confirm the traces of C in the form of C–O. The photoluminescence studies reveal a prominent green luminescence band for ZnO film on ITO.

  3. A comparison of ZnO films deposited on indium tin oxide and soda lime glass under identical conditions

    Directory of Open Access Journals (Sweden)

    Angshuman Deka

    2013-06-01

    Full Text Available ZnO films have been grown via a vapour phase transport (VPT on soda lime glass (SLG and indium-tin oxide (ITO coated glass. ZnO film on ITO had traces of Zn and C which gives them a dark appearance while that appears yellowish-white on SLG. X-ray photoelectron spectroscopy studies confirm the traces of C in the form of C–O. The photoluminescence studies reveal a prominent green luminescence band for ZnO film on ITO.

  4. A comparison of ZnO films deposited on indium tin oxide and soda lime glass under identical conditions

    OpenAIRE

    Angshuman Deka; Karuna Kar Nanda

    2013-01-01

    ZnO films have been grown via a vapour phase transport (VPT) on soda lime glass (SLG) and indium-tin oxide (ITO) coated glass. ZnO film on ITO had traces of Zn and C which gives them a dark appearance while that appears yellowish-white on SLG. X-ray photoelectron spectroscopy studies confirm the traces of C in the form of C–O. The photoluminescence studies reveal a prominent green luminescence band for ZnO film on ITO.

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

    International Nuclear Information System (INIS)

    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)

  6. Preparation of manganese-doped ZnO thin films and their characterization

    Indian Academy of Sciences (India)

    S Mondal; S R Bhattacharyya; P Mitra

    2013-04-01

    In this study, pure and manganese-doped zinc oxide (Mn:ZnO) thin films were deposited on quartz substrate following successive ion layer adsorption and reaction (SILAR) technique. The film growth rate was found to increase linearly with number of dipping cycle. Characterization techniques of XRD, SEM with EDX and UV–visible spectra measurement were done to investigate the effect of Mn doping on the structural and optical properties of Mn:ZnO thin films. Structural characterization by X-ray diffraction reveals that polycrystalline nature of the films increases with increasing manganese incorporation. Particle size evaluated using X-ray line broadening analysis shows decreasing trend with increasing manganese impurification. The average particle size for pure ZnO is 29.71nm and it reduces to 23.76nm for 5%Mn-doped ZnO. The strong preferred c-axis orientation is lost due to manganese (Mn) doping. The degree of polycrystallinity increases and the average microstrain in the films decreases with increasing Mn incorporation. Incorporation of Mn was confirmed from elemental analysis using EDX. As the Mn doping concentration increases the optical bandgap of the films decreases for the range of Mn doping reported here. The value of fundamental absorption edge is 3.22 eV for pure ZnO and it decreases to 3.06 eV for 5%Mn:ZnO.

  7. 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.

  8. Effects of UV-ozone treatment on radio-frequency magnetron sputtered ZnO thin films

    International Nuclear Information System (INIS)

    The effects of UV-ozone treatment on ZnO thin films prepared by using radio-frequency magnetron sputtering are investigated. Decrease in the density of oxygen vacancy as well as increase in the density of oxygen interstitial were inferred from the UV-ozone treated samples. It was also found that a considerable difference in the work function (0.25 eV) is induced by UV-ozone treatment implying a shift in Fermi level. This shift was confirmed by capacitance-voltage measurements, which demonstrated that the boundary between the inversion region and the depletion region of a ZnO-based metal-oxide-semiconductor (MOS) capacitor positively shifts when UV ozone treated. Our results clearly indicate that the threshold voltage of a thin film transistor can be adjusted by modifying the ZnO surface via UV ozone treatment. MOS capacitors fabricated with UV-ozone treated HfO2 and/or ZnO also yielded a smaller leakage current (∼ 73%-90% smaller) and a larger breakdown voltage (∼ 8%-11% larger). The physical mechanism behind the effect of the UV ozone treatment is addressed in this study with the help of X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy.

  9. Achieving highly-enhanced UV photoluminescence and its origin in ZnO nanocrystalline films

    Science.gov (United States)

    Thapa, Dinesh; Huso, Jesse; Morrison, John L.; Corolewski, Caleb D.; McCluskey, Matthew D.; Bergman, Leah

    2016-08-01

    ZnO is an efficient luminescent material in the UV-range ∼3.4 eV with a wide range of applications in optical technologies. Sputtering is a cost-effective and relatively straightforward growth technique for ZnO films; however, most as-grown films are observed to contain intrinsic defects which can significantly diminish the desirable UV-emission. In this research the defect dynamics and optical properties of ZnO sputtered films were studied via post-growth annealing in Ar or O2 ambient, with X-ray diffraction (XRD), imaging, transmission and Urbach analysis, Raman scattering, and photoluminescence (PL). The imaging, XRD, Raman and Urbach analyses indicate significant improvement in crystal morphology and band-edge characteristics upon annealing, which is nearly independent of the annealing environment. The native defects specific to the as-grown films, which were analyzed via PL, are assigned to Zni related centers that luminesce at 2.8 eV. Their presence is attributed to the nature of the sputtering growth technique, which supports Zn-rich growth conditions. After annealing, in either environment the 2.8 eV center diminished accompanied by morphology improvement, and the desirable UV-PL significantly increased. The O2 ambient was found to introduce nominal Oi centers while the Ar ambient was found to be the ideal environment for the enhancement of the UV-light emission: an enhancement of ∼40 times was achieved. The increase in the UV-PL is attributed to the reduction of Zni-related defects, the presence of which in ZnO provides a competing route to the UV emission. Also, the effect of the annealing was to decrease the compressive stress in the films. Finally, the dominant UV-PL at the cold temperature regime is attributed to luminescent centers not associated with the usual excitons of ZnO, but rather to structural defects.

  10. 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.

  11. Effect of Oxidation Condition on Growth of N: ZnO Prepared by Oxidizing Sputtering Zn-N Film.

    Science.gov (United States)

    Qin, Xuesi; Li, Guojian; Xiao, Lin; Chen, Guozhen; Wang, Kai; Wang, Qiang

    2016-12-01

    Nitrogen-doped zinc oxide (N: ZnO) films have been prepared by oxidizing reactive RF magnetron-sputtering zinc nitride (Zn-N) films. The effect of oxidation temperature and oxidation time on the growth, transmittance, and electrical properties of the film has been explored. The results show that both long oxidation time and high oxidation temperature can obtain the film with a good transmittance (over 80 % for visible and infrared light) and a high carrier concentration. The N: ZnO film exhibits a special growth model with the oxidation time and is first to form a N: ZnO particle on the surface, then to become a N: ZnO layer, and followed by the inside Zn-N segregating to the surface to oxidize N: ZnO. The surface particle oxidized more adequately than the inside. However, the X-ray photoemission spectroscopy results show that the lower N concentration results in the lower N substitution in the O lattice (No). This leads to the formation of n-type N: ZnO and the decrease of carrier concentration. Thus, this method can be used to tune the microstructure, optical transmittance, and electrical properties of the N: ZnO film. PMID:27251324

  12. Effect of ZnO Addition on Structural Properties of ZnO-PANi/ Carbon Black Thin Films

    International Nuclear Information System (INIS)

    The aim of this project was to investigate the effect of ZnO addition on the structural properties of ZnO-PANi/ carbon black thin films. The sol gel method was employed for the preparation of ZnO sol. The sol was dried for 24 h at 100 degree Celsius and then annealed at 600 degree Celsius for 5 h. XRD characterization of the ZnO powder showed the formation of wurtzite type ZnO crystals. The ZnO powder were mixed into PANi/ carbon black solution which was dissolved into M-Pyrol, N-Methyl-2-Pyrrolidinone (NMP) to produce a composite solution of ZnO-PANi/ carbon black. The weight ratio of ZnO were 4 wt %, 6 wt % and 8 wt %. The composite solutions were deposited onto glass substrates using a spin-coating technique to fabricate ZnO-PANi/ carbon black thin films. AFM characterization showed the decreasing of average roughness from 7.98 nm to 2.23 nm with the increment of ZnO addition in PANi/ carbon black films. The thickness of the films also decreased from 59.5 nm to 28.3 nm. FESEM image revealed that ZnO-PANi/ carbon black thin films have changed into agglomerated surface morphology resulting in the increment of porosity of the films. (author)

  13. Fabrication and characterization of pristine and annealed Ga doped ZnO thin films using sputtering

    Science.gov (United States)

    Mishra, Abhisek; Mohapatra, Saswat; Gouda, Himanshu Sekhar; Singh, Udai P.

    2016-05-01

    ZnO is a wide-band gap, transparent, polar semiconductor with unparalleled optoelectronic, piezoelectric, thermal and transport properties, which make it the material of choice for a wide range of applications such as blue/UV optoelectronics, energy conversion, transparent electronics, spintronic, plasmonic and sensor devices. We report, three sets of Ga doped Zinc Oxide (GZO) were fabricated in different sputtering power (100 watt, 200 watt and 300 watt). Thereafter films were annealed in nitrogen ambient for 30 minutes at 400° C. From the optical absorption spectroscopy it was found that pristine films are showing a 75% transmittance in the visible region of light and it increases after the annealing. However, for 300 W grown sample opposite trend has been achieved for the post annealed sample. X-ray diffraction pattern of all the pristine and annealed films showed a preferable growth orientation at (002) phase. Some other weak peaks were also appeared in different angle which indicates that films are polycrystalline in nature. XRD data also reveals that crystallite size increases with sputtering power up to 200 W and thereafter it decreases with the deposition power. It also noted that the crystallite size of the annealed film increases with compare to the non annealed films. At room temperature an enhancement in electrical properties of Ga doped ZnO thin films was noted for the annealed ZnO films except for the film deposited at 300 watt. More significantly, it was found that annealed thin films showed the resistivity in the range of 10-3 ˜ 10-4 ohm-cm. Such a high optical transmittance and conducting zinc-oxide thin film can be used as a window layer in solar cell.

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-09-30

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

  16. Structural and optical properties of ZnO films produced by a modified ultrasonic spray pyrolysis technique

    International Nuclear Information System (INIS)

    In this work we present a modification of the usual ultrasonic spray pyrolysis method and tested its ability to produce good quality films by producing ZnO films. Our method consists of keeping the sprayed substrate at room temperature and, after that, a thermal treatment under a chosen environment and temperature is made. We used this method to produce ZnO films considering two environments, air and air + vapor of zinc acetate, and two temperatures, 400 °C and 450 °C. The ZnO films were investigated by X-ray diffraction, scanning electron microscopy, cathodoluminescence, thermogravimetry/simultaneum differential thermal analysis and Raman spectroscopy techniques, and results indicated that ZnO films produced under air + vapor of zinc acetate at 400 °C are the best films obtained by our modified method. - Highlights: • A variation of the ultrasonic spray pyrolysis (USP) technique is introduced. • ZnO films were produced using the modification of the USP technique. • High quality ZnO films were produced at a lower temperature than those used in other studies

  17. 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%)

  18. Investigation of low-temperature excitonic and defect emission from Ni-doped ZnO nanoneedles and V-doped ZnO nanostructured film

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Shubra; Ramachandra Rao, M S [Department of Physics, Materials Science Research Centre and Nanofunctional Materials Technology Centre, IIT Madras, Chennai 600 036 (India); Nakamura, Daisuke; Okada, Tatsuo [Department of Electrical Engineering, Kyushu University, Fukuoka 819-0395 (Japan); Sakai, Kentaro [Cooperative Research Center, University of Miyazaki, Miyazaki 889-2192 (Japan)], E-mail: shubra6@gmail.com

    2010-02-15

    We report the growth and low-temperature photoluminescent characteristics of well-aligned Ni-doped ZnO nanoneedles and V-doped ZnO nanostructured thin film grown by a modified pulsed laser deposition technique. Low-temperature photoluminescence spectra of the as-grown films show the presence of free excitonic as well as bound excitonic transitions, whose relative intensity changes with increasing temperature. Ni-doped ZnO films show a characteristic fine structure in the visible range (2.6-2.9 meV) attributed to either exciton-polariton longitudinal-transverse splitting or the splitting caused by electron-hole exchange interaction. The excitonic and visible region emission can be clearly seen as can the phonon replicas produced from longitudinal optical phonons. Different possible attributions of the various peaks in the emission band at low temperature have been discussed. The as-grown nanostructures of Ni- and V-doped ZnO thin films also clearly show the effect of doping on the microstructure of ZnO.

  19. Advanced LPCVD ZnO - Challenges in application for thin film solar cells and modules

    OpenAIRE

    Messerschmidt, Daniel; Aebi, Philipp

    2014-01-01

    Ethanol is used as a precursor during the growth of zinc oxide (ZnO) by low-pressure chemical vapor deposition (LPCVD). By adding ethanol, the surface of the deposited ZnO layer is flattened and its roughness is decreased about sevenfold. The layers become increasingly stressed and their resistivity grows significantly. The present work proposes an explanation for the observed behavior based on the catalytic decomposition of ethanol at the ZnO surface and on the growth of selected crystal plane...

  20. Electrode loading effect and high temperature performance of ZnO thin film ultrasonic transducers

    Science.gov (United States)

    Zhou, X. S.; Zhang, J.; Hou, R.; Zhao, C.; Kirk, K. J.; Hutson, D.; Hu, P. A.; Peng, S. M.; Zu, X. T.; Fu, Y. Q.

    2014-10-01

    Nanocrystalline ZnO films of 5.8 μm thick were sputter-deposited on ferritic carbon steel plates (25 × 25 × 3 mm3) and characterized for use as ultrasonic transducers at both room temperature and high temperatures. Electrode loading effects have been studied using two types of electrodes, i.e., sputtered Cr/Au (5/50 nm) and silver paste, with electrode diameters 0.7-2.5 mm. Longitudinal and transverse waves were obtained in pulse-echo tests using both types of electrodes. With a silver paste top electrode, a dominant longitudinal mode was obtained, but with a thin Cr/Au film as the top electrode, shear waves were more dominant. Pulse-echo tests of the ZnO transducers were also performed at elevated temperatures up to 450 °C using a carbon paste electrodes. The sputtered ZnO films maintained a stable crystalline structure and orientation at the elevated temperatures, and ZnO devices on ferritic carbon steel could be used successfully up to 400 °C. However, when the temperature was increased further, rapid surface oxidation of the ferritic carbon steel caused the failure of the transducer.

  1. Nanoscale heterogeniety and workfunction variations in ZnO thin films

    Science.gov (United States)

    Sharma, Anirudh; Untch, Maria; Quinton, Jamie S.; Berger, Rüdiger; Andersson, Gunther; Lewis, David A.

    2016-02-01

    Nano-roughened, sol-gel derived polycrystalline ZnO thin films prepared by a thermal ramping procedure were found to exhibit different work function values on a sub-micrometer scale. By Kelvin probe force microscopy (KPFM) two distinct nanoscale regions with work function differing by over 0.1 eV were detected which did not coincide with the nano-roughened surface topography. In contrast, a flat ZnO surface displayed a single, uniform distribution. Ultraviolet photoelectron spectroscopy (UPS) studies showed that the average workfunction across a flat ZnO surface was 3.7 eV while ZnO with a nano-roughened morphology had a lower workfunction of 3.4 eV with indications of electronic heterogeneity across the surface, supporting the KPFM results. Scanning Auger Nanoprobe measurements showed that the chemical composition was uniform across the surface in all samples, suggesting the work function heterogeneity was due to variations in crystallinity or crystal orientation on the surface of these thin films. Such heterogeneity in the electronic properties of materials in thin film devices can significantly influence the interfacial charge transport across materials.

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

    Science.gov (United States)

    Azhar, N. E. A.; Shafura, A. K.; Affendi, I. H. H.; Shariffudin, S. S.; Saurdi, I.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

    2016-07-01

    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.

  3. Spectroscopic ellipsometry, optical, structural and electrical investigation of sprayed pure and Sn-doped ZnO thin films

    Directory of Open Access Journals (Sweden)

    Attaf N.

    2013-03-01

    Full Text Available In this work, we report the transparent pure and Sn-doped zinc oxide (ZnO. The films were deposited onto microscope glass substrate which was heated at 350±5C° by ultrasonic spray pyrolysis (U S P deposition technique. The concentrations of Sn were selected within the range of 0-3% by step of 0.5% and the time deposition is kept at 5 min. A (002-oriented wurtzite crystal structure was confirmed by X-rays patterns; and grain size varied within the range 7.37-14.84nm, and cristanillity is calculated goes from14.4 to 45.9%. Based on UV-VIS-IR analysis, the results revealed the high transparency of the sprayed films which exceeds 90%. The band gap energy was of 3.26-3.30 eV. The film thickness was estimated by spectroscopy ellipsometry and the found values were of 165-270nm. The refractive index is in the range of 2.75.The obtained electrical parameters were around 1018 cm−3, 3.6 cm2/Vs, 1.6Ω.cm; 5.8cm3/C. finally the Sn-doping has influenced the physical parameters of asground ZnO films

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

    International Nuclear Information System (INIS)

    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

  5. Superior environment resistance of quartz crystal microbalance with anatase TiO{sub 2}/ZnO nanorod composite films

    Energy Technology Data Exchange (ETDEWEB)

    Qiang, Wei, E-mail: weiqiang.tju@163.com [Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science and Engineering, Tianjin University, 92 Weijin Road, Tianjin (China); Wei, Li; Shaodan, Wang [Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science and Engineering, Tianjin University, 92 Weijin Road, Tianjin (China); Yu, Bai [Beijing Institute of Spacecrafts Environment Engineering, Beijing 100094 (China)

    2015-08-30

    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{sub 2} by sol–gel methods to form a superhydrophobic TiO{sub 2}/ZnO composite film the anatase TiO{sub 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{sub 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{sub 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{sub 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{sub 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{sub 2}/ZnO composite film is synthesized by surface modification with TiO{sub 2} via sol–gel methods. Results

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

    International Nuclear Information System (INIS)

    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 TiO2 by sol–gel methods to form a superhydrophobic TiO2/ZnO composite film the anatase TiO2/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 TiO2/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 TiO2/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 TiO2/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 TiO2/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 TiO2/ZnO composite film is synthesized by surface modification with TiO2 via sol–gel methods. Results show the anatase TiO2/ZnO nanorod composite film with a

  7. Influence of In doping on electro-optical properties of ZnO films

    Indian Academy of Sciences (India)

    A P Rambu; D Sirbu; A V Sandu; G Prodan; V Nica

    2013-04-01

    Thin metallic films of Zn and In/Zn were deposited onto glass substrates by thermal evaporation under vacuum. The metallic films were submitted to a thermal oxidation in air, at 623 K, for different oxidation times (30–90 min), in order to be oxidized. Structural andmorphological analyses (X-ray diffraction, transmission electron microscopy and scanning electron microscopy) revealed that the obtained undoped and In-doped ZnO thin films possess a polycrystalline structure. Transmission spectra were recorded in spectral domain from 280 to 1400 nm. The influence of In doping and oxidation parameters as well, on the optical parameters (transmittance, optical bandgap, Urbach energy) were analysed. It was clearly evidenced that by In doping, the optical properties of ZnO films were improved. The temperature dependence of electrical conductivity was studied using surface-type cells with Ag electrodes. The obtained results indicate that In-doped ZnO films exhibit an enhancement of electrical conductivity with few orders of magnitude when compared with non-doped ones.

  8. Studies of structural evolution and sensing properties of ZnO nanocrystalline films

    Energy Technology Data Exchange (ETDEWEB)

    Peng, X.Y.; Sajjad, M.; Chu, J. [Department of Physics, University of Puerto Rico, San Juan,00931 (Puerto Rico); Yang, B.Q. [Department of Physics, University of Massachusetts, Amherst, MA 01003 (United States); Feng, P.X., E-mail: peterxianping@vmail.uprrp.edu [Department of Physics, University of Puerto Rico, San Juan, 00931 (Puerto Rico)

    2011-03-15

    ZnO nanocrystalline films have been prepared on Si(1 0 0) substrate using direct current (D.C) magnetron sputtering technique at room temperature. The thickness of nanocrystalline films almost linearly increased with deposition duration and the sizes of crystalline grains almost kept unchanged. After deposition, thermal annealing was performed at 800 deg. C in atmosphere for 2 h in order to improve the qualities of ZnO thin films. Scanning electron microscope (SEM) images showed the surface roughness of the films less than 45 nm. X-ray diffraction (XRD) patterns revealed the slight evolution of the crystal structures. Raman scattering spectra confirmed the data obtained from X-ray diffraction measurements. With these ZnO nanocrystalline films, prototypic gas sensors were fabricated. Both sensitivity and response of the sensors to different gases (H{sub 2} and CH{sub 4}) were investigated. A quick response of time, less than 1 second to CH{sub 4} gas sensor has been achieved.

  9. Structural, morphological, optical and opto-thermal properties of Ni-doped ZnO thin films using spray pyrolysis chemical technique

    Indian Academy of Sciences (India)

    S Rajeh; A Barhoumi; A Mhamdi; G Leroy; B Duponchel; M Amlouk; S Guermazi

    2016-02-01

    Nickel-doped zinc oxide thin films (ZnO : Ni) at different percentages were deposited on glass substrates using a chemical spray technique. The effect of Ni concentration on the structural, morphological, optical and photoluminescence (PL) properties of the ZnO : Ni thin films were investigated. X-ray diffraction analysis revealed that all films consist of single phase ZnO and was well crystallized in würtzite phase with the crystallites preferentially oriented towards the (002) direction parallel to the c-axis. The optical transmittance measurement was found to be higher than 90%, the optical band gap values of ZnO thin films decreased after doping from 3.29 to 3.21 eV. A noticeable change in optical constants was observed between undoped and Ni-doped ZnO. Room-temperature PL is observed for ZnO, and Ni-doped ZnO thin films.

  10. Effect of oxygen partial pressure on the behavior of dual ion beam sputtered ZnO thin films

    International Nuclear Information System (INIS)

    Undoped ZnO thin films were grown on p-type Si (1 0 0) substrates at different oxygen partial pressure by dual ion beam sputtering deposition system at a constant growth temperature of 400 °C. The crystallinity, surface morphology, optical, elemental and electrical properties of these ZnO thin films was studied. The minimum value of full-width at half-maximum of the θ-rocking curve obtained from x-ray diffraction of the ZnO (0 0 2) plane, was reported to be 0.1865° from ZnO film grown at 50% of (O2/(O2 + Ar))%. Crystalline property of ZnO films was observed to degrade with the increase in oxygen partial pressure. Photoluminescence measurements demonstrated sharp near-band-edge emission at ∼381 nm at room temperature. X-ray photoelectron spectroscopy study revealed presence of oxygen interstitials and vacancies as point defects in ZnO films. Electrical resistivity of ZnO was found to increase with the increase in oxygen partial pressure. (paper)

  11. Effect of aluminium doping on structural and optical properties of ZnO thin films by sol-gel method

    International Nuclear Information System (INIS)

    We systematically investigated the structural, morphological and optical properties of 0.05 mol % Al doped ZnO (Al:ZnO) thin films deposited on glass substrates by sol-gel spin coating method. The influences of Al doping in ZnO thin films are characterized by Powder X-ray diffraction study. ZnO and Al:ZnO thin films have showed hexagonal wurtzite structure without any secondary phase in c-axis (002) orientation. The SEM images also proved the hexagonal rod like morphologies for both films. All the films exhibited transmittance of 70-80% in the visible range up to 800 nm and cut-off wavelength observed at ∼390 nm corresponding to the fundamental absorption of ZnO. The band gap of the ZnO thin films slightly widened with the Al doping. The photoluminescence properties have been studied for Al: ZnO thin films and the results are presented in detail

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

    International Nuclear Information System (INIS)

    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

  13. Heteroepitaxial ZnO films on diamond: Optoelectronic properties and the role of interface polarity

    Energy Technology Data Exchange (ETDEWEB)

    Schuster, Fabian, E-mail: Fabian.Schuster@wsi.tum.de; Hetzl, Martin; Garrido, Jose A.; Stutzmann, Martin [Walter Schottky Institut, Technische Universität München, Am Coulombwall 4, 85748 Garching (Germany); Magén, Cesar [Laboratorio de Microscopías Avanzadas (LMA) - Instituto de Nanociencia de Aragon (INA) and Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50018 Zaragoza (Spain); Fundación ARAID, 50018 Zaragoza (Spain); Arbiol, Jordi [Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193 Bellaterra, CAT (Spain); Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, CAT (Spain)

    2014-06-07

    We demonstrate the growth of heteroepitaxial ZnO films on (110) diamond substrates by molecular beam epitaxy and report on a major advance in structural quality, as confirmed by XRD and high-resolution TEM measurements. The growth direction is found to be along the polar c-axis with Zn-polarity, deduced from annular bright-field scanning transmission electron microscopy imaging. This is important information, as simulations of the electronic band structure reveal the ZnO polarity to dominate the electronic structure of the interface: the formation of a two-dimensional electron gas on the ZnO side or a two-dimensional hole gas on the diamond side are predicted for Zn- and O-polarity, respectively. In addition, photoluminescence and absorption studies exhibit good optical properties and reveal stimulated emission for optical excitation above a threshold of 30 kW/cm{sup 2}.

  14. 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.

  15. 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.

  16. Characterization of the ZnO thin film prepared by single source chemical vapor deposition under low vacuum condition

    Institute of Scientific and Technical Information of China (English)

    DENG; Hong(邓宏); B.; GONG; A.; J.; Petrella; J.; J.; Russell; R.; N.; Lamb

    2003-01-01

    A novel technique is developed for growing high quality ZnO thin films by means of single source chemical vapor deposition (SS CVD) under low vacuum conditions with the precursor of zinc carbamate Zn4O(CO2Net2)6. SEM, AFM and XRD studies show that the resultant thin films have high density, smooth surface, uniform polycrystalline structure and excellent c-axis orientation. XPS investigation indicates that the ZnO films are free of decomposed precursor residues in the bulk. Careful quantitative XPS analysis reveals that the ZnO films are stoichiometric with O/Zn atomic ratio very close to that of ZnO single crystal.

  17. Structural and optical properties of dense vertically aligned ZnO nanorods grown onto silver and gold thin films by galvanic effect with iron contamination

    International Nuclear Information System (INIS)

    Highlights: • ZnO nanorods were grown on Au and Ag films in aqueous solution by galvanic effect. • The method is prone to metal contamination which can influence the ZnO properties. • Iron doping improves the lattice matching between ZnO and the substrate. • Energy levels of point defects are lowered and the light emission is red-shifted. • Galvanic-induced nucleation starts and proceeds continuously during the growth. - Abstract: Dense arrays of vertically aligned ZnO nanorods have been grown onto either silver or gold seedless substrates trough a simple hydrothermal method by exploiting the galvanic effect between the substrate and metallic parts. The nanorods exhibit larger bases and more defined hexagonal shapes, in comparison with standard non-galvanic wet-chemistry synthesis. X-ray diffraction (XRD) shows that the iron contamination, associated with the galvanic contact, significantly improves the in-plane compatibility of ZnO with the Au and Ag cubic lattice. Photoluminescence (PL) measurements indicate that the contamination does not affect the number density of localized defects, but lowers their energy levels uniformly; differently, the band-edge emission is not altered appreciably. Finally, we have found that the ZnO hetero-nucleation by galvanic effect initiates at different times in different sites of the substrate area. Our results can be useful for the fabrication of high performance piezonanodevices comprising high-density metal-to-ZnO nanoscaled junctions without intermediate polycrystalline layers

  18. Enhanced ultraviolet emission in photoluminescence of GaN film covered by ZnO nanoflakes

    International Nuclear Information System (INIS)

    In this study, ultraviolet (UV) photoluminescence (PL) emission of gallium nitride (GaN) was improved using ZnO nanoflakes (NFs) as cap layer. Capped ZnO was synthesized by thermal oxidation at different temperatures (470, 520, and 570 °C). The structures, surface morphologies, and optical properties of the samples were analyzed by X-ray diffraction and Raman spectroscopy. The scanning electron microscopy results showed that oxidation temperature strongly affected the density and formation of ZnO NFs. The PL spectra showed that the UV emission of GaN films was considerably enhanced after being covered by ZnO NFs. However, at a relatively high (∼520 °C) oxidation temperature, the intensity of UV emission decreased. The increase in oxidation temperature of the cap layer widened the PL emission band in the UV region, and a red shift occurred in the peak position of UV emission. This phenomenon may be related to the oxygen inter diffusion between ZnO NFs and GaN films. Unlike the as-grown GaN layers, the oxidized ZnO–capped GaN exhibited considerable enhancement in photocurrent and PL responses. A metal-semiconductor-metal-type UV photodetector was fabricated. The current–voltage characteristics showed that the ratio of the maximum photocurrent to dark current decreased from 75,000 to 2000 as the oxidation temperature of the cap layer increased from 470 °C to 570 °C. This phenomenon indicates the sensitivity of the proposed photodetector to NFs with low oxidation temperatures and high densities. - Highlights: ► ZnO nanoflakes cap layer was synthesized on GaN film via a thermal oxidation process. ► PL results show the UV emission of GaN largely enhanced with ZnO NFs cap layer. ► Low oxidation temperature obtained high density of NFs and high UV emission peak. ► The super UV photodetector was obtained with low temperature cap layer at 470 °C. ► The increase in oxidation temperature of the ZnO limited the increase of UV emission of GaN.

  19. Room temperature pulsed laser deposited ZnO thin films as photoluminiscence gas sensors

    Energy Technology Data Exchange (ETDEWEB)

    Padilla-Rueda, D.; Vadillo, J.M. [Department of Analytical Chemistry, Faculty of Science, University of Malaga, UMA Campus Teatinos, s/n, 29071 Malaga (Spain); Laserna, J.J., E-mail: laserna@uma.es [Department of Analytical Chemistry, Faculty of Science, University of Malaga, UMA Campus Teatinos, s/n, 29071 Malaga (Spain)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Elaboration of functional ZnO thin films by PLD at room temperature is possible. Black-Right-Pointing-Pointer Fluorescence quenching of ZnO thin films may be used for NO{sub 2} sensors. Black-Right-Pointing-Pointer Addition of oxygen during deposition is required to get films of better quality. Black-Right-Pointing-Pointer Films exhibited linear behaviour in the range between 26 and 100 ppm. - Abstract: Zinc oxide thin films with optical sensing capabilities for NO{sub 2} have been elaborated by pulsed laser deposition (PLD) onto glass substrates at room temperature with Nd:YAG laser (1064 nm). Morphology, chemical composition and optical characteristics of the films were evaluated as a function of laser fluence, gas pressure and target-to-substrate distance. Films exhibit excellent morphological and optical (transmittance and photoluminescence) properties. The films have been evaluated as fluorescence sensors for NO{sub 2} in the concentration range between 26 and 200 ppm.

  20. Effect of thickness on structural and electrical properties of Al-doped ZnO films

    International Nuclear Information System (INIS)

    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

  1. 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.

  2. Substrate Temperature Effects on Room Temperature Sensing Properties of Nanostructured ZnO Thin Films.

    Science.gov (United States)

    Reddy, Jonnala Rakesh; Mani, Ganesh Kumar; Shankar, Prabakaran; Rayappan, John Bosco Balaguru

    2016-01-01

    Zinc oxide (ZnO) thin films were deposited on glass substrates using chemical spray pyrolysis technique at different substrate temperatures such as 523, 623 and 723 K. X-ray diffraction (XRD) patterns confirmed the formation of polycrystalline films with hexagonal wurtzite crystal structure and revealed the change in preferential orientation of the crystal planes. Scanning electron micrographs showed the formation of uniformly distributed spherical shaped grains at low deposition temperature and pebbles like structure at the higher temperature. Transmittance of 85% was observed for the film deposited at 723 K. The band gap of the films was found to be increased from 3.15 to 3.23 eV with a rise in deposition temperature. The electrical conductivity of the films was found to be improved with an increase in substrate temperature. Surface of ZnO thin films deposited at 523 K, 623 K and 723 K were found to be hydrophobic with the contact angles of 92°, 105° and 128° respectively. The room temperature gas sensing characteristics of all the films were studied and found that the film deposited at 623 K showed a better response towards ammonia vapour. PMID:27398478

  3. Current-voltage characterization of Au contact on sol-gel ZnO films with and without conducting polymer

    International Nuclear Information System (INIS)

    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.

  4. Effect of Nano ZnO on the Optical Properties of Poly(vinyl chloride Films

    Directory of Open Access Journals (Sweden)

    Wasan Al-Taa’y

    2014-01-01

    Full Text Available Optical properties of pure and doped poly(vinyl chloride (PVC films, prepared by using casting technique, with different nanosize zinc oxide (ZnO concentrations (1–20 wt% have been studied. Parameters such as extinction coefficient, refractive index, real and imaginary parts, Urbach energy, optical conductivity, infinitely high frequency dielectric constant, and average refractive index were studied by using the absorbance and transmittance measurement from computerized UV-visible spectrophotometer (Shimadzu UV-1601 PC in the spectral range 200–800 nm. This study reveals that the optical properties of PVC are affected by the doping of ZnO where the absorption increases and transmission decreases as ZnO concentration increases. The extinction coefficient, refractive index, real and imaginary parts, infinitely high frequency dielectric constant, and average refractive index values were found to increase with increasing impurity percentage. The Urbach energy values are found to be decreasing with increasing ZnO concentration. The optical conductivity increased with photon energy after being doped and with the increase of ZnO concentration.

  5. P-Type Conduction of ZnO Thin Film by Codoping Technique

    International Nuclear Information System (INIS)

    Aluminium and zinc target were co-sputtered on silicon (111) substrates using DC magnetron sputtering in the pure argon atmosphere. These films were then underwent the thermal annealing in different ratios of nitrogen and oxygen for 1 hour to form thin oxide films. P-type conduction in ZnO thin films have been realized by the Al-N codoping method, whereby the lowest resistivity of 3.41x10-3 Ω·cm and the highest carrier concentration of 1.54x1022 cm-3 was achieved for sample prepared at annealed temperature of 300 deg. C

  6. Nanostructured ZnO Films Electrodeposited on Hydrophilic Substrate Utilizing Cooperative Surface Assembly

    Institute of Scientific and Technical Information of China (English)

    YANG Lirong; JIN Zhengguo; WU Weibing; BU Shaojing

    2006-01-01

    Nanoporous amorphous ZnO films with lamellar structure were electrodeposited on the hydrophilic substrate by utilizing cooperative surface assembly of anionic sodium dodecyl sulfonate (SDS) at a very low concentration and inorganic species Zn(NO3)2 under the influence of an electrostatic potential. The deposited films were characterized by X-ray diffraction (XRD) in the range of low-angle and wide-angle, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and UV-Vis light absorption spectroscopy. The formation mechanism of the films was elementarily discussed.

  7. Thickness-dependent growth orientation of F-doped ZnO films formed by atomic layer deposition

    International Nuclear Information System (INIS)

    ZnO thin films were doped with fluorine using atomic layer deposition (ALD) with an in-house F source at a deposition temperature of 140 °C. Structural and morphological properties of the resulting F-doped ZnO (ZnO:F) films were investigated by x-ray diffraction analysis, field emission scanning electron microscopy, and grazing incidence wide-angle x-ray diffraction. During the initial growth stage of up to 200 ALD cycles, no difference was observed between the preferred growth orientations of undoped ZnO and ZnO:F films. However, after 300 ALD cycles, ZnO and ZnO:F films showed (002) and (100) preferred orientation, respectively. This difference in preferred growth orientation arose from the perturbation-and-passivation effect of F doping, which involves F anions filling the oxygen-related defect sites in the ZnO lattice. Ultraviolet photoelectron spectroscopic analyses were carried out to investigate the surface plane dependency of the films' work functions, which confirmed that the ZnO and ZnO:F films had different growth behaviors

  8. Thickness-dependent growth orientation of F-doped ZnO films formed by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Kyung-Mun; Choi, Yong-June; Park, Hyung-Ho, E-mail: hhpark@yonsei.ac.kr [Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Yeom, Geun Young [Department of Advanced Materials Science and Engineering, and SKKU Advanced Institute of Nanotechnology, Sungkyunkwan University, Suwon, Kyunggi-do 440-746 (Korea, Republic of)

    2016-01-15

    ZnO thin films were doped with fluorine using atomic layer deposition (ALD) with an in-house F source at a deposition temperature of 140 °C. Structural and morphological properties of the resulting F-doped ZnO (ZnO:F) films were investigated by x-ray diffraction analysis, field emission scanning electron microscopy, and grazing incidence wide-angle x-ray diffraction. During the initial growth stage of up to 200 ALD cycles, no difference was observed between the preferred growth orientations of undoped ZnO and ZnO:F films. However, after 300 ALD cycles, ZnO and ZnO:F films showed (002) and (100) preferred orientation, respectively. This difference in preferred growth orientation arose from the perturbation-and-passivation effect of F doping, which involves F anions filling the oxygen-related defect sites in the ZnO lattice. Ultraviolet photoelectron spectroscopic analyses were carried out to investigate the surface plane dependency of the films' work functions, which confirmed that the ZnO and ZnO:F films had different growth behaviors.

  9. Growth of ZnO Thin Films on Lattice-Matched Substrates by Pulsed-Laser Deposition

    Institute of Scientific and Technical Information of China (English)

    余庆选; 徐波; 吴气虹; 廖源; 王冠中; 方容川

    2003-01-01

    ZnO films were grown on GaN and sapphire substrates by pulse laser deposition, respectively. The effects of crystalline quality on the optical properties in ZnO epitaxial layers were investigated by x-ray rocking curve and photoluminescence. The x-ray rocking curve of the film deposited on the GaN substrate has the full width half maximum (FWHM) of 0.45°, whereas the FWHM of the x-ray θ-rocking curve of the ZnO film deposited on a sapphire substrate was measured to be about 0.77°. In photoluminescence (PL) measurement, the intensity of UV photoluminescence for the ZnO film on the GaN substrate decreased by approximately two orders of magnitude in comparison with that of the ZnO film on sapphire. It is concluded that the UV luminescence intensity almost does not depend on the textured growth of the ZnO thin film.

  10. Annealing temperature dependent electrical and optical properties of ZnO and MgZnO films in hydrogen ambient

    International Nuclear Information System (INIS)

    Un-doped ZnO and MgZnO thin films were deposited on c-plane sapphire substrates by molecular-beam epitaxy (MBE) and subsequently annealed in hydrogen ambient at 200-500 deg. C with a step of 100 deg. C. Hall-effect measurements show that annealing temperature has great effect on the electrical property of both ZnO and MgZnO films. The electron concentration of both ZnO and MgZnO films increases with annealing temperature ranging from 200 deg. C to 400 deg. C, and then decreases, which is attributed to incorporation of H into ZnO as a shallower donor during the annealing process and change of solid solubility of hydrogen in ZnO and MgZnO films with annealing temperature. The D0X emission is related to the hydrogen in MgZnO film and the donor level of the H is estimated to be 33.5 meV. It is also found that the controversial luminescence band at 3.310 eV can be formed in un-doped ZnO film upon annealing and its intensity increases with increasing annealing temperature, implying that this band may be not related to p-type doping.

  11. Growth of b-axis oriented VO2 thin films on glass substrates using ZnO buffer layer

    International Nuclear Information System (INIS)

    VO2 thin films are grown on glass substrates by pulsed laser deposition using vanadium metal as a target. In this study, a ZnO thin film was used as a buffer layer for the growth of VO2 thin films on glass substrates. X-ray diffraction studies showed that the VO2 thin film had b-axis preferential orientation on a c-axis oriented ZnO buffer layer. The thickness of the ZnO buffer layer and the oxygen pressure during VO2 deposition were optimized to grow highly b-axis oriented VO2 thin films. The metal-insulator transition properties of the VO2 film samples were investigated in terms of infrared reflectance and electrical resistance with varying temperatures.

  12. Characterization and device applications of ZnO films deposited by high power impulse magnetron sputtering (HiPIMS)

    International Nuclear Information System (INIS)

    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. (paper)

  13. Facile Synthesis of 3D Porous Flower-like ZnO Micro/nanostructure Films and Their Photocatalytic Performance

    Institute of Scientific and Technical Information of China (English)

    Jin-ling Yang; Guang Tao Fei; Hui Li; Hao-miao Ouyang

    2012-01-01

    3D porous flower-like ZnO micro/nanostructure films grown on Ti substrates are synthesized via a very facile electrodeposition technique followed by heat treatment process.The ZnO architecture is assembled with ultra thin sheets,which consist of numbers of nanoparticles and pores,and the size of the nanoparticles can be controlled by adjusting the electrodeposition time or calcination temperature.It is worth noting that this synthetic method can provide an effective route for other porous metal oxide nanostructure films.Moreover,the photocatalytic performance shows the porous ZnO is an ideal photocatalyst.

  14. Photoluminescence, ellipsometric, optical and morphological studies of sprayed Co-doped ZnO films

    Science.gov (United States)

    Gençyılmaz, O.; Atay, F.; Akyüz, I.

    2016-06-01

    In this study, undoped and cobalt (Co)-doped zinc oxide (ZnO) films were successfully produced by ultrasonic spray pyrolysis (USP) technique at low temperature (350°C). The optical and surface properties were investigated as a function of Co content. The optical parameters (thickness, refractive index and extinction coefficient) were determined using spectroscopic ellipsometry (SE) and it was seen that the refractive index and extinction coefficient values of Co-doped ZnO films decreased slightly depending on the increasing of Co doping. For investigation, the transmittance and photoluminescence (PL) spectra of the films, UV-Vis spectrophotometer and PL spectroscopy were used at room temperature. The transmittance spectra show that transmittance values decreased and Co+2 ions substitute Zn+2 ions of ZnO lattice. The optical band gap values decreased from 3.26 eV to 2.85 eV with the changing of Co content. The results of PL spectra exhibit the position of the different emission peaks unchanged but the intensity of peaks increased with increasing Co doping. Also, the surface properties of the films were obtained by atomic force microscopy (AFM) and these results indicated that the surface morphology and roughness values were prominently changed with Co doping.

  15. Photoelectrochemical properties of highly mobilized Li-doped ZnO thin films.

    Science.gov (United States)

    Shinde, S S; Bhosale, C H; Rajpure, K Y

    2013-03-01

    Li-doped ZnO thin films with preferred (002) orientation have been prepared by spray pyrolysis technique in aqueous medium on to the corning glass substrates. The effect of Li-doping on to the photoelectrochemical, structural, morphological, optical, luminescence, electrical and thermal properties has been investigated. XRD and Raman study indicates that the films have hexagonal crystal structure. The transmittance, reflectance, refractive index, extinction coefficient and bandgap have been analyzed by optical study. PL spectra consist of a near band edge and visible emission due to the electronic defects, which are related to deep level emissions, such as oxide antisite (OZn), interstitial zinc (Zni), interstitial oxygen (Oi) and zinc vacancy (VZn). The Li-doped ZnO films prepared for 1at% doping possesses the highest electron mobility of 102cm(2)/Vs and carrier concentration of 3.62×10(19)cm(-3). Finally, degradation of 2,4,6-Trinitrotoluene using Li-doped ZnO thin films has been reported. PMID:23416707

  16. Quenching of surface traps in Mn doped ZnO thin films for enhanced optical transparency

    International Nuclear Information System (INIS)

    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.

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

    Indian Academy of Sciences (India)

    S Mondal; P Mitra

    2012-10-01

    Cadmium-doped zinc oxide (Cd : ZnO) thin films were deposited from sodium zincate bath following a chemical dipping technique called successive ion layer adsorption and reaction (SILAR). Structural characterization by X-ray diffraction reveals that polycrystalline nature of the films increases with increasing cadmium incorporation. Particle size evaluated using X-ray line broadening analysis shows decreasing trend with increasing cadmium impurification. The average particle size for pure ZnO is 36.73nm and it reduces to 29.9 nm for 10% Cd:ZnO, neglecting strain broadening. The strong preferred c-axis orientation is lost due to cadmium doping and degree of polycrystallinity of the films also increases with increasing Cd incorporation. Incorporation of cadmium was confirmed from elemental analysis using EDX. The optical bandgap of the films decreases with increasing Cd dopant. The value of fundamental absorption edge is 3.18 eV for pure ZnO and it decreases to 3.11 eV for 10% Cd:ZnO.

  18. Enhancement of near-band edge photoluminescence of ZnO film buffered with TiN

    International Nuclear Information System (INIS)

    ZnO films were deposited on Si substrate by RF-sputtering using titanium nitride (TiN) as buffer layer that was deposited at different thicknesses: 160 and 2290 nm. Despite the lattice mismatch of up to 6.35% between ZnO and TiN, the ZnO films deposited on TiN buffer layers show enhanced near-band-edge photoluminescence (PL) emission at room temperature which is two times higher of magnitude than those grown directly on Si. The PL enhancement intensity, provided by TiN buffer introduction, is attributed to the improvement of ZnO crystalline quality and stoichiometry. The use of a good electrical conductor which has high thermal stability like TiN as buffer layer for the blue emission enhancement of ZnO would make it promising for optoelectronic applications. - Highlights: ► Use of TiN buffer layer for blue emission enhancement of ZnO films is reported. ► The near-band edge photoluminescence intensity of buffered ZnO films is doubled. ► Raman, X-ray diffraction and X-ray photoelectron spectroscopy analyses are correlated

  19. The role of seeding in the morphology and wettability of ZnO nanorods films on different substrates

    International Nuclear Information System (INIS)

    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.

  20. Enhancement of near-band edge photoluminescence of ZnO film buffered with TiN

    Energy Technology Data Exchange (ETDEWEB)

    Achour, A., E-mail: a_aminph@yahoo.fr [Institut des Matériaux Jean Rouxel, IMN, Université de Nantes, CNRS, 2 rue de la Houssinière, BP 32229, 44322 Nantes cedex 3 (France); Aissa, K. Ait [Institut des Matériaux Jean Rouxel, IMN, Université de Nantes, CNRS, 2 rue de la Houssinière, BP 32229, 44322 Nantes cedex 3 (France); Mbarek, M. [Unité de Recherche, Matériaux Nouveaux et Dispositifs Electroniques Organiques, Faculté des Sciences de Monastir, University of Monastir, 5000 Monastir (Tunisia); El Hadj, K. [Institut des Matériaux Jean Rouxel, IMN, Université de Nantes, CNRS, 2 rue de la Houssinière, BP 32229, 44322 Nantes cedex 3 (France); Ouldhamadouche, N. [Laboratoire de Physique des Matériaux, Université des Sciences et de la Technologie Houari Boumediene, BP 32 El Alla.16111. Bab Ezzouaur (Algeria); Barreau, N.; Le Brizoual, L.; Djouadi, M.A. [Institut des Matériaux Jean Rouxel, IMN, Université de Nantes, CNRS, 2 rue de la Houssinière, BP 32229, 44322 Nantes cedex 3 (France)

    2013-07-01

    ZnO films were deposited on Si substrate by RF-sputtering using titanium nitride (TiN) as buffer layer that was deposited at different thicknesses: 160 and 2290 nm. Despite the lattice mismatch of up to 6.35% between ZnO and TiN, the ZnO films deposited on TiN buffer layers show enhanced near-band-edge photoluminescence (PL) emission at room temperature which is two times higher of magnitude than those grown directly on Si. The PL enhancement intensity, provided by TiN buffer introduction, is attributed to the improvement of ZnO crystalline quality and stoichiometry. The use of a good electrical conductor which has high thermal stability like TiN as buffer layer for the blue emission enhancement of ZnO would make it promising for optoelectronic applications. - Highlights: ► Use of TiN buffer layer for blue emission enhancement of ZnO films is reported. ► The near-band edge photoluminescence intensity of buffered ZnO films is doubled. ► Raman, X-ray diffraction and X-ray photoelectron spectroscopy analyses are correlated.

  1. The Theoretical Investigation and Analysis of High-Performance ZnO Double-Gate Double-Layer Insulator Thin-Film Transistors

    Institute of Scientific and Technical Information of China (English)

    GAO Hai-Xia; HU Rong; YANG Yin-Tang

    2012-01-01

    A novel structure of a ZnO thin-film transistor with a double-gate and double-layer insulator is proposed to improve device performance.Compared with the conventional ZnO thin-film transistor structure,the novel thinfilm transistor has a higher on-state current,steeper sub-threshold characteristics and a lower threshold voltage,owing to the double-gate and high-k dielectric.Based on two-dimensional simulation,the potential channel distribution and the reasons for the improvement in performance are investigated.%A novei structure of a ZnO thin-film transistor with a double-gate and double-layer insulator is proposed to improve device performance. Compared with the conventional ZnO thin-Rim transistor structure, the novel thin-Sim transistor has a higher on-state current, steeper sub-threshold characteristics and a lower threshold voltage, owing to the double-gate and high-k dielectric. Based on two-dimensional simulation, the potential channel distribution and the reasons for the improvement in performance are investigated.

  2. Investigation of structural and optical properties of ZnO films co-doped with fluorine and indium

    Science.gov (United States)

    Keskenler, E. F.; Turgut, G.; Doğan, S.

    2012-07-01

    Undoped ZnO film and ZnO films, which are co-doped with F and In (FIZO) at different concentrations, were synthesized by sol-gel technique and the effects of co-doping of F and In on structural and optical properties of ZnO thin films were investigated. The concentration ratio of [F]/[Zn] was altered from 0.25 to 1.75 with 0.50 step at.% mole and [In]/[Zn] was altered from 0.25 to 1.00 with 0.25 step at.% mole. X-ray diffraction analysis indicates that the films have polycrystalline nature and the (0 0 2) preferred orientation is the stronger peak. No extra phases involving zinc, fluorine and indium compounds were observed even at high F and In content. The grain size of undoped ZnO and FIZO thin films varied between 15 and 20 nm with a small fluctuation. From the SEM images, although the undoped ZnO had a smooth and particle-shaped surface, FIZO films had nanofiber-networks shapes over the surface with average size of 500 nm. The surface morphologies and crystallite sizes for the F and In doped films were slightly different from than those of undoped film. From the optical study, a slight shrinkage of band gap was backwardly observed from 3.36 to 3.25 eV with the increasing of F and In content.

  3. Photoactive Langmuir-Blodgett, Freely Suspended and Free Standing Films of Carboxylate Ligand-Coated ZnO Nanocrystals.

    Science.gov (United States)

    Paczesny, Jan; Wolska-Pietkiewicz, Małgorzata; Binkiewicz, Ilona; Wadowska, Monika; Wróbel, Zbigniew; Matuła, Kinga; Nogala, Wojciech; Lewiński, Janusz; Hołyst, Robert

    2016-06-01

    A new possibility for the formation of macroscopic and photoactive structures from zinc oxide nanocrystals is described. Photoactive freely suspended and free-standing films of macroscopic area (up to few square millimeters) and submicrometer thickness (up to several hundreds of nanometers) composed of carboxylate ligand-coated zinc oxide nanocrystallites (RCO2-ZnO NCs) of diameter less than 5 nm are prepared according to a modified Langmuir-Schaefer method. First, the suspension of RCO2-ZnO NCs is applied onto the air/water interface. Upon compression, the films become turbid and elastic. The integrity of such structures is ensured by interdigitation of ligands stabilizing ZnO NCs. Great elasticity allows transfer of the films onto a metal frame as a freely suspended film. Such membranes are afterward extracted from the supporting frame to form free-standing films of macroscopic area. Because the integrity of the films is maintained by ligands, no abolishment of quantum confinement occurs, and films retain spectroscopic properties of initial RCO2-ZnO NCs. The mechanism of formation of thin films of RCO2-ZnO NCs at the air/water interface is discussed in detail. PMID:27158733

  4. Electrodeposition of Mg doped ZnO thin film for the window layer of CIGS solar cell

    Science.gov (United States)

    Wang, Mang; Yi, Jie; Yang, Sui; Cao, Zhou; Huang, Xiaopan; Li, Yuanhong; Li, Hongxing; Zhong, Jianxin

    2016-09-01

    Mg doped ZnO (ZMO) film with the tunable bandgap can adjust the conduction band offset of the window/chalcopyrite absorber heterointerface to positive to reduce the interface recombination and resulting in an increasement of chalcopyrite based solar cell efficiency. A systematic study of the effect of the electrodeposition potential on morphology, crystalline structure, crystallographic orientation and optical properties of ZMO films was investigated. It is interestingly found that the prepared doped samples undergo a significant morphological change induced by the deposition potential. With negative shift of deposition potential, an obvious morphology evolution from nanorod structrue to particle covered films was observed. A possible growth mechanism for explaining the morphological change is proposed and briefly discussed. The combined optical techniques including absorption, transmission and photoluminescence were used to study the obtained ZMO films deposited at different potential. The sample deposited at -0.9 V with the hexagonal nanorods morphology shows the highest optical transparency of 92%. The photoluminescence spectra reveal that the crystallization of the hexagonal nanorod ZMO thin film deoposited at -0.9 V is much better than the particles covered ZMO thin film. Combining the structural and optical properties analysis, the obtained normal hexagonal nanorod ZMO thin film could potentially be useful in nanostructured chalcopyrite solar cells to improve the device performance.

  5. Physical properties of Ga-doped ZnO thin films by spray pyrolysis

    International Nuclear Information System (INIS)

    Research highlights: In this work, we report the structural, optical and electrical properties of the transparent conducting GZO thin films prepared by spray pyrolysis method. We sought optimum deposition conditions yielding GZO films with desired physical properties, specifically good crystalline quality microstructure, low resistivity and high transparency. The electrical conductivity and mobilities of GZO thin films are very good as compared with previous reported spray pyrolysed films. - Abstract: Gallium doped zinc oxide (GZO) thin films were prepared using the simple, flexible and cost-effective spray pyrolysis technique. The physical properties of the films were studied as a function of increasing gallium dopant concentration from 1 to 9 at.%. The films were characterized by various methods to understand their structural, morphological, optical and electrical properties. The X-ray diffraction analysis revealed that the films were polycrystalline in nature having a hexagonal wurtzite type crystal structure with a preferred grain orientation in the (0 0 2) direction. Scanning electron microscopy (SEM) measurements reveal that the surface morphology of the films changes continuously with a decrease in the grain size due to Ga doping. All the films showed nearly 90% of transparency in the entire visible region. A blue shift of the optical band gap was observed with an increase in Ga doping. Room temperature photoluminescence (PL) measurement of the deposited films indicates incorporation of Ga in ZnO lattice. At 3 at.% Ga doping, the film has lowest resistivity of 6.8 x 10-3 cm while the carrier concentration is highest.

  6. ZnO Nanowire-Based Corona Discharge Devices Operated Under Hundreds of Volts.

    Science.gov (United States)

    Yang, Wenming; Zhu, Rong; Zong, Xianli

    2016-12-01

    Minimizing the voltage of corona discharges, especially when using nanomaterials, has been of great interest in the past decade or so. In this paper, we report a new corona discharge device by using ZnO nanowires operated in atmospheric air to realize continuous corona discharge excited by hundreds of volts. ZnO nanowires were synthesized on microelectrodes using electric-field-assisted wet chemical method, and a thin tungsten film was deposited on the microchip to enhance discharging performance. The testing results showed that the corona inception voltages were minimized greatly by using nanowires compared to conventional dischargers as a result of the local field enhancement of nanowires. The corona could be continuously generated and self-sustaining. It was proved that the law of corona inception voltage obeyed the conventional Peek's breakdown criterion. An optimal thickness of tungsten film coated over ZnO nanowires was figured out to obtain the lowest corona inception voltage. The ion concentration of the nanowire-based discharger attained 10(17)/m(3) orders of magnitude, which is practicable for most discharging applications. PMID:26880727

  7. ZnO Nanowire-Based Corona Discharge Devices Operated Under Hundreds of Volts

    Science.gov (United States)

    Yang, Wenming; Zhu, Rong; Zong, Xianli

    2016-02-01

    Minimizing the voltage of corona discharges, especially when using nanomaterials, has been of great interest in the past decade or so. In this paper, we report a new corona discharge device by using ZnO nanowires operated in atmospheric air to realize continuous corona discharge excited by hundreds of volts. ZnO nanowires were synthesized on microelectrodes using electric-field-assisted wet chemical method, and a thin tungsten film was deposited on the microchip to enhance discharging performance. The testing results showed that the corona inception voltages were minimized greatly by using nanowires compared to conventional dischargers as a result of the local field enhancement of nanowires. The corona could be continuously generated and self-sustaining. It was proved that the law of corona inception voltage obeyed the conventional Peek's breakdown criterion. An optimal thickness of tungsten film coated over ZnO nanowires was figured out to obtain the lowest corona inception voltage. The ion concentration of the nanowire-based discharger attained 1017/m3 orders of magnitude, which is practicable for most discharging applications.

  8. Preface: Thin Solid Films Topical Special Issue on ZnO Related Transparent Conductive Oxides

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-04-03

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

  9. 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.   

  10. Characterization of piesoelectric ZnO thin films and the fabrication of piezoelectric micro-cantilevers

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Raegan Lynn

    2005-08-01

    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.

  11. Polycrystalline ZnO: B grown by LPCVD as TCO for thin film silicon solar cells

    International Nuclear Information System (INIS)

    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.

  12. Polycrystalline ZnO: B grown by LPCVD as TCO for thin film silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Fay, Sylvie, E-mail: Sylvie.fay@epfl.c [Ecole Polytechnique Federale de Lausanne (EPFL), Institute of Microengineering (IMT), Photovoltaics and Thin Film Electronics Laboratory, Breguet 2, 2000 Neuchatel (Switzerland); Steinhauser, Jerome [Now at Oerlikon Solar Lab, Neuchatel CH-2000 (Switzerland); Nicolay, Sylvain; Ballif, Christophe [Ecole Polytechnique Federale de Lausanne (EPFL), Institute of Microengineering (IMT), Photovoltaics and Thin Film Electronics Laboratory, Breguet 2, 2000 Neuchatel (Switzerland)

    2010-03-31

    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.

  13. Growth behavior and field emission property of ZnO nanowire arrays on Au and Ag films

    Directory of Open Access Journals (Sweden)

    Sung Hyun Kim

    2013-09-01

    Full Text Available We propose a facile method to control the growth and areal density of zinc-oxide (ZnO nanowire arrays using gold or silver films deposited on aluminum-doped ZnO (AZO layers coated on glass substrates. Nanowires exceeding 5 μm in length grew on both the glass/AZO-layer and on the glass/AZO-layer/Au-film where the areal array density was controlled primarily by changing the annealing temperature. In contrast, the nanowire arrays grew only on the AZO surface but not on the Ag film owing to the formation of an Ag-oxide layer. We fabricated field emitter devices with density controlled ZnO nanowire arrays and low turn-on electric field of ∼6 V/μm and a field enhancement factor of up to 1188 were obtained with density controlled ZnO nanowire arrays.

  14. MEMS-based ZnO Piezoelectric Tactile Sensor for Minimally Invasive Surgery

    Institute of Scientific and Technical Information of China (English)

    Minrui Wang; Jing Wang; Yan Cui; Liding Wang

    2006-01-01

    This paper reports the design and fabrication of a MEMS-based ZnO piezoelectric tactile sensor, which can be integrated on to the endoscopic grasper used in minimally invasive surgery (MIS). The sensor includes a silicon substrate,platinum bottom electrode, platinum top electrode, and a ZnO piezoelectric thin film, which is sandwiched between the two-electrode layers. The sensitivity of the micro-force sensor is analyzed in theory and the sensor exhibits high sensitivity about 7 pc/uN. The application of this tactile sensor to MIS will allow the surgeon feeling the touch force between the endoscopic grasper and tissue in real-time, and manipulating the tissue safely.

  15. Particle-on-Film Gap Plasmons on Antireflective ZnO Nanocone Arrays for Molecular-Level Surface-Enhanced Raman Scattering Sensors.

    Science.gov (United States)

    Lee, Youngoh; Lee, Jiwon; Lee, Tae Kyung; Park, Jonghwa; Ha, Minjung; Kwak, Sang Kyu; Ko, Hyunhyub

    2015-12-01

    When semiconducting nanostructures are combined with noble metals, the surface plasmons of the noble metals, in addition to the charge transfer interactions between the semiconductors and noble metals, can be utilized to provide strong surface plasmon effects. Here, we suggest a particle-film plasmonic system in conjunction with tapered ZnO nanowire arrays for ultrasensitive SERS chemical sensors. In this design, the gap plasmons between the metal nanoparticles and the metal films provide significantly improved surface-enhanced Raman spectroscopy (SERS) effects compared to those of interparticle surface plasmons. Furthermore, 3D tapered metal nanostructures with particle-film plasmonic systems enable efficient light trapping and waveguiding effects. To study the effects of various morphologies of ZnO nanostructures on the light trapping and thus the SERS enhancements, we compare the performance of three different ZnO morphologies: ZnO nanocones (NCs), nanonails (NNs), and nanorods (NRs). Finally, we demonstrate that our SERS chemical sensors enable a molecular level of detection capability of benzenethiol (100 zeptomole), rhodamine 6G (10 attomole), and adenine (10 attomole) molecules. This work presents a new design platform based on the 3D antireflective metal/semiconductor heterojunction nanostructures, which will play a critical role in the study of plasmonics and SERS chemical sensors. PMID:26575302

  16. Comparisons of Structural and Optical Properties of ZnO Films Grown on Sapphire and Si(001)

    Institute of Scientific and Technical Information of China (English)

    邱东江; 吴惠桢; 徐晓玲; 陈奶波

    2002-01-01

    Zinc oxide films were grown on sapphire and Si(001) substrates by reactive electron beam evaporation at low substrate temperatures. Atomic force microscopy (AFM), x-ray diffraction (XRD), and photoluminescence excitation (PLE) are employed to characterize the as-grown films. The AFM measurements have shown that all of the ZnO films present pillar-like growth properties, but the dimensional uniformity of the ZnO crystal pillars grown on sapphire was better than that on Si(001). The XRD results indicated that the prepared ZnO films both on sapphire and Si(001) were all highly c-axis oriented; the linewidths of ZnO (002) are only 0.19° and 0.28°, respectively. The PLE characterizations revealed the continuum absorption of the samples grown on sapphire. However, in the PLE spectra of the ZnO films grown on Si(001) substrates, a broad peak appears at the high-energy region, which indicates the formation of ZnO quantum dot structures on Si(001).

  17. Effects of annealing temperature on the magnetoresistance in Ta/NiFe/Ta films by ZnO intercalations

    International Nuclear Information System (INIS)

    Zinc oxide (ZnO) exhibiting many superior physical properties was inserted into the Ta/NiFe/Ta films as nano-oxide intercalations. Different annealing temperatures and ZnO thickness significantly affected the magnetoresistance (MR) in NiFe films. The 4-nm thick ZnO film annealed at 200 °C had a MR of 2.41%, which was more than 70% higher than that of the 1-nm thick ZnO annealed film (MR=1.40%). However, the further increase in annealing temperature to 300 °C rapidly deteriorated the MR performance of the films. Diffusion and interface reactions occur between the crystal ZnO and the adjacent NiFe layer. Lower-temperature annealing improved the interface, increasing the specular reflection of spin-polarized electrons to some extent. However, higher-temperature annealing induced severe diffusion and interface reactions, which led to a sharp decline in MR performance. - Highlights: • Combining NiFe with ZnO, thereby producing NiFe/ZnO interfaces. • Investigating the effects of annealing temperatures on the magnetoresistance. • Explaining the corresponding relationship between MR and microstructure

  18. Effects of annealing temperature on the magnetoresistance in Ta/NiFe/Ta films by ZnO intercalations

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Lei, E-mail: Lding@hainu.edu.cn [Key Laboratory of Advanced Materials of Tropical Island Resources, Ministry of Education, Hainan University, Haikou 570228 (China); Yu, Guang-hua; Zhang, Min; Zhao, Chong-jun; Teng, Jiao [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Xiang, Dao-ping [Key Laboratory of Advanced Materials of Tropical Island Resources, Ministry of Education, Hainan University, Haikou 570228 (China)

    2015-09-01

    Zinc oxide (ZnO) exhibiting many superior physical properties was inserted into the Ta/NiFe/Ta films as nano-oxide intercalations. Different annealing temperatures and ZnO thickness significantly affected the magnetoresistance (MR) in NiFe films. The 4-nm thick ZnO film annealed at 200 °C had a MR of 2.41%, which was more than 70% higher than that of the 1-nm thick ZnO annealed film (MR=1.40%). However, the further increase in annealing temperature to 300 °C rapidly deteriorated the MR performance of the films. Diffusion and interface reactions occur between the crystal ZnO and the adjacent NiFe layer. Lower-temperature annealing improved the interface, increasing the specular reflection of spin-polarized electrons to some extent. However, higher-temperature annealing induced severe diffusion and interface reactions, which led to a sharp decline in MR performance. - Highlights: • Combining NiFe with ZnO, thereby producing NiFe/ZnO interfaces. • Investigating the effects of annealing temperatures on the magnetoresistance. • Explaining the corresponding relationship between MR and microstructure.

  19. Slope selection-driven Ostwald ripening in ZnO thin film growth

    OpenAIRE

    González-González, A; Polop, C.; Vasco, E.

    2012-01-01

    The morphology evolution of polycrystalline ZnO films grown by pulsed laser deposition was investigated by atomic force microscopy and compared with morphologies simulated in 2 + 1 dimensions from a mesoscopic continuum model of selection of surface slopes. The distinctive feature of such an evolution is that the competition between grains gives rise to a singular grain coarsening mechanism, which although it matches the fingerprints of the Ostwald ripening, it remains operative under atypica...

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

    Czech Academy of Sciences Publication Activity Database

    Melikhova, O.; Čížek, J.; Procházka, I.; Kužel, R.; Novotný, Michal; Bulíř, Jiří; Lančok, Ján; Anwand, W.; Brauer, G.; Connolly, J.; McCarthy, E.; Krishnamurthy, S.; Mosnier, J.-P.

    Bristol : IOP Publishing Ltd, 2013, 012018. ISSN 1742-6588. - (Journal of Physics: Conference Series. vol. 443). [International Conference on Positron Annihilation /16./, ICPA 2012. Bristol (GB), 19.08.2012-24.12.2012] R&D Projects: GA ČR(CZ) GAP108/11/0958 Institutional support: RVO:68378271 Keywords : ZnO thin film * pulsed laser deposition * point defects * slow positron implantation spectroscopy * x-ray diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism

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

    Czech Academy of Sciences Publication Activity Database

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

    Vol. 505. Bristol : IOP Publishing Ltd, 2014 - (Hugenschmidt, C.; Piochacz, C.), "012021-1"-"012021-4" ISSN 1742-6588. [International workshop on slow positron beam techniques and applications /13./ (SLOPOS13). München (DE), 15.09.2013-20.09.2013] R&D Projects: GA ČR(CZ) GAP108/11/0958 Institutional support: RVO:68378271 Keywords : ZnO films * nanocrystalline diamond * slow positron implantation spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism

  2. Optical and structural properties of ultrathin ZnO films prepared by PLD

    Czech Academy of Sciences Publication Activity Database

    Novotný, Michal; Bulíř, Jiří; Lančok, Ján; Connolly, J.; McCarthy, E.; Krishnamurthy, S.; Mosnier, J.-P.

    Strasbourg: EMRS, 2010. 15 RPII27. [E- MRS 2010 Spring: Laser processing and diagnostics for micro and nano applications. 07.06.2010-11.06.2010, Strasbourg] R&D Projects: GA AV ČR IAA100100729; GA ČR GP202/09/P324 Institutional research plan: CEZ:AV0Z10100522 Keywords : ZnO ultra thin films * Pulsed Laser Deposition sapphire * MgO * fused silica Subject RIV: BH - Optics, Masers, Lasers

  3. Carrier dynamics and gain spectra at room-temperature in epitaxial ZNO thin films

    DEFF Research Database (Denmark)

    Yu, Ping; Hvam, Jørn Märcher; Wong, K. S.;

    1999-01-01

    Carrier dynamics of epitaxial ZnO thin film was investigated using a frequency up-conversion tehcnique. At lower carrier densities, the decay time of free exciton recombination was measured to be 24 ps. Rapid decay times of a few picoseconds were observed at higher carrier densities, which show a...... transition of two dynamic processes. The comparison of calculated gain spectrum and experimental data gave evidence that the transition is form exciton-exciton scattering to the recombination of electron hole plasma....

  4. Thermal conductivity of ZnO thin film produced by reactive sputtering

    International Nuclear Information System (INIS)

    ZnO thin films have been produced by reactive sputtering with different oxygen contents in the sputtering gas. As a result of transmission electronic microscopy observation, each film consist of two layers: an interfacial layer close to the substrate, with a thickness of about 200 nm, composed of very fine crystal grains and an upper layer above the interfacial layer, composed of column-shaped grains aligned along the out-plane direction. The grain diameter ranges from 35 to 100 nm depending on the oxygen partial pressure. The in-plane and out-plane thermal conductivity have been measured at room temperature. The out-plane thermal conductivity of the interfacial layer is 2.3 W m-1 K-1, independent on the oxygen partial pressure. The out-plane thermal conductivity of the upper layer is 5.4, 7.1, and 4.0 W m-1 K-1, and the in-plane thermal conductivity 4.86, 6.01, and 2.66 W m-1 K-1, for the O2 30%, 60%, and 90% ZnO film, respectively. Both out-plane and in-plane thermal conductivity decrease with the decrease of grain diameter. The thermal conductance of grain boundary has been estimated with the phonon diffusion mismatch model, and the intrinsic thermal conductivity within ZnO grains has been calculated with a cylinder-structured composite model. The result shows that the thermal conductivity of the ZnO thin films is dominated by the intrinsic thermal conductivity, which is a function of grain size.

  5. Improved sensing response of photo activated ZnO thin film for hydrogen peroxide detection.

    Science.gov (United States)

    Parthasarathy, S; Nandhini, V; Jeyaprakash, B G

    2016-11-15

    The nanostructured ZnO thin films were deposited using spray pyrolysis technique. Formation of polycrystalinity with hexagonal wurtzite structure was observed from the structural study. Highly dense spherical shaped nanoparticles with fine crystallites were observed from the surface morphological studies. The light induced hydrogen peroxide vapour sensing was done using chemi-resistive method and its effect on the sensing response was studied and reported. PMID:27491004

  6. Pump-probe measurement of ZnO epitaxial thin films

    CERN Document Server

    Yamamoto, A; Goto, T; Chen, Y; Yao, T; Kasuya, A

    1999-01-01

    Time-resolved optical absorption spectra of ZnO epitaxial thin films have been measured by using a pump-probe technique with subpicosecond time resolution. We have observed following three structures in the differential absorption spectra: saturation of the exciton absorption, bandgap renormalization and optical gain. The optical gain is thought to be due to electron-hole plasma. From the temporal changes of these structures, the dynamical properties of the photo-excited carriers are discussed.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-01-05

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

  8. On tuning the orientation of grains of spray pyrolysed ZnO thin films

    International Nuclear Information System (INIS)

    Effect of varying spray rate on the structure and optoelectronic properties of spray pyrolysed ZnO film is analysed. ZnO films were characterised using different techniques such as X-ray diffraction (XRD), photoluminescence, electrical resistivity measurement, and optical absorption. The XRD analysis proved that, with the increase in spray rate, orientation of the grains changed from (1 0 1) plane to (0 0 2) plane. The films exhibited luminescence in two regions-one was the 'near band-edge' (NBE) (∼380 nm) emission and the other one was the 'blue-green emission' (∼503 nm). Intensity of the blue-green emission decreased after orientation of grains shifted to (0 0 2) plane. Scanning electron microscope (SEM) analysis of the films asserts that spray rate has major role in improving the crystallographic properties of the films. Moreover resistivity of the films could be lowered to 2.4 x 10-2 Ω cm without any doping or post-deposition annealing.

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

    Indian Academy of Sciences (India)

    S Angappane; N R Selvi; G U Kulkarni

    2009-06-01

    We have employed pulsed reactive crossed-beam laser ablation (PRCLA) to deposit a (101) oriented ZnO film. In this method, a supersonic jet of oxygen pulse is made to cross the laser plume from a zinc metal target while being carried to the Si(111) substrate. The obtained deposit was nanocrystalline ZnO as confirmed by a host of characterization techniques. When the substrate was held at varying temperatures, from room temperature to 900°C, the crystallinity of the obtained films increased as expected, but importantly, the crystallographic orientation of the films was varied. High substrate temperatures produced the usual (001) oriented films, while lower substrate temperatures gave rise to increasingly (101) oriented films. The substrate held at room temperature contained only the (101) orientation. The film morphology also varied with the substrate temperature, from being nanoparticulate to rod-like deposits for higher deposition temperatures. Surprisingly, the (101) orientation showed reactivity with acetone forming carbonaceous nanostructures on the surface.

  10. Structural and optical properties of electrodeposited ZnO thin films

    International Nuclear Information System (INIS)

    Zinc oxide thin films were electrodeposited on different substrates. Electrodeposition was performed with hydrogen peroxide, as hydroxide ions source, at - 1.5 V versus mercurial sulfate electrode during one hour, and a temperature maintained at 70 deg. C . The resulting thin films have a good crystallinity and a high c-axis orientation, and the unit cell parameters determined by X-ray diffraction experiment are a = 0.326 nm and c = 0.523 nm, respectively. Microstructure studies using scanning electron microscopy and atomic force microscopy show a good homogeneity of the film and a roughness around 22 nm. Optical properties were studied with Raman spectroscopy and photoluminescence spectroscopy. Optical properties of the films revealed a low defect emission in photoluminescence spectra. The E2 vibration mode for ZnO was observed near 439 cm-1, indicating that the as-deposited films were under compressive stress. Oscillations were observed in the photoluminescence spectra, from which the refractive index of ZnO thin films was extracted, that is ∼ 1.90

  11. Oxidation of ZnO thin films during pulsed laser deposition process

    Indian Academy of Sciences (India)

    E De Posada; L Moreira; J Pérez De La Cruz; M Arronte; L V Ponce; T Flores; J G Lunney

    2013-06-01

    Pulsed laser deposition of ZnO thin films, using KrF laser, is analysed. The films were deposited on (001) sapphire substrates at 400 °C, at two different oxygen pressures (0.3 and 0.4 mbar) and two different target–substrate distances (30 and 40 mm). It is observed that in order to obtain good quality in the photoluminescence of the films, associated with oxygen stoichiometry, it is needed to maximize the time during which the plasma remains in contact with the growing film (plasma residence time), which is achieved by selecting suitable combinations of oxygen pressures and target to substrate distances. It is also discussed that for the growth parameters used, the higher probability for ZnO films growth results from the oxidation of Zn deposited on the substrate and such process takes place during the time that the plasma is in contact with the substrate. Moreover, it is observed that maximizing the plasma residence time over the growing film reduces the rate of material deposition, favouring the surface diffusion of adatoms, which favours both Zn–O reaction and grain growth.

  12. Amorphous-nanocrystalline Al doped ZnO transparent conducting thin films

    Energy Technology Data Exchange (ETDEWEB)

    Diez-Betriu, X., E-mail: xdiezbetriu@icmm.csic.es [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco 28049 Madrid (Spain); Jimenez-Rioboo, R.; Marcos, J. Sanchez-; Cespedes, E.; Espinosa, A.; Andres, A. de [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco 28049 Madrid (Spain)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Al- doped ZnO films by RF- sputtering as amorphous TCO. Black-Right-Pointing-Pointer Structural characterization confirms amorphous-nanocrystalline nature of samples. Black-Right-Pointing-Pointer Optical gap dependence on substrate and grain size. Black-Right-Pointing-Pointer Resistivity correlates to the optical bandgap. - Abstract: Al-doped ZnO films have been deposited at room temperature by means of RF sputtering under different conditions and subjected to annealing treatments looking for amorphous Transparent Conducting Oxide (TCO) films in the search for their integration into the emerging area of the flexible electronics. Structural studies have been performed as well as optical and electrical characterization. Spectroscopic ellipsometry has been used for the determination of the optical gap for films grown on Si and the films thickness. The amorphous fraction of the films (up to 86%) depends on the substrate and RF power but not on the annealing temperature up to 600 Degree-Sign C for glass substrates. The resistivity is found to be independent of the amorphous degree and correlates to the optical bandgap which presents three regimes depending on the annealing temperature.

  13. Microstructures, optical and electrical properties of In-doped ZnO thin films prepared by sol-gel method

    International Nuclear Information System (INIS)

    ZnO and indium-doped ZnO (IxZO) thin films were prepared on silica-glass substrates by the sol-gel method. The thin films were crystallized at 600 deg. C and 700 deg. C for 1 h in 6.9 x 10-1 Torr under pure O2 atmosphere. The analyzed results were compared to investigate the structural characteristics and optical properties. The surface morphology of the IxZO films was different from that of the ZnO films, and showed a thin overlay structure. In addition, the crystallization of IxZO film was depleted at higher crystallized temperatures. From XRD analysis, the ZnO and IxZO thin films possessed hexagonal structures. Notably, micro-In2O3 phases were observed in the IxZO thin films using EDS. Both of In2O3 phases and the crystallization mechanism not only improved the peeling of structure, but also improved the electrical conductivity of IxZO thin films. For the PL spectrum, the optical property of the IxZO film was raised at a higher crystallization temperature. Although the In2O3 phases reduced the structural defects of IxZO thin film, the optical effect of the residual In3+ was not enhanced completely at higher crystallized temperatures.

  14. Characterization of nanostructured ZnO thin films deposited through vacuum evaporation

    Science.gov (United States)

    Maldonado, Arturo; Juarez, Héctor; Pacio, Mauricio; Perez, Rene

    2015-01-01

    Summary 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. PMID:25977868

  15. 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.

  16. Thickness-dependent fracture behaviour of flexible ZnO : Al thin films

    International Nuclear Information System (INIS)

    The effects of thickness on flexibility and crack initiation in ZnO : Al thin films sputter-deposited on polyethersulfone substrates have been investigated. With an increase in thickness, root-mean-square roughness and average crystallite size increase linearly. It is found that the higher the thickness, the lower is the strain required to initiate cracks in the film. The thinnest film (∼240 nm) exhibits a crack-initiating critical strain of 0.96% and a saturated crack density of 0.10 μm-1. A critical energy release rate of 68.5 J m-2 and a mode I fracture toughness of 3.2 MPa m0.5 are estimated for the films. These parameters are found to exhibit a linear dependence on film thickness.

  17. Bias-voltage dependent ultraviolet photodetectors prepared by GaOx + ZnO mixture phase nanocrystalline thin films

    International Nuclear Information System (INIS)

    Highlights: •GaOx + ZnO thin films sputtered and annealed exhibit interesting and unique optical properties, especially deep UV photo response. •GaOx + ZnO thin films can be used to fabricate efficient deep UV photodetectors. •The mixture phase nature of GaOx + ZnO thin films is revealed to be responsible for the unique characteristics of the photodetectors. •Two bands in UV range can be adjusted by a applied voltage when the PDs were fabricated using the mixture phase nature of GaOx + ZnO thin films. -- Abstract: Ultraviolet (UV) photodetectors were prepared by using the GaOx + ZnO mixture phase thin films sputtered on sapphire as the photoresponse layer. The devices show good photoresponse in UV range. More interestingly, the device responsivity in the wavelength less than 280 nm range rapidly increases with increasing the applied voltage and becomes dominant for the bias ⩾3.0 V. X-ray diffraction, absorption and cathodoluminescence measurements firmly reveal the mixture phases in the thin films. Electric field dependent detrapping of photo-excited carriers in nanocrystals in the films shall be responsible for the observed bias-voltage dependent deep UV photoresponse of the devices

  18. Electrical and optical properties of p-type codoped ZnO thin films prepared by spin coating technique

    Science.gov (United States)

    Pathak, Trilok Kumar; Kumar, Vinod; Swart, H. C.; Purohit, L. P.

    2016-03-01

    Undoped, doped and codoped ZnO thin films were synthesized on glass substrates using a spin coating technique. Zinc acetate dihydrate, ammonium acetate and aluminum nitrate were used as precursor for zinc, nitrogen and aluminum, respectively. X-ray diffraction shows that the thin films have a hexagonal wurtzite structure for the undoped, doped and co-doped ZnO. The transmittance of the films was above 80% and the band gap of the film varied from 3.20 eV to 3.24 eV for undoped and doped ZnO. An energy band diagram to describe the photoluminescence from the thin films was also constructed. This diagram includes the various defect levels and possible quasi-Fermi levels. A minimum resistivity of 0.0834 Ω-cm was obtained for the N and Al codoped ZnO thin films with p-type carrier conductivity. These ZnO films can be used as a window layer in solar cells and in UV lasers.

  19. 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.)

  20. Growth of epitaxial p-type ZnO thin films by codoping of Ga and N

    International Nuclear Information System (INIS)

    Codoping of Ga and N was utilized to realize p-type conduction in ZnO films using rf magnetron sputtering. The films obtained at 550 deg. C on sapphire showed resistivity and hole concentrations of 38 Ω cm and 3.9x1017 cm-3, respectively. ZnO films also showed a p-type behavior on p-Si with better electrical properties. ZnO homojunctions synthesized by in situ deposition of Ga-N codoped p-ZnO layer on Ga doped n-ZnO layer showed clear p-n diode characteristics. Low temperature photoluminescence spectra of codoped films also revealed a dominant peak at 3.12 eV. The codoped films showed a dense columnar structure with a c-axis preferred orientation

  1. Photovoltaic performance of Gallium-doped ZnO thin film/Si nanowires heterojunction diodes

    Science.gov (United States)

    Akgul, Guvenc; Aksoy Akgul, Funda; Emrah Unalan, Husnu; Turan, Rasit

    2016-04-01

    In this work, photovoltaic performance of Ga-doped ZnO thin film/Si NWs heterojunction diodes was investigated. Highly dense and vertically well-aligned Si NW arrays were successfully synthesised on a p-type (1 0 0)-oriented Si wafer through cost-effective metal-assisted chemical etching technique. Ga-doped ZnO thin films were deposited onto Si NWs via radio frequency magnetron sputtering to construct three-dimensional heterostructures. Photovoltaic characteristics of the fabricated diodes were determined with current density (J)-voltage (V) measurements under simulated solar irradiation of AM 1.5 G. The optimal open-circuit voltage, short-circuit current density, fill factor and power conversion efficiency were found to be 0.37 V, 3.30 mA cm-2, 39.00 and 0.62%, respectively. Moreover, photovoltaic diodes exhibited relatively high external quantum efficiency over the broadband wavelengths between 350 and 1100 nm interval of the spectrum. The observed photovoltaic performance in this study clearly indicates that the investigated device structure composed of Ga-doped ZnO thin film/Si NWs heterojunctions could facilitate an alternative pathway for optoelectronic applications in future, and be a promising alternative candidate for high-performance low-cost new-generation photovoltaic diodes.

  2. Growth of epitaxial ZnO films on sapphire substrates by plasma assisted molecular beam epitaxy

    Science.gov (United States)

    Hyndman, Adam R.; Allen, Martin W.; Reeves, Roger J.

    2014-03-01

    Epitaxial layers of ZnO have been grown on c-plane, (0001) sapphire substrates by plasma assisted molecular beam epitaxy. The oxygen:zinc flux ratio was found to be crucial in obtaining a film with a smooth surface and good crystallinity. When increasing film thickness from ~80 to 220 nm we observed an increase in the streakiness of RHEED images, and XRD revealed a reduction in crystal strain and increase in crystal alignment. A film with surface roughness of 0.5 nm and a XRD rocking curve FWHM of 0.1 for the main ZnO peak (0002) was achieved by depositing a low temperature ZnO buffer layer at 450 °C and then growing for 120 minutes at 700 °C with a Zn-cell temperature of 320 °C and an oxygen partial pressure of 7e-7 Torr. We found novel structures on two samples grown outside of our ideal oxygen:zinc flux ratio. SEM images of a sample believed to have been grown in a Zn-rich environment showed flower like structures up to 150 um in diameter which appear to have formed during growth. Another sample believed to have been deposited in a Zn-deficient environment had rings approximately 1.5 um in diameter scattered on its surface.

  3. Ethanol gas sensing properties of Al2O3-doped ZnO thick film resistors

    Indian Academy of Sciences (India)

    D R Patil; L A Patil; D P Amalnerkar

    2007-12-01

    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 ethanol vapours at 300°C. Aluminium oxide grains dispersed around ZnO grains would result into the barrier height among the grains. Upon exposure of ethanol vapours, the barrier height would decrease greatly leading to drastic increase in conductance. It is reported that the surface misfits, calcination temperature and operating temperature can affect the microstructure and gas sensing performance of the sensor. The efforts are, therefore, made to create surface misfits by doping Al2O3 into zinc oxide and to study the sensing performance. The quick response and fast recovery are the main features of this sensor. The effects of microstructure and additive concentration on the gas response, selectivity, response time and recovery time of the sensor in the presence of ethanol vapours were studied and discussed.

  4. Synthesis and Characterization of Varying Concentrations of Ag-doped ZnO Thin Films

    Science.gov (United States)

    Hachlica, Justin; Wadie-Ibrahim, Patrick; Sahiner, M. Alper

    Silver doped ZnO is a promising compound for photovoltaic solar cell use. Doping this compound with varying amounts of silver will theoretically make this type of thin film more efficient by reducing the overall resistance and increasing the voltage and current output. The extent of this promise is being tested experimentally, by analysis of both the electrical and the surface roughness properties of the cells. Ag-doped Zinc Oxide is deposited by method of Pulsed Laser Deposition (PLD) onto Indium Tin Oxide (ITO) coated Glass. Annealing effects were also observed by varying the temperature at which the annealing occurred after synthesis of the sample. Thickness is confirmed by use of Ellipsometery. X-Ray Diffraction (XRD) measurements confirmed a ZnO crystal structure on the thin films. The active dopant carrier concentrations were determined using a Hall Effect Measuring System. Finally, the photovoltaic properties of the film are recorded by using a Keithley Source Meter. The structural characterization and electrical results of the effect of Ag doping on ZnO will then be discussed.

  5. A lateral field excited ZnO film bulk acoustic wave sensor working in viscous environments

    International Nuclear Information System (INIS)

    We present a lateral field excited ZnO film bulk acoustic resonator (FBAR) operated in pure-shear mode and analyze its performances in viscous liquids. The electrodes of the device are located on the film surface and normal to the c-axis of the ZnO film. The proposed device works near 1.44 GHz with a Q-factor up to 360 in air and 310 in water, which are higher than those of the quasi-shear thickness field excited FBAR. The resonant frequency is decreased with the increasing square root of the product of the viscosity and density with a linear dependence in the viscosity below 148.7 mPa s. The mass sensitivity of 670 Hz cm2 ng−1 was measured by monitoring the frequency change during the volatilization of saline solution loaded on the resonator. In addition, the levels of the noise and the mass resolutions were measured in various viscous environments. The proposed device yields the mass resolution of 670 Hz cm2 ng−1 and the high mass resolution of 0.06 ng cm−2. These results indicated that the lateral field excited ZnO FBAR had superior sensitivity for the bio-sensing applications in viscous biological liquids. (paper)

  6. Analysis of stability improvement in ZnO thin film transistor with dual-gate structure under negative bias stress

    Science.gov (United States)

    Yun, Ho-Jin; Kim, Young-Su; Jeong, Kwang-Seok; Kim, Yu-Mi; Yang, Seung-dong; Lee, Hi-Deok; Lee, Ga-Won

    2014-01-01

    In this study, we fabricated dual-gate zinc oxide thin film transistors (ZnO TFTs) without additional processes and analyzed their stability characteristics under a negative gate bias stress (NBS) by comparison with conventional bottom-gate structures. The dual-gate device shows superior electrical parameters, such as subthreshold swing (SS) and on/off current ratio. NBS of VGS = -20 V with VDS = 0 was applied, resulting in a negative threshold voltage (Vth) shift. After applying stress for 1000 s, the Vth shift is 0.60 V in a dual-gate ZnO TFT, while the Vth shift is 2.52 V in a bottom-gate ZnO TFT. The stress immunity of the dual-gate device is caused by the change in field distribution in the ZnO channel by adding another gate as the technology computer aided design (TCAD) simulation shows. Additionally, in flicker noise analysis, a lower noise level with a different mechanism is observed in the dual-gate structure. This can be explained by the top side of the ZnO film having a larger crystal and fewer grain boundaries than the bottom side, which is revealed by the enhanced SS and XRD results. Therefore, the improved stability of the dual-gate ZnO TFT is greatly related to the E-field cancellation effect and crystal quality of the ZnO film.

  7. Optical and Recombination Losses in Thin Film Solar Cells Based on Heterojunctions n-ZnS (n-CdS) / p-CdTe with Current Collecting Contacts ITO and ZnO

    OpenAIRE

    O.A. Dobrozhan; A.S. Opanasyuk; V.V. Grynenko

    2014-01-01

    The optical and recombination losses in auxiliary and absorbing layers of solar cells based on heterojunctions n-ZnS / p-CdTe and n-CdS / p-CdTe with current collecting front sublayers ITO and ZnO were determined. As a result, spectral dependence of light transmittance (T) of solar cells, taking into account its reflections from the boundaries of the contacting materials and in case of absorption in the auxiliary layers of solar cells was calculated. The influence of optical and recombination...

  8. Water-assisted nitrogen mediated crystallisation of ZnO films

    International Nuclear Information System (INIS)

    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 (μe), concentration of free electrons (Ne) and sheet resistance (Rsh) 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 Rsh of thin (130–270 nm) functional ZnO:Al films twice compared to the glass substrate. Both provide this effect: increase in μe and increase of Ne. - 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 Rsh

  9. 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

  10. RF magnetron-sputtered ZNO thin films: on the evolution of microstructure and residual stresses

    OpenAIRE

    Özen, İstem; Ozen, Istem

    2006-01-01

    Thin ZnO films (200-500 nm) were deposited onto glass, mica, and Si(100) substrates, to study the relations between microstructure and residual stresses. The ranges for the substrate temperature, chamber pressure, and RF power were room temperature-200 °C, 0.009-0.4 mbar, and 100-125 W, respectively. The strain measurements by x-ray diffraction and the biaxial stress model showed that the films were under residual compressive stresses from -2 to -8 GPa. 5-11 percent of those stresses were ind...

  11. 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 (

  12. Detailed microstructure analysis of as-deposited and etched porous ZnO films

    International Nuclear Information System (INIS)

    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 m2 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

  13. Tuning of undoped ZnO thin film via plasma enhanced atomic layer deposition and its application for an inverted polymer solar cell

    Directory of Open Access Journals (Sweden)

    Mi-jin Jin

    2013-10-01

    Full Text Available We studied the tuning of structural and optical properties of ZnO thin film and its correlation to the efficiency of inverted solar cell using plasma-enhanced atomic layer deposition (PEALD. The sequential injection of DEZn and O2 plasma was employed for the plasma-enhanced atomic layer deposition of ZnO thin film. As the growth temperature of ZnO film was increased from 100 °C to 300 °C, the crystallinity of ZnO film was improved from amorphous to highly ordered (002 direction ploy-crystal due to self crystallization. Increasing oxygen plasma time in PEALD process also introduces growing of hexagonal wurtzite phase of ZnO nanocrystal. Excess of oxygen plasma time induces enhanced deep level emission band (500 ∼ 700 nm in photoluminescence due to Zn vacancies and other defects. The evolution of structural and optical properties of PEALD ZnO films also involves in change of electrical conductivity by 3 orders of magnitude. The highly tunable PEALD ZnO thin films were employed as the electron conductive layers in inverted polymer solar cells. Our study indicates that both structural and optical properties rather than electrical conductivities of ZnO films play more important role for the effective charge collection in photovoltaic device operation. The ability to tune the materials properties of undoped ZnO films via PEALD should extend their functionality over the wide range of advanced electronic applications.

  14. Effect of doping concentration on the conductivity and optical properties of p-type ZnO thin films

    Science.gov (United States)

    Pathak, Trilok Kumar; Kumar, Vinod; Swart, H. C.; Purohit, L. P.

    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 cm2/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.

  15. 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.

  16. Significant mobility enhancement in extremely thin highly doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Look, David C., E-mail: david.look@wright.edu [Semiconductor Research Center, Wright State University, 3640 Colonel Glenn Hwy., Dayton, Ohio 45435 (United States); Wyle Laboratories, Inc., 2601 Mission Point Blvd., Dayton, Ohio 45431 (United States); Air Force Research Laboratory Sensors Directorate, 2241 Avionics Circle, Wright-Patterson AFB, Ohio 45433 (United States); Heller, Eric R. [Air Force Research Laboratory Materials and Manufacturing Directorate, 3005 Hobson Way, Wright-Patterson AFB, Ohio 45433 (United States); Yao, Yu-Feng; Yang, C. C., E-mail: ccycc@ntu.edu.tw [Institute of Photonics and Optoelectronics, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan (China)

    2015-04-13

    Highly Ga-doped ZnO (GZO) films of thicknesses d = 5, 25, 50, and 300 nm, grown on 160-nm ZnO buffer layers by molecular beam epitaxy, had 294-K Hall-effect mobilities μ{sub H} of 64.1, 43.4, 37.0, and 34.2 cm{sup 2}/V-s, respectively. This extremely unusual ordering of μ{sub H} vs d is explained by the existence of a very high-mobility Debye tail in the ZnO, arising from the large Fermi-level mismatch between the GZO and the ZnO. Scattering theory in conjunction with Poisson analysis predicts a Debye-tail mobility of 206 cm{sup 2}/V-s at the interface (z = d), falling to 58 cm{sup 2}/V-s at z = d + 2 nm. Excellent fits to μ{sub H} vs d and sheet concentration n{sub s} vs d are obtained with no adjustable parameters.

  17. Significant mobility enhancement in extremely thin highly doped ZnO films

    International Nuclear Information System (INIS)

    Highly Ga-doped ZnO (GZO) films of thicknesses d = 5, 25, 50, and 300 nm, grown on 160-nm ZnO buffer layers by molecular beam epitaxy, had 294-K Hall-effect mobilities μH of 64.1, 43.4, 37.0, and 34.2 cm2/V-s, respectively. This extremely unusual ordering of μH vs d is explained by the existence of a very high-mobility Debye tail in the ZnO, arising from the large Fermi-level mismatch between the GZO and the ZnO. Scattering theory in conjunction with Poisson analysis predicts a Debye-tail mobility of 206 cm2/V-s at the interface (z = d), falling to 58 cm2/V-s at z = d + 2 nm. Excellent fits to μH vs d and sheet concentration ns vs d are obtained with no adjustable parameters

  18. Bandgap-controlled non-equilibrium ZnO1−xSx thin films grown by pulsed laser deposition method

    International Nuclear Information System (INIS)

    Although ZnO and ZnS are chemically and structurally similar, these binary compounds do not form a solid solution at room temperature for all proportions of sulfur (S) and oxygen (O) due to solubility limits of S in ZnO and O in ZnS in equilibrium states. To fabricate ZnO1−xSx thin films with 0 < x < 1, films were intentionally deposited in a non-equilibrium state using pulsed laser deposition while controlling oxygen pressures. The deposited ZnO1−xSx thin film structures were investigated by X-ray diffraction, confirming the formation of hexagonal wurtzite structures with c-axis lattice constants larger than that of ZnO and smaller than that of ZnS. Furthermore, phase segregation to ZnO and ZnS was observed by increasing the temperature of the ZnO0.5S0.5 thin film, suggesting non-equilibrium state of the deposited film. The observed optical energy bandgaps of the ZnO1−xSx thin films were smaller than those of both ZnO (~ 3.3 eV) and ZnS (~ 3.68 eV), suggesting a bandgap bowing effect due to valance and conduction band shifts. - Highlights: • We successfully deposited a II–VI type of semiconductors, ZnO1−xSx thin films. • We study about ZnO0.5S0.5 phase with temperature dependent XRD. • The contents of ZnO1−xSx thin films are from 1(ZnS) to 0(ZnO)

  19. Effect of Nd3+ incorporation on the microstructure and chemical structure of RF sputtered ZnO thin films

    International Nuclear Information System (INIS)

    Highlights: ► Effects of Nd incorporation on ZnO thin films chemical and structural properties. ► Very low Nd concentrations were quantified by combining XRF and AES data. ► At low Nd concentration, Nd ions were successfully incorporated in the ZnO lattice. ► Structural changes turns up with increasing Nd doping level. ► At high Nd concentration, precipitation of a Nd2O3 separate phase occurs. -- Abstract: The present work aims at investigating the effects that different levels of Nd atoms incorporation can have on the microstructure and chemical structure of ZnO thin films. Undoped and Nd-doped ZnO films were deposited by RF co-sputtering from pure ZnO and metallic Nd targets in Ar plasma onto Si, quartz and glass substrates. The Nd concentration in the ZnO host matrix was varied in the range 0–26 at.% by varying the bias applied to the Nd target. A comprehensive characterization of the films properties was performed by X-ray photoelectron and Auger electron spectroscopies, X-ray fluorescence analysis, X-ray diffraction and scanning electron microscopy. At low Nd atomic concentration (Nd/Zn 2O3

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

    International Nuclear Information System (INIS)

    A ZnO thin film was successfully synthesized on glass, flat surface and textured silicon substrates by chemical spray deposition. The textured silicon substrate was carried out using two solutions (NaOH/IPA and Na2CO3). Textured with Na2CO3 solution, the sample surface exhibits uniform pyramids with an average height of 5 μm. The properties and morphology of ZnO films were investigated. X-ray diffraction (XRD) spectra revealed a preferred orientation of the ZnO nanocrystalline film along the c-axis where the low value of the tensile strain 0.26% was obtained. SEM images show that all films display a granular, polycrystalline morphology. The morphology of the ZnO layers depends dramatically on the substrate used and follows the contours of the pyramids on the substrate surface. The average reflectance of the textured surface was found to be around 13% and it decreases dramatically to 2.57% after deposition of a ZnO antireflection coating. FT-IR peaks arising from the bonding between Zn-O are clearly represented using a silicon textured surface. A very intense photoluminescence (PL) emission peak is observed for ZnO/textured Si, revealing the good quality of the layer. The PL peak at 380.5 nm (UV emission) and the high-intensity PL peak at 427.5 nm are observed and a high luminescence occurs when using a textured Si substrate.

  1. Characterization of dilute magnetic semiconducting transition metal doped ZnO thin films by sol–gel spin coating method

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Diluted magnetic semiconducting TM (Ni, Mn, Co) doped ZnO thin films were fabricated by sol–gel spin coating technique. • The XRD analyses revealed that the TM (Ni, Mn, Co) doped ZnO films have hexagonal wurtzite structure. • Photoluminescence and micro-Raman spectra were interpreted for TM (Ni, Mn, Co) doped ZnO thin films. • SEM morphology studies were made for Zn0.97 Ni0.03O, Zn0.97 Mn0.03O and Zn0.97 Co0.03O thin films. • Room temperature ferromagnetism was observed in TM (Ni, Mn, Co) doped ZnO thin films. - Abstract: Pure and transition metal (TM = Ni, Mn, Co) doped zinc oxide (ZnO) thin films were prepared by sol–gel spin coating method with a concentration of 0.03 mol% of transition metals. X-ray diffraction studies revealed the polycrystalline nature of the films with the presence of hexagonal wurtzite structure. UV transmittance spectra showed that all the films are highly transparent in the visible region and in the case of doped ZnO thin films, d–d transition was observed in the violet region due to the existence of crystalline defects and grain boundaries. The optical band gap of the films decreases with increasing orbital occupation numbers of 3d electrons due to the orbital splitting of magnetic ions. Ultraviolet and near-infrared electronic transitions were observed which reveals a strong relationship with the doping of transition metal into ZnO site. The observed luminescence in the green, violet and red regions strongly depends on the doping elements owing to the different oxygen vacancy, oxygen interstitial, and surface morphology. The surface morphology of thin films was investigated by scanning electron microscope (SEM). The energy dispersive X-ray analysis (EDX) confirmed the stoichiometric composition of the TM doped ZnO thin films. Magnetic measurements at room temperature exhibited well defined ferromagnetic features of the thin films

  2. Characterization of dilute magnetic semiconducting transition metal doped ZnO thin films by sol–gel spin coating method

    Energy Technology Data Exchange (ETDEWEB)

    Vijayaprasath, G.; Murugan, R. [Department of Physics, Alagappa University, Karaikudi 630004, Tamil Nadu (India); Ravi, G., E-mail: gravicrc@gmail.com [Department of Physics, Alagappa University, Karaikudi 630004, Tamil Nadu (India); Mahalingam, T. [Department of Electrical and Computer Engineering, Ajou University, Suwon 443-749 (Korea, Republic of); Hayakawa, Y. [Research Institute of Electronics, Shizuoka University, Hamamatsu 432-8011 (Japan)

    2014-09-15

    Graphical abstract: - Highlights: • Diluted magnetic semiconducting TM (Ni, Mn, Co) doped ZnO thin films were fabricated by sol–gel spin coating technique. • The XRD analyses revealed that the TM (Ni, Mn, Co) doped ZnO films have hexagonal wurtzite structure. • Photoluminescence and micro-Raman spectra were interpreted for TM (Ni, Mn, Co) doped ZnO thin films. • SEM morphology studies were made for Zn{sub 0.97} Ni{sub 0.03}O, Zn{sub 0.97} Mn{sub 0.03}O and Zn{sub 0.97} Co{sub 0.03}O thin films. • Room temperature ferromagnetism was observed in TM (Ni, Mn, Co) doped ZnO thin films. - Abstract: Pure and transition metal (TM = Ni, Mn, Co) doped zinc oxide (ZnO) thin films were prepared by sol–gel spin coating method with a concentration of 0.03 mol% of transition metals. X-ray diffraction studies revealed the polycrystalline nature of the films with the presence of hexagonal wurtzite structure. UV transmittance spectra showed that all the films are highly transparent in the visible region and in the case of doped ZnO thin films, d–d transition was observed in the violet region due to the existence of crystalline defects and grain boundaries. The optical band gap of the films decreases with increasing orbital occupation numbers of 3d electrons due to the orbital splitting of magnetic ions. Ultraviolet and near-infrared electronic transitions were observed which reveals a strong relationship with the doping of transition metal into ZnO site. The observed luminescence in the green, violet and red regions strongly depends on the doping elements owing to the different oxygen vacancy, oxygen interstitial, and surface morphology. The surface morphology of thin films was investigated by scanning electron microscope (SEM). The energy dispersive X-ray analysis (EDX) confirmed the stoichiometric composition of the TM doped ZnO thin films. Magnetic measurements at room temperature exhibited well defined ferromagnetic features of the thin films.

  3. High quality ZnO film prepared on ITO substrate for H{sub 2} sensing application

    Energy Technology Data Exchange (ETDEWEB)

    Karthick, K.; Vijayalakshmi, K., E-mail: viji71naveen@yahoo.com

    2015-05-15

    In this paper, we report the temperature effect on the properties of ZnO films prepared on ITO coated glass substrate by a spray pyrolysis technique. XRD studies revealed the polycrystalline hexagonal wurtzite ZnO structure. The promoting effect of ITO on the crystal quality of ZnO film is reflected in the film prepared at 350 °C. The red-shift in the PL peak with increase in temperature was confirmed from the decrease in the optical band gap of the film, contributed partially by the size effect and partially by the strain relaxation of ZnO crystallites. Highly compact and porous morphology of the films with large RMS roughness favored the surface reactivity with H{sub 2} gas. The large response of ZnO/ITO sensor at low operating temperature, with fast response and recovery was attributed to the microstructure of the ITO underlayer. - Highlights: • Preferred (0 0 2) orientation of ZnO improved with substrate temperature. • Intense red-shift was observed with less violet emission. • SEM revealed highly compact morphology of the films with large RMS roughness. • High sensitivity of ZnO/ITO towards H{sub 2} at lower operating temperature.

  4. Synthesis and characterization of thermally oxidized ZnO films

    Indian Academy of Sciences (India)

    A P Rambu; N Iftimie

    2014-05-01

    Metallic zinc thin films were deposited onto glass substrates using vacuum thermal evaporation method. By thermal oxidation of as-deposited Zn films, in ambient conditions, at different temperatures (570, 670 and 770 K, respectively, for 1 h) zinc oxide thin films were obtained. The structural characteristics of the obtained films were investigated by X-ray diffraction technique and atomic force microscopy. Characteristic XRD patterns of oxidized films show small and narrow peaks superimposed on the large broad background of the amorphous component of the substrate. Optical transmittance spectra were recorded and it was observed that the transmittances of the studied films increased with increasing oxidation temperature. The values of the optical bandgap, g, evaluated from Tauc plots, were found to be ranged between 3.22 and 3.27 eV. Electrical conductivity measurements were performed and it was observed that, after performing a heat treatment, the electrical conductivity of analysed samples decreased with one or two orders of magnitude. The gas sensitivity was investigated for some reducing gases such as acetone, methane and liquefied petroleum gas and it was observed that the films studied were selective to acetone.

  5. A comparison between different ohmic contacts for ZnO thin films

    International Nuclear Information System (INIS)

    There are several metals that form ohmic contacts for ZnO thin films, such as copper, aluminum and silver. The aim of this work is to make a comparison between these ohmic contacts. To achieve this purpose, polycrystalline ZnO thin films were prepared by the spray pyrolysis technique, and characterized by the I–V measurements at room temperature. Two strips of each metal were thermally evaporated on the surface of the film and measurements were first recorded in the dark and room light, then in the dark before and after annealing for Al, which was found to be the best in the set. Films with aluminum contacts gave the smallest resistivity, best ohmicity and they are slightly affected by light as required. On the other hand, copper was found to be the worst, and films with copper contacts gave the largest resistivity, worst ohmicity and they are the most affected by light. Annealing improved the aluminum contacts due to alloying and doping. (paper)

  6. 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.

  7. Optical SHG for ZnO films with different morphology stimulated by UV-laser thermotreatment

    Energy Technology Data Exchange (ETDEWEB)

    Ebothe, J [Laboratoire LTME, Universite de Reims, Reims (France); Miedzinski, R [Institute of Physics, J. Dlugosz University of Czestochowa, Czestochowa (Poland); Kapustianyk, V [Scientific-Technical and Educational Centre of Low Temperature Studies, Ivan FrankoNational University of Lviv, Lviv (Ukraine); Turko, B [Scientific-Technical and Educational Centre of Low Temperature Studies, Ivan FrankoNational University of Lviv, Lviv (Ukraine); Kulyk, B [Scientific-Technical and Educational Centre of Low Temperature Studies, Ivan FrankoNational University of Lviv, Lviv (Ukraine); Gruhn, W [Institute of Physics, J. Dlugosz University of Czestochowa, Czestochowa (Poland); Kityk, I V [Institute of Physics, J. Dlugosz University of Czestochowa, Czestochowa (Poland)

    2007-08-15

    We have discovered a strong influence of the ZnO grain sizes on the output second harmonic generation stimulated by nanosecond pulses of 371 nm nitrogen laser during simultaneous superposition of the electrostatic electric field with electric strength about 2 kV/cm. To explore an influence of film morphology on the second order optical susceptibility we have explored the films prepared by electron sputtering with averaged grain sizes about 1000 nm and films synthesized by rf-magnetron sputtering on the two different substrates - glass and amorphous quartz with average grain sizes about 137 nm and 29 nm, respectively. Comparing the UV-induced optical second harmonic generation for the ZnO films with different grain sizes we have concluded that the samples with nanorods are characterized by considerably larger second order susceptibility (up to 5.7 pm/V at 1064 nm fundamental wavelength) compared to those for the films with smaller grain sizes (1.5 pm/V). This may be caused by a fact that UV-illumination deals only effectively with simultaneous electric field treatment enhancing the second order optical susceptibility. A correlation between the temperature of local laser thermo-heating and the output optical second harmonic generation may indicate on principal role of the local thermal expansion in the observed output second harmonic generation.

  8. Transparent conductive Al-doped ZnO thin films grown at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yuping; Lu Jianguo; Bie Xun; Gong Li; Li Xiang; Song Da; Zhao Xuyang; Ye Wenyi; Ye Zhizhen [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

    2011-05-15

    Aluminum-doped ZnO (ZnO:Al, AZO) thin films were prepared on glass substrates by dc reactive magnetron sputtering from a Zn-Al alloy target at room temperature. The effects of the Ar-to-O{sub 2} partial pressure ratios on the structural, electrical, and optical properties of AZO films were studied in detail. AZO films grown using 100:4 to 100:8 Ar-to-O{sub 2} ratio result in acceptable quality films with c-axis orientated crystals, uniform grains, 10{sup -3} {Omega} cm resistivity, greater than 10{sup 20} cm{sup -3} electron concentration, and high transmittance, 90%, in the visible region. The lowest resistivity of 4.11x10{sup -3} {Omega} cm was obtained under the Ar-to-O{sub 2} partial pressure ratio of 100:4. A relatively strong UV emission at {approx}3.26 eV was observed in the room-temperature photoluminescence spectrum. X-ray photoelectron spectroscopy analysis confirmed that Al was introduced into ZnO and substitutes for Zn and doped the film n-type.

  9. Different magnetothermoelectric behavior in Al- and Ga-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Han; Fang, Liang, E-mail: lfang@cqu.edu.cn; Tian, Dexiang; Wu, Fang; Li, Wanjun

    2014-03-05

    Highlights: • The effect of magnetic field on the thermoelectric property was investigated. • The tendencies of the |S| for AZO and GZO varying with magnetic field were observed. • Magnetic field can decrease the |S| of AZO but increase that of GZO. -- Abstract: This essay mainly focuses on the influence of magnetic filed on thermoelectric properties of Al-doped ZnO (AZO) and Ga-doped ZnO (GZO) thin films. The Seebeck coefficients (S) of AZO and GZO films show opposite behavior as a function of the magnetic field intensity (B), which should be attributed to the effect of magnetic field on the effective electron number and potential barrier at grain boundary. For GZO film, with higher electron number, the influence of magnetic field on the effective electron number is the dominant factor, while more potential barriers at grain boundaries exist in AZO film due to the Al–O bond length with a higher mismatch to Zn–O bond length than the Ga–O bond length, so the effect of magnetic field on the potential barriers at grain boundaries dominates in AZO film.

  10. Microstructure, magnetic and optical properties of sputtered polycrystalline ZnO films with Fe addition

    International Nuclear Information System (INIS)

    Microstructure, magnetic and optical properties of polycrystalline Fe-doped ZnO films fabricated by cosputtering with different Fe atomic fractions (xFe) have been examined systematically. Fe addition could affect the growth of ZnO grains and surface morphology of the films. As xFe is larger than 7.0%, ZnFe2O4 grains appear in the films. All the films are ferromagnetic. The ferromagnetism comes from the ferromagnetic interaction activated by defects between the Fe ions that replace Zn ions. The average moment per Fe ion reaches a maximum value of 1.61 μB at xFe = 4.8%. With further increase in xFe, the average moment per Fe ion decreases because the antiferromagnetic energy is lower than the ferromagnetic one due to the reduced distance between the adjacent Fe ions. The optical band gap value decreases from 3.245 to 3.010 eV as xFe increases from 0% to 10%. Photoluminescence spectra analyses indicate that many defects that affect the optical and magnetic properties exist in the films.

  11. Effect of band gap energy on the electrical conductivity in doped ZnO thin film

    International Nuclear Information System (INIS)

    The transparent conductive pure and doped zinc oxide thin films with aluminum, cobalt and indium were deposited by ultrasonic spray technique on glass substrate at 350 °C. This paper is to present a new approach to the description of correlation between electrical conductivity and optical gap energy with dopants' concentration of Al, Co and In. The correlation between the electrical and optical properties with doping level suggests that the electrical conductivity of the films is predominantly estimated by the band gap energy and the concentrations of Al, Co and In. The measurement in the electrical conductivity of doped films with correlation is equal to the experimental value, the error of this correlation is smaller than 13%. The minimum error value was estimated in the cobalt-doped ZnO thin films. This result indicates that such Co-doped ZnO thin films are chemically purer and have far fewer defects and less disorder owing to an almost complete chemical decomposition. (semiconductor materials)

  12. Characterization of ZnO film grown on polycarbonate by atomic layer deposition at low temperature

    International Nuclear Information System (INIS)

    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

  13. Research update : Atmospheric pressure spatial atomic layer deposition of ZnO thin films : reactors, doping and devices

    OpenAIRE

    Hoye, Robert L.Z.; David Muñoz-Rojas; Nelson, Shelby F.; Andrea Illiberi; Paul Poodt; Fred Roozeboom; MacManus-Driscoll, Judith L

    2015-01-01

    Atmospheric pressure spatial atomic layer deposition (AP-SALD) has recently emerged as an appealing technique for rapidly producing high quality oxides. Here, we focus on the use of AP-SALD to deposit functional ZnO thin films, particularly on the reactors used, the film properties, and the dopants that have been studied. We highlight how these films are advantageous for the performance of solar cells, organometal halide perovskite light emitting diodes, and thin-film transistors. Future AP-S...

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

    Science.gov (United States)

    Nomoto, Junichi; Makino, Hisao; Yamamoto, Tetsuya

    2016-12-01

    Five hundred-nanometer-thick ZnO-based textured polycrystalline films consisting of 490-nm-thick Al-doped ZnO (AZO) films deposited on 10-nm-thick Ga-doped ZnO (GZO) films exhibited a high Hall mobility (μ H) of 50.1 cm(2)/Vs with a carrier concentration (N) of 2.55 × 10(20) cm(-3). Firstly, the GZO films were prepared on glass substrates by ion plating with dc arc discharge, and the AZO films were then deposited on the GZO films by direct current magnetron sputtering (DC-MS). The GZO interface layers with a preferential c-axis orientation play a critical role in producing AZO films with texture development of a well-defined (0001) orientation, whereas 500-nm-thick AZO films deposited by only DC-MS showed a mixture of the c-plane and the other plane orientation, to exhibit a μ H of 38.7 cm(2)/Vs with an N of 2.22 × 10(20) cm(-3). PMID:27365000

  15. Optical constants and near infrared emission of Er doped ZnO sol–gel thin films

    International Nuclear Information System (INIS)

    Erbium (Er) doped zinc oxide (ZnO) sol–gel thin films were deposited on glass substrate using the spin coating method. The effect of erbium concentration and annealing temperature on structural and optical properties was studied. The annealed film was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray spectrum (EDX), micro-Raman, photoluminescence (PL) and UV–vis spectroscopy. All the films showed a wurtzite structure of polycrystalline nature with an average crystal size of 27.44 nm at 500 °C and 29.28 nm at 600 °C. The Raman spectra confirmed the absence of secondary phases in the Er doped ZnO films and the longitudinal optical phonon mode was upto the fifth order. Densely packed surfaces of the films were observed from SEM images. The presence and distribution of Zn, O and Er elements in the deposited films were confirmed by EDX analysis. The calculated value of exciton binding energy of ZnO film was 60 meV with a maximum value of 72 meV being observed for Er doped films. The near infra-red emission peak was observed at 1.63 eV through PL spectra studies. The average transmission was 80% with the calculated value of optical band gap being 3.26–3.32 eV. An increase in the refractive index value predicts the substitutional incorporation of Er ions in ZnO with the maximum optical conductivity being observed in the UV region. - Highlights: • Higher exciton binding energy in the doped ZnO films. • Near infrared emission is observed and better than ZnO. • Refractive index is calculated by theoretical and experimental means. • Maximum optical conductivity in the UV region

  16. Optical constants and near infrared emission of Er doped ZnO sol–gel thin films

    Energy Technology Data Exchange (ETDEWEB)

    Vettumperumal, R. [P.G. and Research Department of Physics, Sri Paramakalyani College, Alwarkurichi 627412, Tamil Nadu (India); Kalyanaraman, S., E-mail: mayura_priya2003@yahoo.co.in [P.G. and Research Department of Physics, Sri Paramakalyani College, Alwarkurichi 627412, Tamil Nadu (India); Thangavel, R., E-mail: rtvel_au@yahoo.co.in [Department of Applied Physics, Indian School of Mines, Dhanbad (India)

    2015-02-15

    Erbium (Er) doped zinc oxide (ZnO) sol–gel thin films were deposited on glass substrate using the spin coating method. The effect of erbium concentration and annealing temperature on structural and optical properties was studied. The annealed film was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray spectrum (EDX), micro-Raman, photoluminescence (PL) and UV–vis spectroscopy. All the films showed a wurtzite structure of polycrystalline nature with an average crystal size of 27.44 nm at 500 °C and 29.28 nm at 600 °C. The Raman spectra confirmed the absence of secondary phases in the Er doped ZnO films and the longitudinal optical phonon mode was upto the fifth order. Densely packed surfaces of the films were observed from SEM images. The presence and distribution of Zn, O and Er elements in the deposited films were confirmed by EDX analysis. The calculated value of exciton binding energy of ZnO film was 60 meV with a maximum value of 72 meV being observed for Er doped films. The near infra-red emission peak was observed at 1.63 eV through PL spectra studies. The average transmission was 80% with the calculated value of optical band gap being 3.26–3.32 eV. An increase in the refractive index value predicts the substitutional incorporation of Er ions in ZnO with the maximum optical conductivity being observed in the UV region. - Highlights: • Higher exciton binding energy in the doped ZnO films. • Near infrared emission is observed and better than ZnO. • Refractive index is calculated by theoretical and experimental means. • Maximum optical conductivity in the UV region.

  17. Velocity surface measurements for ZnO films over /001/-cut GaAs

    Science.gov (United States)

    Kim, Yoonkee; Hunt, William D.; Liu, Yongsheng; Jen, Cheng-Kuei

    1994-01-01

    A potential application for a piezoelectic film deposited on a GaAs substrate is the monolithic integration of surface acoustic wave (SAW) devices with GaAs electronics. Knowledge of the SAW properties of the filmed structure is critical for the optimum design of such devices. In this article, the measurements of the velocity surface, which directly affects the SAW diffraction, on the bare and metallized ZnO/SiO2 or Si3N4/GaAs /001/-cut samples are reported using two different techniques: (1) knife-edge laser probe, (2) line-focus-beam scanning acoustic microscope. Comparisons, such as measurement accuracy and tradeoffs, between the former (dry) and the latter (wet) method are given. It is found that near the group of zone axes (110) propagation direction the autocollimating SAW property of the bare GaAs changes into a noncollimating one for the layered structure, but a reversed phenomenon exists near the group of zone axes (100) direction. The passivation layer of SiO2 or Si3N4 (less than 0.2 micrometer thick) and the metallization layer change the relative velocity but do not significantly affect the velocity surface. On the other hand, the passivation layer reduces the propagation loss by 0.5-1.3 dB/microseconds at 240 MHz depending upon the ZnO film thickness. Our SAW propagation measurements agree well with theorectical calculations. We have also obtained the anisotropy factors for samples with ZnO films of 1.6, 2.8, and 4.0 micrometer thickness. Comparisons concerning the piezoelectric coupling and acoustic loss between dc triode and rf magnetron sputtered ZnO films are provided.

  18. Optical and structural properties of electrochemically deposited ZnO nanorod arrays suitable for improvement of the light harvesting in thin film solar cells

    International Nuclear Information System (INIS)

    The results of study of the optical and structural properties of ZnO nanorods (NR) arrays electrochemically deposited on two type substrates – the ITO surface on the front side of Si heterojunction (SHJ) solar cells and on stainless steel plate used for formation of a-Si:H thin film solar cells, are reported. The surface morphology of the NS arrays is examined by Scanning Electron Microscopy and AFM. The spectra of specular diffused and total reflection, and haze ratio in reflectance are compared before and after deposition of the ZnO NR arrays. In the case of deposition on ITO surface of SHJ solar cells the values of the direct and diffused reflection of the ZnO NR array decrease demonstrating good antireflection properties. Deposition of ZnO NS arrays on stainless steel plates leads to increasing the values of the diffused reflection and the total reflectance. Possible application of ZnO NS structures for the processing of advanced Si based solar cells for increasing light harvesting is discussed

  19. Annealing induced reorientation of crystallites in Sn doped ZnO films

    Science.gov (United States)

    Ravichandran, K.; Vasanthi, M.; Thirumurugan, K.; Sakthivel, B.; Karthika, K.

    2014-11-01

    Tin doped ZnO thin films were prepared by employing a simplified spray pyrolysis technique using a perfume atomizer and subsequently annealed under different temperatures from 350 °C to 500 °C in steps of 50 °C. The structural, optical, electrical, photoluminescence and surface morphological properties of the as-deposited films were studied and compared with that of the annealed films. The X-ray diffraction studies showed that as-deposited film exhibits preferential orientation along the (0 0 2) plane and it changes in favour of (1 0 0) plane after annealing. The increase in crystallite size due to annealing is explained on the basis of Ostwald ripening effect. It is found that the optical transmittance and band gap increases with increase in annealing temperature. A slight decrease in resistivity caused by annealing is discussed in correlation with annealing induced defect modifications and surface morphology.

  20. p-Type Sb-Doped ZnO Thin Films Prepared with Filtered Vacuum Arc Deposition

    OpenAIRE

    David, T; Goldsmith, S.; Boxman, R. L.

    2005-01-01

    Thin p-type Sb-doped ZnO films were grown by filtered vacuum arc deposition (FVAD), on untreated glass samples. The arc cathode was prepared by dissolving Sb into molten Zn. The deposition was performed with 200 A arc current, running for 120-240 s in 0.426 Pa oxygen pressure. The film thickness was 330-500 nm. The aotmic concentration of Sb in the films was ~1.5%, whereas the O/Zn atomic concentration ratio was ~0.7. Sb incorporation into the polycrystalline ZnO matrix was concluded from XRD...

  1. Effect of Annealing on the Structure and Photoluminescence of Eu-Doped ZnO Nanorod Ordered Array Thin Films

    OpenAIRE

    Wen-Wu Zhong; Da-Wei Guan; Yue-Lin Liu; Li Zhang; Yan-Ping Liu; Zhi-Gang Li; Wei-Ping Chen

    2012-01-01

    Eu-doped ZnO nanorod ordered array thin films were synthesized on glass substrates with a ZnO seed layer via hydrothermal method. XRD reveals that the (002) diffraction peak of films annealed in hydrogen is sharper than that annealed in air. SEM reveals that the nanorods of films annealed in hydrogen are shortened and widened. TEM results demonstrate that the nanorods are single crystalline and the lattice spacing of 0.52 nm agrees with the d spacing of (001) crystal planes along c-axis. Room...

  2. The porous nature of ZnO thin films deposited by sol-gel Spin-Coating technique

    Science.gov (United States)

    Karyaoui, M.; Ben Jaballah, A.; Mechiak, R.; Chtourou, R.

    2012-02-01

    Zinc oxide (ZnO) thin films were deposited on silicon and quartz substrates, by sol-gel method, using zinc acetate dehydrate [Zn(CH3COO)2.2H2O] dissolved in isopropanol and glycerol. The structural, morphologic and optical properties of ZnO thin films subsequently annealed at 700°C in air for 30 min have leads to a porous nature of these films. To calculate, the refraction index and the extinction coefficient values, Cauchy formalism is used to evaluate the Spectroscopic Ellipsometry results. Two distinct configurations were proposed for each sample: in the first, the film is considered as mixture of randomly distributed voids and ZnO crystallites while in the second, the effect of porosity gradient is highlighted. This optical analysis gives a better agreement between experiment and theory for a wide range of wavelengths regarding the second configuration.

  3. Oxygen pressure-dependent band gap modification in Cu-doped and -undoped ZnO films

    International Nuclear Information System (INIS)

    A study of the effect of oxygen flow rate on the energy band gap of the c-axis-oriented ZnO and Zn0.95Cu0.05O films, deposited on glass substrates by RF magnetron sputtering, is reported. An increase of the oxygen flow rate (partial pressure) during deposition results in an increase in the band gap (Eg) of Zn0.95Cu0.05O films from 2.80 to 3.10 eV. The maximum observed enhancement is 10.5%. For the same oxygen flow rate (partial pressure), the band gap of a Zn0.95Cu0.05O film is found to be lower than that of ZnO as predicted by Ferhat et al (2009 Appl. Phys. Lett. 94 142502). A correlation has been observed between the residual strain and the band gap of doped and undoped ZnO films. (paper)

  4. Real structure of the ZnO epitaxial films on (0001) leucosapphire substrates coated by ultrathin gold layers

    Energy Technology Data Exchange (ETDEWEB)

    Muslimov, A. E., E-mail: amuslimov@mail.ru; Butashin, A. V.; Kolymagin, A. B.; Vasilyev, A. L.; Kanevsky, V. M. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2016-01-15

    The real structure of ZnO films formed by magnetron sputtering on (0001) leucosapphire substrates coated by an ultrathin (less than 0.7 nm) Au buffer layer has been studied by high-resolution microscopy. It is shown that modification of the leucosapphire substrate surface by depositing ultrathin Au layers does not lead to the formation of Au clusters at the film–substrate interface but significantly improves the structural quality of ZnO epitaxial films. It is demonstrated that the simplicity and scalability of the technique used to modify the substrate surface in combination with a high (above 2 nm/s) film growth rate under magnetron sputtering make it possible to obtain high-quality (0001) ZnO epitaxial films with an area of 5–6 cm{sup 2}.

  5. Double-beam pulsed laser deposition for the growth of Al-incorporated ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, L. [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Circuito Exterior S/N, Ciudad Universitaria, AP 70-186, C.P. 04510 México D.F., México (Mexico); Sánchez-Aké, C., E-mail: citlali.sanchez@ccadet.unam.mx [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Circuito Exterior S/N, Ciudad Universitaria, AP 70-186, C.P. 04510 México D.F., México (Mexico); Bizarro, M. [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apartado Postal 70-186, C.P. 04510 México D.F., México (Mexico)

    2014-05-01

    Pulsed laser deposition in a delayed-double beam configuration is used to incorporate in situ Al in ZnO thin films. In this configuration, two synchronized pulsed-laser beams are employed to ablate independently a ZnO and an Al target. We investigated the effects of relative time delay of plasma plumes on the composition of the films with the aim of evaluating the performance of this technique to produce doped materials. Relative delay between plumes was found to control the incorporation of Al in the film in the range from 14% to 30%. However, to produce low impurity concentration of Al-doped ZnO (with Al incorporation less than 2%) the fluence used to produce the plasmas has more influence over the film composition than the relative plume delay. The minimum incorporation of Al corresponded to a relative delay of 0 μs, due to the interaction between plumes during their expansion.

  6. Fabrication and photoelectric properties of Er3+ and Yb3+ co-doped ZnO films

    Science.gov (United States)

    Feng, Wei; Wang, Xiangfu; Meng, Lan; Yan, Xiaohong

    2016-01-01

    In this paper, the Er3+ and Yb3+ co-doped ZnO films deposited by a novel thermal decomposition method under different annealing temperature process have been reported. The effects of annealing temperature on the morphology and properties of the films are systematically studied. The resulting spectra demonstrate that the Er3+ and Yb3+ co-doped ZnO films possessed the property of up-conversion, converting IR light into visible light that can be absorbed by amorphous silicon solar cell. After all, inner photoelectric effect of the Er3+ and Yb3+ co-doped ZnO films in the amorphous as a light scattering layer are also found with an infrared 980 nm laser as excitation source.

  7. Improvement in the Grain Growth of Plasma-Treated Nano-Sized ZnO Films and Their Characterization.

    Science.gov (United States)

    Chen, Mi; Chou, Ching-Chuan; Lin, Ching-Cheng; Koo, Horng-Show

    2015-11-01

    The well-aligned ZnO nanorods were rapidly grown on an indium tin oxide (ITO)-coated glass substrate using Al-doped ZnO (AZO) thin film as seed layer by the microwave-assisted hydrothermal chemical route. The optimal growth conditions for the well-aligned ZnO nanorods were obtained by modulating H2 plasma pretreatment time for the seed layer and synthesis time for ZnO nanorods. The H2 plasma effect of the seed layer on the alignment, growth rate and crysallinity of ZnO nanods is also demonstrated. The synthesized ZnO nanorods were annealed in atmosphere of N2, O2 and H2 + N2 mixed gas to improve the related physical characteristics, the ZnO nanorods on grapheme/ITO substrate were also investigated. The results show that the alignment and growth rate of ZnO nanorods depends on the physical characteristics and roughness of the seed layer, which can be improved by H2 plasma pretreatment. The average growth rate of ZnO nanorods synthesized by microwave hydrothermal technique is about 2.2 μm/hr which significantly superior to other conventional techniques. After the appropriate N2 annealing treatment, good quality and well-aligned ZnO nanorods, which are single crystal with stacking defects and pyramid or candle shape, were obtained. A fundamental model of the effect of H2 plasma pretreatment on the surface of seed layer and the growth of ZnO nanorods using a microwave-assisted hydrothermal chemical route is also described. PMID:26726662

  8. Structural, electrical and optical studies on spray-deposited aluminium-doped ZnO thin film

    Indian Academy of Sciences (India)

    S Tewari; A Bhattacharjee

    2011-01-01

    Thin films of zinc oxide (ZnO) were deposited on cleaned glass substrates by chemical spray pyrolysis technique using Zn(CH3COO)2 as precursor solution. Also, aluminium-doped thin films of ZnO were prepared by using AlCl3 as doping solution for aluminium. The dopant concentration [Al/Zn atomic percentage (at%)] was varied from 0 to 1.5 at% in thin films of ZnO prepared in different depositions. Structural characterization of the deposited films was performed with X-ray diffraction (XRD) studies. It confirmed that all the films were of zinc oxide having polycrystalline nature and possessing typical hexagonal wurtzite structure with crystallite size varying between 100.7 and 268.6 nm. The films exhibited changes in relative intensities and crystallite size with changes in the doping concentration of Al. The electrical studies established that 1 at% of Aldoping was the optimum for enhancing electrical conduction in ZnO thin films and beyond that the distortion caused in the lattice lowered the conductivity. The films also exhibited distinct changes in their optical properties at different doping concentrations, including a blue shift and slight widening of bandgap with increasing Al dopant concentration.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-12-15

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

  10. Photoluminescence properties of ZnO thin films prepared by DC magnetron sputtering

    Institute of Scientific and Technical Information of China (English)

    YANG Bing-chu; LIU Xiao-yan; GAO Fei; MA Xue-long

    2008-01-01

    ZnO thin films were prepared by direct current(DC) reactive magnetron sputtering under different oxygen partial pressures.And then the samples were annealed in vacuum at 450 ℃. The effects of the oxygen partial pressures and the treatment of annealing in vacuum on the photoluminescence and the concentration of six intrinsic defects in ZnO thin films such as oxygen vacancy(Vo),zinc vacancy(VZn), antisite oxygen(OZn), antisite zinc(ZnO), interstitial oxygen(Oi) and interstitial zinc(Zni) were studied. The results show that a green photoluminescence peak at 520 nm can be observed in all the samples, whose intensity increases with increasing oxygen partial pressure; for the sample annealed in vacuum, the intensity of the green peak increases as well. The green photoluminescence peak observed in ZnO may be attributed to zinc vacancy, which probably originates from transitions between electrons in the conduction band and zinc vacancy levels, or from transitions between electrons in zinc vacancy levels and up valence band.

  11. Selective etching of ZnO films on an ITO substrate using a scanning electrochemical microscope

    International Nuclear Information System (INIS)

    A scanning electrochemical microscope (SECM) combined with an inverse optical microscope has been used in its lithographic mode to fabricate microstructures on a ZnO coated ITO substrate. The UME electrode generated the protons which served as the etchant to dissolve the ZnO film. High resolution microstructuring was achieved with the SECM after the addition of Tris(hydroxymethyl)aminomethane (Tris) to the solution. In the etching solution, Tris was used as an efficient reactant to consume the protons, so that the etchant could not diffuse far from the tip electrode. The cyclic voltammetry technique was employed to determine the appropriate potential, about 1.2 V vs. SCE, for the generation of protons at the tip electrode. The dimensions of the etched microstructures were measured using the optical microscopic images at different stages of the etching process in order to optimize the lithographic conditions. “Point by point” etching with the SECM tip was used to create the logo “FZU” of Fuzhou University on the ZnO film.

  12. The structure, photoluminescence, optical and magnetic properties of ZnO films doped with ferromagnetic impurities

    Science.gov (United States)

    Gritskova, E. V.; Mukhamedshina, D. M.; Mit', K. A.; Dolya, N. A.; Abdullin, Kh. A.

    2009-12-01

    In this paper we report on ZnO-CoO thin films grown by sol-gel technology with using different solvent. As precursors zinc acetate dehydrate (Zn(CH 3COO) 2·2H 2O), cobalt acetate tetrahydrate (Co(CH 3COO) 2·4H 2O) as well as manganese chloride (MnCl 2) were used. The films grown from solvent with methanol have a highly preferred orientation along the (1 0 0) plane. The films deposited from C=0.5 and 0.7 mol/l solvent with isopropanol and monoethanolamin and in smaller degree the C=0.3 mol/l film consist of disordered crystallites whereas the C=0.1 mol/l film has the intensive (0 0 2) peak, revealing a more obvious [0 0 2] preferred orientation. The all obtained films are highly transparent. The PL of ZnO-CoO films are more intensive in ultra-violet region in comparison the PL of ZnO film. The ESR spectra of ZnO-CoO multilayer films were investigated.

  13. Optical and structural properties of ZnO nanorods grown on graphene oxide and reduced graphene oxide film by hydrothermal method

    International Nuclear Information System (INIS)

    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 °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.

  14. Producing CuO and ZnO composite thin films using the spin coating method on microscope glasses

    International Nuclear Information System (INIS)

    Highlights: ► Annealing at 600 °C and 700 °C creates crystallinity in all doping concentrations. ► Starting with pure ZnO thin films and ending up with CuO by doping Cu in various percentages (ranging from 0% to 100%). ► Justification of the crystal phases by XRD spectra. ► Pure ZnO thin films have the absorption band at 370 nm and CuO has a strong absorption band at 570 nm. -- Abstract: In this work, we have presented a new route to produce pure ZnO and composite ZnO-CuO thin films. In the process we have started with pure ZnO thin films and ended up with CuO by doping Cu in various percentages, ranging from 0% to 100%. We have managed to attain crystal phases in all doping concentrations. All the produced thin films have been crystallized at the annealing temperatures of 600 and 700 °C for 6 h. The X-ray diffraction (XRD) spectra have been performed to see the formation of crystal phases of all pure ZnO and composite ZnO-CuO thin films. These give insight that the two crystal phases related to ZnO and CuO stayed together within the thin film matrices, which were produced in different doping concentrations, i.e. nZnO + mCuO (0 ≤ n, m ≤ 100%). The scanning electron microscopy (SEM) micrographs and UV–vis absorption spectra have also been taken to elucidate the structure and composition of the all films

  15. Structural, optical and electrical properties of ZnO thin films prepared by spray pyrolysis: Effect of precursor concentration

    Indian Academy of Sciences (India)

    F Zahedi; R S Dariani; S M Rozati

    2014-05-01

    ZnO thin films have been prepared using zinc acetate precursor by spray pyrolytic decomposition of zinc acetate on glass substrates at 450 °C. Effect of precursor concentration on structural and optical properties has been investigated. ZnO films are polycrystalline with (002) plane as preferential orientation. The optical transmission spectrum shows that transmission increases with decrease in the concentration and the maximum transmission in visible region is about 95% for ZnO films prepared with 0.1 M. The direct band-gap value decreases from 3.37 to 3.19 eV, when the precursor concentration increases from 0.1 to 0.4 M. Photoluminescence spectra at room temperature show an ultraviolet (UV) emission at 3.26 eV and two visible emissions at 2.82 and 2.38 eV. Lowest resistivity is obtained at 2.09 cm for 0.3 M. The current–voltage characteristic of the ZnO thin films were measured in dark and under UV illumination. The values of photocurrent and photoresponsivity at 5 V are increased with increase in precursor concentration and reaches to maximum value of 1148 A and 0.287 A/W, respectively which is correlated to structural properties of ZnO thin films.

  16. Influence of pH on ZnO nanocrystalline thin films prepared by sol–gel dip coating method

    Indian Academy of Sciences (India)

    K Sivakumar; V Senthil Kumar; N Muthukumarasamy; M Thambidurai; T S Senthil

    2012-06-01

    ZnO nanocrystalline thin films have been prepared on glass substrates by sol–gel dip coating method. ZnO thin films have been coated at room temperature and at four different pH values of 4, 6, 8 and 10. The X-ray diffraction pattern showed that ZnO nanocrystalline thin films are of hexagonal structure and the grain size was found to be in the range of 25–45 nm. Scanning electron microscopic images show that the surface morphology improves with increase of pH values. TEM analysis reveals formation of ZnO nanocrystalline with an average grain size of 44 nm. The compositional analysis results show that Zn and O are present in the sample. Optical band studies show that the films are highly transparent and exhibit a direct bandgap. The bandgap has been found to lie in the range of 3.14–3.32 eV depending on pH suggesting the formation of ZnO nanocrystalline thin films.

  17. Synthesis of PS colloidal crystal templates and ordered ZnO porous thin films by dip-drawing method

    Energy Technology Data Exchange (ETDEWEB)

    Liu Zhifeng [Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, School of Materials, Tianjin University, Tianjin 300072 (China); Jin Zhengguo [Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, School of Materials, Tianjin University, Tianjin 300072 (China)]. E-mail: zhgjin@tju.edu.cn; Li Wei [Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, School of Materials, Tianjin University, Tianjin 300072 (China); Qiu Jijun [Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, School of Materials, Tianjin University, Tianjin 300072 (China); Zhao Juan [Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, School of Materials, Tianjin University, Tianjin 300072 (China); Liu Xiaoxin [Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, School of Materials, Tianjin University, Tianjin 300072 (China)

    2006-05-15

    Polystyrene spheres (PS) were synthesized by an emulsifier-free emulsion polymerization technique and the PS colloidal crystal templates were assembled orderly on clean glass substrates by dip-drawing method from emulsion of PS. Porous ZnO thin films were prepared by filling the ZnO sol into the spaces among the close-packed PS templates and then annealing to remove the PS templates. The effects of ZnO precursor sol concentration and dipping time in sol on the porous structure of the thin films were studied. The results showed an ordered ZnO porous thin film with designed pore size that depended on the sol concentration and PS size could be obtained. And the shrinkage of pore diameter was about 30-43%. X-ray diffraction (XRD) spectra indicated the thin film was wurtzite structure. The transmittance spectrum showed that optical transmittance decreased with the decrease of wavelength, but kept above 80% optical transmittances beyond the wavelength of 550 nm. Optical band gap of the porous ZnO thin film (fired at 500 deg. C) was 3.22 eV.

  18. Effect of self-organization, defects, impurities, and autocatalytic processes on the parameters of ZnO films and nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Mezdrogina, M. M., E-mail: Margaret.M@mail.ioffe.ru; Eremenko, M. V. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Levitskii, V. S. [Saint-Petersburg State Electrotechnical University (LETI) (Russian Federation); Petrov, V. N.; Terukov, E. I. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Kaidashev, E. M.; Langusov, N. V. [Southern Federal University (Russian Federation)

    2015-11-15

    The effects of the parameters of ZnO-film deposition onto different substrates using the method of ac magnetron sputtering in a gas mixture of argon and oxygen hare studied. The phenomenon of self-organization is observed, which leads to invariability of the surface morphology of the ZnO films upon a variation in the substrate materials and deposition parameters. The parameters of the macro- and micro-photoluminescence spectra of the films differ insignificantly from the parameters of the photoluminescence spectra of bulk ZnO crystals obtained by the method of hydrothermal growth. The presence of intense emission with a narrow full-width at half-maximum (FWHM) in different regions of the spectrum allows ZnO films obtained by magnetron sputtering doped with rare-earth metal impurities (REIs) to be considered as a promising material for the creation of optoelectronic devices working in a broad spectral range. The possibility of the implementation of magnetic ordering upon legierung with REIs significantly broadens the functional possibilities of ZnO films. The parameters of the photoluminescence spectra of ZnO nanorods are determined by their geometrical parameters and by the concentration and type of the impurities introduced.

  19. Synthesis of PS colloidal crystal templates and ordered ZnO porous thin films by dip-drawing method

    International Nuclear Information System (INIS)

    Polystyrene spheres (PS) were synthesized by an emulsifier-free emulsion polymerization technique and the PS colloidal crystal templates were assembled orderly on clean glass substrates by dip-drawing method from emulsion of PS. Porous ZnO thin films were prepared by filling the ZnO sol into the spaces among the close-packed PS templates and then annealing to remove the PS templates. The effects of ZnO precursor sol concentration and dipping time in sol on the porous structure of the thin films were studied. The results showed an ordered ZnO porous thin film with designed pore size that depended on the sol concentration and PS size could be obtained. And the shrinkage of pore diameter was about 30-43%. X-ray diffraction (XRD) spectra indicated the thin film was wurtzite structure. The transmittance spectrum showed that optical transmittance decreased with the decrease of wavelength, but kept above 80% optical transmittances beyond the wavelength of 550 nm. Optical band gap of the porous ZnO thin film (fired at 500 deg. C) was 3.22 eV

  20. Effect of self-organization, defects, impurities, and autocatalytic processes on the parameters of ZnO films and nanorods

    International Nuclear Information System (INIS)

    The effects of the parameters of ZnO-film deposition onto different substrates using the method of ac magnetron sputtering in a gas mixture of argon and oxygen hare studied. The phenomenon of self-organization is observed, which leads to invariability of the surface morphology of the ZnO films upon a variation in the substrate materials and deposition parameters. The parameters of the macro- and micro-photoluminescence spectra of the films differ insignificantly from the parameters of the photoluminescence spectra of bulk ZnO crystals obtained by the method of hydrothermal growth. The presence of intense emission with a narrow full-width at half-maximum (FWHM) in different regions of the spectrum allows ZnO films obtained by magnetron sputtering doped with rare-earth metal impurities (REIs) to be considered as a promising material for the creation of optoelectronic devices working in a broad spectral range. The possibility of the implementation of magnetic ordering upon legierung with REIs significantly broadens the functional possibilities of ZnO films. The parameters of the photoluminescence spectra of ZnO nanorods are determined by their geometrical parameters and by the concentration and type of the impurities introduced

  1. 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...

  2. 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.

  3. The magnetic ordering in high magnetoresistance Mn-doped ZnO thin films

    Science.gov (United States)

    Venkatesh, S.; Baras, A.; Lee, J.-S.; Roqan, I. S.

    2016-03-01

    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.

  4. 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.)

  5. Transparent and conductive Al/F and In co-doped ZnO thin films deposited by spray pyrolysis

    Science.gov (United States)

    Hadri, A.; Taibi, M.; El hat, A.; Mzerd, A.

    2016-02-01

    In doped ZnO (IZO), In-Al co-doped ZnO (IAZO) and In-F co-doped ZnO (IFZO) were deposited on glass substrates at 350 °C by spray pyrolysis technique. The structural, optical and electrical properties of as-deposited thin films were investigated and compared. A polycrystalline and (002) oriented wurtzite crystal structure was confirmed by X-ray patterns for all films; and the full width at half -maximum (FWHM) of (002) diffraction peak increased after co-doping. The investigation of the optical properties was performed using Uv-vis spectroscopy. The average transmittances of all the films were between 70 and 85%. Hall Effect measurements showed that the electrical conductivity of co-doped films increased as compared with IZO thin film. The highest conductivity of about 16.39 Ω-1 cm-1 was obtained for as-deposited IFZO thin film. In addition, the thin films were annealed at 350 °C for two hour under Ar atmosphere and their optical, electrical properties and the associated photoluminescence (PL) responses of selected films were analysed. After annealing, the electrical conductivity of all thin films was improved and the optical transmittance remained above 70%. Room temperature PL revealed that the annealed IAZO thin film had a strong green emission than that of IZO film.

  6. Realization of As-doped p-type ZnO thin films using sputter deposition

    International Nuclear Information System (INIS)

    Arsenic-doped p-type ZnO (p-ZnO:As) thin films were deposited by the magnetron sputtering technique. High-resolution low-temperature photoluminescence (PL) spectra of the films revealed emissions at 3.35 eV and 3.32 eV, representing the neutral-acceptor-bound exciton transition and the free electron to acceptor level transition. Electroluminescence spectra of the p–n diodes fabricated from the p-ZnO:As/n-GaN heterostructure showed UV emission at about 380 nm and yellowish visible lights centered at 600–650 nm, which resembled the PL spectrum of the ZnO:As layer. The p-type ZnO films with 1at% As grown at 500°C showed a hole concentration of 5 × 1012–7 × 1013 cm−3 after the deposition and 4 × 1014–1 × 1016 cm−3 after annealing at 600 °C in oxygen atmosphere. High-resolution x-ray photoelectron spectroscopy indicated that most of the As dopants occupy Zn sites within the ZnO:As films

  7. 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.

  8. Influences on photovoltage performance by interfacial modification of FTO/mesoporous TiO2 using ZnO and TiO2 as the compact film

    International Nuclear Information System (INIS)

    Highlights: → ZnO has been introduced as the compact layer in dye-sensitized solar cells by a facile spin-coating method. → The influences of ZnO and TiO2 compact films to photoelectron conversion process have been systematically investigated. → The duel effect to photoelectron conversion process of ZnO compact film has been found. → A new methodology of introducing an energy barrier at FTO/TiO2 interface rather than the surface of TiO2 electrode has been brought up. - Abstract: An effective ZnO compact film (ZCF) has been introduced at the interface of fluorine doped tin oxide (FTO) substrate and mesoporous TiO2 layer, and its effect on dye-sensitized solar cells (DSSCs) has been compared to that of conventional TiO2 compact film (TCF). The ZCF and TCF prepared by spin-coating method on FTO are characterized by energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and UV-vis spectrophotometer. The existence of TiO2 can suppress the recombination occurring at the interface of FTO/electrolyte, resulting in a higher Jsc and Voc than bare FTO. The ZCF creates an energy barrier between FTO substrate and mesoporous TiO2 layer, which not only reduces the electron back transfer from FTO to I3- in the electrolyte, but also leads to the accumulation of photogenerated electrons, and increases the electron density in the conduction band of TiO2. The device based on FTO/ZCF substrate remarkably improves Voc and FF, finally increases energy conversion efficiency by 13.1% compared to the device based on bare FTO and 4.7% compared to the counterpart based on FTO/TCF.

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

    Directory of Open Access Journals (Sweden)

    Elif Peksu

    2015-01-01

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

  10. Preparation and photocatalytic activity of Cu-doped ZnO thin films prepared by the sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Jongnavakit, P. [Department of Chemistry and Center for Innovation in Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Amornpitoksuk, P., E-mail: ampongsa@yahoo.com [Department of Chemistry and Center for Innovation in Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); NANOTEC Center of Excellence at Prince of Songkla University (CENE), Hat Yai, Songkhla 90112 (Thailand); Suwanboon, S. [Department of Materials Science and Technology, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); NANOTEC Center of Excellence at Prince of Songkla University (CENE), Hat Yai, Songkhla 90112 (Thailand); Ndiege, N. [Nanoscience and Nanotechnology Institute, W181 Chemistry Building, University of Iowa, Iowa City 52242, IA (United States)

    2012-08-01

    Cu-doped ZnO thin films were fabricated on glass substrates by the sol-gel dip-coating method. All samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The grain size and film thickness of the Cu-doped ZnO thin film decreased as a function of the Cu concentrations. All prepared films showed a very high transmittance above 89% in the visible region (400-800 nm). Two oxidation states of Cu in +1 and +2 were identified in the ZnO thin film by X-ray photoelectron spectroscopy (XPS). Their photocatalytic activities were investigated by the degradation of methylene blue (MB) dye under blacklight fluorescent tubes. The film prepared from the Zn{sup 2+} solution containing 0.5 mol% of copper ions had the highest photocatalytic activity. The photocatalytic degradation of methylene blue solution as a function of the initial concentrations was evaluated according to the Langmuir-Hinshelwood model. The reaction rate (k) and adsorption equilibrium constant (K) over 1 cm{sup 2} of 0.5 mol% Cu-doped ZnO thin film are 15.92 {mu}M h{sup -1} and 0.049 {mu}M{sup -1}, respectively.

  11. Preparation and photocatalytic activity of Cu-doped ZnO thin films prepared by the sol-gel method

    International Nuclear Information System (INIS)

    Cu-doped ZnO thin films were fabricated on glass substrates by the sol-gel dip-coating method. All samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The grain size and film thickness of the Cu-doped ZnO thin film decreased as a function of the Cu concentrations. All prepared films showed a very high transmittance above 89% in the visible region (400-800 nm). Two oxidation states of Cu in +1 and +2 were identified in the ZnO thin film by X-ray photoelectron spectroscopy (XPS). Their photocatalytic activities were investigated by the degradation of methylene blue (MB) dye under blacklight fluorescent tubes. The film prepared from the Zn2+ solution containing 0.5 mol% of copper ions had the highest photocatalytic activity. The photocatalytic degradation of methylene blue solution as a function of the initial concentrations was evaluated according to the Langmuir-Hinshelwood model. The reaction rate (k) and adsorption equilibrium constant (K) over 1 cm2 of 0.5 mol% Cu-doped ZnO thin film are 15.92 μM h-1 and 0.049 μM-1, respectively.

  12. Characterization and properties of ZnO1-xSx alloy films fabricated by radio-frequency magnetron sputtering

    International Nuclear Information System (INIS)

    A series of ZnO1-xSx alloy films (0 ≤ x ≤ 1) were grown on quartz substrates by radio-frequency (rf) magnetron sputtering of ZnS ceramic target, using oxygen and argon as working gas. X-ray diffraction measurement shows that the ZnO1-xSx films have wurtzite structure with (0 0 2) preferential orientation in O-rich side (0 ≤ x ≤ 0.23) and zinc blende structure with (1 1 1) preferential orientation in S-rich side (0.77 ≤ x ≤ 1). However, when the S content is in the range of 0.23 1-xSx film consists of two phases of wurtzite and zinc blende or amorphous ZnO1-xSx phase. The band gap energy of the films shows non-linear dependence on the S content, with an optical bowing parameter of about 2.9 eV. The photoluminescence (PL) measurement reveals that the PL spectrum of the wurtzite ZnO1-xSx is dominated by visible band and its PL intensity and intensity ratio of UV to visible band decrease greatly compared with undoped ZnO. All as-grown ZnO1-xSx films behave insulating, but show n-type conductivity for w-ZnO1-xSx and maintain insulating properties for β-ZnO1-xSx after annealed. Mechanisms of effects of S on optical and electrical properties of the ZnO1-xSx alloy are discussed in the present work.

  13. 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.

  14. Transparent nanocrystalline ZnO films prepared by spin coating

    International Nuclear Information System (INIS)

    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

  15. 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.

  16. Effect of In doping on the properties and antibacterial activity of ZnO films prepared by spray pyrolysis.

    Science.gov (United States)

    Manoharan, C; Pavithra, G; Dhanapandian, S; Dhamodharan, P

    2015-10-01

    Pure and In-doped ZnO thin films were deposited onto glass substrates by spray pyrolysis technique. XRD results showed that all films were polycrystalline in nature with the wurzite structure. A change in preferential orientation from (002) to (101) plane was observed with increase in content of Indium. A reduce in crystallite size was observed with increase of In content. The small sized grains with the porous nature of the film was observed from SEM analysis. AFM study depicted polycrystalline nature and uniformly distributed grains with small pores in the doped film. A decrease in band gap was noticed with increase in In content. The absence of green emission in PL spectra indicated the decreased oxygen defects. The decrease in the resistivity with increase of Hall mobility was noted for the doped film. A better antibacterial activity was observed against Staphylococcus aureus by doped ZnO thin film. PMID:25997176

  17. Effect of tin doping on optical properties of nanostructured ZnO thin films grown by spray pyrolysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Bedia, F.Z.; Bedia, A. [URMER, Abou-Bakr Belkaid University, 13000 Tlemcen (Algeria); Maloufi, N., E-mail: nabila.maloufi@univ-lorraine.fr [Laboratoire d’Étude des Microstructures et de Mécanique des Matériaux (LEM3), UMR-CNRS 7239, Université de Lorraine, 57045 Metz (France); Laboratory of Excellence on Design of Alloy Metals for low-mAss Structures (DAMAS), Université de Lorraine (France); Aillerie, M.; Genty, F. [LMOPS-EA 4423, Université de Lorraine, 57070 Metz (France); Supelec, LMOPS, 57070 Metz (France); Benyoucef, B. [URMER, Abou-Bakr Belkaid University, 13000 Tlemcen (Algeria)

    2014-12-15

    Highlights: • (0–2%) Sn-doped ZnO films grown by spray pyrolysis on glass substrates. • Transmittance up to 93% in visible region, sharp absorption edge at 360 nm. • Blue shift of optical band gap: E{sub g} = 3.27 eV for 0% Sn; Eg{sub max} = 3.30 eV for 0.5% Sn. • All the optical parameters reach threshold values for 0.5% Sn-doped ZnO films. • Good physical properties suited for films integration in optoelectronic devices. - Abstract: Sn-doped ZnO thin films with 0%, 0.5%, 1%, 1.5% and 2% Sn were grown by spray pyrolysis method on glass substrates under optimized conditions. High resolution Field Effect Scanning Electron Microscopy characterization showed that the films consist of hexagonal-like grains. A comprehensive study of the optical properties was performed and the dispersion constants were determined. The effect of Sn content on the optical band gap and the optical constants (refractive index, extinction coefficient, dielectric constants, and dispersion parameters) was studied. These Sn-doped ZnO thin films are highly transparent (73–93%) in the visible region. A blue shift of the optical band gap, attributed to the Burstein Moss effect, was observed for the Sn-doped films. All the optical dispersion parameters depend on the Sn content of the films, but were found to reach threshold values at a Sn content of 0.5%. These optical parameters are discussed in terms of the single oscillator model. This study demonstrated that this 0.5% Sn-doped ZnO thin film has enhanced physical properties, allowing its better integration in optoelectronic devices.

  18. Effect of tin doping on optical properties of nanostructured ZnO thin films grown by spray pyrolysis technique

    International Nuclear Information System (INIS)

    Highlights: • (0–2%) Sn-doped ZnO films grown by spray pyrolysis on glass substrates. • Transmittance up to 93% in visible region, sharp absorption edge at 360 nm. • Blue shift of optical band gap: Eg = 3.27 eV for 0% Sn; Egmax = 3.30 eV for 0.5% Sn. • All the optical parameters reach threshold values for 0.5% Sn-doped ZnO films. • Good physical properties suited for films integration in optoelectronic devices. - Abstract: Sn-doped ZnO thin films with 0%, 0.5%, 1%, 1.5% and 2% Sn were grown by spray pyrolysis method on glass substrates under optimized conditions. High resolution Field Effect Scanning Electron Microscopy characterization showed that the films consist of hexagonal-like grains. A comprehensive study of the optical properties was performed and the dispersion constants were determined. The effect of Sn content on the optical band gap and the optical constants (refractive index, extinction coefficient, dielectric constants, and dispersion parameters) was studied. These Sn-doped ZnO thin films are highly transparent (73–93%) in the visible region. A blue shift of the optical band gap, attributed to the Burstein Moss effect, was observed for the Sn-doped films. All the optical dispersion parameters depend on the Sn content of the films, but were found to reach threshold values at a Sn content of 0.5%. These optical parameters are discussed in terms of the single oscillator model. This study demonstrated that this 0.5% Sn-doped ZnO thin film has enhanced physical properties, allowing its better integration in optoelectronic devices

  19. 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.

  20. Temperature dependence of the spin relaxation in highly degenerate ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Prestgard, M. C.; Siegel, G.; Tiwari, A., E-mail: tiwari@eng.utah.edu [Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Materials Research Science and Engineering Center, University of Utah, Salt Lake City, Utah 84112 (United States); Roundy, R.; Raikh, M. [Materials Research Science and Engineering Center, University of Utah, Salt Lake City, Utah 84112 (United States); Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112 (United States)

    2015-02-28

    Zinc oxide is considered a potential candidate for fabricating next-generation transparent spintronic devices. However, before this can be achieved, a thorough scientific understanding of the various spin transport and relaxation processes undergone in this material is essential. In the present paper, we are reporting our investigations into these processes via temperature dependent Hanle experiments. ZnO thin films were deposited on c-axis sapphire substrates using a pulsed laser deposition technique. Careful structural, optical, and electrical characterizations of the films were performed. Temperature dependent non-local Hanle measurements were carried out using an all-electrical scheme for spin injection and detection over the temperature range of 20–300 K. From the Hanle data, spin relaxation time in the films was determined at different temperatures. A detailed analysis of the data showed that the temperature dependence of spin relaxation time follows the linear-in-momentum Dyakonov-Perel mechanism.

  1. Effect of Al and N Doping on Structural and Optical Properties of Sol-Gel Derived ZnO Thin Films

    International Nuclear Information System (INIS)

    In this work, the preparation of ZnO, N-doped ZnO (NZO), Al-doped ZnO (AZO) and Al, N-doped ZnO (ANZO) thin films by the sol-gel spin-coating method is reported. The structural properties and surface morphologies of films were characterized by X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM). The optical properties of the films were interpreted from their transmission spectra using UV-VIS spectrophotometer. The XRD and SEM results disclosed that the crystallization quality and grain size of as-prepared films were highly influenced by N and Al doping. UV-VIS spectrophotometer results indicated that Al and N additives could significantly enhance the optical transparency and induce the blue-shift in optical bandgap of ZnO films. (author)

  2. Effects of cooling rate and post-heat treatment on properties of ZnO thin films deposited by sol-gel method

    International Nuclear Information System (INIS)

    Sol-gel spin-coated ZnO thin films are cooled with different rates after the pre-heat treatment. Atomic force microscopy (AFM), X-ray diffraction (XRD), Raman, and photoluminescence (PL) were carried out to investigate the effects of the cooling rate during pre-heat treatment on structural and optical properties of the ZnO thin films. The ZnO thin films cooled slowly exhibit mountain chain structure while the ones cooled rapidly have smooth surface. The ZnO thin films cooled rapidly have higher c-axis orientation compared to the ones cooled slowly. The narrower and the higher near-band-edge emission (NBE) peaks are observed in the ZnO thin films cooled rapidly.

  3. Electrical characterization and device characterization of ZnO microring shaped films by sol-gel method

    International Nuclear Information System (INIS)

    Research highlights: → Zinc oxide microrings formed nanoparticles were prepared by Sol Gel method. → The ZnO film exhibits a polycrystalline grown with a hexagonal wurtzite-type and optical band gap of 3.22 eV. → Au/n-ZnO/n-Si Schottky diode exhibits a rectifying behavior with a higher ideality factor of 2.01 and barrier height of 0.80 eV. - Abstract: Zinc oxide microrings formed nanoparticles were prepared on n-type silicon substrate by sol-gel method. The structure of ZnO film is confirmed by XRD analysis and ZnO film exhibits a polycrystalline grown with a hexagonal wurtzite-type. The optical band gap of the ZnO film deposited on silicon substrate was determined using the reflectance spectra by means of Kubelka-Munk formula and was found to be 3.22 eV. The structural properties of the ZnO film were investigated by atomic force microscopy. The AFM results indicate that the ZnO film is consisted of microrings with nanoparticles. A single phase of ZnO microring with outer diameter is ranging from 2.2 μm to 1.72 μm and inner diameters ranging from 125 nm to 470 nm was obtained. A Schottky diode having Au/n-type ZnO plus n-type silicon structure was fabricated. The current-voltage and impedance spectroscopy properties of the diode have been investigated. The barrier height φb and ideality factor n values for the diode were found to be 0.80 eV and 2.01, respectively. The series resistance for the diode was calculated from the admittance behavior in accumulation region. The interface state density profile for the diode was obtained. The obtained results indicate that the electric parameters of the diode are affected by structural properties of ZnO film.

  4. Influence of Doping and Annealing on Structural, Optical and Electrical properties Amorphous ZnO Thin Films Prepared by PLD

    Directory of Open Access Journals (Sweden)

    Azhar AbduAlwahab Ali

    2015-03-01

    Full Text Available The optical gap of the films was calculated from the curve of absorption coefficient (αhע2 vs. hע and was found to be 3.8 eV at room temperature, and this value decreases from 3.8 to 3.58 eV with increasing of annealing temperature up to 473-673 K, and increases with the Ga doping. λ cutoff was calculated for ZnO and showed an increase with increasing annealing temperature and shifting to longer wavelength, while with doping the λcutoff shifted to shorter wavelength. The photoluminescence (PL results indicate that the pure ZnO thin films grown at room temperature show strong peaks at 640 nm , but  GaO doped ZnO films showed a band emission in the yellow-green spectral region (380 to 450nm.

  5. Co doping induced structural and optical properties of sol–gel prepared ZnO thin films

    International Nuclear Information System (INIS)

    Highlights: • Transparent metal oxides are related to ZnO. • Optical transmission spectrum of Co doped ZnO thin films. • Determination of optical band gap using photoluminescence measurement. • Deposition thin film by using ultrasonic spray pyrolysis. - Abstract: The preparation conditions for Co doping process into the ZnO structure were studied by the ultrasonic spray pyrolysis technique. Structural and optical properties of the Co:ZnO thin films as a function of Co concentrations were examined. It was observed that hexagonal wurtzite structure of ZnO is dominant up to the critical value, and after the value, the cubic structural phase of the cobalt oxide appears in the X-ray diffraction patterns. Every band-edge of Co:ZnO films shifts to the lower energies and all are confirmed with the PL measurements. Co substitution in ZnO lattice has been proved by the optical transmittance measurement which is observed as the loss of transmission appearing in specific region due to Co2+ characteristic transitions

  6. An insight into doping mechanism in Sn–F co-doped transparent conducting ZnO films by correlating structural, electrical and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Mallick, Arindam; Sarkar, Sanjit; Ghosh, Tushar; Basak, Durga, E-mail: sspdb@iacs.res.in

    2015-10-15

    On the face of massively growing market of transparent optoelectronics, developing ZnO-based transparent conductive thin films as a promising substitute for indium-free transparent electrode is extremely important. However, the detailed function of the dopants, especially co-dopants acting on the electrical and optical properties of ZnO-based transparent conductive thin films is not clear yet. We present a detailed comparative investigation on the structural, electrical and optical properties of pulsed laser deposited ZnO thin films co-doped with Sn and F for the first time. An unexpected expansion in the lattice structure has been observed when Zn{sup 2+} are replaced by Sn{sup 4+} having smaller ionic radius. Electrical measurements show that there is no anticipated change in the carrier concentration with the dopant concentration. A minimum resistivity of 2.56 × 10{sup −3} Ohm-cm with a carrier concentration of 4.41 × 10{sup 20} cm{sup −3} has been obtained for 1 at.% each Sn–F co-doped film. Most interestingly, a significant improvement in the ultraviolet (UV)/visible (VIS) photoluminescence peak intensity in Sn doped and Sn–F co-doped films in correlation with the structural and electrical properties allows us to propose that Sn doping into ZnO lattice causes a screening of the native Zn vacancy defects. While the presence of F co-dopant induces Sn{sup 2+} to occupy the lattice sites, as evidenced from the lattice expansion, an insignificant increase in the carrier concentration as well as enhanced UV emission of the co-doped films. The results obtained in this study shed light on the development of ZnO-based transparent electrodes. - Highlights: • A comparative investigation on electrical and optical properties of F, Sn and Sn–F co-doped ZnO films has been done. • There is no significant correlation between the carrier concentration and dopant content. • The UV/vis PL peak intensity of the films gets better in Sn doped and best in the Sn

  7. Role of growth temperature on the structural, optical and electrical properties of ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Ashish, E-mail: dr.akmr@gmail.com [Materials Science Division, Inter University Accelerator Centre, New Delhi, 110067 (India); Kumar, Parmod [Materials Science Division, Inter University Accelerator Centre, New Delhi, 110067 (India); Kumar, Kaushal [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Roorkee, 247667 (India); Singh, Trilok [Graduate School of Engineering, Toin University of Yokohama, 1614 Kurogane-cho, Aoba, Yokohama, Kanagawa 225-8503 (Japan); Singh, R. [Department of Physics, Indian Institute of Technology, New Delhi, 110016 (India); Asokan, K.; Kanjilal, D. [Materials Science Division, Inter University Accelerator Centre, New Delhi, 110067 (India)

    2015-11-15

    Present study focuses on the influence of growth temperature on electrical and optical properties of polycrystalline ZnO thin films on sapphire substrates grown by atomic layer deposition technique. Dimethylzinc and de-ionized water were used as precursors by varying the growth temperature ranging from 70 to 130 °C. X-ray diffraction pattern confirms the formation of hexagonal wurtzite phase of ZnO with preferred (103) orientation. AFM results infer the growth of good quality films with root mean square roughness ∼1 nm for all these films having same thickness. The free carrier concentration and mobility of samples is found to increase whereas resistivity decreases with increasing growth temperature. The electrical results are well corroborated on the basis of photoluminescence and X-ray photoelectron spectroscopy. Photoluminescence and Raman measurements show that these ZnO thin films have very low defect concentrations. In particular, this study demonstrates that a device quality ZnO material with improved electrical parameters is obtained at the level of 100 °C which can be used for applications such as Schottky diodes for cross-bar memory applications and in hybrid organic/semiconductor junction devices. - Highlights: • Influence of growth temperature on various properties of ALD grown ZnO thin films. • Very smooth surface with root mean square roughness ∼1 nm. • Free carrier concentration and mobility increases with growth temperature. • Device quality ZnO films (improved electrical parameters) are obtained at 100 °C.

  8. Heavy lithium-doped ZnO thin films prepared by spray pyrolysis method

    Indian Academy of Sciences (India)

    M Ardyanian; N Sedigh

    2014-10-01

    Lithium-doped ZnO thin films (ZnO : Li) were prepared by spray pyrolysis method on the glass substrates for ( = [Li]/[Zn]) value varied between 5 and 70%. Structural, electrical and optical properties of the samples were studied by X-ray diffraction (XRD), UV–Vis–NIR spectroscopy, scanning electron microscopy (SEM), Hall effect and sheet resistance measurements. XRD results show that for ≤ 50%, the structure of the films tends to be polycrystals of wurtzite structure with preferred direction along (0 0 2). The best crystalline order is found at = 20% and the crystal structure is stable until = 60%. The Hall effect results describe that Li doping leads to change in the conduction type from - to -type, again it changes to -type at = 70% and is attributed to self-compensation effect. Moreover, the carrier density was calculated in the order of 1013 cm-3. The resistivity of Li-doped films decreases until 22 cm at = 50%. Optical bandgap was reduced slightly, from 3.27 to 3.24 eV as a function of the grain size. Optical transmittance in the visible range reaches = 97%, by increasing of Li content until = 20%. Electrical and optical properties are coherent with structural results.

  9. Synthesis of Various Nanopatterns of ZnO Thin Film Using Sol Gel Method

    Science.gov (United States)

    Julia, Sri; Yuliarto, Brian; Nugraha

    2010-10-01

    In order to achieve the different types of nanostructures of Zinc Oxide thin film using the low cost method, this research applied sol gel method and varying volume of solvent composition as the parameter. The volume of solvent composition was varying in amount of 75% distilled water + 25% ethanol, 50% distilled water + ethanol, and 25% distilled water + 75% ethanol. These compositions yield the different in pH value of solution, consequently yield the different of nanopatterns. Other parameter which also used is varying the substrates. In this investigation, kind of substrates used were glass, alumina and silicon. Through these parameters, the morphology of ZnO thin films was formed in various nanopatterns and observed by X-ray diffraction (XRD) and Scanning Electron Microscopic (SEM). X-ray diffraction determined all of the grown films are true ZnO, with wurtzite hexagonal crystal phase. Various patterns that obtained from SEM investigation are nanorod, flowerlike, nanoball and nanofiber. Uniquely, our flowerlike structure is arranged by nanosheet and nanofiber. The particle size of nanorods and nanoballs is about ±250 nm, while particle size of nanosheets is found to be ±500 nm and nanofiber is in the range of ± hundreds nm.

  10. Effect of Al and Mg Doping on Optical Properties of ZnO Thin Films Prepared by Spin Coating

    Directory of Open Access Journals (Sweden)

    G. T Yusuf

    2014-08-01

    Full Text Available This paper investigated the influence of aluminum and magnesium doping on the optical and electrical properties of zinc oxide (ZnO thin films for solar cell application. Zinc acetate dehydrates was used as starting material. Aluminum chloride and tin chloride were added to each solution to serve as dopants. X-ray diffractions were analyzed by X-ray diffraction (XRD which revealed crystalline and hexagonal wurtzite structure. All the films showed more than 80% transparency in the visible region. The optical band gap of undoped ZnO thin film was found to be 3.12ev while that of Al-doped and Mg-doped ZnO film was estimated to be 3.16eV and 3.26eV respectively. The resistivity of the films measured were 2.51×10–4 Ω cm for Al-doped, 2.53×10–4 Ω cm for mg-doped and 2.61×10-4 Ω cm for undoped ZnO respectively. The quality of the films deposited in this work is a promising window layer component of a solar cell. The variation in the band gap observed in this work could be explained by Burstein–Moss effect which was fully explained in the discussion section of this work.

  11. Combined effect of oxygen deficient point defects and Ni doping in radio frequency magnetron sputtering deposited ZnO thin films

    International Nuclear Information System (INIS)

    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