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Sample records for sb-doped zno thin

  1. Effect of Sb-doping on the morphology and dielectric properties of chrysanthemum-like ZnO nanowire clusters

    Science.gov (United States)

    Yan, Jun-Feng; You, Tian-Gui; Zhang, Zhi-Yong; Tian, Jiang-Xiao; Yun, Jiang-Ni; Zhao, Wu

    2012-09-01

    Chrysanthemum-like ZnO nanowire clusters with different Sb-doping concentrations were prepared using a hydrothermal process. The microstructures, morphologies, and dielectric properties of the as-prepared products were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), field emission environment scanning electron microscope (FEESEM), and microwave vector network analyzer respectively. The results indicate that the as-prepared products are Sb-doped ZnO single crystallines with a hexagonal wurtzite structure, the flower bud saturation degree Fd is obviously different from that of the pure ZnO nanowire clusters, the good dielectric loss property is found in Sb-doped ZnO products with low density, and the dielectric loss tangent tanδe increases with the increase of the Sb-doping concentration in a certain concentration range.

  2. Origin of p-type conductivity of Sb-doped ZnO nanorods and the local structure around Sb ions

    International Nuclear Information System (INIS)

    Liang, J. K.; Su, H. L.; Wu, Y. C.; Chuang, P. Y.; Kuo, C. L.; Huang, S. Y.; Chan, T. S.; Huang, J. C. A.

    2015-01-01

    To probe the origin of p-type conductivity in Sb-doped ZnO, a careful and detailed synchrotron radiation study was performed. The extended X-ray absorption fine structure and X-ray photoelectron spectroscopy investigations provided the evidence for the formation of the complex defects comprising substitution Sb ions at Zn sites (Sb Zn ) and Zn vacancies within the Sb-doped ZnO lattice. Such complex defects result in the increases of Sb-O coordination number and the Sb valence and thereby lead to the p-type conductivity of Sb-doped ZnO. The back-gate field-effect-transistors based on single nanorod of Sb-doped ZnO were constructed, and the stable p-type conduction behavior was confirmed

  3. Preparation, characterization of Sb-doped ZnO nanocrystals and their excellent solar light driven photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Nasser, Ramzi; Othmen, Walid Ben Haj [Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95 Hammam-Lif, 2050 (Tunisia); Département de Physique, Faculté des Sciences de Tunis, University of Tunis El Manar 2092 (Tunisia); Elhouichet, Habib, E-mail: habib.elhouichet@fst.rnu.tn [Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95 Hammam-Lif, 2050 (Tunisia); Département de Physique, Faculté des Sciences de Tunis, University of Tunis El Manar 2092 (Tunisia); Férid, Mokhtar [Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95 Hammam-Lif, 2050 (Tunisia)

    2017-01-30

    Highlights: • Sb-ZnO was obtained by modified sol-gel method using citric acid as stabilizing agent. • Sb incorporated both in lattice and interstitial sites. • The formation of (Sb{sub Zn}–2 V{sub Zn}) acceptor level was revealed by photoluminescence studies. • Optimum Sb content to show higher photocatalytic activity was found to be 3%. - Abstract: In the present study, undoped and antimony (Sb) doped ZnO nanocrystals (NCs) were prepared by a simple and economical sol-gel method. X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed the purity of the obtained phase and its high crystallinity. Raman analysis confirms the hexagonal Wurtzite ZnO structure. According to the diffuse reflectance results, the band gap was found to decrease up to 3% of Sb doping (ZSb3 sample). The results of X-ray photoelectron spectroscopy (XPS) measurements reveal that Sb ions occupied both Zn and interstitials sites. The successful substitution of antimony in ZnO lattice suggests the formation of the complex (Sb{sub Zn}–2 V{sub Zn}) acceptor level above the valence band. Particularly for ZSb3 sample, the UV photoluminescence (PL) band presents an obvious red-shift attributed to the formation of this complex. Rhodamine B (RhB) was used to evaluate the photocatalytic activity of Sb-doped ZnO NCs under sunlight irradiation. It was found that oxygen vacancies play a major role in the photocatalytic process by trapping the excited electrons and inhibiting the radiative recombination. During the photocatalytic mechanism, the Sb doping, expressed through the apparition of the (Sb{sub Zn}–2 V{sub Zn}) correspondent acceptor level, enhances the sunlight absorption within the ZnO band gap, which stimulates the generation of hydroxyl radicals and promotes the photocatalytics reaction rates. Such important contribution of the hydroxyl radicals was confirmed experimentally when using ethanol as scavenger in the photocatalytic reaction. The photodegradation

  4. Optical Properties of Al- and Sb-Doped CdTe Thin Films

    Directory of Open Access Journals (Sweden)

    A. A. J. Al-Douri

    2010-01-01

    Full Text Available Nondoped and (Al, Sb-doped CdTe thin films with 0.5, 1.5, and 2.5  wt.%, respectively, were deposited by thermal evaporation technique under vacuum onto Corning 7059 glass at substrate temperatures ( of room temperature (RT and 423 K. The optical properties of deposited CdTe films such as band gap, refractive index (n, extinction coefficient (, and dielectric coefficients were investigated as function of Al and Sb wt.% doping, respectively. The results showed that films have direct optical transition. Increasing and the wt.% of both types of dopant, the band gap decrease but the optical is constant as n, and real and imaginary parts of the dielectric coefficient increase.

  5. High-mobility transparent thin-film transistors with an Sb-doped SnO2 nanocrystal channel fabricated at room temperature

    International Nuclear Information System (INIS)

    Sun Jia; Lu Aixia; Wang Liping; Hu Yu; Wan Qing

    2009-01-01

    Transparent thin-film transistors with bottom-gate figure are fabricated by sputter deposition of an Sb-doped SnO 2 nanocrystal channel layer onto glass substrates at room temperature with plasma-enhanced chemical vapor deposition SiO 2 gate dielectrics and sputtering ITO electrodes. These devices exhibit high-performance n-type transistor characteristics operating in depletion mode with an ultrahigh field-effect mobility of 158 cm 2 V -1 s -1 . The current on/off ratio and the subthreshold swing are found to be 3 x 10 4 and 0.2 V/decade, respectively. These achievements demonstrate that SnO 2 -based nanocrystal thin-film transistors are promising for high-speed transparent and flexible electronics on temperature-sensitive substrates.

  6. High-mobility transparent thin-film transistors with an Sb-doped SnO{sub 2} nanocrystal channel fabricated at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Sun Jia; Lu Aixia; Wang Liping; Hu Yu; Wan Qing, E-mail: wanqing7686@hotmail.co [Key Laboratory for Micro-Nano Optoelectronic Devices of Ministry of Education, and State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China)

    2009-08-19

    Transparent thin-film transistors with bottom-gate figure are fabricated by sputter deposition of an Sb-doped SnO{sub 2} nanocrystal channel layer onto glass substrates at room temperature with plasma-enhanced chemical vapor deposition SiO{sub 2} gate dielectrics and sputtering ITO electrodes. These devices exhibit high-performance n-type transistor characteristics operating in depletion mode with an ultrahigh field-effect mobility of 158 cm{sup 2} V{sup -1} s{sup -1}. The current on/off ratio and the subthreshold swing are found to be 3 x 10{sup 4} and 0.2 V/decade, respectively. These achievements demonstrate that SnO{sub 2}-based nanocrystal thin-film transistors are promising for high-speed transparent and flexible electronics on temperature-sensitive substrates.

  7. Sb doping effects and oxygen adsorption in SnO2 thin films deposited via sol-gel

    OpenAIRE

    Viviany Geraldo; Luis Vicente de Andrade Scalvi; Evandro Augusto de Morais; Celso Valentim Santilli; Sandra Helena Pulcinelli

    2003-01-01

    Transparent electrically conducting antimony-doped SnO2 thin films have been prepared by sol-gel dip-coating process from colloidal aqueous suspension. The effect of doping content on the structural, optical and electrical properties is analyzed. Results from infrared optical transmission and reflection have shown that the higher the Sb concentration the lower the transmission intensity and the higher the reflection signal. Absorption intensity increases as well. Results of X-ray reflectometr...

  8. Sb doping effects and oxygen adsorption in SnO2 thin films deposited via sol-gel

    Directory of Open Access Journals (Sweden)

    Viviany Geraldo

    2003-12-01

    Full Text Available Transparent electrically conducting antimony-doped SnO2 thin films have been prepared by sol-gel dip-coating process from colloidal aqueous suspension. The effect of doping content on the structural, optical and electrical properties is analyzed. Results from infrared optical transmission and reflection have shown that the higher the Sb concentration the lower the transmission intensity and the higher the reflection signal. Absorption intensity increases as well. Results of X-ray reflectometry and electron microscopy have shown that the density of films fired at 400 °C after each dip is higher than that of multi-dipped films prepared with a single annealing. Both the electrical characteristics in the dark and the increase in conductivity as function of illumination through different filters, at 190 K, evidence that the transport properties of these films are dominated by the presence of defects, including the trapping at grain boundary due to excess of oxygen.

  9. Optoelectronic Investigation of Sb-Doped Cu(In, Ga)Se2

    Energy Technology Data Exchange (ETDEWEB)

    Mansfield, Lorelle M.; Kuciauskas, Darius; Dippo, Patricia; Li, Jian V.; Bowers, Karen; To, Bobby; DeHart, Clay; Ramanathan, Kannan

    2015-06-14

    Doping Cu(In,Ga)Se2 (CIGS) thin films with Sb can provide large grains at lower processing temperatures than are normally required. In this study, we incorporated Sb into the precursor of a two-step selenization process. We saw enhanced grain size and improved device performance compared to similarly processed CIGS films made without Sb. The optoelectronic properties of the Sb-doped CIGS films were examined with photoluminescence (PL) and admittance spectroscopy. These techniques allowed us to evaluate the origin of a lower-energy PL peak that is not typically seen in CIGS.

  10. 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

  11. 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.

  12. Structural, optical and electrical properties of Sb doped and undoped AgIn1-xGaxSe2 and Ag(InGa)5Se8 thin films

    International Nuclear Information System (INIS)

    Jacob, Rajani; Sreenivasan, P.V.; Philip, Rachel Reena; Remillard, Stephen K.; DeYoung, Paul A.; Deshpande, Uday P.; Shripathi, T.; Ganesan, V.; Naduvath, Johns

    2014-01-01

    Antimony doped and undoped nanostructured thin films of AgIn 1 - x Ga x Se 2 and Ag(InGa) 5 Se 8 on optically flat soda lime glass substrates are prepared by a three stage co-evaporation process. Energy dispersive analysis of X-rays (EDAX) and X-ray photoelectron spectroscopy in conjunction with atomic force microscopic technique and scanning electron microscopic technique are used, respectively, for compositional and surface morphological analysis of the films. X-ray diffraction (XRD) data on the films are analysed to estimate the influence of antimony doping and indium replacement by gallium, on the structure of the films, by determining the anion-cation bond lengths and anion displacement in the thin films. The obvious dependence of band gap on the composition of the films establishes the possibility of band gap tailoring of the films. Low temperature optical absorbance measurements in the temperature regime 90-301 K are used for investigating the effect of doping on the temperature coefficient of band gaps of the films. Rutherford scattering spectra quantify the thickness of the films for conductivity (σ) measurements. The films exhibit n-type conductivity with two linear regions in the ln(σ) versus temperature inverse graphs, which indicate a defect activated conduction and intrinsic conduction, respectively, in the near room temperature and high temperature regions. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Influence of pH on ZnO nanocrystalline thin films prepared by sol ...

    Indian Academy of Sciences (India)

    Abstract. 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 ...

  14. Some physical properties of ZnO thin films prepared by RF sputtering technique

    Energy Technology Data Exchange (ETDEWEB)

    Ekem, N.; Korkmaz, S.; Pat, S.; Cetin, E.N.; Ozmumcu, M. [Eskisehir Osmangazi University, Physics Department, 26480 Meselik, Eskisehir (Turkey); Balbag, M.Z. [Eskisehir Osmangazi University, Education Faculty, Physics Education, 26480 Meselik, Eskisehir (Turkey)

    2009-06-15

    ZnO thin films were deposited with RF sputtering using pure Zn target. In order to generate oxidation process of Zn, Ar:O{sub 2} gas mixing in (9:1), (7:3) and (5:5) ratios of Ar:O{sub 2} was used. To characterize ZnO thin films thickness and transparency were measured using optical method, and refractive index and band gap energies were calculated. Electrical conductivity of the ZnO thin films was also determined. AFM images were used to determine surface morphology of produced ZnO thin films. (author)

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

    Indian Academy of Sciences (India)

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

  16. Structural and optical properties of ZnO thin films prepared by laser ...

    Indian Academy of Sciences (India)

    2017-06-09

    Jun 9, 2017 ... Abstract. ZnO thin films were deposited on ITO/glass substrates by pulsed laser deposition (PLD) using two different kinds of targets. One of the targets was made of pure ZnO powder and the other one consisted of a mixture of ZnO powder with cyanoacrylate glue. The structural and morphological ...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-03-31

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

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

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

    KAUST Repository

    Wang, Xudong

    2009-02-05

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

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

    Science.gov (United States)

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

    2015-09-01

    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 of the corresponding perovskite solar cell. Precise surface engineering of ZnO thin film was found to be one of the key steps to fabricate ZnO based regular planar perovskite solar cell with high power conversion efficiency. Sputtering method is proved to be one of the excellent techniques to prepare ZnO thin film with controllable properties.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  2. 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 - others: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

  3. Point defect states in Sb-doped germanium

    International Nuclear Information System (INIS)

    Patel, Neil S.; Monmeyran, Corentin; Agarwal, Anuradha; Kimerling, Lionel C.

    2015-01-01

    Defect states in n-type Sb-doped germanium were investigated by deep-level transient spectroscopy. Cobalt-60 gamma rays were used to generate isolated vacancies and interstitials which diffuse and react with impurities in the material to form four defect states (E 37 , E 30 , E 22 , and E 21 ) in the upper half of the bandgap. Irradiations at 77 K and 300 K as well as isothermal anneals were performed to characterize the relationships between the four observable defects. E 37 is assigned to the Sb donor-vacancy associate (E-center) and is the only vacancy containing defect giving an estimate of 2 × 10 11  cm −3  Mrad −1 for the uncorrelated vacancy-interstitial pair introduction rate. The remaining three defect states are interstitial associates and transform among one another. Conversion ratios between E 22 , E 21 , and E 30 indicate that E 22 likely contains two interstitials

  4. Mott-Schottky analysis of thin ZnO films

    International Nuclear Information System (INIS)

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

    2000-01-01

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

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

    NARCIS (Netherlands)

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

    1995-01-01

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

  6. Optoelectronic properties of doped hydrothermal ZnO thin films

    KAUST Repository

    Mughal, Asad J.

    2017-03-10

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

  7. Direct current magnetron sputter-deposited ZnO thin films

    International Nuclear Information System (INIS)

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

    2011-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Cheng Da-Long

    2017-01-01

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

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

    Indian Academy of Sciences (India)

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

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

    Indian Academy of Sciences (India)

    Administrator

    Abstract. 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 pro- perties has been investigated. ZnO films are polycrystalline with (002) plane as preferential orientation. The.

  11. Heavy lithium-doped ZnO thin films prepared by spray pyrolysis ...

    Indian Academy of Sciences (India)

    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), ...

  12. Enhanced photocurrent and photocatalytic properties of porous ZnO thin film by Ag nanoparticles

    Science.gov (United States)

    Lv, Jianguo; Zhu, Qianqian; Zeng, Zheng; Zhang, Miao; Yang, Jin; Zhao, Min; Wang, Wenhao; Cheng, Yuebing; He, Gang; Sun, Zhaoqi

    2017-12-01

    ZnO thin films were deposited using an electrodeposition method and porous morphologies could be achieved by annealing treatment. A variety of Ag nanoparticles were loaded on the surface of the ZnO thin films. Surface morphology, chemical composition, crystal phase and optical properties were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), UV-vis spectrophotometer and micro-Raman spectroscopy. Evidence of Ag nanoparticles on the Ag-4/ZnO thin film was be verified by the SEM and XPS measurements. The XRD results indicated that the Ag nanoparticles had little effect on crystallinity of the thin films. The photoresponse and photocatalytic results indicated that the photocurrent and photocatalytic performance could be enhanced by moderate Ag nanoparticles modification on the surface of the ZnO thin film. The best photoresponse and photocatalytic activity in Ag-4/ZnO thin film results from the moderate Ag nanoparticles on the surface of ZnO thin film, which could enhanced separation and suppressed recombination of photogenerated electron-hole pairs.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-05-23

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

  14. 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.

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

    International Nuclear Information System (INIS)

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

    2007-01-01

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

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

    OpenAIRE

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

    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...

  17. Effect of ZnO Nanostructured Thin Films on Pseudomonas Putida Cell Division

    Science.gov (United States)

    Ivanova, I.; Lukanov, A.; Angelov, O.; Popova, R.; Nichev, H.; Mikli, V.; Dimova-Malinovska, Doriana; Dushkin, C.

    In this report we study the interaction between the bacteria Pseudomonas putida and nanostructured ZnO and ZnO:H thin films prepared by magnetron sputtering of a ZnO target. The nanostructured ZnO and ZnO:H thin films possess some biological-active properties when in contact with bacteria. Our experimental data show that these films have no destructive effect on the cell division of Pseudomonas putida in poor liquid medium and can be applied in biosensor devices.

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  19. 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.

  20. Probing Photocatalytic Characteristics of Sb-Doped TiO2 under Visible Light Irradiation

    Directory of Open Access Journals (Sweden)

    Lingjing Luo

    2014-01-01

    Full Text Available Sb-doped TiO2 nanoparticle with varied dopant concentrations was synthesized using titanium tetrachloride (TiCl4 and antimony chloride (SbCl3 as the precursors. The properties of Sb-doped TiO2 nanoparticles were characterized by X-ray diffraction (XRD, scanning electron microscope (SEM, fluorescence spectrophotometer, and Uv-vis spectrophotometer. The absorption edge of TiO2 nanoparticles could be extended to visible region after doping with antimony, in contrast to the UV absorption of pure TiO2. The results showed that the photocatalytic activity of Sb-doped TiO2 nanoparticles was much more active than pure TiO2. The 0.1% Sb-doped TiO2 nanoparticles demonstrated the best photocatalytic activity which was better than that of the Degussa P25 under visible light irradiation using terephthalic acid as fluorescent probe. The effects of Sb dopant on the photocatalytic activity and the involved mechanism were extensively investigated in this work as well.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

  2. 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 ...

  3. Effects of Ge- and Sb-doping and annealing on the tunable bandgaps of SnS films

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Hsuan-Tai; Chiang, Ming-Hung; Huang, Chen-Hao [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Lin, Wen-Tai, E-mail: wtlin@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Fu, Yaw-Shyan [Department of Greenergy, National University of Tainan, Tainan 700, Taiwan (China); Guo, Tzung-Fang [Department of Photonics, Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 701, Taiwan (China)

    2015-06-01

    SnS, Ge- and Sb-doped SnS films with single orthorhombic SnS phase were fabricated via solvothermal routes and subsequent spin-coating, respectively. The substitution solubilities of Ge and Sb in SnS are about 6 and 5 at.%, respectively. The bandgaps of Ge- and Sb-doped SnS films can be tuned in the ranges of 1.25–1.35 and 1.30–1.39 eV, respectively. The possible mechanisms for the tunable bandgaps of Ge- and Sb-doped SnS films are discussed. For the Ge- and Sb-doped SnS films subjected to annealing at 200–350 °C in N{sub 2}, the bandgaps of 200 °C-annealed films remain unchanged, while those of 300 °C- and 350 °C-annealed films decrease with the annealing temperature because of the evaporation of Ge and Sb respectively. - Highlights: • Ge- and Sb-doped SnS films were fabricated via spin-coating. • The solubilities of Ge and Sb in SnS are about 6 and 5 at.%, respectively. • The bandgaps of SnS films can be tuned by Ge and Sb doping respectively. • Annealing above 300 °C reduces the bandgaps of Ge- and Sb-doped SnS films.

  4. Impact of nanostructured thin ZnO film in ultraviolet protection.

    Science.gov (United States)

    Sasani Ghamsari, Morteza; Alamdari, Sanaz; Han, Wooje; Park, Hyung-Ho

    2017-01-01

    Nanoscale ZnO is one of the best choices for ultraviolet (UV) protection, not only because of its antimicrobial properties but also due to its potential application for UV preservation. However, the behavior of nanostructured thin ZnO films and long-term effects of UV-radiation exposure have not been studied yet. In this study, we investigated the UV-protection ability of sol gel-derived thin ZnO films after different exposure times. Scanning electron microscopy, atomic force microscopy, and UV-visible optical spectroscopy were carried out to study the structure and optical properties of the ZnO films as a function of the UV-irradiation time. The results obtained showed that the prepared thin ZnO films were somewhat transparent under the visible wavelength region and protective against UV radiation. The UV-protection factor was 50+ for the prepared samples, indicating that they were excellent UV protectors. The deposited thin ZnO films demonstrated promising antibacterial potential and significant light absorbance in the UV range. The experimental results suggest that the synthesized samples have potential for applications in the health care field.

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

    Directory of Open Access Journals (Sweden)

    Haridas D. Dhaygude

    2016-03-01

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

  6. Investigation of thin ZnO layers in view of laser desorption-ionization

    Energy Technology Data Exchange (ETDEWEB)

    Grechnikov, A A; Borodkov, A S [Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, 19 Kosygin Str., 119991 Moscow (Russian Federation); Georgieva, V B [Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee, 1784 Sofia (Bulgaria); Alimpiev, S S; Nikiforov, S M; Simanovsky, Ya O [General Physics Institute, Russian Academy of Sciences, 38 Vavilov Str., 119991 Moscow (Russian Federation); Dimova-Malinovska, D; Angelov, O I, E-mail: lazarova@issp.bas.b [Laboratory for Solar Energy and New Energy Sources, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee, 1784 Sofia (Bulgaria)

    2010-04-01

    Thin zinc oxide films (ZnO) were developed as a matrix-free platform for surface assisted laser desorption-ionization (SALDI) time-of-flight mass spectrometry. The ZnO films were deposited by RF magnetron sputtering of ZnO ceramic targets in Ar atmospheres on monocrystalline silicon. The generation under UV (355 nm) laser irradiation of positive ions of atenolol, reserpine and gramicidin S from the ZnO layers deposited was studied. All analytes tested were detected as protonated molecules with no or very structure-specific fragmentation. The mass spectra obtained showed low levels of chemical background noise. All ZnO films studied exhibited high stability and good reproducibility. The detection limits for test analytes are in the 10 femtomol range.

  7. Optical and photoelectrical properties of nanostructured thin ZnO films for UV-sensors

    Science.gov (United States)

    Grigoryev, L. V.; Kulakov, S. V.; Nefedov, V. G.; Shakin, O. V.; Grigoryeva, M. L.; Moskalenko, S. D.

    2017-05-01

    The article presents the results investigations of the optical and photoelectric properties thin films zinc oxide obtained by the reactive ion-plasma method. It is shown that the optical and photoelectric properties of thin ZnO films has equivalent characteristics to the properties of single crystal zinc oxide and can be used to create UV-photoresistors.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-11-01

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

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

    International Nuclear Information System (INIS)

    Shafura, A. K.; Azhar, N. E. I.; Uzer, M.; Mamat, M. H.; Sin, N. D. Md.; Saurdi, I.; Shuhaimi, A.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

    2016-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-07-06

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-03-31

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

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

    International Nuclear Information System (INIS)

    Boyadjiev, S.I.; Georgieva, V.; Yordanov, R.; Raicheva, Z.; Szilágyi, I.M.

    2016-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-11-30

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

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

    Directory of Open Access Journals (Sweden)

    M.I. Khan

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

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

    International Nuclear Information System (INIS)

    Tynell, Tommi; Yamauchi, Hisao; Karppinen, Maarit; Okazaki, Ryuji; Terasaki, Ichiro

    2013-01-01

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

  16. Reversible wettability of nanostructured ZnO thin films by sol-gel method

    Science.gov (United States)

    Lü, Jianguo; Huang, Kai; Chen, Xuemei; Zhu, Jianbo; Meng, Fanming; Song, Xueping; Sun, Zhaoqi

    2010-05-01

    Nanostructured ZnO thin films were deposited on Si(1 1 1) and quartz substrate by sol-gel method. The thin films were annealed at 673 K, 873 K, and 1073 K for 60 min. Microstructure, surface topography, and water contact angle of the thin films have been measured by X-ray diffractometer, atomic force microscopy, and water contact angle apparatus. XRD results showed that the ZnO thin films are polycrystalline with hexagonal wurtzite structure. AFM studies revealed that rms roughness changes from 2.3 nm to 7.4 nm and the grain size grow up continuously with increasing annealing temperature. Wettability results indicated that hydrophobicity of the un-irradiated ZnO thin films enhances with annealing temperature increase. The hydrophobic ZnO surfaces could be reversibly switched to hydrophilic by alternation of UV illumination and dark storage (thermal treatment). By studying the magnitude and the contact angle reduction rate of the light-induced process, the contribution of surface roughness is discussed.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-07-01

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

  18. 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.

  19. 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.

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

    International Nuclear Information System (INIS)

    Şenay, Volkan; Pat, Suat; Korkmaz, Şadan; Aydoğmuş, Tuna; Elmas, Saliha; Özen, Soner; Ekem, Naci; Balbağ, M. Zafer

    2014-01-01

    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

  1. EPD-deposited ZnO thin films: a review

    Directory of Open Access Journals (Sweden)

    Verde, M.

    2014-08-01

    Full Text Available ZnO-based materials and specifically ZnO films with tailored morphology have been subjected to extensive research in the past few years due to their high potential for multiple prospective applications, mainly in electronics. Electrophoretic Deposition (EPD constitutes an economical, ecofriendly, low energy consuming and easily scalable alternative to the high energy consuming evaporative techniques which are commonly used for the obtaining of these ZnO films. For its application, however, the use of stable, well dispersed suspensions is a necessary requirement, and thus a thorough study of their colloidal chemistry is essential. In this work the main contributions to the study of colloidal chemistry of ZnO nanoparticle suspensions and their shaping into ZnO films by EPD are summarized.Los materiales basados en ZnO y en particular las láminas de ZnO con morfología controlada han sido objeto en los últimos años de numerosas investigaciones debido al elevado potencial que presentan para múltiples aplicaciones emergentes, principalmente en electrónica. La deposición electroforética (EPD constituye un método alternativo económico, ecológico, de bajo coste energético y elevada escalabilidad para la producción de éstas láminas de ZnO, en contraste con las técnicas evaporativas empleadas habitualmente, las cuales presentan un elevado impacto energético, así como una escalabilidad complicada. Para su aplicación, sin embargo, y puesto que el principal requisito es el uso de suspensiones estables y bien dispersas, es necesario un detallado estudio de la coloidequímica de las mismas. En este trabajo se resumen las aportaciones más relevantes relativas al estudio de los distintos parámetros que afectan a la estabilidad coloidal de las suspensiones de nanopartículas de ZnO y al proceso de obtención de las láminas mediante EPD a partir de las mismas.

  2. 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.

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

    Directory of Open Access Journals (Sweden)

    Gerardo Gordillo

    2016-07-01

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

  4. 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

  5. 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...

  6. Preparation and characterization of nanostructured ZnO thin films for ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. 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.

  7. Preparation and characterization of nanostructured ZnO thin films for ...

    Indian Academy of Sciences (India)

    Administrator

    Owing to such defects ZnO shows a broad low intensity spectrum centred at green ... posed into volatile compounds under heat treatment (Ar- melao et al 2003). .... 2⋅37 ± 0⋅04. 9⋅3 ± 0⋅8. *Values represent a mean of 10–15 observations; SD: Standard deviation. Thin films of zinc oxide were subjected to phase analy-.

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

    Indian Academy of Sciences (India)

    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 ...

  9. Influence of pH on ZnO nanocrystalline thin films prepared by sol ...

    Indian Academy of Sciences (India)

    bDepartment of Physics, Hindusthan College of Engineering and Technology, Coimbatore 641 032, India. cDepartment of ... dDepartment of Physics, Erode Sengunthar Engineering College, Erode 638 057, India ... ZnO thin films have been coated at room temperature and at four different pH values of 4, 6, 8 and 10. The.

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

    Indian Academy of Sciences (India)

    Administrator

    Indian Academy of Sciences. 433. Structural, optical and electrical properties of ZnO thin films prepared by spray pyrolysis: Effect of precursor concentration. F ZAHEDI1, R S DARIANI1,* and S M ROZATI2. 1Department of Physics, Alzahra University, Tehran 1993893973, Iran. 2Department of Physics, University of Guilan, ...

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

    Directory of Open Access Journals (Sweden)

    Domenico D’Agostino

    2017-05-01

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

  12. Luminescence and structural properties of ZnO thin films annealing in air

    Energy Technology Data Exchange (ETDEWEB)

    Baca, R; Martinez, J [Centro de Investigacion de Dispositivos Semiconductores, BUAP, Puebla, Pue. C.P. 72570 (Mexico); Esparza, A [Centro de Ciencias Aplicadas y Desarrollo de TecnologIa - UNAM. C.P. 04510, Mexico D.F (Mexico); Kryshtab, T [Departamento de Ciencias de Materiales, ESFM - IPN, Mexico D.F (Mexico); Juarez, G; Solache, H; Andraca, J; Pena, R, E-mail: rbaca02006@yahoo.com.mx

    2010-02-15

    All ZnO thin films deposited on (001) silicon substrates by DC reactive magnetron sputtering were annealed in air atmosphere with different times at 800deg. C. The samples were studied by X-ray diffraction technique (XRD), atomic force microscopy (AFM) and photoluminescence (PL) measurements. XRD investigation showed that ZnO phase was hexagonal wurtzite structure growing along the (002) direction. The as grown ZnO films presented macrostrain and microstrain caused a shift of the line diffraction (002) and a broadening respectively. However after 1 hour annealing these strains disappear. The grain size of ZnO films increased with an increase of annealing time. The as-deposited reactive sputtering ZnO films resulted semi-insulating with poor PL response. After high temperature annealing in air, the crystallinity and the PL response considerably improved, but their semi-insulating property also increased. The PL spectra of the annealed samples showed well defined transitions close to the near-band-edge and a wide visible deep-level band emission (430-640 nm). The main interest of this work was to enhance the PL response and to identify the origin of deep-level luminescence bands. The AFM, PL and XRD results indicated that the ZnO films annealing have potential applications in optoelectronic devices.

  13. Luminescence and structural properties of ZnO thin films annealing in air

    Science.gov (United States)

    Baca, R.; Juárez, G.; Solache, H.; Andraca, J.; Martinez, J.; Esparza, A.; Kryshtab, T.; Peña, R.

    2010-02-01

    All ZnO thin films deposited on (001) silicon substrates by DC reactive magnetron sputtering were annealed in air atmosphere with different times at 800°C. The samples were studied by X-ray diffraction technique (XRD), atomic force microscopy (AFM) and photoluminescence (PL) measurements. XRD investigation showed that ZnO phase was hexagonal wurtzite structure growing along the (002) direction. The as grown ZnO films presented macrostrain and microstrain caused a shift of the line diffraction (002) and a broadening respectively. However after 1 hour annealing these strains disappear. The grain size of ZnO films increased with an increase of annealing time. The as-deposited reactive sputtering ZnO films resulted semi-insulating with poor PL response. After high temperature annealing in air, the crystallinity and the PL response considerably improved, but their semi-insulating property also increased. The PL spectra of the annealed samples showed well defined transitions close to the near-band-edge and a wide visible deep-level band emission (430-640 nm). The main interest of this work was to enhance the PL response and to identify the origin of deep-level luminescence bands. The AFM, PL and XRD results indicated that the ZnO films annealing have potential applications in optoelectronic devices.

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

    Science.gov (United States)

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

    2017-01-20

    We present a study on the formation of p-type ZnO thin film through ion implantation. Group V dopants (N, P) with different ionic radii are implanted into chemical vapor deposition grown ZnO thin film on GaN/sapphire substrates prior to thermal activation. It is found that mono-doped ZnO by N + implantation results in n-type conductivity under thermal activation. Dual-doped ZnO film with a N:P ion implantation dose ratio of 4:1 is found to be p-type under certain thermal activation conditions. Higher p-type activation levels (10 19 cm -3 ) under a wider thermal activation range are found for the N/P dual-doped ZnO film co-implanted by additional oxygen ions. From high resolution x-ray diffraction and x-ray photoelectron spectroscopy it is concluded that the observed p-type conductivities are a result of the promoted formation of P Zn -4N O complex defects via the concurrent substitution of nitrogen at oxygen sites and phosphorus at zinc sites. The enhanced solubility and stability of acceptor defects in oxygen co-implanted dual-doped ZnO film are related to the reduction of oxygen vacancy defects at the surface. Our study demonstrates the prospect of the formation of stable p-type ZnO film through co-implantation.

  15. Influence of Surface Modification on Physicochemical Properties of ZnO Thin Films and Nanostructures: a Review

    Science.gov (United States)

    Xian, Fenglin; Xu, Linhua

    The surface modification plays an important role on both physical and chemical properties of zinc oxide (ZnO) materials. In this review paper, efforts are made to summarize and analyze reported results regarding surface modification method, surface modification effect on the luminescence and superhydrophobic properties of ZnO thin films and nanostructures. Furthermore, the photocatalytic activity and gas sensor property of modified ZnO using both organic and inorganic species are also involved.

  16. 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.

  17. 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.

  18. Microstructure of ZnO Thin Films Deposited by High Power Impulse Magnetron Sputtering (Postprint)

    Science.gov (United States)

    2015-03-01

    Avrutin, S. Cho , H. Morkoc, A comprehensive review of ZnO materials and devices, J. Appl. Phys. 98 (2005) 41301. [4] M. Shimizu, T. Shiosaki, A...cathodic vacuum arc, Thin Solid Films 398–399 (2001) 244. [11] C.F. Yu, C.W. Sung , S.H. Chen, S.J. Sun, Relationship between the photoluminescence...L. Sanghun, C. Dongkeun, K. Won-Jeong, H. Moon- Ho , L. Woong, Ga-doped ZnO films deposited with varying sputtering powers and substrate temperatures by

  19. 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.

  20. 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.

  1. Effect of Al doping on performance of ZnO thin film transistors

    Science.gov (United States)

    Dong, Junchen; Han, Dedong; Li, Huijin; Yu, Wen; Zhang, Shendong; Zhang, Xing; Wang, Yi

    2018-03-01

    In this work, we investigate the Aluminum-doped Zinc Oxide (AZO) thin films and their feasibility as the active layer for thin film transistors (TFTs). A comparison on performance is made between the AZO TFTs and ZnO TFTs. The electrical properties such as saturation mobility, subthreshold swing, and on-to-off current ratio are improved when AZO is utilized as the active layer. Oxygen component of the thin film materials indicates that Al is the suppressor for oxygen defect in active layer, which improves the subthreshold swing. Moreover, based on band structure analyzation, we observe that the carrier concentration of AZO is higher than ZnO, leading to the enhancement of saturation mobility. The microstructure of the thin films convey that the AZO films exhibit much smaller grain boundaries than ZnO films, which results in the lower off-state current and higher on-to-off current ratio of AZO TFTs. The AZO thin films show huge potential to be the active layer of TFTs.

  2. 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.

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

    Directory of Open Access Journals (Sweden)

    Wenwang Li

    2018-02-01

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

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  6. Effect of Sm doping on the physical properties of ZnO thin films deposited by spray pyrolysis technique

    Science.gov (United States)

    Velusamy, P.; Babu, R. Ramesh; Aparna, K. T.

    2017-05-01

    Undoped and Sm doped ZnO thin films have been prepared by chemical spray pyrolysis method on a glass substrate at 430°C. The physical properties of undoped and Sm doped ZnO thin films are characterized by XRD, FE-SEM, UV-VIS spectroscopy, Hall measurement and PL analysis. XRD pattern reveals that all the films are polycrystalline nature. The FE-SEM study of CdO shows the smooth and uniform surface with the spherical shaped particle. The electrical study reveals the n-type semiconductor and the optical study shows that Sm doped ZnO thin films about 92% transparency and optical band gap vary between 3.266-3.276 eV. Sm doped ZnO thin films have strong green emission behavior.

  7. Investigation of the properties of Sb doping on tin oxide SNO2 materials for technological applications

    Science.gov (United States)

    Hachoun, Z.; Ouerdane, A.; Bouslama, M.; Ghaffour, M.; Abdellaoui, A.; Caudano, Y.; benamara, A. Ali

    2016-04-01

    The conductivities of the oxide SnO2 is dependent on the nature of the surrounding gas. This property stems from the adsorption or desorption on the surface of oxide grains. These phenomena are usually accompanied by electronic transfer between the adsorbed molecule and the semiconductor material, changing its conductivity. Tin oxidation and Sb doping were realized without and with heating process. The XPS technique and the TEM microscopy showed the synthesized nanocrystals. Simulated Monte Carlo program Casino is used for a scanning its profile. The surface characteristics are highlighted in the aim to be used as spatial gas sensors.

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

    Science.gov (United States)

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

    2017-06-01

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

  9. Structural and optical characterization of ZnO nanostructured thin films.

    Science.gov (United States)

    Gonzalez Gonzalez, J. C.; Urbina Yarupetan, M.

    Magnetron sputtering is surely the most common technique in the industry for large-scale growth for thin films with low emissivity, where the oxide deposited is usually ZnO. One of the recognized advantages of this technique is that the effects due to ion bombardment contribute to obtain surfaces with very little roughness, in the order of nanometers, and therefore improves the quality of the silver layer deposited at the end in windows with low emissivity. Therefore, a complete characterization of the surface layers of ZnO is required. In this sense, we have analyzed three thin layers of ZnO grown on commercial glass substrates deposited by the magnetron sputtering technique with thicknesses of 20, 50 and 100 nm. We used techniques such as: XRR, XRD, SEM and Raman spectroscopy, to assess roughness, microstructure, ZnO phonons profile and other properties like as density and refraction index. The X'Pert reflectivity program was used to fit the reflectivity data; the intensity of reflections was modeled through homogeneous and uniform layers with a well-defined limit to take into account the glass substrate. Finally, the structural results were correlated with the optical results. Ciencia Activa: Grant 221-2015-FONDECYT. PERU.

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

    Science.gov (United States)

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

    2012-08-06

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

  11. Improved efficiency of the chemical bath deposition method during growth of ZnO thin films

    International Nuclear Information System (INIS)

    Ortega-Lopez, Mauricio; Avila-Garcia, Alejandro; Albor-Aguilera, M.L.; Resendiz, V.M. Sanchez

    2003-01-01

    Chemical bath deposition (CBD) is an inexpensive and low temperature method (25-90 deg. C) that allows to deposit large area semiconductor thin films. However, the extent of the desired heterogeneous reaction upon the substrate surface is limited first by the competing homogeneous reaction, which is responsible for colloidal particles formation in the bulk solution, and second, by the material deposition on the CBD reactor walls. Therefore, the CBD method exhibits low efficiency in terms of profiting the whole amount of starting materials. The present work describes a procedure to deposit ZnO thin films by CBD in an efficient way, since it offers the possibility to minimize both the undesirable homogeneous reaction in the bulk solution and the material deposition on the CBD reactor walls. In a first stage, zinc peroxide (ZnO 2 ) crystallizing with cubic structure is obtained. This compound shows a good average transparency (90%) and an optical bandgap of 4.2 eV. After an annealing process, the ZnO 2 suffers a transformation toward polycrystalline ZnO with hexagonal structure and 3.25 eV of optical bandgap. The surface morphology of the films, analyzed by atomic force microscope (AFM), reveals three-dimensional growth features as well as no colloidal particles upon the surface, therefore indicating the predominance of the heterogeneous reaction during the growth

  12. 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

  13. 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.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  15. 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.   

  16. Effect of magnesium doping on the light-induced hydrophilicity of ZnO thin films

    Science.gov (United States)

    Kai, Huang; Jianguo, Lü; Li, Zhang; Zhen, Tang; Jiangying, Yu; Ping, Li; Feng, Liu

    2012-05-01

    Undoped and Mg-doped ZnO thin films were deposited on Si (111) and quartz substrates by using the sol-gel method. Microstructure, surface topography and water contact angle of the thin films have been measured by X-ray diffraction (XRD), an atomic force microscope (AFM) and water contact angle apparatus, respectively. The XRD results show that all the thin films are polycrystalline with a hexagonal structure and have a preferred orientation along the c-axis perpendicular to the substrate. With the increase of Mg concentration, the RMS roughness increases from 2.14 to 9.56 nm and the contact angle of the un-irradiated thin films decreases from 89° to 82°. The wetting behavior of the resulting films can be reversibly switched from hydrophobic to hydrophilic, through alternation of UV illumination and dark storage. The light-induced efficiency of the thin films increases with the increase of Mg concentration.

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

    Indian Academy of Sciences (India)

    36, No. 3, June 2013, pp. 385–388. c Indian Academy of Sciences. Oxidation of ZnO thin films during pulsed laser deposition process. E DE POSADA1,∗. , L MOREIRA1, J PÉREZ DE LA CRUZ2, M ARRONTE1, L V PONCE1,. T FLORES1 and J G LUNNEY3. 1CICATA-Instituto Politécnico Nacional, Altamira 89600, México.

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

    Indian Academy of Sciences (India)

    firmed 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. Keywords. SILAR; Cd:ZnO thin film; X-ray line broadening; SEM; optical bandgap. 1. Introduction.

  19. Defect and Optical Properties of Sb doped and hydrogenated BaSnO3

    Science.gov (United States)

    Sarkar, Ankita; De, S. K.

    2018-03-01

    Polycrystalline undoped and Sb doped BaSnO3 powder samples, BaSn1‑x SbxO3 (0 ≤ x ≤ 0.1) have been prepared by hydrogen peroxide assisted method. Hydrogen is incorporated into BaSn1‑x Sb x O3 to tune the defect and optical properties of the parent oxide. Three localized vibrational modes at 2800–3000 cm‑1 in Fourier transform infrared spectra originate from positive and neutral charge states of hydrogen. The observation of strong Raman lines indicate a local structural distortion in a cubic phase of BaSnO3. X-ray photoelectron studies indicate Sn4+ and Sb5+ oxidation states of Sn and Sb in doped samples. The replacement of Sn4+ by Sb5+ enhances the optical band gap from 3.14 ± 0.24 eV in undoped to 3.25 ± 0.20 eV in the 10% Sb-doped sample. Hydrogen impurities act as electron donors and also increase the optical band gap. The overall band gap enhancement has been explained by the Burstein-Moss band filling effect. Two electron paramagnetic resonance signals, corresponding to two kinds of oxygen vacancy centres, are strongly influenced by Sb and hydrogen dopants.

  20. Applying RF Magnetron sputtering to prepare ZnO thin films and their characterization

    International Nuclear Information System (INIS)

    Saad, M.; Kassis, A.

    2009-05-01

    ZnO thin films were prepared using Rf magnetron sputtering under several preparation conditions (different values of deposition pressure, Rf power, substrate temperature). The optical properties of these films were investigated by measuring their transmission in the spectral range (300-1000 nm), and the electrical properties were investigated by measuring their electrical resistance. Results have been discussed in terms of the modified Thornton model for sputtered thin metal oxide films. Preparation conditions for depositing the highly resistive transparent i-ZnO buffer layer and the highly conducting transparent n-ZnO window layer for solar cells were proposed. (author)

  1. Defect-band mediated ferromagnetism in Gd-doped ZnO thin films

    KAUST Repository

    Venkatesh, S.

    2015-01-07

    Gd-doped ZnO thin films prepared by pulsed laser deposition with Gd concentrations varying from 0.02–0.45 atomic percent (at. %) showed deposition oxygen pressure controlled ferromagnetism. Thin films prepared with Gd dopant levels (

  2. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-06-15

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

  4. Properties of ZnO thin films deposited by chemical bath deposition and post annealed

    International Nuclear Information System (INIS)

    Ouerfelli, J; Regragui, M; Morsli, M; Djeteli, G; Jondo, K; Amory, C; Tchangbedji, G; Napo, K; Bernede, J C

    2006-01-01

    ZnO thin films deposited by chemical bath deposition (CBD) have been studied using x-ray diffraction, scanning electron microscopy, electron microprobe analysis and electrical measurements. The optimum CBD conditions for achieving structured, but adherent, ZnO films are as follows. Zinc acetate (0.0188 mol l -1 ) and ethylenediamine (0.03 mol l -1 ) are mixed. The pH of the bath is raised by addition of a base (0.5 mol l -1 , NaOH). The solution is maintained at a temperature between 60 deg. C and 65 0 C, while the bath is continuously stirred. We proceeded to anneal in room air for 30 min at 300 deg. C and under vacuum for 2 h at 300 deg. C. All the films obtained are nearly stoichiometric ZnO films crystallized in the usual hexagonal structure. As expected the films are rough and porous. The main difference between the two ZnO film families is their conductivity. The conductivity of the films annealed under vacuum is five orders of magnitude higher than that of those annealed in room air

  5. Sputter-Grown Sb-DOPED Silicon Nanocrystals Embedded in Silicon-Rich Carbide for si Heterojunction Solar Cells

    Science.gov (United States)

    Chen, Xiaobo; Tang, Yu; Hao, Jiabo

    Sb-doped silicon nanocrystals (Si-NCs) films were fabricated by magnetron co-sputtering combined with rapid-thermal annealing. The effects of Sb content on the structural and electrical properties of the films were studied. The dot size increased with the increasing Sb content, and could be correlated to the effect of Sb-induced crystallization. The variation in the concentration of Sb shows a significant impact on the film properties, where as doped with 0.8at.% of Sb exhibited major property improvements when compared with other films. By employing Sb-doped Si-NCs films as emitter layers, Si-NCs/monocrystalline silicon heterojunction solar cells were fabricated and the effect of the Sb doping concentration on the photovoltaic properties was studied. It is found that the doping level in the Si-NCs layer is a key factor in determining the short-circuit current density and power conversion efficiency (PCE). With an optimized doping concentration of 0.8at.% of Sb, a maximal PCE of 7.10% was obtained. This study indicates that the Sb-doped Si-NCs can be good candidates for all-silicon tandem solar cells.

  6. Structural, elastic and magnetic properties of Mn and Sb doped chromium nitride – An ab initio study

    International Nuclear Information System (INIS)

    Ikram Un Nabi Lone; Sheik Sirajuddeen M Mohamed; Shameem Banu, I.B.; Sathik Basha, S.

    2017-01-01

    Structural, magnetic and elastic properties of Mn and Sb doped CrN were investigated by the electronic band structure calculations using Full Potential Linear Augmented Plane Wave (FP-LAPW) method. The host compound CrN was doped with Mn and Sb separately, in the doping concentration of 12.5% to replace Cr atoms. The introduction of Mn and Sb atoms replacing the Cr atoms does not change the structural stability of the compound. The changes in magnetic and elastic properties were investigated and compared in GGA and GGA+U methods. The doped CrN undergoes a relative increase in the magnetic order with the substitution of Mn and Sb atoms. In GGA method, the magnetic moments are found to be greater in Mn doped CrN than that found in Sb doped Cr 0.875 NSb 0.125 . When doped with Sb, the elastic moduli such as Young’s modulus, bulk modulus and rigidity modulus show a relative increase in comparison with that in Mn doped CrN. Using Hubbard model in GGA+U method, both the magnetic and elastic properties increase in Mn and Sb doped compounds. - Highlights: • Mn and Sb doped Chromium Nitride. • Structural properties. • Magnetic properties. • Elastic properties.

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

    International Nuclear Information System (INIS)

    Wang, Rongxin; Yang, Lechen; Xu, Shijie; Zhang, Xiaodong; Dong, Xue; Zhao, Yingchun; Fu, Kai; Zhang, Baoshun; Yang, Hui

    2013-01-01

    Highlights: •GaO x + ZnO thin films sputtered and annealed exhibit interesting and unique optical properties, especially deep UV photo response. •GaO x + ZnO thin films can be used to fabricate efficient deep UV photodetectors. •The mixture phase nature of GaO x + 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 GaO x + ZnO thin films. -- Abstract: Ultraviolet (UV) photodetectors were prepared by using the GaO x + 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

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

    Science.gov (United States)

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

    2018-03-01

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

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

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  10. Preferential orientation growth of ITO thin film on quartz substrate with ZnO buffer layer by magnetron sputtering technique

    Science.gov (United States)

    Du, Wenhan; Yang, Jingjing; Xiong, Chao; Zhao, Yu; Zhu, Xifang

    2017-07-01

    In order to improve the photoelectric transformation efficiency of thin-film solar cells, one plausible method was to improve the transparent conductive oxides (TCO) material property. In-doped tin oxide (ITO) was an important TCO material which was used as a front contact layer in thin-film solar cell. Using magnetron sputtering deposition technique, we prepared preferential orientation ITO thin films on quartz substrate. XRD and SEM measurements were used to characterize the crystalline structure and morphology of ITO thin films. The key step was adding a ZnO thin film buffer layer before ITO deposition. ZnO thin film buffer layer increases the nucleation center numbers and results in the (222) preferential orientation growth of ITO thin films.

  11. Improved damp heat stability of Ga-Doped ZnO thin film by pretreatment of the polyethylene terephthalate substrate

    Science.gov (United States)

    Kim, B. B.; Seo, S. G.; Lim, Y. S.; Choi, H.-S.; Seo, W.-S.; Park, H.-H.

    2013-09-01

    A study on the damp heat stability of transparent conducting ZnO thin film grown on a polyethylene terephthalate substrate (PET) is reported. By thermal annealing of the PET substrate at 100°C with Ar flow in a vacuum chamber prior to the sputtering growth of Ga-doped ZnO (GZO) thin film, significantly enhanced damp heat stability was achieved at 60°C with a 90% relative humidity. Electrical and structural characterizations of the GZO thin films were carried out and the effects of the pretreatment on the improved damp heat stability are discussed.

  12. 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.)

  13. Perovskite solar cells based on nanocolumnar plasma-deposited ZnO thin films.

    Science.gov (United States)

    Ramos, F Javier; López-Santos, Maria C; Guillén, Elena; Nazeeruddin, Mohammad Khaja; Grätzel, Michael; Gonzalez-Elipe, Agustin R; Ahmad, Shahzada

    2014-04-14

    ZnO thin films having a nanocolumnar microstructure are grown by plasma-enhanced chemical vapor deposition at 423 K on pre-treated fluorine-doped tin oxide (FTO) substrates. The films consist of c-axis-oriented wurtzite ZnO nanocolumns with well-defined microstructure and crystallinity. By sensitizing CH3NH3PbI3 on these photoanodes a power conversion of 4.8% is obtained for solid-state solar cells. Poly(triarylamine) is found to be less effective when used as the hole-transport material, compared to 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD), while the higher annealing temperature of the perovskite leads to a better infiltration in the nanocolumnar structure and an enhancement of the cell efficiency. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Elaboration and Characterization of Sprayed Tb-Doped ZnO Thin Films

    Directory of Open Access Journals (Sweden)

    Amina ELFAKIR

    2014-05-01

    Full Text Available ZnO and Tb-doped ZnO (TZO thin films were deposited on glass substrate at 350 °C by spray pyrolysis technique. Structural, optical and electrical properties of the films were investigated as a function of dopant concentration, which was varied between 0 and 5 at % of terbium. TZO films were polycrystalline and exhibit hexagonal quartzite crystal structure with a preferential orientation along 2 direction. The AFM measurements show that the roughness of the films increased with Tb doping. All the TZO films exhibit a transmittance between 70 and 80 % in the visible range. The TZO films were n-type degenerate semiconductor with a lowest electrical resistivity of about 6.0´10- 2 W.cm.

  15. 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.

  16. Growth and optical properties of sol-gel ZnO thin films grown on R-plane sapphire substrates

    Science.gov (United States)

    Nam, Giwoong; Kim, Min Su; Lee, Jewon; Leem, Jae-Young; Lee, Sang-heon; Jung, Jae Hak; Kim, Jin Soo; Kim, Jong Su

    2013-04-01

    Zinc-oxide (ZnO) thin films were grown on R-plane sapphire substrates by using the sol-gel spincoating method. They were annealed at temperatures ranging from 600 to 800 °C. The effects of the annealing temperature on the properties of the ZnO thin films were investigated using scanning electron microscopy, X-ray diffraction, and photoluminescence. When the annealing temperature was increased to 700 °C, the grains of the ZnO thin films coalesced, their size increased, and the residual stress in the ZnO thin films was relaxed. In addition, the intensity of the deep-level emission peak caused by defects decreased, and the full width at half maximum of the near-bandedge emission peak decreased as the annealing temperature was increased to 700 °C. However, when the annealing temperature was increased further, degradation of the structural and the optical properties was observed. The reflective index of the ZnO thin films in the UV region increased as the annealing temperature was increased to 700 °C, and n in the visible region decreased with increasing wavelength. The extinction coefficient in the UV and the visible regions decreased as the annealing temperature was increased to 700 °C. However, inflection points in the reflective index and the extinction coefficient were observed with a further increase in the annealing temperature.

  17. 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

  18. 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.

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

    International Nuclear Information System (INIS)

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

    2013-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-02-28

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

  1. Surface excitons on a ZnO (000-1) thin film

    Energy Technology Data Exchange (ETDEWEB)

    Kuehn, S., E-mail: skuehn@mbi-berlin.de; Friede, S.; Elsaesser, T. [Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Str. 2A, Berlin D-12489 (Germany); Sadofev, S.; Blumstengel, S.; Henneberger, F. [Institut für Physik, Humboldt-Universität zu Berlin, Newtonstrasse 15, Berlin D-12489 (Germany)

    2013-11-04

    Elementary excitations at the polar (000-1) surface of a 20 nm pseudomorphically grown ZnO thin film are examined by steady state and time-resolved photoluminescence spectroscopy at low temperature. We control the density of emission centers through the deposition of prototypical organic molecules with a carboxylic acid anchor group by the Langmuir-Blodgett technique. Knowledge of the precise film thickness, defect concentrations and number density of deposited molecules leads us to associate the surface exciton emission to defect-related localization centers that are generated through a photochemical process.

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

    Czech Academy of Sciences Publication Activity Database

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

    2012-01-01

    Roč. 45, č. 22 (2012), 1-12 ISSN 0022-3727 R&D Projects: GA ČR(CZ) GAP108/11/0958; GA ČR GP202/09/P324 Institutional research plan: CEZ:AV0Z10100522 Keywords : ZnO thin film * pulsed laser deposition * x-ray diffraction positron implantation spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.528, year: 2012 http://dx.doi.org/10.1088/0022-3727/45/22/225101

  3. Photoelectrocatrocatalytic hydrolysis of starch by using sprayed ZnO thin films

    Science.gov (United States)

    Sapkal, R. T.; Shinde, S. S.; Rajpure, K. Y.; Bhosale, C. H.

    2013-05-01

    Thin films of zinc oxide have been deposited onto glass/FTO substrates at optimized 400 °C by using a chemical spray pyrolysis technique. Deposited films are character photocatalytic activity by using XRD, an SEM, a UV-vis spectrophotometer, and a PEC single-cell reactor. Films are polycrystalline and have a hexagonal (wurtzite) crystal structure with c-axis (002) orientation growth perpendicular to the substrate surface. The observed direct band gap is about 3.22 eV for typical films prepared at 400 °C. The photocatalytic activity of starch with a ZnO photocatalyst has been studied by using a novel photoelectrocatalytic process.

  4. P-type ZnO thin films prepared by plasma molecular beam epitaxy using radical NO

    Energy Technology Data Exchange (ETDEWEB)

    Liang, H.W.; Lu, Y.M.; Shen, D.Z.; Liu, Y.C.; Yan, J.F.; Li, B.H.; Zhang, Z.Z.; Zhang, J.Y.; Fan, X.W. [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 16-Dongnanhu Road, Changchun 130033 (China); Shan, C.X. [Department of Physics, Chinese University of Hong Kong, Shatin, Hong Kong (China)

    2005-05-01

    N-doped p-type ZnO thin films were grown by plasma molecular beam epitaxy (P-MBE) on c-plane sapphire (Al{sub 2}O{sub 3}) using radical NO as oxygen source and nitrogen dopant. The reproducible ZnO thin films have maximum net hole concentration (N{sub A}-N{sub D}) of 1.2 x 10{sup 18} cm{sup -3} and minimum resistivity of 9.36 {omega} cm. The influence of N incorporation on the quality of the ZnO thin films was studied using X-ray diffraction and absorption spectra. The photoluminescence spectra at 77 K of p-type ZnO thin films are dominated by the emission from donor-acceptor pair recombination. The formation mechanism of p-type ZnO is explained by the optical emission spectra of radical N{sub 2} and radical NO. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Zinc Vacancy induced magnetism in ZnO thin films and nanowires

    Science.gov (United States)

    Wang, Qian; Sun, Qiang; Jena, Puru

    2008-03-01

    Extensive theoretical studies based on first-principles have been carried out for the mechanism of magnetism in ZnO thin films and nanowires. It has been identified that the observed magnetism is introduced by Zn vacancy and is affected by its concentration. The main source of the magnetic moment comes from the unpaired 2p- electrons in oxygen sites around the Zn vacancy, instead of Zn 3d electrons. Moreover, Zn vacancy is more energetically favorable to reside on the surface, and its formation energy is found to be less than that of oxygen vacancy that does not introduce any magnetism. These findings suggest that the main vacancy species is Zn vacancy as expected by experiments. The present theoretical study not only provides some deep understandings for the experimentally observed magnetism in un-doped ZnO samples, but also suggests that introducing Zn vacancy is a natural and an effective way to fabricate magnetic ZnO structure for bio-magnetic applications.

  6. 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.

  7. Morphological, structural and optical properties of ZnO thin films deposited by dip coating method

    Energy Technology Data Exchange (ETDEWEB)

    Marouf, Sara; Beniaiche, Abdelkrim; Guessas, Hocine, E-mail: aziziamor@yahoo.fr [Laboratoire des Systemes Photoniques et Optiques Non Lineaires, Institut d' Optique et Mecanique de Precision, Universite Ferhat Abbas-Setif 1, Setif (Algeria); Azizi, Amor [Laboratoire de Chimie, Ingenierie Moleculaire et Nanostructures, Universite Ferhat Abbas-Setif 1, Setif (Algeria)

    2017-01-15

    Zinc oxide (ZnO) thin films were deposited on glass substrate by dip coating technique. The effects of sol aging time on the deposition of ZnO films was studied by using the field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and optical transmission techniques. The morphology of the films strongly depends on preparation route and deposition technique. It is noteworthy that films deposited from the freshly prepared solution feature indistinct characteristics; had relatively poor crystalline quality and low optical transmittance in the visible region. The increase in sol aging time resulted in a gradual improvement in crystallinity (in terms of peak sharpness and peak intensity) of the hexagonal phase for all diffraction peaks. Effect of sol aging on optical transparency is quite obvious through increased transmission with prolonged sol aging time. Interestingly, 72-168 h sol aging time was found to be optimal to achieve smooth surface morphology, good crystallinity and high optical transmittance which were attributed to an ideal stability of solution. These findings present a better-defined and more versatile procedure for production of clean ZnO sols of readily adjustable nanocrystalline size. (author)

  8. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-05-23

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

  10. Effect of high-energy electron beam irradiation on the transmittance of ZnO thin films on transparent substrates

    International Nuclear Information System (INIS)

    Yun, Eui-Jung; Jung, Jin-Woo; Han, Young-Hwan; Kim, Min-Wan; Lee, Byung Cheol

    2010-01-01

    We investigated in this study the effects of high-energy electron beam irradiation (HEEBI) on the optical transmittance of undoped ZnO films grown on transparent substrates, such as corning glass and polyethersulfone (PES) plastic substrates, with a radio frequency (rf) magnetron sputtering technique. The ZnO thin films were treated with HEEBI in air at RT with an electron beam energy of 1 MeV and doses of 4.7 x 10 14 - 4.7 x 10 16 electrons/cm 2 . The optical transmittance of the ZnO films was measured using an ultraviolet visible near-infrared spectrophotometer. The detailed estimation process for separating the transmittance of HEEBI-treated ZnO films from the total transmittance of ZnO films on transparent substrates treated with HEEBI is given in this paper. We concluded that HEEBI causes a slight suppression in the optical transmittance of ZnO thin films. We also concluded that HEEBI treatment with a high dose shifted the optical band gap (E g ) toward the lower energy region from 3.29 to 3.28 eV whereas that with a low dose unchanged E g at 3.25 eV. This shift suggested that HEEBI at RT at a high dose acts like an annealing treatment at high temperature.

  11. Evidence of Negative Capacitance in Piezoelectric ZnO Thin Films Sputtered on Interdigital Electrodes.

    Science.gov (United States)

    Laurenti, Marco; Verna, Alessio; Chiolerio, Alessandro

    2015-11-11

    The scaling paradigm known as Moore's Law, with the shrinking of transistors and their doubling on a chip every two years, is going to reach a painful end. Another less-known paradigm, the so-called Koomey's Law, stating that the computing efficiency doubles every 1.57 years, poses other important challenges, since the efficiency of rechargeable energy sources is substantially constant, and any other evolution is based on device architecture only. How can we still increase the computational power/reduce the power consumption of our electronic environments? A first answer to this question comes from the quest for new functionalities. Within this aim, negative capacitance (NC) is becoming one of the most intriguing and studied phenomena since it can be exploited for reducing the aforementioned limiting effects in the downscaling of electronic devices. Here we report the evidence of negative capacitance in 80 nm thick ZnO thin films sputtered on Au interdigital electrodes (IDEs). Highly (002)-oriented ZnO thin films, with a fine-grained surface nanostructure and the desired chemical composition, are deposited at room temperature on different IDEs structures. Direct-current electrical measurements highlighted the semiconducting nature of ZnO (current density in the order of 1 × 10(-3) A/cm(2)). When turned into the alternating current regime (from 20 Hz to 2 MHz) the presence of NC values is observed in the low-frequency range (20-120 Hz). The loss of metal/semiconductor interface charge states under forward bias conditions, together with the presence of oxygen vacancies and piezoelectric/electrostriction effects, is believed to be at the basis of the observed negative behavior, suggesting that ZnO thin-film-based field-effect transistors can be a powerful instrument to go beyond the Boltzmann limit and the downscaling of integrated circuit elements required for the fabrication of portable and miniaturized electronic devices, especially for electric household

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

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Raegan Lynn [Iowa State Univ., Ames, IA (United States)

    2005-01-01

    In Atomic Force Microscopy (AFM), a microcantilever is raster scanned across the surface of a sample in order to obtain a topographical image of the sample's surface. In a traditional, optical AFM, the sample rests on a bulk piezoelectric tube and a control loop is used to control the tip-sample separation by actuating the piezo-tube. This method has several disadvantages--the most noticeable one being that response time of the piezo-tube is rather long which leads to slow imaging speeds. One possible solution aimed at improving the speed of imaging is to incorporate a thin piezoelectric film on top of the cantilever beam. This design not only improves the speed of imaging because the piezoelectric film replaces the piezo-tube as an actuator, but the film can also act as a sensor. In addition, the piezoelectric film can excite the cantilever beam near its resonance frequency. This project aims to fabricate piezoelectric microcantilevers for use in the AFM. Prior to fabricating the cantilevers and also part of this project, a systematic study was performed to examine the effects of deposition conditions on the quality of piezoelectric ZnO thin films deposited by RF sputtering. These results will be presented. The deposition parameters that produced the highest quality ZnO film were used in the fabrication of the piezoelectric cantilevers. Unfortunately, the fabricated cantilevers warped due to the intrinsic stress of the ZnO film and were therefore not usable in the AFM. The complete fabrication process will be detailed, the results will be discussed and reasons for the warping will be examined.

  13. Enhanced stimulated emission in ZnO thin films using microdisk top-down structuring

    Energy Technology Data Exchange (ETDEWEB)

    Nomenyo, K.; Kostcheev, S.; Lérondel, G. [Laboratoire de Nanotechnologie et d' Instrumentation Optique, Institut Charles Delaunay, CNRS UMR 6281, Université de Technologie de Troyes, 12 rue Marie Curie, CS 42060, 10004 Troyes Cedex (France); Gadallah, A.-S. [Laboratoire de Nanotechnologie et d' Instrumentation Optique, Institut Charles Delaunay, CNRS UMR 6281, Université de Technologie de Troyes, 12 rue Marie Curie, CS 42060, 10004 Troyes Cedex (France); Department of Laser Sciences and Interactions, National Institute of Laser Enhanced Sciences, Cairo University, Giza (Egypt); Rogers, D. J. [Nanovation, 8, route de Chevreuse, 78117 Châteaufort (France)

    2014-05-05

    Microdisks were fabricated in zinc oxide (ZnO) thin films using a top-down approach combining electron beam lithography and reactive ion etching. These microdisk structured thin films exhibit a stimulated surface emission between 3 and 7 times higher than that from a reference film depending on the excitation power density. Emission peak narrowing, reduction in lasing threshold and blue-shifting of the emission wavelength were observed along with enhancement in the emitted intensity. Results indicate that this enhancement is due to an increase in the internal quantum efficiency combined with an amplification of the stimulated emission. An analysis in terms of waveguiding is presented in order to explain these effects. These results demonstrate that very significant gains in emission can be obtained through conventional microstructuration without the need for more onerous top-down nanostructuration techniques.

  14. Ultraviolet Stimulated Emission from Sol-Gel Spin Coated ZnO Thin Films

    Directory of Open Access Journals (Sweden)

    Ahmed S. Razeen

    2017-01-01

    Full Text Available Low cost ultraviolet stimulated emission has been generated using optical excitation of ZnO thin films deposited by sol-gel spin coating on n+ As-doped 100 Si-substrate. The number of deposited layers and the heat treatment have been investigated to obtain a film that can generate stimulated emission under optical excitation. The optimum condition for preparation of the film has been presented. X-ray diffraction and scanning electron microscope have been used for structural and morphological investigations. Input-output intensity dependence and spectral width, peak emission wavelength, and the quantum efficiency versus the pump intensity have been presented. A quantum efficiency of about 24.2% has been reported, a power exponent higher than 8 has been obtained in input-output intensity dependence, and a threshold of about 23 Mw/cm2 has been evaluated for the samples. The mechanism by which stimulated emission occurs has been discussed. The results show that sol-gel spin coating is a promising method for generating ultraviolet stimulated emission from ZnO thin films.

  15. ZnO transparent conductive oxide for thin film silicon solar cells

    Science.gov (United States)

    Söderström, T.; Dominé, D.; Feltrin, A.; Despeisse, M.; Meillaud, F.; Bugnon, G.; Boccard, M.; Cuony, P.; Haug, F.-J.; Faÿ, S.; Nicolay, S.; Ballif, C.

    2010-03-01

    There is general agreement that the future production of electric energy has to be renewable and sustainable in the long term. Photovoltaic (PV) is booming with more than 7GW produced in 2008 and will therefore play an important role in the future electricity supply mix. Currently, crystalline silicon (c-Si) dominates the market with a share of about 90%. Reducing the cost per watt peak and energy pay back time of PV was the major concern of the last decade and remains the main challenge today. For that, thin film silicon solar cells has a strong potential because it allies the strength of c-Si (i.e. durability, abundancy, non toxicity) together with reduced material usage, lower temperature processes and monolithic interconnection. One of the technological key points is the transparent conductive oxide (TCO) used for front contact, barrier layer or intermediate reflector. In this paper, we report on the versatility of ZnO grown by low pressure chemical vapor deposition (ZnO LP-CVD) and its application in thin film silicon solar cells. In particular, we focus on the transparency, the morphology of the textured surface and its effects on the light in-coupling for micromorph tandem cells in both the substrate (n-i-p) and superstrate (p-i-n) configurations. The stabilized efficiencies achieved in Neuchâtel are 11.2% and 9.8% for p-i-n (without ARC) and n-i-p (plastic substrate), respectively.

  16. Al-doped and in-doped ZnO thin films in heterojunctions with silicon

    Energy Technology Data Exchange (ETDEWEB)

    Chabane, L.; Zebbar, N.; Kechouane, M. [LCMS, Faculty of Physics, University of Sciences and Technology (USTHB), BP 32-16111, Algiers (Algeria); Aida, M.S. [LCMet Interface, Faculty of Sciences, University of Constantine, 25000 (Algeria); Trari, M. [Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry (USTHB), BP 32-16111 Algiers (Algeria)

    2016-04-30

    The undoped, Al-doped and In-doped ZnO thin films were deposited by ultrasonic spray pyrolysis technique, onto glass and p-Si substrates and the physical properties of the films were investigated. The X-ray diffraction, optical analysis and electrical characterisations, indicate that the films were polycrystalline with hexagonal würtzite type structure and revealed that the aluminium doping deteriorates the crystalline and optical properties and enhances the electrical conductivity whereas indium doping improves all properties. The transport mechanism controlling the conduction through the heterojunctions was studied. For the heterostructures, the temperature dependent current–voltage characteristics showed rectifying behaviour in the dark, but current transport mechanism is not the same for all heterojunctions. Therefore, the presence of the interface states and volume defects are identified as limiting factors for obtaining a high quality heterojunction interface. - Highlights: • Al-doped and In-doped ZnO thin films have been deposited onto Si. • In-doped ZnO/p-Si heterojunction showed poor rectifying behaviour. • Al-doped ZnO/p-Si heterojunction showed a good rectifying at room temperature. • The carriers transport mechanisms was controlled by interfacial and volume defects.

  17. Performance improvement of Ge-Sb-Te material by GaSb doping for phase change memory

    International Nuclear Information System (INIS)

    Lu, Yegang; Zhang, Zhonghua; Song, Sannian; Cheng, Limin; Song, Zhitang; Shen, Xiang; Wang, Guoxiang; Dai, Shixun

    2013-01-01

    Effects of GaSb doping on phase change characteristics of Ge-Sb-Te material are investigated by in situ resistance and x-ray diffraction measurement, optical spectroscopy, and x-ray photoelectron spectroscopy. The crystallization temperature and data retention of Ge-Sb-Te material increase significantly by the addition of GaSb, which results from the high thermal stability of amorphous GaSb. In addition, GaSb-doped Ge-Sb-Te material exhibits faster crystallization speed due to the change in electronic states as a result of the formation of chemical bonds with Ga element. Incorporation of GaSb is highly effective way to enhance the comprehensive performance of Ge-Sb-Te material for phase change memory.

  18. Mechanisms involved in the hydrothermal growth of ultra-thin and high aspect ratio ZnO nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Demes, Thomas [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Ternon, Céline, E-mail: celine.ternon@grenoble-inp.fr [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Univ. Grenoble Alpes, CNRS, LTM, F-38000 Grenoble (France); Morisot, Fanny [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Univ. Grenoble Alpes, CNRS, Grenoble-INP" 2, IMEP-LaHC, F-38000 Grenoble (France); Riassetto, David [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Legallais, Maxime [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Univ. Grenoble Alpes, CNRS, Grenoble-INP" 2, IMEP-LaHC, F-38000 Grenoble (France); Roussel, Hervé; Langlet, Michel [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France)

    2017-07-15

    Highlights: • ZnO nanowires are grown on sol-gel ZnO seed layers by hydrothermal synthesis. • Ultra-thin and high aspect ratio nanowires are obtained without using additives. • Nanowire diameter is 20–25 nm regardless of growth time and seed morphology. • A nanowire growth model is developed on the basis of thermodynamic considerations. • The nanowires are intended for integration into electrically conductive nanonets. - Abstract: Hydrothermal synthesis of ZnO nanowires (NWs) with tailored dimensions, notably high aspect ratios (AR) and small diameters, is a major concern for a wide range of applications and still represents a challenging and recurring issue. In this work, an additive-free and reproducible hydrothermal procedure has been developed to grow ultra-thin and high AR ZnO NWs on sol-gel deposited ZnO seed layers. Controlling the substrate temperature and using a low reagent concentration (1 mM) has been found to be essential for obtaining such NWs. We show that the NW diameter remains constant at about 20–25 nm with growth time contrary to the NW length that can be selectively increased leading to NWs with ARs up to 400. On the basis of investigated experimental conditions along with thermodynamic and kinetic considerations, a ZnO NW growth mechanism has been developed which involves the formation and growth of nuclei followed by NW growth when the nuclei reach a critical size of about 20–25 nm. The low reagent concentration inhibits NW lateral growth leading to ultra-thin and high AR NWs. These NWs have been assembled into electrically conductive ZnO nanowire networks, which opens attractive perspectives toward the development of highly sensitive low-cost gas- or bio-sensors.

  19. The investigation of the Cr doped ZnO thin films deposited by thermionic vacuum arc technique

    Science.gov (United States)

    Mohammadigharehbagh, Reza; Pat, Suat; Musaoglu, Caner; Korkmaz, Şadan; Özen, Soner

    2018-02-01

    Cr doped ZnO thin films were prepared onto glass and polyethylene terephthalate (PET) substrates using thermionic vacuum arc. XRD patterns show the polycrystalline nature of the films. Cr, Zn, ZnO and Cr2O3 were detected in the layers. The mean crystallite sizes of the films were calculated about 20 nm for the films onto glass and PET substrates. The maximum dislocation density and internal strain values of the films are calculated. According to the optical analysis, the average transmittance and reflectance of the films were found to be approximately 53% and 16% for glass and PET substrates, respectively. The mean refractive index of the layer decreased to 2.15 from 2.38 for the PET substrate. The band gap values of the Cr-doped ZnO thin films were determined as 3.10 and 3.13 eV for glass and PET substrates.

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

    NARCIS (Netherlands)

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

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

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

    NARCIS (Netherlands)

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

    1994-01-01

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

  2. Investigation of ZnO Thin Film Synthesized by Spray Pyrolysis Method as a Toxic Gases Sensor

    Science.gov (United States)

    Khojier, K.

    2017-10-01

    In recent years, environmental pollution, particularly toxic gases and vapors, have greatly increased; hence, their detection has become increasingly important. This paper investigates ZnO thin films fabricated by the spray pyrolysis method to fabricate a toxic gases sensor. A ZnO thin film of 100 nm thickness was deposited on a glass substrate at 100°C. The crystallographic structure was characterized by x-ray diffraction and a field-emission scanning electron microscope was employed to investigate the surface physical morphology and chemical composition. Sensitivity and selectivity of the sample were tested with respect to different toxic gases and vapors including carbon monoxide, ammonia, hydrogen sulfide, chlorine, nitrogen dioxide, benzene, formaldehyde and toluene in the temperature range of 100-300°C. The results showed that the ZnO thin film is more selective to NO2 gas than the other toxic gases and vapors in the studied temperature range. The ZnO thin film-based NO2 gas sensor also showed a good reproducibility, stability, and detection limit of 10 ppm at the operating temperature of 200°C.

  3. Study of p-type ZnO and MgZnO Thin Films for Solid State Lighting

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jianlin [Univ. of California, Riverside, CA (United States)

    2015-07-31

    This project on study of p-type ZnO and MgZnO thin films for solid state lighting was carried out by research group of Prof. Jianlin Liu of UCR during the four-year period between August 2011 and July 2015. Tremendous progress has been made on the proposed research. This final report summarizes the important findings.

  4. Research Update: Atmospheric pressure spatial atomic layer deposition of ZnO thin films: Reactors, doping, and devices

    NARCIS (Netherlands)

    Hoye, R.L.Z.; Muñoz-Rojas, D.; Nelson, S.F.; Illiberi, A.; Poodt, P.; Roozeboom, F.; Macmanus-Driscoll, J.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

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  6. Functionalized carbon nanotubes in ZnO thin films for photoinactivation of bacteria

    International Nuclear Information System (INIS)

    Akhavan, O.; Azimirad, R.; Safa, S.

    2011-01-01

    Highlights: → Unfunctionalized and functionalized MWCNT/ZnO thin films were synthesized by sol-gel method. → Zn-O-C carbonaceous bonds formed in the functionalized MWCNT/ZnO thin films. → The functionalized MWCNT/ZnO had stronger photoinactivation of the bacteria than the unfunctionalize type. → 10 wt% functionalized MWCNT content had the optimum antibacterial property. - Abstract: Two types of unfunctionalized and functionalized multi-wall carbon nanotubes (MWCNTs) were prepared to be applied in fabrication of MWCNT-ZnO nanocomposite thin films with various MWCNT contents. X-ray photoelectron spectroscopy indicated formation of functional groups on surface of the functionalized MWCNTs in the MWCNT-ZnO nanocomposite. Formation of the effective carbonaceous bonds between the ZnO and the MWCNTs was also investigated through photoinactivation of Escherichia coli bacteria on surface of the both unfunctionalized and functionalized MWCNT-ZnO nanocomposites. The functionalized MWCNT-ZnO nanocomposites showed significantly stronger photoinactivation of the bacteria than the unfunctionalized ones, for all of the various MWCNT contents (from 2 to 30 wt%). While the functionalized MWCNT-ZnO nanocomposites with the optimum MWCNT content of 10 wt% inactivated whole of the bacteria after 10 min UV-visible light irradiation, the unfunctionalized ones could inactivate only 63% of the bacteria under the same conditions. The significant enhancement of the photoinactivation of the bacteria onto the surface of the functionalized MWCNT-ZnO nanocomposites was assigned to charge transfer through Zn-O-C bands formed between the Zn atoms of the ZnO film and oxygen atoms of the carboxylic functional groups of the functionalized MWCNTs.

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

    Science.gov (United States)

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

    2017-05-01

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

  8. Plasmonic enhancement of UV emission from ZnO thin films induced by Al nano-concave arrays

    International Nuclear Information System (INIS)

    Norek, Małgorzata; Łuka, Grzegorz; Włodarski, Maksymilian

    2016-01-01

    Highlights: • Al nano-concave arrays with different interpore distance (D c ) were prepared. • PL of ZnO thin films deposited directly on the Al nano-concaves were studied. • The effect of 10 nm Al 2 O 3 spacer on PL emission from ZnO thin films was analyzed. • Plasmonic enhancement of the PL emission was dependent on the D c and the spacer. • The highest 9-fold enhancement was obtained for the Al/ZnO sample with D c ∼333 nm. - Abstract: Surface plasmons (SPs) supported by Al nano-concave arrays with increasing interpore distance (D c ) were used to enhance the ultraviolet light emission from ZnO thin films. Two sets of samples were prepared: in the first set the thin ZnO films were deposited directly on Al nanoconcaves (the Al/ZnO samples) and in the second set a 10 nm − Al 2 O 3 spacer was placed between the textured Al and the ZnO films (the Al/Al 2 O 3 -ALD/ZnO samples). In the Al/ZnO samples the enhancement was limited by a nonradiative energy dissipation due to the Ohmic loss in the Al metal. However, for the ZnO layer deposited directly on Al nanopits synthesized at 150 V (D c = 333 ± 18 nm), the largest 9-fold enhancement was obtained by achieving the best energy fit between the near band-edge (NBE) emission from ZnO and the λ (0,1) SPP resonance mode. In the Al/Al 2 O 3 -ALD/ZnO samples the amplification of the UV emission was smaller than in the Al/ZnO samples due to a big energy mismatch between the NBE emission and the λ (0,1) plasmonic mode. The results obtained in this work indicate that better tuning of the NBE − λ (0,1) SPP resonance mode coupling is possible through a proper modification of geometrical parameters in the Al/Al 2 O 3 -ALD/ZnO system such as Al nano-concave spacing and the thickness of the corresponding layer. This approach will reduce the negative influence of the non-radiative plasmonic modes and most likely will lead to further enhancement of the SP-modulated UV emission from ZnO thin films.

  9. Plasmonic enhancement of UV emission from ZnO thin films induced by Al nano-concave arrays

    Energy Technology Data Exchange (ETDEWEB)

    Norek, Małgorzata, E-mail: mnorek@wat.edu.pl [Department of Advanced Materials and Technologies, Faculty of Advanced Technologies and Chemistry, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland); Łuka, Grzegorz [Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warsaw (Poland); Włodarski, Maksymilian [Institute of Optoelectronics, Military University of Technology, Str. Kaliskiego 2, 00-908 Warszawa (Poland)

    2016-10-30

    Highlights: • Al nano-concave arrays with different interpore distance (D{sub c}) were prepared. • PL of ZnO thin films deposited directly on the Al nano-concaves were studied. • The effect of 10 nm Al{sub 2}O{sub 3} spacer on PL emission from ZnO thin films was analyzed. • Plasmonic enhancement of the PL emission was dependent on the D{sub c} and the spacer. • The highest 9-fold enhancement was obtained for the Al/ZnO sample with D{sub c} ∼333 nm. - Abstract: Surface plasmons (SPs) supported by Al nano-concave arrays with increasing interpore distance (D{sub c}) were used to enhance the ultraviolet light emission from ZnO thin films. Two sets of samples were prepared: in the first set the thin ZnO films were deposited directly on Al nanoconcaves (the Al/ZnO samples) and in the second set a 10 nm − Al{sub 2}O{sub 3} spacer was placed between the textured Al and the ZnO films (the Al/Al{sub 2}O{sub 3}-ALD/ZnO samples). In the Al/ZnO samples the enhancement was limited by a nonradiative energy dissipation due to the Ohmic loss in the Al metal. However, for the ZnO layer deposited directly on Al nanopits synthesized at 150 V (D{sub c} = 333 ± 18 nm), the largest 9-fold enhancement was obtained by achieving the best energy fit between the near band-edge (NBE) emission from ZnO and the λ{sub (0,1)} SPP resonance mode. In the Al/Al{sub 2}O{sub 3}-ALD/ZnO samples the amplification of the UV emission was smaller than in the Al/ZnO samples due to a big energy mismatch between the NBE emission and the λ{sub (0,1)} plasmonic mode. The results obtained in this work indicate that better tuning of the NBE − λ{sub (0,1)} SPP resonance mode coupling is possible through a proper modification of geometrical parameters in the Al/Al{sub 2}O{sub 3}-ALD/ZnO system such as Al nano-concave spacing and the thickness of the corresponding layer. This approach will reduce the negative influence of the non-radiative plasmonic modes and most likely will lead to further

  10. Effect of surface microstructure and wettability on plasma protein adsorption to ZnO thin films prepared at different RF powers.

    Science.gov (United States)

    Huang, Zhan-Yun; Chen, Min; Pan, Shi-Rong; Chen, Di-Hu

    2010-10-01

    In this paper, the adsorption behavior of plasma proteins on the surface of ZnO thin films prepared by radio frequency (RF) sputtering under different sputtering powers was studied. The microstructures and surface properties of the ZnO thin films were investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible optical absorption spectroscopy and contact angle techniques. The results show that the ZnO thin films have better orientation of the (0 0 2) peak with increasing RF power, especially at around 160 W, and the optical band gap of the ZnO films varies from 3.2 to 3.4 eV. The contact angle test carried out by the sessile drop technique denoted a hydrophobic surface of the ZnO films, and the surface energy and adhesive work of the ZnO thin films decreased with increasing sputtering power. The amounts of human fibrinogen (HFG) and human serum albumin (HSA) adsorbing on the ZnO films and reference samples were determined by using enzyme-linked immunosorbent assay (ELISA). The results show that fewer plasma proteins and a smaller HFG/HSA ratio adsorb on the ZnO thin films' surface.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-12-31

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

  12. 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.

  13. Acceptor-modulated optical enhancements and band-gap narrowing in ZnO thin films

    Directory of Open Access Journals (Sweden)

    Ali Hassan

    2018-03-01

    Full Text Available Fermi-Dirac distribution for doped semiconductors and Burstein-Moss effect have been correlated first time to figure out the conductivity type of ZnO. Hall Effect in the Van der Pauw configuration has been applied to reconcile our theoretical estimations which evince our assumption. Band-gap narrowing has been found in all p-type samples, whereas blue Burstein-Moss shift has been recorded in the n-type films. Atomic Force Microscopic (AFM analysis shows that both p-type and n-type films have almost same granular-like structure with minor change in average grain size (∼ 6 nm to 10 nm and surface roughness rms value 3 nm for thickness ∼315 nm which points that grain size and surface roughness did not play any significant role in order to modulate the conductivity type of ZnO. X-ray diffraction (XRD, Energy Dispersive X-ray Spectroscopy (EDS and X-ray Photoelectron Spectroscopy (XPS have been employed to perform the structural, chemical and elemental analysis. Hexagonal wurtzite structure has been observed in all samples. The introduction of nitrogen reduces the crystallinity of host lattice. 97% transmittance in the visible range with 1.4 × 107 Ω-1cm-1 optical conductivity have been detected. High absorption value in the ultra-violet (UV region reveals that NZOs thin films can be used to fabricate next-generation high-performance UV detectors.

  14. Acceptor-modulated optical enhancements and band-gap narrowing in ZnO thin films

    Science.gov (United States)

    Hassan, Ali; Jin, Yuhua; Irfan, Muhammad; Jiang, Yijian

    2018-03-01

    Fermi-Dirac distribution for doped semiconductors and Burstein-Moss effect have been correlated first time to figure out the conductivity type of ZnO. Hall Effect in the Van der Pauw configuration has been applied to reconcile our theoretical estimations which evince our assumption. Band-gap narrowing has been found in all p-type samples, whereas blue Burstein-Moss shift has been recorded in the n-type films. Atomic Force Microscopic (AFM) analysis shows that both p-type and n-type films have almost same granular-like structure with minor change in average grain size (˜ 6 nm to 10 nm) and surface roughness rms value 3 nm for thickness ˜315 nm which points that grain size and surface roughness did not play any significant role in order to modulate the conductivity type of ZnO. X-ray diffraction (XRD), Energy Dispersive X-ray Spectroscopy (EDS) and X-ray Photoelectron Spectroscopy (XPS) have been employed to perform the structural, chemical and elemental analysis. Hexagonal wurtzite structure has been observed in all samples. The introduction of nitrogen reduces the crystallinity of host lattice. 97% transmittance in the visible range with 1.4 × 107 Ω-1cm-1 optical conductivity have been detected. High absorption value in the ultra-violet (UV) region reveals that NZOs thin films can be used to fabricate next-generation high-performance UV detectors.

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

    Science.gov (United States)

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

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

  16. Determination of the transport mechanisms in mixed conduction of reactively sputtered ZnO thin films

    International Nuclear Information System (INIS)

    Tuezemen, S; Guer, Emre; Dogan, S

    2008-01-01

    Material grown at highly Zn-rich conditions in reactive sputtering of ZnO thin films resulted in mixed conduction, indicating that stable p-type ZnO can be produced. In n-type conductivity, neutral flaw scattering transport mechanism via V O 0 centres seems to be dominant due to the existence of oxygen vacancies in high concentrations. An exponential decrease in electron mobility is observed upon cooling from room temperature to 210 K while the concentration of the inactive V O 0 state increases. This is also a cause of p-type conduction in the low temperature range ( O 0 scattering. Quantitative evaluations of V O centres show that fractional distribution of V O 0 , V O + and V O ++ charge states are, respectively, around 4%, 95% and 1% of the total [V O ] at the room temperature conditions. The energy of phonons interacting with the centre is estimated to be 38.5 meV which is a local phonon mode relaxation, most probably resulting in negative-U behaviour of V O centres

  17. 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.

  18. Improvement of optical transmittance and electrical properties for the Si quantum dot-embedded ZnO thin film

    OpenAIRE

    Kuo, Kuang-Yang; Liu, Chuan-Cheng; Huang, Pin-Ruei; Hsu, Shu-Wei; Chuang, Wen-Ling; Chen, You-Jheng; Lee, Po-Tsung

    2013-01-01

    A Si quantum dot (QD)-embedded ZnO thin film is successfully fabricated on a p-type Si substrate using a ZnO/Si multilayer structure. Its optical transmittance is largely improved when increasing the annealing temperature, owing to the phase transformation from amorphous to nanocrystalline Si QDs embedded in the ZnO matrix. The sample annealed at 700?C exhibits not only high optical transmittance in the long-wavelength range but also better electrical properties including low resistivity, sma...

  19. Photoelectrocatrocatalytic hydrolysis of starch by using sprayed ZnO thin films

    International Nuclear Information System (INIS)

    Sapkal, R. T.; Shinde, S. S.; Rajpure, K.Y.; Bhosale, C. H.

    2013-01-01

    Thin films of zinc oxide have been deposited onto glass/FTO substrates at optimized 400 °C by using a chemical spray pyrolysis technique. Deposited films are character photocatalytic activity by using XRD, an SEM, a UV-vis spectrophotometer, and a PEC single-cell reactor. Films are polycrystalline and have a hexagonal (wurtzite) crystal structure with c-axis (002) orientation growth perpendicular to the substrate surface. The observed direct band gap is about 3.22 eV for typical films prepared at 400 °C. The photocatalytic activity of starch with a ZnO photocatalyst has been studied by using a novel photoelectrocatalytic process. (semiconductor materials)

  20. Investigations of rapid thermal annealing induced structural evolution of ZnO: Ge nanocomposite thin films via GISAXS

    Energy Technology Data Exchange (ETDEWEB)

    Ceylan, Abdullah, E-mail: aceylanabd@yahoo.com [Department of Physics Eng., Hacettepe University, Beytepe, 06800 Ankara (Turkey); Ozcan, Yusuf [Department of Electricity and Energy, Pamukkale University, Denizli (Turkey); Orujalipoor, Ilghar [Department of Nanotechnology and Nanomedicine, Hacettepe University, Beytepe, 06800 Ankara (Turkey); Huang, Yen-Chih; Jeng, U-Ser [National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu, Taiwan (China); Ide, Semra [Department of Physics Eng., Hacettepe University, Beytepe, 06800 Ankara (Turkey); Department of Nanotechnology and Nanomedicine, Hacettepe University, Beytepe, 06800 Ankara (Turkey)

    2016-06-07

    In this work, we present in depth structural investigations of nanocomposite ZnO: Ge thin films by utilizing a state of the art grazing incidence small angle x-ray spectroscopy (GISAXS) technique. The samples have been deposited by sequential r.f. and d.c. sputtering of ZnO and Ge thin film layers, respectively, on single crystal Si(100) substrates. Transformation of Ge layers into Ge nanoparticles (Ge-np) has been initiated by ex-situ rapid thermal annealing of asprepared thin film samples at 600 °C for 30, 60, and 90 s under forming gas atmosphere. A special attention has been paid on the effects of reactive and nonreactive growth of ZnO layers on the structural evolution of Ge-np. GISAXS analyses have been performed via cylindrical and spherical form factor calculations for different nanostructure types. Variations of the size, shape, and distributions of both ZnO and Ge nanostructures have been determined. It has been realized that GISAXS results are not only remarkably consistent with the electron microscopy observations but also provide additional information on the large scale size and shape distribution of the nanostructured components.

  1. ZnO and ZnSe thin films grown by Atomic Layer Epitaxy in a gas flow system

    Science.gov (United States)

    Godlewski, Marek; Guziewicz, Elzbieta; Kopalko, Krzysztof; Lusalowska, Elzbieta

    2003-03-01

    In the presentation we will briefly review our recent works on thin films of ZnO and ZnSe for possible applications in opto-electronics. Thin films of ZnO were grown by four different methods on either semiconductor substrates or on a glass plates. The latter system was successfully used as a substrate for deposition of amorphous GaN epilayers, using low temperature plasma-assisted MOCVD technique. Properties of ALE-grown ZnO films and of GaN epilayers grown on ZnO buffer layer will be shortly analyzed. Thin films of ZnSe were grown using synthesis from Zn and Se. These films show bright white color light emission. Temperature of the emission and brightness can be optimized by either modifications in a growth procedure or variations in excitation conditions. Nature of white emission and optimization procedures will be described. This work was partly supported by grant no. PBZ-KBN-044/P03/2001 of KBN. The ALE reactor was bought using SEZAM grant of Foundation for Polish Science.

  2. Influence of Annealing on Properties of Spray Deposited ZnO Thin Films

    Directory of Open Access Journals (Sweden)

    Kalyani Nadarajah

    2013-01-01

    Full Text Available Zinc Oxide (ZnO thin films were deposited on glass substrates via the spray pyrolysis technique. The films were subsequently annealed in ambient air from 300°C to 500°C. The morphology and structural properties of the thin films were studied by field emission scanning electron microscope (FESEM, atomic force microscopy (AFM, and X-ray diffractometry (XRD techniques. Electrical resistivity of the thin films was measured using a data acquisition unit. The optical properties of the films were characterized by UV-vis spectroscopy and photoluminescence (PL technique. X-ray diffraction data showed that the films were grown in the (002 direction with a hexagonal wurtzite structure. The average grain size ranged from 15 to 27 nm. Increasing annealing temperatures resulted in larger grain sizes and higher crystallinity, with the surface roughness of annealed films being more than twice if compared to unannealed film. The electrical resistivity of the films decreased with the increasing annealing temperature. The UV and visible band emissions were observed in the photoluminescence spectra, due to exciton and defect-related emissions, respectively. The transmission values of the films were as high as 90% within the visible range (400–700 nm.

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

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

    Science.gov (United States)

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

    2017-06-01

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

  5. Optical and electrical properties of transparent conducting B-doped ZnO thin films prepared by various deposition methods

    Energy Technology Data Exchange (ETDEWEB)

    Nomoto, Jun-ichi; Miyata, Toshihiro; Minami, Tadatsugu [Optoelectronic Device System R and D Center, Kanazawa Institute of Technology, 7-1 Ohgigaoka, Nonoichi, Ishikawa 921-8501 (Japan)

    2011-07-15

    B-doped ZnO (BZO) thin films were prepared with various thicknesses up to about 500 nm on glass substrates at 200 deg. C by dc or rf magnetron sputtering deposition, pulsed laser deposition (PLD), and vacuum arc plasma evaporation (VAPE) methods. Resistivities of 4-6 x 10{sup -4}{Omega} cm were obtained in BZO thin films prepared with a B content [B/(B + Zn) atomic ratio] around 1 at. % by PLD and VAPE methods: Hall mobilities above 40 cm{sup 2}/Vs and carrier concentrations on the order of 10{sup 20} cm{sup -3}. All 500-nm-thick-BZO thin films prepared with a resistivity on the order of 10{sup -3}-10{sup -4}{Omega} cm exhibited an averaged transmittance above 80% in the wavelength range of 400-1100 nm. The resistivity in BZO thin films prepared with a thickness below about 500 nm was found to increase over time with exposure to various high humidity environments. In heat-resistance tests, the resistivity stability of BZO thin films was found to be nearly equal to that of Ga-doped ZnO thin films, so these films were judged suitable for use as a transparent electrode for thin-film solar cells.

  6. High energy electron irradiation effects on Ga-doped ZnO thin films for optoelectronic space applications

    Science.gov (United States)

    Serrao, Felcy Jyothi; Sandeep, K. M.; Bhat, Shreesha; Dharmaprakash, S. M.

    2018-03-01

    Gallium-doped ZnO (GZO) thin films of thickness 394 nm were prepared by a simple, cost-effective sol-gel spin coating method. The effect of 8 MeV electron beam irradiation with different irradiation doses ranging from 0 to 10 kGy on the structural, optical and electrical properties was investigated. Electron irradiation influences the changes in the structural properties and surface morphology of GZO thin films. X-ray diffraction analysis showed that the polycrystalline nature of the GZO films is unaffected by the high energy electron irradiation. The grain size and the surface roughness were found maximum for the GZO film irradiated with 10 kGy electron dosage. The average transmittance of GZO thin films decreased after electron irradiation. The optical band gap of Ga-doped ZnO films was decreased with the increase in the electron dosage. The electrical resistivity of GZO films decreased from 4.83 × 10-3 to 8.725 × 10-4 Ω cm, when the electron dosage was increased from 0 to 10 kGy. The variation in the optical and electrical properties in the Ga-doped ZnO thin films due to electron beam irradiation in the present study is useful in deciding their compatibility in optoelectronic device applications in electron radiation environment.

  7. Matrix assisted pulsed laser evaporation of zinc benzoate for ZnO thin films and non-isothermal decomposition kinetics

    International Nuclear Information System (INIS)

    Rotaru, A.; Constantinescu, C.; Mandruleanu, Anca; Rotaru, P.; Moldovan, A.; Gyoryova, Katarina; Dinescu, Maria; Balek, V.

    2010-01-01

    Zinc(II) coordination compounds may provide a better source for ZnO thin films obtaining, since ZnO was found as the final product of their thermal decomposition. Thin films of zinc benzoate have been obtained on silicon substrates by matrix assisted pulsed laser evaporation (MAPLE) technique, using a Nd:YAG laser working at 266 nm. A comparative study of 1% zinc benzoate frozen solution in methanol at different fulences was carried out for 20,000 laser pulses; for the best deposition fluence a double deposition time was employed. Comparative thermal analysis and non-isothermal kinetic investigation of Zn(C 6 H 5 COO) 2 .2H 2 O dehydration and decomposition was performed. Thin films of ZnO have been obtained by thermal treatment of the MAPLE obtained thin films, according to the thermal analysis and decomposition kinetics of zinc benzoate. The obtained morphologies, before and after thermal treatment, have been investigated by atomic force microscopy (AFM).

  8. Optical and Electrical Characteristic of Layer-by-layer Sol-gel Spin Coated Nanoparticles ZnO Thin Films

    International Nuclear Information System (INIS)

    Shafinaz Sobihana Shariffudin; Farah Farliana Samat; Sukreen Hana; Mohamad Rusop

    2011-01-01

    Transparent ZnO thin films have been deposited on glass substrate using sol-gel spin coating technique. 0.35 M sol were prepared by dissolving zinc acetate dehydrate in 2-methoxyethanol with monoethanolamine as the stabilizer. In this paper, a novel method called layer-by-layer is introduced, where the thin film is not only dried after each layer is spin-coated, but also directly annealed at 500 degree Celsius to improve the crystallinity of the films. Samples without annealing were also prepared as the control sample. ZnO thin films were characterized using field emission scanning electron microscopy, X-ray diffraction, current-voltage measurement, UV-Vis spectroscopy and photoluminescence spectroscopy. The results revealed that layer by- layer ZnO thin films have better conductivity and higher intensity peak for PL spectra at visible spectra of 580 nm. FE-SEM images shows nanoparticles almost hexagonal shaped with high crystallinity compared to control samples. (author)

  9. Application of Thin ZnO ALD Layers in Fiber-Optic Fabry-Pérot Sensing Interferometers

    Directory of Open Access Journals (Sweden)

    Daria Majchrowicz

    2016-03-01

    Full Text Available In this paper we investigated the response of a fiber-optic Fabry-Pérot sensing interferometer with thin ZnO layers deposited on the end faces of the optical fibers forming the cavity. Standard telecommunication single-mode optical fiber (SMF-28 segments were used with the thin ZnO layers deposited by Atomic Layer Deposition (ALD. Measurements were performed with the interferometer illuminated by two broadband sources operating at 1300 nm and 1550 nm. Reflected interference signal was acquired by an optical spectrum analyzer while the length of the air cavity was varied. Thickness of the ZnO layers used in the experiments was 50 nm, 100 nm, and 200 nm. Uncoated SMF-28 fiber was also used as a reference. Based on the results of measurements, the thickness of the ZnO layers and the length of the cavity were selected in order to achieve good visibility. Following, the interferometer was used to determine the refractive index of selected liquids.

  10. Low-temperature deposition of ZnO thin films on PET and glass substrates by DC-sputtering technique

    International Nuclear Information System (INIS)

    Banerjee, A.N.; Ghosh, C.K.; Chattopadhyay, K.K.; Minoura, Hideki; Sarkar, Ajay K.; Akiba, Atsuya; Kamiya, Atsushi; Endo, Tamio

    2006-01-01

    The structural, optical and electrical properties of ZnO thin films (260 - 490 nm thick) deposited by direct-current sputtering technique, at a relatively low-substrate temperature (363 K), onto polyethylene terephthalate and glass substrates have been investigated. X-ray diffraction patterns confirm the proper phase formation of the material. Optical transmittance data show high transparency (80% to more than 98%) of the films in the visible portion of solar radiation. Slight variation in the transparency of the films is observed with a variation in the deposition time. Electrical characterizations show the room-temperature conductivity of the films deposited onto polyethylene terephthalate substrates for 4 and 5 h around 0.05 and 0.25 S cm -1 , respectively. On the other hand, for the films deposited on glass substrates, these values are 8.5 and 9.6 S cm -1 for similar variation in the deposition time. Room-temperature conductivity of the ZnO films deposited on glass substrates is at least two orders of magnitude higher than that of ZnO films deposited onto polyethylene terephthalate substrates under identical conditions. Hall-measurements show the maximum carrier concentration of the films on PET and glass substrate around 2.8 x 10 16 and 3.1 x 10 2 cm -3 , respectively. This report will provide newer applications of ZnO thin films in flexible display technology

  11. Synthesis, Optical and Photoluminescence Properties of Cu-Doped Zno Nano-Fibers Thin Films: Nonlinear Optics

    Science.gov (United States)

    Ganesh, V.; Salem, G. F.; Yahia, I. S.; Yakuphanoglu, F.

    2018-03-01

    Different concentrations of copper-doped zinc oxide thin films were coated on a glass substrate by sol-gel/spin-coating technique. The structural properties of pure and Cu-doped ZnO films were characterized by different techniques, i.e., atomic force microscopy (AFM), photoluminescence and UV-Vis-NIR spectroscopy. The AFM study revealed that pure and doped ZnO films are formed as nano-fibers with a granular structure. The photoluminescence spectra of these films showed a strong ultraviolet emission peak centered at 392 nm and a strong blue emission peak cantered at 450 nm. The optical band gap of the pure and copper-doped ZnO thin films calculated from optical transmission spectra (3.29-3.23 eV) were found to be increasing with increasing copper doping concentration. The refractive index dispersion curve of pure and Cu-doped ZnO film obeyed the single-oscillator model. The optical dispersion parameters such as E o , E d , and n_{∞}2 were calculated. Further, the nonlinear refractive index and nonlinear optical susceptibility were also calculated and interpreted.

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

    Energy Technology Data Exchange (ETDEWEB)

    Lare, Y. [Laboratoire sue l' Energie Solaire, Universite de Lome, Lome (Togo); Godoy, A. [Facultad Ciencias de la Salud, Universidad Diego Portales, Ejercito 141, Santiago de Chile (Chile); Cattin, L. [Universite de Nantes, Nantes Atlantique Universites, IMN, Faculte des Sciences et des Techniques, 2 rue de la Houssiniere, BP 92208, Nantes, F-44000 France (France); Jondo, K. [Laboratoire sue l' Energie Solaire, Universite de Lome, Lome (Togo); Abachi, T. [Ecole Normale Superieure, Kouba, Alger (Algeria); Diaz, F.R. [Laboratorio de Polimeros, Facultad de Quimica, Pontificia Universidad Catolica de Chile, Casilla 306, Correo 22, Santiago (Chile); Morsli, M. [Universite de Nantes, Nantes Atlantique Universites, LAMP, EA 3825, Faculte des Sciences et des Techniques, 2 rue de la Houssiniere, BP 92208, Nantes, F-44000 France (France); Napo, K. [Laboratoire sue l' Energie Solaire, Universite de Lome, Lome (Togo); del Valle, M.A. [Laboratorio de Polimeros, Facultad de Quimica, Pontificia Universidad Catolica de Chile, Casilla 306, Correo 22, Santiago (Chile); Bernede, J.C., E-mail: jean-christian.bernede@univ-nantes.fr [Universite de Nantes, Nantes Atlantique Universites, LAMP, EA 3825, Faculte des Sciences et des Techniques, 2 rue de la Houssiniere, BP 92208, Nantes, F-44000 France (France)

    2009-04-15

    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.

  13. 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.

  14. Determination of the transport mechanisms in mixed conduction of reactively sputtered ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Tuezemen, S; Guer, Emre; Dogan, S [Department of Physics, Faculty of Arts and Sciences, Atatuerk University, 25240, Erzurum (Turkey)], E-mail: stuzemen@atauni.edu.tr

    2008-07-07

    Material grown at highly Zn-rich conditions in reactive sputtering of ZnO thin films resulted in mixed conduction, indicating that stable p-type ZnO can be produced. In n-type conductivity, neutral flaw scattering transport mechanism via V{sub O}{sup 0} centres seems to be dominant due to the existence of oxygen vacancies in high concentrations. An exponential decrease in electron mobility is observed upon cooling from room temperature to 210 K while the concentration of the inactive V{sub O}{sup 0} state increases. This is also a cause of p-type conduction in the low temperature range (<170 K). Mobility of holes has rather usual behaviour as the longitudinal acoustic phonon scattering takes place at temperatures 35-170 K. Ionized acceptor scattering is shown to be effective for holes below 35 K. P-type conduction is not affected by V{sub O}{sup 0} scattering. Quantitative evaluations of V{sub O} centres show that fractional distribution of V{sub O}{sup 0}, V{sub O}{sup +} and V{sub O}{sup ++} charge states are, respectively, around 4%, 95% and 1% of the total [V{sub O}] at the room temperature conditions. The energy of phonons interacting with the centre is estimated to be 38.5 meV which is a local phonon mode relaxation, most probably resulting in negative-U behaviour of V{sub O} centres.

  15. Structural and magnetic properties of cobalt-doped ZnO thin films on sapphire (0 0 0 1) substrate deposited by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Shanying, E-mail: yshy_150@163.com [Laiwu Vocational and Technical College, Laiwu, Shandong Province, 271100 (China); Lv, Rongqing [Laiwu Vocational and Technical College, Laiwu, Shandong Province, 271100 (China); Wang, Changzheng [School of Physics Science and Information Engineering, Liaocheng University, Liaocheng, Shandong Province, 252059 (China); Liu, Yunyan [School of Science, Shandong University of Technology, Zibo, Shandong Province, 255049 (China); Song, Zeqing [Laiwu Vocational and Technical College, Laiwu, Shandong Province, 271100 (China)

    2013-12-05

    Highlights: •Co-doped ZnO thin films on sapphire (0 0 0 1) substrates were deposited. •ZnLMM Auger spectrum indicated that Zn interstitials existed in thin films. •The lattice constant increasing was ascribed to the stress and interstitial atoms. •The average moment per Co atom related to the distribution of Co{sup 2+} ions and defects. -- Abstract: Co-doped ZnO thin films on sapphire (0 0 0 1) substrates were deposited by PLD at various substrate temperatures in a one Pa oxygen ambient condition. The structural and magnetic properties of as-grown thin films were characterized by using XRD, UV–Visible absorption spectrophotometer, XPS and AGM. All samples possessed wurtzite hexagonal structure of ZnO. Co atoms incorporated into ZnO matrix and substituted for Zn in ZnO lattice, and Zn interstitials existed in as-grown thin films. The c-axis lattice constants of as-deposited thin films were larger than the standard data. Crystallization of as-prepared thin films increased and then decreased with substrate temperatures enhancing. All samples exhibited room-temperature ferromagnetism. The average moment per Co atom was much smaller than that of Co{sup 2+} (3d{sup 7}), due to the different distribution of Co{sup 2+} ions and defects, as well as the different defect concentrations in thin films.

  16. Identification of Tequila with an Array of ZnO Thin Films: A Simple and Cost-Effective Method

    Directory of Open Access Journals (Sweden)

    Pedro Estanislao Acuña-Avila

    2017-12-01

    Full Text Available An array of ZnO thin film sensors was obtained by thermal oxidation of physical vapor deposited thin Zn films. Different conditions of the thermal treatment (duration and temperature were applied in view of obtaining ZnO sensors with different gas sensing properties. Films having undergone a long thermal treatment exhibited high responses to low ethanol concentrations, while short thermal treatments generally led to sensors with high ethanol sensitivity. The sensor array was used to distinguish among Tequilas and Agave liquor. Linear discriminant analysis and the multilayer perceptron neural network reached 100% and 86.3% success rates in the discrimination between real Tequila and Agave liquor and in the identification of Tequila brands, respectively. These results are promising for the development of an inexpensive tool offering low complexity and cost of analysis for detecting fraud in spirits.

  17. Effect of surface carbon contamination on the chemical states of N-doped ZnO thin films

    Science.gov (United States)

    Zhang, Hong; Li, Wanjun; Qin, Guoping; Fang, Liang; Ruan, Haibo; Tan, Mi; Wu, Fang; Kong, Chunyang

    2018-02-01

    Nitrogen-doped ZnO thin films [ZnO:N] and intentional surface carbon-contaminated ZnO:N thin films [ZnO:N@C] were grown on quartz substrates by radio frequency magnetron sputtering deposition method. The structural, electrical and optical properties as well as chemical states of elements were investigated by means of X-ray diffraction (XRD), Hall effect measurement (Hall), UV-Vis-Near infrared spectrophotometer and X-ray photoelectron spectroscopy (XPS). The results indicate that surface carbon contamination almost does not affect the band gap of ZnO:N thin films but has a strong impact on the crystal quality of ZnO:N thin film surface and results in a significant increase in tensile stress. The XPS analysis shows that the effect of surface carbon contamination treatment on the chemical states of ZnO:N thin films is remarkable. Because the stability of Zn-N bonds in N-rich local environments is nowhere near that of those in O-rich local environments, the N atoms in N-rich local environments easily bond with surface carbon atoms to form undesirable C-N bonds, thus resulting in a decrease of NO acceptors in N-rich local environments. Obviously, it is unfavorable to subsequently prepare high stability of N-doped p-type ZnO thin films.

  18. Decrease in electrical contact resistance of Sb-doped n+-BaSi2 layers and spectral response of an Sb-doped n+-BaSi2/undoped BaSi2 structure for solar cells

    Science.gov (United States)

    Kodama, Komomo; Takabe, Ryota; Yachi, Suguru; Toko, Kaoru; Suemasu, Takashi

    2018-03-01

    We investigated how the electron concentration n in a 300-nm-thick Sb-doped n+-BaSi2 layer grown by molecular beam epitaxy affected the contact resistance R C to surface electrodes (Al, indium-tin-oxide). As the n of n-BaSi2 increased, R C decreased and reached a minimum of 0.019 Ω cm2 at n = 2.4 × 1018 cm-3 for the Al electrodes. This value was more than 1 order of magnitude smaller than that obtained for Al/B-doped p-BaSi2. We believe that this significant decrease in R C came from Sb segregation. Furthermore, the internal quantum efficiency (IQE) spectrum was evaluated for an Sb-doped n+-BaSi2 (20 nm)/undoped BaSi2 (500 nm)/n+-Si(111) structure. Its IQE reached as high as ˜50% over a wide wavelength range under a small bias voltage of 0.1 V applied between the top and bottom electrodes.

  19. Correlation between structural and electrical properties of PLD prepared ZnO thin films used as a photodetector material

    Energy Technology Data Exchange (ETDEWEB)

    Triolo, C., E-mail: trioloc@unime.it [Dipartimento di Fisica e di Scienze della Terra, Università degli Studi di Messina, Viale F. Stagno d‘Alcontres 31, 98166, Messina (Italy); Fazio, E.; Neri, F.; Mezzasalma, A.M. [Dipartimento di Fisica e di Scienze della Terra, Università degli Studi di Messina, Viale F. Stagno d‘Alcontres 31, 98166, Messina (Italy); Trusso, S. [CNR-IPCF Istituto per i Processi Chimico-Fisici, Viale F. Stagno d’Alcontres 37, 98158, Messina (Italy); Patanè, S. [Dipartimento di Fisica e di Scienze della Terra, Università degli Studi di Messina, Viale F. Stagno d‘Alcontres 31, 98166, Messina (Italy)

    2015-12-30

    Highlights: • ZnO thin filmswere deposited by pulsed laser ablation from a metallic zinc target in a controlled oxygen atmosphere in shock wave regime. • The samples morphology is tuned, varying the growth temperature. • The transport properties were measured at RT and at 30 K under vacuumboth illuminating the sample by an UV laser and in dark conditions. • All samples are sensible to the UV radiations; the oxygen chemisorbed on the grain surface affects the speed of photoresponse. - Abstract: The electrical transport properties of a set of zinc oxide (ZnO) thin films, prepared by pulsed laser ablation, were investigated at the temperatures of 30 K and 300 K. Information about the structural and morphological properties of the samples were obtained by means of atomic force microscopy (AFM) and X-ray diffraction (XRD). A significant variation in the surface morphology and photoresponse characteristics of the ZnO thin films were observed as a function of the deposition temperature. Upon increasing the deposition temperature, the surface topography changes from a more fine-grained to a more coarse-grained structure, showing a tetragonal wurtzite crystalline structure. Time resolved photocurrent measurements showed significantly variations as function of the observed samples morphologies. A photocurrent value of about three order of magnitude larger is observed for samples showing a more coarse-grained structure with respect to the fine-grained ones. Such a result is interpreted as due to the contributions of both “bulk” and defect centers that affect the conduction mechanisms and influence both the photoconductivity values and the photoresponse speed. The observed decay times are very long with respect to films grown by other techniques, due to the reduction of the surface localized centers of defect available for recombination. In this context, the sample morphology appears to be a key parameter to control the photoconductivity in ZnO thin films.

  20. The frequency-dependent AC photoresistance behavior of ZnO thin films grown on different sapphire substrates.

    Science.gov (United States)

    Cholula-Díaz, Jorge L; Barzola-Quiquia, José; Videa, Marcelo; Yin, Chunhai; Esquinazi, Pablo

    2017-09-13

    Zinc oxide (ZnO) thin films were grown by pulsed layer deposition under an N 2 atmosphere at low pressures on a- and r-plane sapphire substrates. Structural studies using X-ray diffraction confirmed that all films had a wurtzite phase. ZnO thin films on a- and r-plane sapphire have grown with orientations along the [0002] and [112[combining macron]0] directions, respectively. Room temperature photoluminescence measurements indicate that the presence of native point defects (interstitial zinc, oxygen vacancies, oxygen antisites and zinc vacancies) is more preponderant for ZnO thin films grown on the r-plane sapphire substrate than the sample grown on the a-plane sapphire substrate. Room temperature impedance spectroscopy measurements were performed in an alternating current frequency range from 40 to 10 5 Hz in the dark and under normal light. An unusual positive photoresistance effect is observed at frequencies above 100 kHz, which we suggest to be due to intrinsic defects present in the ZnO thin films. Furthermore, an analysis of the optical time response revealed that the film grown on the r-plane sapphire substrate responds faster (characteristic relaxation times for τ 1 , τ 2 and τ 3 of 0.05, 0.26 and 6.00 min, respectively) than the film grown on the a-plane sapphire substrate (characteristic relaxation times for τ 1 , τ 2 and τ 3 of 0.10, 0.73 and 4.02 min, respectively).

  1. Effects of deposition temperature on the crystallinity of Ga-doped ZnO thin films on glass substrates prepared by sputtering method

    International Nuclear Information System (INIS)

    Park, Yu Jin; Kim, Hyuk Nyun; Shin, Hyun Ho

    2009-01-01

    The microstructural characterization of Ga-doped (5 at.%) ZnO thin film was conducted by a transmission electron microscopy study. The atomic arrangement of Ga-doped ZnO having an wurtzite structure was identified by the experimental HRTEM and Fourier filtered images as well as the electron diffractions. As a result, we have revealed that the orientation and defect density of Ga-doped ZnO thin films were greatly influenced by the deposition temperature, resulting in the variation of electrical property. In other words, the tendency forming a c-axis oriented texture grows up and the defects such as dislocations and stacking faults decrease, as the temperature of sputtering deposition increases. Consequently, the electrical properties of Ga-doped ZnO thin films can be controlled by the deposition temperature directly related with the defect density.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-15

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

  3. A ferroelectric transparent thin-film transistor

    NARCIS (Netherlands)

    Prins, MWJ; GrosseHolz, KO; Muller, G; Cillessen, JFM; Giesbers, JB; Weening, RP; Wolf, RM

    1996-01-01

    Operation is demonstrated of a field-effect transistor made of transparant oxidic thin films, showing an intrinsic memory function due to the usage of a ferroelectric insulator. The device consists of a high mobility Sb-doped n-type SnO2 semiconductor layer, PbZr0.2Ti0.8Os3 as a ferroelectric

  4. Fabrication of thin ZnO films with wide-range tuned optical properties by reactive magnetron sputtering

    Science.gov (United States)

    Davydova, A.; Tselikov, G.; Dilone, D.; Rao, K. V.; Kabashin, A. V.; Belova, L.

    2018-02-01

    We report the manufacturing of thin zinc oxide films by reactive magnetron sputtering at room temperature, and examine their structural and optical properties. We show that the partial oxygen pressure in DC mode can have dramatic effect on absorption and refractive index (RI) of the films in a broad spectral range. In particular, the change of the oxygen pressure from 7% to 5% can lead to either conventional crystalline ZnO films having low absorption and characteristic descending dependence of RI from 2.4–2.7 RIU in the visible to 1.8–2 RIU in the near-infrared (1600 nm) range, or to untypical films, composed of ZnO nano-crystals embedded into amorphous matrix, exhibiting unexpectedly high absorption in the visible–infrared region and ascending dependence of RI with values varying from 1.5 RIU in the visible to 4 RIU in the IR (1600 nm), respectively. Untypical optical characteristics in the second case are explained by defects in ZnO structure arising due to under-oxidation of ZnO crystals. We also show that the observed defect-related film structure remains stable even after annealing of films under relatively high temperatures (30 min under 450 °C). We assume that both types of films can be of importance for photovoltaic (as contact or active layers, respectively), as well as for chemical or biological sensing, optoelectronics etc.

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

    International Nuclear Information System (INIS)

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

    2011-12-01

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

  6. Praseodymium - A Competent Dopant for Luminescent Downshifting and Photocatalysis in ZnO Thin Films

    Science.gov (United States)

    Narayanan, Nripasree; Deepak, N. K.

    2018-05-01

    Highly transparent and conducting Zinc oxide (ZnO) thin films doped with Praseodymium (Pr) were deposited on glass substrates by using the spray pyrolysis method. The X-ray diffraction (XRD) analysis revealed the polycrystallinity of the deposited films with a hexagonal wurtzite structure, whereas the energy-dispersive X-ray spectroscopy (EDX) analysis confirmed the incorporation of Pr in the films. The optical energy gap decreased by Pr doping due to the merging of the conduction band with the impurity bands formed within the forbidden gap. The room temperature photoluminescence spectra of the Pr-doped film showed enhancement of visible emission, suggesting efficient luminescent downshifting. The photocatalytic activity of the Pr-doped films is higher than that of undoped films due to the effective suppression of the rapid recombination of the photo-generated electron-hole pairs. The impurity levels formed within the forbidden gap act as efficient luminescent centers and electron traps, which lead to luminescent downshifting and enhanced photocatalytic activity.

  7. Surface characterization and cathodoluminescence degradation of ZnO thin films

    Science.gov (United States)

    Hasabeldaim, E.; Ntwaeaborwa, O. M.; Kroon, R. E.; Craciun, V.; Coetsee, E.; Swart, H. C.

    2017-12-01

    ZnO thin films were successfully synthesized by the sol-gel method using the spin coater technique. The films were annealed at 600 °C in air for two hours and in Ar/H2(5%) flow for 30 and 60 min, respectively. Structural analysis, surface morphology and characterization, as well as optical analysis (photoluminescence and cathodeluminescence (CL)) were done on the samples and discussed in detail. CL degradation during prolonged electron irradiation on the films was also determined. A preferential orientation of the c-axis perpendicular to the surface was observed from X-ray diffraction data showing the peak from the (002) plane for the films annealed in both the air and in the H2 flow. The film annealed in air exhibited a broad visible emission as well as a strong ultraviolet emission. A single-green emission peak around 511 nm was obtained from the film that was annealed in Ar/H2 flow for 60 min. The CL study revealed that the intensity of the green emission (511 nm) was very stable during electron bombardment for electron doses of more than 160 C/cm2.

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

    Science.gov (United States)

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

    2016-08-23

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

  9. 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.

  10. Structural and Optical Properties of Group III Doped Hydrothermal ZnO Thin Films

    KAUST Repository

    Mughal, Asad J.

    2017-01-11

    In this work, we employ a simple two-step growth technique to deposit impurity doped heteroepitaxial thin films of (0001) ZnO onto (111) MgAl2O4 spinel substrates through a combination of atomic layer deposition (ALD) and hydrothermal growth. The hydrothermal layer is doped with Al, Ga, and In through the addition of their respective nitrate salts. We evaluated the effect that varying the concentrations of these dopants has on both the structural and optical properties of these films. It was found that the epitaxial ALD layer created a ⟨111⟩MgAl2O4∥⟨0001⟩ZnO out-of-plane orientation and a ⟨1¯1¯2⟩MgAl2O4∥∥⟨011¯0⟩ZnO in-plane orientation between the film and substrate. The rocking curve line widths ranged between 0.75° and 1.80° depending on dopant concentration. The optical bandgap determined through the Tauc method was between 3.28 eV and 3.39 eV and showed a Burstein-Moss shift with increasing dopant concentration.

  11. Bias-voltage dependent ultraviolet photodetectors prepared by GaO{sub x} + ZnO mixture phase nanocrystalline thin films

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Rongxin, E-mail: rxwang2008@sinano.ac.cn [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Yang, Lechen [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Xu, Shijie [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Department of Physics and HKU-CAS Joint Laboratory on New Materials, The University of Hong Kong, Pokfulam Road, Hong Kong (China); Zhang, Xiaodong; Dong, Xue; Zhao, Yingchun; Fu, Kai; Zhang, Baoshun; Yang, Hui [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China)

    2013-07-25

    Highlights: •GaO{sub x} + ZnO thin films sputtered and annealed exhibit interesting and unique optical properties, especially deep UV photo response. •GaO{sub x} + ZnO thin films can be used to fabricate efficient deep UV photodetectors. •The mixture phase nature of GaO{sub x} + 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 GaO{sub x} + ZnO thin films. -- Abstract: Ultraviolet (UV) photodetectors were prepared by using the GaO{sub x} + 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.

  12. Transparent conductive ZnO layers on polymer substrates: Thin film deposition and application in organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Dosmailov, M. [Institute of Applied Physics, Johannes Kepler University Linz, A-4040 Linz (Austria); Leonat, L.N. [Linz Institute for Organic Solar Cells (LIOS)/Institute of Physical Chemistry, Johannes Kepler University Linz, A-4040 Linz (Austria); Patek, J. [Institute of Applied Physics, Johannes Kepler University Linz, A-4040 Linz (Austria); Roth, D.; Bauer, P. [Institute of Experimental Physics, Johannes Kepler University Linz, A-4040 Linz (Austria); Scharber, M.C.; Sariciftci, N.S. [Linz Institute for Organic Solar Cells (LIOS)/Institute of Physical Chemistry, Johannes Kepler University Linz, A-4040 Linz (Austria); Pedarnig, J.D., E-mail: johannes.pedarnig@jku.at [Institute of Applied Physics, Johannes Kepler University Linz, A-4040 Linz (Austria)

    2015-09-30

    Aluminum doped ZnO (AZO) and pure ZnO thin films are grown on polymer substrates by pulsed-laser deposition and the optical, electrical, and structural film properties are investigated. Laser fluence, substrate temperature, and oxygen pressure are varied to obtain transparent, conductive, and stoichiometric AZO layers on polyethylene terephthalate (PET) that are free of cracks. At low fluence (1 J/cm{sup 2}) and low pressure (10{sup −3} mbar), AZO/PET samples of high optical transmission in the visible range, low electrical sheet resistance, and high figure of merit (FOM) are produced. AZO films on fluorinated ethylene propylene have low FOM. The AZO films on PET substrates are used as electron transport layer in inverted organic solar cell devices employing P3HT:PCBM as photovoltaic polymer-fullerene bulk heterojunction. - Highlights: • Aluminum doped and pure ZnO thin films are grown on polyethylene terephthalate. • Growth parameters laser fluence, temperature, and gas pressure are optimized. • AZO films on PET have high optical transmission and electrical conductance (FOM). • Organic solar cells on PET using AZO as electron transport layer are made. • Power conversion efficiency of these OSC devices is measured.

  13. 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.

  14. RETRACTED: Investigation of structural, optical and electronic properties in Al-Sn co-doped ZnO thin films

    Science.gov (United States)

    Pan, Zhanchang; Tian, Xinlong; Wu, Shoukun; Yu, Xia; Li, Zhuliang; Deng, Jianfeng; Xiao, Chumin; Hu, Guanghui; Wei, Zhigang

    2013-01-01

    This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Figures 3 and 4 of this paper have also been presented as belonging to other materials in other publications. This observation is evidence of fraud and therefore it is not certain that the described research and conclusions of this paper belong to the presented images. Figures 3 and 4 of this paper can also be found in: Effect of annealing on the structures and properties of Al and F co-doped ZnO nanostructures, Materials Science in Semiconductor Processing, 2014, 17, 162-167, http://dx.doi.org/10.1016/j.mssp.2013.09.023 Highly transparent and conductive Sn/F and Al co-doped ZnO thin films prepared by sol-gel method, Journal of Alloys and Compounds, 2014,583, 32-38, http://dx.doi.org/10.1016/j.jallcom.2013.06.192 Properties of fluorine and tin co-doped ZnO thin films deposited by sol-gel method, Journal of Alloys and Compounds, 2013,576, 31-37, http://dx.doi.org/10.1016/j.jallcom.2013.04.132

  15. Realizing luminescent downshifting in ZnO thin films by Ce doping with enhancement of photocatalytic activity

    Science.gov (United States)

    Narayanan, Nripasree; Deepak, N. K.

    2018-04-01

    ZnO thin films doped with Ce at different concentration were deposited on glass substrates by spray pyrolysis technique. XRD analysis revealed the phase purity and polycrystalline nature of the films with hexagonal wurtzite geometry and the composition analysis confirmed the incorporation of Ce in the ZnO lattice in the case of doped films. Crystalline quality and optical transmittance diminished while electrical conductivity enhanced with Ce doping. Ce doping resulted in a red-shift of optical energy gap due to the downshift of the conduction band minimum after merging with Ce related impurity bands formed below the conduction band in the forbidden gap. In the room temperature photoluminescence spectra, UV emission intensity of the doped films decreased while the intensity of the visible emission band increased drastically implying the degradation in crystallinity as well as the incorporation of defect levels capable of luminescence downshifting. Ce doping showed improvement in photocatalytic efficiency by effectively trapping the free carriers and then transferring for dye degradation. Thus Ce doped ZnO thin films are capable of acting as luminescent downshifters as well as efficient photocatalysts.

  16. 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.

  17. Temperature-dependent electrical characterization of nitrogen-doped ZnO thin film: vacuum annealing effect

    Energy Technology Data Exchange (ETDEWEB)

    Guer, Emre; Tuezemen, S; Dogan, S [Department of Physics, Faculty of Arts and Sciences, Atatuerk University, 25240 Erzurum (Turkey)], E-mail: emregur@atauni.edu.tr

    2009-03-15

    Temperature-dependent Hall effect measurements were carried out at an N-doped ZnO thin film grown by the reactive sputtering method onto (001) Si substrate before and after being vacuum annealed at 900 deg. 403{sup 1} C. p-Type ZnO thin film was obtained with a relatively high mobility of {approx}60 cm{sup 2} V {sup -} {sup 1} s {sup -} {sup 1}, a high carrier concentration of 2.5x10{sup 17} cm {sup -} {sup 3} and a low resistivity of 0.4 ohm cm. After vacuum annealing, the temperature dependence of electrical parameters such as mobility and carrier concentration showed highly different characteristics. Time-resolved photoluminescence (TRPL), PL and x-ray diffraction measurements (XRD) were performed after the annealing process to check whether the high-temperature annealing can remove the ZnO film on Si or not. The PL measurement shows band-to-band recombination at 360 nm and TRPL shows the exciton recombination lifetime to be 571.7 ps. The XRD measurement reveals highly preferred c-axis (0002) orientation. Activation energies were calculated using the ln {sigma} versus 1000 T {sup -} {sup 1} plot to be 20 meV for the as-grown and 24 and 6.8 meV after the vacuum annealing process.

  18. Effect of Al and N Doping on Structural and Optical Properties of Sol-Gel Derived ZnO Thin Films

    International Nuclear Information System (INIS)

    Bangbai, C.; Chongsri, K.; Pecharapa, W.; Techitdheera, W.

    2013-01-01

    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)

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

    Indian Academy of Sciences (India)

    et al 2008) and electrical measurements (Look and Claflin. 2004; Mohamed et al 2005). Here, we report the effects of annealing ambient on Li-related defects in ZnO films. For- mation mechanism of Li-related defects in ZnO was stud- ied by calculating formation energies of Li-related defects structure. 2. Experimental.

  20. Title: Using Alignment and 2D Network Simulations to Study Charge Transport Through Doped ZnO Nanowire Thin Film Electrodes

    KAUST Repository

    Phadke, Sujay

    2011-09-30

    Factors affecting charge transport through ZnO nanowire mat films were studied by aligning ZnO nanowires on substrates and coupling experimental measurements with 2D nanowire network simulations. Gallium doped ZnO nanowires were aligned on thermally oxidized silicon wafer by shearing a nanowire dispersion in ethanol. Sheet resistances of nanowire thin films that had current flowing parallel to nanowire alignment direction were compared to thin films that had current flowing perpendicular to nanowire alignment direction. Perpendicular devices showed ∼5 fold greater sheet resistance than parallel devices supporting the hypothesis that aligning nanowires would increase conductivity of ZnO nanowire electrodes. 2-D nanowire network simulations of thin films showed that the device sheet resistance was dominated by inter-wire contact resistance. For a given resistivity of ZnO nanowires, the thin film electrodes would have the lowest possible sheet resistance if the inter-wire contact resistance was one order of magnitude lower than the single nanowire resistance. Simulations suggest that the conductivity of such thin film devices could be further enhanced by using longer nanowires. Solution processed Gallium doped ZnO nanowires are aligned on substrates using an innovative shear coating technique. Nanowire alignment has shown improvement in ZnO nanowire transparent electrode conductivity. 2D network simulations in conjunction with electrical measurements have revealed different regimes of operation of nanowire thin films and provided a guideline for improving electrical performance of nanowire electrodes. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Thin Film growth and characterization of Ti doped ZnO by RF/DC magnetron sputtering

    KAUST Repository

    Baseer Haider, M.

    2015-01-01

    Thin film Ti doped ZnO (Ti-ZnO) film were grown on sapphire (0001) substrate by RF and DC magnetron sputtering. Films were grown at a substrate temperature of 250 °C with different Ti/Zn concentration. Surface chemical study of the samples was performed by X-ray photoelectron spectroscopy to determine the stoichiometry and Ti/Zn ratio for all samples. Surface morphology of the samples were studied by atomic force microscopy. X-ray diffraction was carried out to determine the crystallinity of the film. No secondary phases of TixOy was observed. We observed a slight increase in the lattice constant with the increase in Ti concentration in ZnO. No ferromagnetic signal was observed for any of the samples. However, some samples showed super-paramagnetic phase. © 2015 Materials Research Society.

  2. Effect of praseodymium incorporation on the structural and optical properties of ZnO thin films by RF magnetron sputtering

    International Nuclear Information System (INIS)

    Vinodkumar, R.; Navas, I.; Chalana, S.R.; Mahadevan Pillai, V.P.

    2011-01-01

    In order to study the effect of praseodymium doping, thin films of ZnO and praseodymium doped ZnO (1, 3 and 5 wt %) were prepared by RF Magnetron Sputtering and the structural and optical properties are investigated by X-ray diffraction, SEM, atomic force microscopy, UV-Visible spectroscopy and photoluminescence spectroscopy. All the films posses a hexagonal Wurtzite crystal structure with preferred orientation along (002) direction. The SEM images of the doped films show a porous structure for the films. From the PL spectra all the films shows emission in the UV and visible region. The UV emission of the near band edge is due to free exciton recombination and the other is the deep-level emission in the visible region. (author)

  3. Identifying the influence of the intrinsic defects in Gd-doped ZnO thin-films

    KAUST Repository

    Flemban, Tahani H.

    2016-02-08

    Gd-doped ZnO thin films were prepared using pulsed laser deposition at different oxygen pressures and varied Gd concentrations. The effects of oxygen deficiency-related defects on the Gd incorporation, optical and structural properties, were explored by studying the impact of oxygen pressure during deposition and post-growth thermal annealing in vacuum. Rutherford Backscattering Spectrometry revealed that the Gd concentration increases with increasing oxygen pressure for samples grown with the same Gd-doped ZnO target. Unexpectedly, the c-lattice parameter of the samples tends to decrease with increasing Gd concentration, suggesting that Gd-defect complexes play an important role in the structural properties. Using low-temperature photoluminescence(PL), Raman measurements and density functional theory calculations, we identified oxygen vacancies as the dominant intrinsic point defects. PL spectra show a defect band related to oxygen vacancies for samples grown at oxygen deficiency.

  4. Effect of Pre-Annealing on Thermal and Optical Properties of ZnO and Al-ZnO Thin Films

    Science.gov (United States)

    Saravanan, P.; Gnanavelbabu, A.; Pandiaraj, P.

    Zinc oxide (ZnO) nanoparticles were synthesized by a simple solution route method using zinc acetate as the precursor and ethanol as the solvent. At a temperature of 60∘C, a clear homogenous solution is heated to 100∘C for ethanol evaporation. Then the obtained precursor powder is annealed at 600∘C for the formation of ZnO nanocrystalline structure. Doped ZnO particle is also prepared by using aluminum nitrate nonahydrate to produce aluminum (Al)-doped nanoparticles using the same solution route method followed by annealing. Thin film fabrication is done by air evaporation method using the polymer polyvinyl alcohol (PVA). To analyze the optical and thermal properties for undoped and doped ZnO nanocrystalline thin film by precursor annealing, characterizations such as UV, FTIR, AFM, TGA/DTA, XRD, EDAX and Photoluminescence (PL) were also taken. It was evident that precursor annealing had great influence on thermal and optical properties of thin films while ZnO and AZO film showed low crystallinity and intensity than in the powder form. TGA/DTA suggests pre-annealing effect improves the thermal stability, which ensures that Al ZnO nanoparticle can withstand at high temperature too which is the crucial advantage in the semiconductor devices. UV spectroscopy confirmed the presence of ZnO nanoparticles in the thin film by an absorbance peak observed at 359nm with an energy bandgap of 3.4eV. A peak obtained at 301nm with an energy bandgap of 4.12eV shows a blue shift due to the presence of Al-doped ZnO nanoparticles. Both ZnO and AZO bandgap increased due to precursor annealing. In this research, PL spectrum is also studied in order to determine the optical property of the nanoparticle embedded thin film. From PL spectrum, it is observed that the intensity of the doped ZnO is much more enhanced as the dopant concentration is increased to 1wt.% and 2wt.% of Al in ZnO.

  5. Research Update: Atmospheric pressure spatial atomic layer deposition of ZnO thin films: Reactors, doping, and devices

    Energy Technology Data Exchange (ETDEWEB)

    Hoye, Robert L. Z., E-mail: rlzh2@cam.ac.uk, E-mail: jld35@cam.ac.uk; MacManus-Driscoll, Judith L., E-mail: rlzh2@cam.ac.uk, E-mail: jld35@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Muñoz-Rojas, David [LMGP, University Grenoble-Alpes, CNRS, F-3800 Grenoble (France); Nelson, Shelby F. [Kodak Research Laboratories, Eastman Kodak Company, Rochester, New York 14650 (United States); Illiberi, Andrea; Poodt, Paul [Holst Centre/TNO Thin Film Technology, Eindhoven, 5656 AE (Netherlands); Roozeboom, Fred [Holst Centre/TNO Thin Film Technology, Eindhoven, 5656 AE (Netherlands); Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, Eindhoven, 5600 MB (Netherlands)

    2015-04-01

    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-SALD technology will enable the commercial processing of thin films over large areas on a sheet-to-sheet and roll-to-roll basis, with new reactor designs emerging for flexible plastic and paper electronics.

  6. Research Update: Atmospheric pressure spatial atomic layer deposition of ZnO thin films: Reactors, doping, and devices

    Directory of Open Access Journals (Sweden)

    Robert L. Z. Hoye

    2015-04-01

    Full Text Available 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-SALD technology will enable the commercial processing of thin films over large areas on a sheet-to-sheet and roll-to-roll basis, with new reactor designs emerging for flexible plastic and paper electronics.

  7. A quantum chemical analysis of Zn and Sb doping and co-doping in SnO2

    Directory of Open Access Journals (Sweden)

    Luis Villamagua

    2017-10-01

    Full Text Available This work presents a quantum chemical study of Zn and Sb doping and co-doping in SnO2 carried out by a DFT+U method. The analysis has been developed by introducing three different modifications in the otherwise pure SnO2 system. In the first place, an oxygen vacancy was introduced within the crystal. Following, such a system was doped (separately by Zn or Sb impurities. Finally, the best energetic positions for both Zn and Sb atoms were simultaneously introduced within the lattice. Results of the simulations show that the confined charge that appeared due to the introduction of the oxygen vacancy interacts with the dopants atoms, being this interaction mostly responsible of the observed effects, i.e., EG shrinkage, F-centers formations, and magnetic momentum rise.

  8. Electrical properties of ZnO thin films grown by MOCVD

    International Nuclear Information System (INIS)

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

    2006-01-01

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

  9. Electrical properties of ZnO thin films grown by MOCVD

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-04-01

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

  10. Fabrication of ZnO Thin Films by Sol-Gel Spin Coating and Their UV and White-Light Emission Properties

    Science.gov (United States)

    Kumar, Mirgender; Dubey, Sarvesh; Rajendar, Vanga; Park, Si-Hyun

    2017-10-01

    ZnO thin films have been fabricated by the sol-gel spin-coating technique and annealed under different conditions, and their ultraviolet (UV) and white-light emission properties investigated. Different ambient conditions including oxygen, nitrogen, zinc-rich nitrogen, and vacuum were used to tune the main properties of the ZnO thin films. The resistivity varied from the conductive to semi-insulating regime, and the luminescence emission from fairly intense UV to polychromatic. The emission intensity was also found to be a function of the annealing conditions. Possible routes to compensate the loss of emission characteristics are discussed. X-ray photoelectron spectroscopy (XPS) analysis was carried out to detect the chemical states of the zinc/oxygen species. The changes in the electrical and emission properties are explained based on annihilation/formation of inherent donor/acceptor-type defects. Such ZnO thin films could have potential applications in solid-state lighting.

  11. Negative permittivity of ZnO thin films prepared from aluminum and gallium doped ceramics via pulsed-laser deposition

    DEFF Research Database (Denmark)

    Bodea, M. A.; Sbarcea, G.; Naik, G. V.

    2013-01-01

    Aluminum and gallium doped zinc oxide thin films with negative dielectric permittivity in the near infrared spectral range are grown by pulsed laser deposition. Composite ceramics comprising ZnO and secondary phase Al2O3 or Ga2O3 are employed as targets for laser ablation. Films deposited on glass...... from dense and small-grained ceramic targets show optical transmission larger than 70 % in the visible and reveal an onset of metallic reflectivity in the near infrared at 1100 nm and a crossover to a negative real part of the permittivity at approximately 1500 nm. In comparison to noble metals, doped...

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

    Czech Academy of Sciences Publication Activity Database

    Pauporté, T.; Rathouský, Jiří

    2007-01-01

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

  13. Study on silver doped and undoped ZnO thin films working as capacitive sensor

    Science.gov (United States)

    Kiran, S.; Kumar, N. Santhosh; Kumar, S. K. Naveen

    2013-06-01

    Nanomaterials have been found to exhibit interesting properties like good conductivity, piezoelectricity, high band gap etc. among those metal oxide family, Zinc Oxide has become a material of interest among scientific community. In this paper, we present a method of fabricating capacitive sensors, in which Silver doped ZnO and pure ZnO nanoparticles act as active layer. For the synthesis of the nanoparticle, we followed biosynthesis method and wet chemical method for Ag and Ag doped ZnO nanoparticles respectively. Characterization has been done for both the particles. The XRD pattern taken for the Ag Doped ZnO nanoparticles confirmed the average size of the particles to be 15nm. AFM image of the sample is taken by doping on Silicon wafer. Also we have presented the results of CV characteristics and IV characteristics of the capacitive sensor.

  14. Simulation, fabrication and characterization of ZnO based thin film transistors grown by radio frequency magnetron sputtering.

    Science.gov (United States)

    Singh, Shaivalini; Chakrabarti, P

    2012-03-01

    We report the performance of the thin film transistors (TFTs) using ZnO as an active channel layer grown by radio frequency (RF) magnetron sputtering technique. The bottom gate type TFT, consists of a conventional thermally grown SiO2 as gate insulator onto p-type Si substrates. The X-ray diffraction patterns reveal that the ZnO films are preferentially orientated in the (002) plane, with the c-axis perpendicular to the substrate. A typical ZnO TFT fabricated by this method exhibits saturation field effect mobility of about 0.6134 cm2/V s, an on to off ratio of 102, an off current of 2.0 x 10(-7) A, and a threshold voltage of 3.1 V at room temperature. Simulation of this TFT is also carried out by using the commercial software modeling tool ATLAS from Silvaco-International. The simulated global characteristics of the device were compared and contrasted with those measured experimentally. The experimental results are in fairly good agreement with those obtained from simulation.

  15. The Effect of Tin Addition to ZnO Nanosheet Thin Films for Ethanol and Isopropyl Alcohol Sensor Applications

    Directory of Open Access Journals (Sweden)

    Brian Yuliarto

    2015-01-01

    Full Text Available The requirements of green environmental and public health monitoring have become stricter along with greater world attention for global warming. The most common pollutants in the environment that need tightened control are volatile organic compounds (VOC. Compared to other kinds of sensors, semiconductor sensors have certain advantages, including high sensitivity, fast response, simplicity, high reliability and low cost. In this work, ZnO and Sn-doped ZnO nanostructure materials with high surface nanosheet areas were synthesized using chemical bath deposition. The X-ray diffraction patterns could be indexed according to crystallinity mainly to a hexagonal wurzite ZnO structure. The scanning electron microscopy (SEM results showed that in all samples, the thin films after the addition of Sn consisted of many kinds of microstructure patterns on a nanoscale, with various sheet shapes. The sensor performance characterizations showed that VOC levels as low as 3 vol% of isopropyl alcohol (IPA and ethanol could be detected at sensitivities of 83.86% and 85.57%, respectively. The highest sensitivity of all sensors was found at an Sn doping of 1.4 at%. This high sensor sensitivity is a result of the high surface area and Sn doping, which in turn produced a higher absorption of the targeted gas.

  16. Rectifying Behavior of Aligned ZnO Nano rods on Mg0.3Zn0.7O Thin Film Template

    International Nuclear Information System (INIS)

    Salina Muhamad; Suriani Abu Bakar; Mohamad Hafiz Mamat; Rafidah Ahmad; Mohamad Rusop

    2011-01-01

    Rectifying behavior more than 3 orders of aligned zinc oxide (ZnO) nano rods grown on Mg 0.3 Zn 0.7 O thin film template using chemical bath deposition method was observed, giving a barrier height of 0.75 eV, and the ideality factor achieved was almost 6, which was analyzed using thermionic emission theory. Field emission scanning electron microscope (FESEM) images revealed that the grown ZnO was in hexagonal shape, uniformly distributed and in vertically aligned form. The crystallinity of the sample being studied using X-ray diffraction (XRD), where the highest peak was found at (002) phase, confirming that high crystallinity of ZnO was attained. The effect of metal/semiconductor junction between metal and aligned ZnO nano rods was discussed in further details. (author)

  17. Influence of Mg content on tailoring optical bandgap of Mg-doped ZnO thin film prepared by sol-gel method

    Directory of Open Access Journals (Sweden)

    M.N.H. Mia

    Full Text Available Tailoring optical bandgap of ZnO nanostructured thin films doped with different elements facilitates potential material for photonic applications. Different methods of fabrication process result in different optical and structural properties for the same amount of Mg content. Therefore, details investigation of structural and optical parameters, and their correlation need to be revealed to utilize the fabricated thin films. In this work, Mg-doped ZnO thin film of 200 nm thickness was fabricated by sol-gel spin coating method on a glass substrate for four different Mg content levels. Multiple layers were deposited by a spin coater to increase the film thickness. The prepared thin films were characterized by SEM, XRD, EDS, and UV–Vis spectroscopy. The spectroscopic analysis showed a uniform crystalline nanostructured surface with less structural defects, enhanced transmittance, and higher optical bandgap than that of pure ZnO nanostructured thin film. Change of Mg content from 2% to 8% facilitated tuning of bandgap in the range of 3.30–3.39 eV. Changing trend of structural and optical parameters with Mg content showed non-linear, non-monotonic relation. In-depth analysis of structural and optical properties provides crucial information to form a better view about bandgap dependency on structural parameters. Keywords: Mg-doped ZnO, MgZnO, Bandgap tuning, Sol-gel, Spin coating

  18. Resistive switching: An investigation of the bipolar–unipolar transition in Co-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Daniel A.A., E-mail: danielandrade.ufs@gmail.com [Department of Physics, Federal University of Sergipe, São Cristóvão 49100-000 (Brazil); Department of Physics, University at Buffalo, The State University of New York, Buffalo, NY 14260 (United States); Zeng, Hao [Department of Physics, University at Buffalo, The State University of New York, Buffalo, NY 14260 (United States); Macêdo, Marcelo A. [Department of Physics, Federal University of Sergipe, São Cristóvão 49100-000 (Brazil)

    2015-06-15

    Highlights: • A purely bipolar behavior on a Co-doped ZnO thin film has been demonstrated. • We have shown what can happen if a unipolar test is performed in a purely bipolar device. • An explanation for how a sample can show a purely bipolar switching behavior was suggested. • An important open issue about resistive switching effect was put in debate. - Abstract: In order to investigate the resistive switching effect we built devices in a planar structure in which two Al contacts were deposited on the top of the film and separated by a small gap using a shadow mask. Therefore, two samples of 10% Co-doped ZnO thin films were sputtered on glass substrate. High resolution X-ray diffraction (HRXRD) revealed a highly c-axis oriented crystalline structure, without secondary phase. The high resolution scanning electron microscopy (HRSEM) showed a flat surface with good coverage and thickness about 300 nm. A Keithley 2425 semiconductor characterization system was used to perform the resistive switching tests in the bipolar and unipolar modes. Considering only the effect of compliance current (CC), the devices showed a purely bipolar behavior since an increase in CC did not induce a transition to unipolar behavior.

  19. Area-Selective ZnO Thin Film Deposition on Variable Microgap Electrodes and Their Impact on UV Sensing

    Directory of Open Access Journals (Sweden)

    Q. Humayun

    2013-01-01

    Full Text Available ZnO thin films were deposited on patterned gold electrodes using the sol-gel spin coating technique. Conventional photolithography process was used to obtain the variable microgaps of 30 and 43 μm in butterfly topology by using zero-gap chrome mask. The structural, morphological, and electrical properties of the deposited thin films were characterized by X-ray diffraction (XRD, scanning electron microscope (SEM, and Keithley SourceMeter, respectively. The current-voltage (I-V characterization was performed to investigate the effect of UV light on the fabricated devices. The ZnO fabricated sensors showed a photo to dark current (Iph/Id ratios of 6.26 for 30 μm and 5.28 for 43 μm gap electrodes spacing, respectively. Dynamic responses of both fabricated sensors were observed till 1V with good reproducibility. At the applied voltage of 1 V, the response time was observed to be 4.817 s and 3.704 s while the recovery time was observed to be 0.3738 s and 0.2891 s for 30 and 43 μm gaps, respectively. The signal detection at low operating voltages suggested that the fabricated sensors could be used for miniaturized devices with low power consumption.

  20. Photoluminescence and electrochemical properties of transparent CeO2-ZnO nanocomposite thin films prepared by Pechini method

    Science.gov (United States)

    Sani, Z. Khosousi; Ghodsi, F. E.; Mazloom, J.

    2017-02-01

    Nanocomposite thin films of CeO2-ZnO with different molar ratios of Zn/Ce (=0, 0.25, 0.5, 0.75 and 1) were prepared by the Pechini sol-gel route. Various spectroscopic and electrochemical techniques were applied to investigate the films. XRD patterns of all the samples exhibited the peaks corresponding to cubic fluorite structure of ceria and the (101) and (103) peaks of ZnO with hexagonal structure was just observed in the sample with molar ratio of 1. EDS confirmed the presence of constituent of element in the samples. FESEM images of the films showed a surface composed of nanograins. AFM analysis revealed that root mean square roughness was enhanced as molar ratio of Zn/Ce increased. Moreover, fractal dimension of surfaces were calculated by cube counting approach. Optical measurements indicated that the film with molar ratio of 1 has the highest transmission and lowest reflectivity. The optical band gap values varied between 2.95 and 3.42 eV. The compositional dependence of refractive index and extinction coefficient were reported. The UV and blue emission appeared in PL spectra. The highest photoluminescence emission intensity was observed in the 1:1 molar ratio sample. The cyclic voltammetry measurements indicated the highest charge density (9.75 mC cm-2) and diffusion coefficient (3.507 × 10-17 cm2 s-1) belonged to the Ce/Zn (1:1) thin film.

  1. 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.

  2. Effect of thermal annealing on properties of polycrystalline ZnO thin films

    Science.gov (United States)

    Gritsenko, L. V.; Abdullin, Kh. A.; Gabdullin, M. T.; Kalkozova, Zh. K.; Kumekov, S. E.; Mukash, Zh. O.; Sazonov, A. Yu.; Terukov, E. I.

    2017-01-01

    Electrical properties (density, carriers mobility, resistivity), optical absorption and photoluminescence spectra of ZnO, grown by MOCVD and hydrothermal methods, have been investigated depending on the annealing and treatment modes in a hydrogen plasma. It has been shown that the electrical and photoluminescent (PL) properties of ZnO are strongly dependent on gas atmosphere during annealing. The annealing in oxygen atmosphere causes a sharp drop of carrier mobility and films conductivity due to the absorption of oxygen on grain boundaries. The process of ZnO electrical properties recovery by the thermal annealing in inert atmosphere (nitrogen), in oil (2×10-2 mbar) and oil-free (1×10-5 mbar) vacuum has been investigated. The hydrogen plasma treatment influence on the intensity of near-band-gap emission (NBE) has been studied. The effect of annealing and subsequent plasma treatment on PL intensity depends on the gas atmosphere of preliminary thermal annealing.

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

    KAUST Repository

    Alshammari, Fwzah Hamud

    2016-08-24

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

  4. Structural, electrical and magnetic properties of Sb-doped Pr2/3Ba1/3MnO3 perovskite manganites

    International Nuclear Information System (INIS)

    Sen, Vikram; Panwar, Neeraj; Bhalla, G.L.; Agarwal, S.K.

    2007-01-01

    We report here the electrical, magnetic and micro-structural features of the Sb-doped (nominally at Mn-sites) Pr 2/3 Ba 1/3 MnO 3 perovskite manganites. Pristine material shows two insulator-metal (I-M) like transitions in the resistivity-temperature (ρ-T) behaviour. While the higher temperature transition (T P1 ) at ∼195 K is reminiscent of the usual metal-insulator transition, the lower temperature transition (T P2 ) at ∼160 K has been ascribed to the grain boundary (GB) effects arising out of the ionic size mismatch between the ions present at the rare-earth site (Pr and Ba). With Sb doping at the Mn-site, both the resistivity peaks are seen to shift to lower temperatures. Room temperature resistivity and the peak values are also successively increasing with Sb doping. Scanning electron micrographs of the samples indicate a gradual increase in their grain sizes with Sb which indicates a gradual decrease in the GB density. The higher temperature insulator-metal transition (T P1 ) shift is explained on the basis of a competition between double-exchange and super-exchange mechanisms. The observed overall resistivity increase and the shift in the resistivity hump (T P2 ) with Sb are found related to the gradually decreasing GB density and the ensuing lattice strain increase at the grain boundaries. The intrinsic MR gets suppressed and the extrinsic MR gets enhanced with Sb doping. The observed low temperature resistivity upturn related to the localization of carriers, is also seen to increase with Sb

  5. Structural, Optical Constants and Photoluminescence of ZnO Thin Films Grown by Sol-Gel Spin Coating

    Directory of Open Access Journals (Sweden)

    Abdel-Sattar Gadallah

    2013-01-01

    Full Text Available We report manufacturing and characterization of low cost ZnO thin films grown on glass substrates by sol-gel spin coating method. For structural properties, X-ray diffraction measurements have been utilized for evaluating the dominant orientation of the thin films. For optical properties, reflectance and transmittance spectrophotometric measurements have been done in the spectral range from 350 nm to 2000 nm. The transmittance of the prepared thin films is 92.4% and 88.4%. Determination of the optical constants such as refractive index, absorption coefficient, and dielectric constant in this wavelength range has been evaluated. Further, normal dispersion of the refractive index has been analyzed in terms of single oscillator model of free carrier absorption to estimate the dispersion and oscillation energy. The lattice dielectric constant and the ratio of free carrier concentration to free carrier effective mass have been determined. Moreover, photoluminescence measurements of the thin films in the spectral range from 350 nm to 900 nm have been presented. Electrical measurements for resistivity evaluation of the films have been done. An analysis in terms of order-disorder of the material has been presented to provide more consistency in the results.

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

    Indian Academy of Sciences (India)

    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 ...

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

    Indian Academy of Sciences (India)

    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 ...

  8. Thickness dependence of structural, electrical and optical behaviour of undoped ZnO thin films

    Czech Academy of Sciences Publication Activity Database

    Bouderbala, M.; Hamzaoui, S.; Amrani, B.; Reshak, Ali H; Adnane, M.; Sahraoui, T.; Zerdali, M.

    2008-01-01

    Roč. 403, č. 18 (2008), s. 3326-3330 ISSN 0921-4526 Institutional research plan: CEZ:AV0Z60870520 Keywords : thickness effect * structural and optical properties * hall effect * ZnO Subject RIV: BO - Biophysics Impact factor: 0.822, year: 2008

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

    Indian Academy of Sciences (India)

    Administrator

    ties were measured using four-probe Hall measurement set-up in Van der Pauw geometry with a magnetic field of. 0⋅50 Tesla. 3. Results and discussion. 3.1 Structural properties. Figure 1(a) demonstrated the variation of XRD spectra from ZnO films for different annealing temperatures. It should be mentioned at this point ...

  10. A method for electrochemical growth of homogeneous nanocrystalline ZnO thin films at room temperature

    Czech Academy of Sciences Publication Activity Database

    Pauporté, T.; Jirka, Ivan

    2009-01-01

    Roč. 54, č. 28 (2009), s. 7558-7564 ISSN 0013-4686 R&D Projects: GA AV ČR IAA400400909 Institutional research plan: CEZ:AV0Z40400503 Keywords : electrodeposition * ZnO * room temperature * photoluminiscence Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.325, year: 2009

  11. Determination of electrical types in the P-doped ZnO thin films by the control of ambient gas flow

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Yi; Han, Won Suk [School of Advanced Materials Science and Engineering, Sungkyunkwan University, 300 Cheoncheon-dong, Jangan-gu, Suwon, Gyeonggi-do 440-746 (Korea, Republic of); Cho, Hyung Koun, E-mail: chohk@skku.edu [School of Advanced Materials Science and Engineering, Sungkyunkwan University, 300 Cheoncheon-dong, Jangan-gu, Suwon, Gyeonggi-do 440-746 (Korea, Republic of)

    2010-05-01

    Phosphorus (P)-doped ZnO thin films with amphoteric doping behavior were grown on c-sapphire substrates by radio frequency magnetron sputtering with various argon/oxygen gas ratios. Control of the electrical types in the P-doped ZnO films was achieved by varying the gas ratio without post-annealing. The P-doped ZnO films grown at a argon/oxygen ratio of 3/1 showed p-type conductivity with a hole concentration and hole mobility of 1.5 x 10{sup 17} cm{sup -3} and 2.5 cm{sup 2}/V s, respectively. X-ray diffraction showed that the ZnO (0 0 0 2) peak shifted to lower angle due to the positioning of P{sup 3-} ions with a larger ionic radius in the O{sup 2-} sites. This indicates that a p-type mechanism was due to the substitutional P{sub O}. The low-temperature photoluminescence of the p-type ZnO films showed p-type related neutral acceptor-bound exciton emission. The p-ZnO/n-Si heterojunction light emitting diode showed typical rectification behavior, which confirmed the p-type characteristics of the ZnO films in the as-deposited status, despite the deep-level related electroluminescence emission.

  12. A study of Eu incorporated ZnO thin films: An application of Al/ZnO:Eu/p-Si heterojunction diode

    Energy Technology Data Exchange (ETDEWEB)

    Turgut, G. [Department of Basic Sciences, Faculty of Science, Erzurum Technical University, Erzurum, 25240 (Turkey); Duman, S., E-mail: sduman@atauni.edu.tr [Department of Physics, Faculty of Science, Ataturk University, Erzurum, 25240 (Turkey); Sonmez, E. [Department of Physics, Faculty of K.K. Education, Ataturk University, Erzurum, 25240 (Turkey); Ozcelik, F.S. [Department of Physics, Faculty of Science, Ataturk University, Erzurum, 25240 (Turkey)

    2016-04-15

    Highlights: • Eu incorporated ZnO thin films were grown by sol–gel spin coating. • The influence of Eu contribution on features of ZnO was investigated. • Al/ZnO:Eu/p-Si heterojunction diodes were also fabricated. • The diode parameters were calculated from I–V measurements. - Abstract: In present work, the pure and europium (Eu) incorporated zinc oxide (ZnO) thin films were deposited with sol-gel spin coating by using zinc acetate dehydrate and Eu (III) chloride salts. The coated films were examined by means of XRD, AFM and UV/VIS spectrophotometer. The ZnO hexagonal wurtzite nanoparticles with (002) preferential direction were observed for all films. The values of crystallite size, micro-strain and surface roughness continuously increased from 21 nm, 1.10 × 10{sup −3} and 2.43 nm to the values of 35.56 nm, 1.98 × 10{sup −3} and 28.99 nm with Eu doping, respectively. The optical band gap value of the pure ZnO initially increased from 3.296 eV to 3.328 eV with Eu doping up to 2 at.% doping level, then it started to decrease with more Eu content. The electrical features of Al/n-ZnO:Eu/p-Si heterojunction diodes were inquired by current-voltage (I–V) measurements at the room temperature.

  13. Structural and magnetic properties of Co-doped ZnO thin films grown by ultrasonic spray pyrolysis method

    Science.gov (United States)

    Baghdad, R.; Lemée, N.; Lamura, G.; Zeinert, A.; Hadj-Zoubir, N.; Bousmaha, M.; Bezzerrouk, M. A.; Bouyanfif, H.; Allouche, B.; Zellama, K.

    2017-04-01

    Cobalt-doped ZnO thin films with several different percentage of Co from 0 up to 15 at% were synthesized via a cheap, simple and versatile method i.e. ultrasonic spray pyrolysis at atmospheric pressure and a substrate temperature of 350 °C. The structure of the as-prepared samples was characterized by X-ray diffraction (XRD), Raman spectroscopy and FTIR. The Co-doping effect is revealed by the presence of three additional peaks around 235, 470 and 538 cm-1 respect to the Raman spectra of the unsubstituted film. Fourier transform infrared spectroscopy (FTIR) put in evidence the decrease of the bond force constant f with increasing Co-doping. By ultra-violet visible near infrared (UV-Vis-NIR) spectroscopy on Co-doped samples it was possible to show the presence of additional absorption bands at approximately 570, 620 and 660 nm suggesting that Co2+ ions do not change their oxidation when substituted to zinc and the ZnO lattice does not change its wurtzite structure as well. Finally, all our samples exhibit a paramagnetic behavior without any trace of intrinsic room temperature ferromagnetism.

  14. Development of Room Temperature Excitonic Lasing From ZnO and MgZnO Thin Film Based Metal-Semiconductor-Metal Devices

    Science.gov (United States)

    Suja, Mohammad Zahir Uddin

    Room temperature excitonic lasing is demonstrated and developed by utilizing metal-semiconductor-metal devices based on ZnO and MgZnO materials. At first, Cu-doped p-type ZnO films are grown on c-sapphire substrates by plasma-assisted molecular beam epitaxy. Photoluminescence (PL) experiments reveal a shallow acceptor state at 0.15 eV above the valence band edge. Hall effect results indicate that a growth condition window is found for the formation of p-type ZnO thin films and the best conductivity is achieved with a high hole concentration of 1.54x1018 cm-3, a low resistivity of 0.6 O cm and a moderate mobility of 6.65 cm2 V -1 s-1 at room temperature. Metal oxide semiconductor (MOS) capacitor devices have been fabricated on the Cu-doped ZnO films and the characteristics of capacitance-voltage measurements demonstrate that the Cu-doped ZnO thin films under proper growth conditions are p-type. Seebeck measurements on these Cu-doped ZnO samples lead to positive Seebeck coefficients and further confirm the p-type conductivity. Other measurements such as XRD, XPS, Raman and absorption are also performed to elucidate the structural and optical characteristics of the Cu-doped p-type ZnO films. The p-type conductivity is explained to originate from Cu substitution of Zn with a valency of +1 state. However, all p-type samples are converted to n-type over time, which is mostly due to the carrier compensation from extrinsic defects of ZnO. To overcome the stability issue of p-type ZnO film, alternate devices other than p-n junction has been developed. Electrically driven plasmon-exciton coupled random lasing is demonstrated by incorporating Ag nanoparticles on Cu-doped ZnO metal-semiconductor-metal (MSM) devices. Both photoluminescence and electroluminescence studies show that emission efficiencies have been enhanced significantly due to coupling between ZnO excitons and Ag surface plasmons. With the incorporation of Ag nanoparticles on ZnO MSM structures, internal quantum

  15. A comparison of different spray chemical vapour deposition methods for the production of undoped ZnO thin films

    International Nuclear Information System (INIS)

    Garnier, Jerome; Bouteville, Anne; Hamilton, Jeff; Pemble, Martyn E.; Povey, Ian M.

    2009-01-01

    Two different methods of spray chemical vapour deposition have been used to grow ZnO thin films on glass substrates from zinc acetate solution over the temperature range 400 o C to 550 o C. The first of these is named InfraRed Assisted Spray Chemical Vapour Deposition (IRAS-CVD). This method uses intense IR radiation to heat not only the substrate but also the gaseous species entering the reactor. The second method is a more conventional approach known simply as ultrasonic spray CVD, which utilises IR lamps to heat the substrate only. By way of comparing these two approaches we present data obtained from contact angle measurements, crystallinity and mean crystallite size, photoluminescence, electrical and optical properties. Additionally we have examined the role of annealing within the IRAS-CVD reactor environment.

  16. Effect of deposition conditions on the growth rate and electrical properties of ZnO thin films grown by MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    Roro, K.T.; Botha, J.R.; Leitch, A.W.R. [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa)

    2008-07-01

    ZnO thin films have been grown on glass substrates by MOCVD. The effect of deposition conditions such as VI/II molar ratio, DEZn flow rate and total reactor pressure on the growth rate and electrical properties of the films was studied. It is found that the growth rate decreases with an increase in the VI/II molar ratio. This behaviour is ascribed to the competitive adsorption of reactant species on the growth surface. The growth rate increases with an increase in DEZn flow rate, as expected. It is shown that the carrier concentration is independent of the DEZn flow rate. An increase in the total reactor pressure yields a decrease in growth rate. This phenomenon is attributed to the depletion of the gas phase due to parasitic prereactions between zinc and oxygen species at high pressure. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Optical and structural properties of ZnO thin films; effects of high energy electron irradiation and annealing

    International Nuclear Information System (INIS)

    Guer, Emre; Asil, Hatice; Coskun, C.; Tuezemen, S.; Meral, Kadem; Onganer, Y.; Serifoglu, Korkmaz

    2008-01-01

    High energy electron irradiation (HEEI) effects on the as-grown and annealed ZnO thin films grown by electrochemical deposition were investigated. Both samples were exposed to the sequential electron irradiations of 6, 12 and 15 MeV energies at a fluence of 1 x 10 12 e - /cm 2 . The results of X-ray diffraction suggest that a highly strong crystallographic structure can be produced by annealing process. Photoluminescence (PL) studies show that the EI produces violet emission which results from the zinc interstitial. Recombination lifetime (RL) values of the both films reveal that the high quality crystals are obtained. The decreasing trends of RL values with increasing electron energy have been explained by the formation of crystal defects due to the HEEI

  18. Optical and structural properties of ZnO thin films; effects of high energy electron irradiation and annealing

    Energy Technology Data Exchange (ETDEWEB)

    Guer, Emre; Asil, Hatice [Atatuerk University, Art and Science Faculty, Physics Department, 25240 Erzurum (Turkey); Coskun, C. [Atatuerk University, Art and Science Faculty, Physics Department, 25240 Erzurum (Turkey)], E-mail: ccoskun@atauni.edu.tr; Tuezemen, S. [Atatuerk University, Art and Science Faculty, Physics Department, 25240 Erzurum (Turkey); Meral, Kadem; Onganer, Y. [Atatuerk University, Art and Science Faculty, Chemistry Department, 25240 Erzurum (Turkey); Serifoglu, Korkmaz [Atatuerk University, Faculty of Medicine, Radiation Oncology Department, 25240 Erzurum (Turkey)

    2008-05-15

    High energy electron irradiation (HEEI) effects on the as-grown and annealed ZnO thin films grown by electrochemical deposition were investigated. Both samples were exposed to the sequential electron irradiations of 6, 12 and 15 MeV energies at a fluence of 1 x 10{sup 12} e{sup -}/cm{sup 2}. The results of X-ray diffraction suggest that a highly strong crystallographic structure can be produced by annealing process. Photoluminescence (PL) studies show that the EI produces violet emission which results from the zinc interstitial. Recombination lifetime (RL) values of the both films reveal that the high quality crystals are obtained. The decreasing trends of RL values with increasing electron energy have been explained by the formation of crystal defects due to the HEEI.

  19. ZnO thin film characterization by X-ray reflectivity optimization using genetic algorithm and Fourier transformation

    International Nuclear Information System (INIS)

    Solookinejad, Ghahraman; Rozatian, Amir Sayid Hassan; Habibi, Mohammad Hossein

    2011-01-01

    Zinc oxide (ZnO) thin film was fabricated by sol-gel spin coating method on glass substrate. X-ray reflectivity (XRR) and its optimization have been used for characterization and extracting physical parameters of the film. Genetic algorithm (GA) has been applied for this optimization process. The model independent information was needed to establish data analyzing process for X-ray reflectivity before optimization process. Independent information was exploited from Fourier transform of Fresnel reflectivity normalized X-ray reflectivity. This Fourier transformation (Auto Correlation Function) yields thickness of each coated layer on substrate. This information is a keynote for constructing optimization process. Specular X-ray reflectivity optimization yields structural parameters such as thickness, roughness of surface and interface and electron density profile of the film. Acceptable agreement exists between results obtained from Fourier transformation and X-ray reflectivity fitting.

  20. Influence of baking method and baking temperature on the optical properties of ZnO thin films

    International Nuclear Information System (INIS)

    Ng, Zi-Neng; Chan, Kah-Yoong

    2015-01-01

    In this work, sol-gel spin coating technique was utilised to coat ZnO thin films on glass substrates. During the intermediate 3 minutes baking process, either hotplate or convection oven was employed to bake the samples. The temperature for the baking process was varied from 150°C to 300°C for both instruments. Avantes Optical Spectrophotometer was used to characterise the optical property. The optical transmittances of hotplate-baked and oven-baked samples showed different trends with increasing baking temperatures, ranging from below 50% transmittance to over 90% transmittance in the visible range of wavelength. The difference in baking mechanisms using hotplate and convection oven will be discussed in this paper

  1. p-Channel and n-Channel Thin-Film-Transistor Operation on Sprayed ZnO Nanoparticle Layers

    Directory of Open Access Journals (Sweden)

    Daiki Itohara

    2016-01-01

    Full Text Available Both n-channel and p-channel thin-film transistors have been realized on ZnO nanoparticle (NP layers sprayed onto quartz substrates. In this study, nitrogen-doped ZnO-NPs were synthesized using an arc-discharge-mediated gas-evaporation method that was recently developed. Sprayed NP layers were characterized by scanning electron microscopy and Hall effect measurements. It was confirmed that p-type behaving NP layers can be obtained using ZnO-NPs synthesized with lower chamber pressure, whereas n-type conductivity can be obtained with higher chamber pressure. pn-junction diodes were also tested, resulting in clear rectifying characteristics. The possibility of particle-process-based ZnO-NP electronics was confirmed.

  2. Photocatalytic Activity and Stability of Porous Polycrystalline ZnO Thin-Films Grown via a Two-Step Thermal Oxidation Process

    Directory of Open Access Journals (Sweden)

    James C. Moore

    2014-08-01

    Full Text Available The photocatalytic activity and stability of thin, polycrystalline ZnO films was studied. The oxidative degradation of organic compounds at the ZnO surface results from the ultraviolet (UV photo-induced creation of highly oxidizing holes and reducing electrons, which combine with surface water to form hydroxyl radicals and reactive oxygen species. Therefore, the efficiency of the electron-hole pair formation is of critical importance for self-cleaning and antimicrobial applications with these metal-oxide catalyst systems. In this study, ZnO thin films were fabricated on sapphire substrates via direct current sputter deposition of Zn-metal films followed by thermal oxidation at several annealing temperatures (300–1200 °C. Due to the ease with which they can be recovered, stabilized films are preferable to nanoparticles or colloidal suspensions for some applications. Characterization of the resulting ZnO thin films through atomic force microscopy and photoluminescence indicated that decreasing annealing temperature leads to smaller crystal grain size and increased UV excitonic emission. The photocatalytic activities were characterized by UV-visible absorption measurements of Rhodamine B dye concentrations. The films oxidized at lower annealing temperatures exhibited higher photocatalytic activity, which is attributed to the increased optical quality. Photocatalytic activity was also found to depend on film thickness, with lower activity observed for thinner films. Decreasing activity with use was found to be the result of decreasing film thickness due to surface etching.

  3. Impact of nanostructured thin ZnO film in ultraviolet protection

    OpenAIRE

    Sasani Ghamsari, Morteza; Alamdari, Sanaz; Han, Wooje; Park, Hyung-Ho

    2016-01-01

    Morteza Sasani Ghamsari,1 Sanaz Alamdari,1 Wooje Han,2 Hyung-Ho Park2 1Laser and Optics Research School, Nuclear Science and Technology Research Institute, Tehran, Iran; 2Department of Materials Science and Engineering, Yonsei University, Seoul, South Korea Abstract: Nanoscale ZnO is one of the best choices for ultraviolet (UV) protection, not only because of its antimicrobial properties but also due to its potential application for UV preservation. However, the behavior of nanostructured t...

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

    Indian Academy of Sciences (India)

    pH measurement was carried out in a systronics pH meter. (Model 335). Cadmium doping was carried out by adding cadmium chloride (CdCl2·H2O, GR grade, Loba Chemie, mol. wt 201·32) in sodium zincate bath. Details of pure ZnO film deposition process from sodium or ammonium zincate bath has been reported earlier.

  5. Influence of Different Annealing Conditions on Optical and Electrical Properties of Sn Doped ZnO Thin Films

    Directory of Open Access Journals (Sweden)

    LIU Tao

    2017-08-01

    Full Text Available Sn doped ZnO thin films(SZO was prepared on glasses by sol-gel method.The influence of six kinds of annealing conditions,including air annealing,low vacuum annealing,high vacuum annealing,N2 annealing,triple high vacuum annealing,cycle annealing on the crystal structure, optical and electrical properties of the SZO film was studied.The results show that all the SZO samples show preferential orientation along the c-axis.The SZO thin films has the optimum crystal structure and electrical property on the high vacuum annealing conditions.The minimum resistivity of the film is 5.4×10-2Ω·cm.The average visible transmittance of SZO thin film is above 85%.The photoluminescence peaks at 390nm and 440nm is observed in all the samples (the excitation wavelength is set at 325nm.The intensity of the peak at 440nm is enhanced significantly on air annealing,N2 annealing and low vacuum annealing.

  6. X-ray photoelectron spectroscopy study and thermoelectric properties of Al-doped ZnO thin films

    International Nuclear Information System (INIS)

    Li Li; Fang Liang; Zhou Xianju; Liu Ziyi; Zhao Liang; Jiang Sha

    2009-01-01

    In this paper, high quality Al-doped ZnO (AZO) thin films were prepared by direct current (DC) reactive magnetron sputtering using a Zn target (99.99%) containing Al of 1.5 wt.%. The films obtained were characterized by X-ray photoelectron spectroscopy (XPS) and thermoelectric measurements. The XPS results reveal that Zn and Al exist only in oxidized state, while there are dominant crystal lattice and rare adsorbed oxygen for O in the annealed AZO thin films. The studies of thermoelectric property show a striking thermoelectric effect in the AZO thin films. On the one hand, the thermoelectromotive and magnetothermoelectromotive forces increase linearly with increasing temperature difference (ΔT). On the other hand, the thermoelectric power (TEP) decreases with the electrical resistance of the sample. But the TEP increases with the increase of temperature below 300 K, and it nearly does not change around room temperature. The experimental results also demonstrate that the annealing treatment increases TEP, while the external magnetic field degrades TEP.

  7. The electrical, elemental, optical, and surface properties of Si-doped ZnO thin films prepared by thermionic vacuum arc

    Science.gov (United States)

    Mohammadigharehbagh, Reza; Özen, Soner; Yudar, Hafizittin Hakan; Pat, Suat; Korkmaz, Şadan

    2017-09-01

    The purpose of this work is to study the properties of Si-doped ZnO (SZO) thin films, which were prepared using the non-reactive thermionic vacuum arc technique. The analysis of the elemental, optical, and surface properties of ZnO:Si thin films was carried out using energy dispersive x-ray spectroscopy, UV-VIS spectrophotometry, atomic force microscopy, and scanning electron microscopy, respectively. The current-voltage measurement was employed in order to study the electrical properties of the films. The effect of Si doping on the physical properties of ZnO films was investigated. The film thicknesses were measured as 55 and 35 nm for glass and PET substrates, respectively. It was clearly observed from the x-ray diffraction results that the Si and ZnO peaks were present in the coated SZO films for all samples. The morphological studies showed that the deposited surfaces are homogenous, dense, and have a uniform surface, with the existence of some cracks only on the glass substrate. The elemental composition has confirmed the existence of Zn, Si, and O elements within the prepared films. Using a UV-VIS spectrophotometer, the optical parameters such as transmittance, absorbance, refractive index, and reflectance were calculated. It should be noted that the transparency and refractive indices obtained from the measurements decrease with increasing Si concentration. The obtained optical bandgap values using transmittance spectra were determined to be 3.74 and 3.84 eV for the glass and PET substrates, respectively. An increase in the bandgap results demonstrates that the Si doping concentration is comparable to the pure ZnO thin films. The current versus voltage curves revealed the ohmic nature of the films. Subsequently, the development and fabrication of excellent transparent conducting electrodes enabled the appropriate use of Si-doped ZnO thin films.

  8. Fabrication of undoped ZnO thin film via photosensitive sol–gel method and its applications for an electron transport layer of organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Luong, Chi Hieu [Department of Materials Science and Engineering and Graduate School of Energy Science and Technology, Chungnam National University, Yuseong-gu, Daejeon 305-764 (Korea, Republic of); Kim, Sarah [Central Research Division, LG Chem., Yuseong-gu, Daejeon 305-738 (Korea, Republic of); Surabhi, Srivathsava; Vo, Thanh Son; Lee, Kyung-Min; Yoon, Soon-Gil [Department of Materials Science and Engineering and Graduate School of Energy Science and Technology, Chungnam National University, Yuseong-gu, Daejeon 305-764 (Korea, Republic of); Jeong, Jun-Ho [Nanomechanical Systems Research Division, Korea Institute of Machinery and Materials, Yuseong-gu, Daejeon 305-343 (Korea, Republic of); Choi, Jun-Hyuk, E-mail: junhyuk@kimm.re.kr [Nanomechanical Systems Research Division, Korea Institute of Machinery and Materials, Yuseong-gu, Daejeon 305-343 (Korea, Republic of); Jeong, Jong-Ryul, E-mail: jrjeong@cnu.ac.kr [Department of Materials Science and Engineering and Graduate School of Energy Science and Technology, Chungnam National University, Yuseong-gu, Daejeon 305-764 (Korea, Republic of)

    2015-10-01

    Highlights: • Investigated the effect of the interfacial ZnO for ETL synthesized by photochemical reaction using photosensitive 2-nitrobenzaldehyde on the inverted P3HT:PCBM OSC. • The abrupt increase of grain size and surface roughness was observed as increasing the annealing temperature above 350 °C. • The sheet resistance abruptly decreased with increasing the annealing temperature above 350 °C. • Increase of surface roughness caused by the high annealing temperature could be detrimental to the OSCs characteristics due to a high contact resistance and a large leakage current. - Abstract: We have investigated ZnO thin films prepared via photochemical reaction as the electron transport layer (ETL) of inverted organic solar cells (OSCs). Morphological and electrical properties of the ZnO thin films prepared by the photosensitive ZnO sol were studied according to the annealing temperature and their effects on the performance of the inverted poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester (P3HT:PCBM) OSCs was characterized. It was found that the optimal annealing temperature of the ZnO thin films was 330 °C, and that devices with the ZnO ETL annealed at this temperature exhibited the largest short-circuit current density (J{sub sc}) of 9.39 mA/cm{sup 2}, as well as the highest power conversion efficiency (PCE) of 2.31%, which can be attributed to enhanced electron transport and interfacial properties. Devices containing ZnO films formed at optimal annealing condition exhibited an open circuit voltage (V{sub oc}) of 0.60 V and a fill factor (FF) of 41.0%. However, further increase of the annealing temperature led to degradation of the device performance, despite further improvements in electrical properties. We have found that marked increase in the surface roughness of the ZnO films occurred at temperatures above 350 °C which could be detrimental to the OSCs characteristics due to a high contact resistance and a large leakage current.

  9. UV and visible photoluminescence emission intensity of undoped and In-doped ZnO thin film and photoresponsivity of ZnO:In/Si hetero-junction

    International Nuclear Information System (INIS)

    Zebbar, N.; Chabane, L.; Gabouze, N.; Kechouane, M.; Trari, M.; Aida, M.S.; Belhousse, S.; Hadj Larbi, F.

    2016-01-01

    Undoped zinc oxide (ZnO) and indium-doped (ZnO:In) thin films were grown at different temperatures (250–400 °C) on alkali-free borosilicate glass and n-Si (100) substrates by Ultrasonic Spray Pyrolysis method. The structural, compositional, optical and electrical properties of ZnO films were investigated by X-ray diffraction, Scanning Electron Microscopy, Rutherford Back Scattering Spectroscopy, Fourier Transform Infrared spectroscopy, photoluminescence (PL) and the four-point probe technique. The predominance of ultraviolet (UV) and blue emission intensities was found to be closely dependent on the resistivity of the film. The visible emission band (peaking at 432 nm) prevails for low film resistivity, ranging from 10 −2 to 1 Ω·cm. By contrast, for higher resistivity (> 1 Ω·cm), there is a predominance of the UV band (382 nm). The PL and photoresponsivity results of fabricated ZnO:In/n-Si(100) heterojunctions prepared at different temperatures are discussed. The maximum spectral response of the ZnO:8%In/Si heterojunction diode fabricated at 250 °C was about 80 mA/W at zero bias. The highlighted results are attractive for the optoelectronic applications. - Highlights: • Properties of ZnO thin films grown by Ultrasonic Spray Pyrolysis at 350 °C. • Photoluminescence emission intensity in undoped ZnO film: effect of the resistivity • Photoluminescence emission intensity of In-doped ZnO film is resistivity dependent. • The spectral response of ZnO:In/Si hetero-junction deposited in the range (250–400 °C)

  10. UV and visible photoluminescence emission intensity of undoped and In-doped ZnO thin film and photoresponsivity of ZnO:In/Si hetero-junction

    Energy Technology Data Exchange (ETDEWEB)

    Zebbar, N., E-mail: nacbar2003@yahoo.fr [LCMS, Faculty of Physics, University of Sciences and Technology (USTHB), BP 32, El-Alia, Algiers (Algeria); Chabane, L. [LCMS, Faculty of Physics, University of Sciences and Technology (USTHB), BP 32, El-Alia, Algiers (Algeria); Gabouze, N. [CRTSE, 02 Bd. Frantz Fanon, BP 140, Algiers (Algeria); Kechouane, M. [LCMS, Faculty of Physics, University of Sciences and Technology (USTHB), BP 32, El-Alia, Algiers (Algeria); Trari, M. [Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry (USTHB), BP 32, El-Alia, Algiers (Algeria); Aida, M.S. [LCM et Interface, Faculty of Sciences, University of Constantine, 25000 (Algeria); Belhousse, S. [CRTSE, 02 Bd. Frantz Fanon, BP 140, Algiers (Algeria); Hadj Larbi, F. [MEMS & Sensors, Division Microélectronique et Nanotechnologie, Centre de Développement des Technologies Avancées (CDTA), BP 17, Baba Hassen, Algiers (Algeria)

    2016-04-30

    Undoped zinc oxide (ZnO) and indium-doped (ZnO:In) thin films were grown at different temperatures (250–400 °C) on alkali-free borosilicate glass and n-Si (100) substrates by Ultrasonic Spray Pyrolysis method. The structural, compositional, optical and electrical properties of ZnO films were investigated by X-ray diffraction, Scanning Electron Microscopy, Rutherford Back Scattering Spectroscopy, Fourier Transform Infrared spectroscopy, photoluminescence (PL) and the four-point probe technique. The predominance of ultraviolet (UV) and blue emission intensities was found to be closely dependent on the resistivity of the film. The visible emission band (peaking at 432 nm) prevails for low film resistivity, ranging from 10{sup −2} to 1 Ω·cm. By contrast, for higher resistivity (> 1 Ω·cm), there is a predominance of the UV band (382 nm). The PL and photoresponsivity results of fabricated ZnO:In/n-Si(100) heterojunctions prepared at different temperatures are discussed. The maximum spectral response of the ZnO:8%In/Si heterojunction diode fabricated at 250 °C was about 80 mA/W at zero bias. The highlighted results are attractive for the optoelectronic applications. - Highlights: • Properties of ZnO thin films grown by Ultrasonic Spray Pyrolysis at 350 °C. • Photoluminescence emission intensity in undoped ZnO film: effect of the resistivity • Photoluminescence emission intensity of In-doped ZnO film is resistivity dependent. • The spectral response of ZnO:In/Si hetero-junction deposited in the range (250–400 °C)

  11. Tin dioxide sol-gel derived thin films deposited on porous silicon

    NARCIS (Netherlands)

    Cobianu, C.; Savaniu, Cristian; Buiu, Octavian; Zaharescu, Maria; Parlog, Constanta; van den Berg, Albert; Pecz, Bela; Dascula, Dan

    1996-01-01

    Undoped and Sb-doped SnO2 sol–gel derived thin films have been prepared for the first time from tin (IV) ethoxide precursor and SbCl3 in order to be utilised for gas sensing applications where porous silicon is used as a substrate. Transparent, crack-free and adherent layers were obtained on

  12. Tin dioxide sol-gel derived thin films deposited on porous silicon

    NARCIS (Netherlands)

    Cobianu, C.; Savaniu, Cristian; Buiu, Octavian; Dascalu, Dan; Zaharescu, Maria; Parlog, Constanta; van den Berg, Albert; Pecz, Bela

    1997-01-01

    Undoped and Sb-doped SnO2 sol¿gel derived thin films have been prepared for the first time from tin (IV) ethoxide precursor and SbCl3 in order to be utilised for gas sensing applications where porous silicon is used as a substrate. Transparent, crack-free and adherent layers were obtained on

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-02-01

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

  14. Dopant-driven enhancements in the optoelectronic properties of laser ablated ZnO: Ga thin films

    Science.gov (United States)

    Hassan, Ali; Jin, Yuhua; Chao, Feng; Irfan, Muhammad; Jiang, Yijian

    2018-04-01

    Theoretically and experimentally evaluated optoelectronic properties of GZO (Ga-doped zinc oxide) were correlated in the present article. Density functional theory and Hubbard U (DFT + Ud + Up) first-principle calculations were used for the theoretical study. The pulsed laser deposition technique was used to fabricate GZO thin films on p-GaN, Al2O3, and p-Si substrates. X-ray diffraction graphs show single crystal growth of GZO thin films with (002) preferred crystallographic orientation. The chemical composition was studied via energy dispersive X-ray spectroscopy, and no other unwanted impurity-related peaks were found, which indicated the impurity-free thin film growth of GZO. Field emission scanning electron microscopic micrographs revealed noodle-, seed-, and granular-like structures of GZO/GaN, GZO/Al2O3, and GZO/Si, respectively. Uniform growth of GZO/GaN was found due to fewer mismatches between ZnO and GaN (0.09%). Hall effect measurements in the van der Pauw configuration were used to check electrical properties. The highest mobility (53 cm2/Vs) with a high carrier concentration was found with low laser shots (1800). A 5-fold photoluminescence enhancement in the noodle-like structure of GZO/GaN compared with GZO/Al2O3 and GZO/Si was detected. This points toward shape-driven optical properties because the noodle-like structure is more favorable for optical enhancements in GZO thin films. Theoretical (3.539 eV) and experimental (3.54 eV) values of the band-gap were also found to be comparable. Moreover, the lowest resistivity (3.5 × 10-4 Ωcm) with 80% transmittance is evidence that GZO is a successful alternate of ITO.

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

    Science.gov (United States)

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

    2018-04-01

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

  16. Effect of thermal annealing on the optical and electronic properties of ZnO thin films grown on p-Si substrates

    Energy Technology Data Exchange (ETDEWEB)

    Han, W.G. [Department of Materials Science and Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Kang, S.G. [Department of Materials Science and Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Kim, T.W. [Advanced Semiconductor Research Center, Division of Electrical and Computer Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of)]. E-mail: twk@hanyang.ac.kr; Kim, D.W. [Semiconductor Materials Laboratory, Nano-Device Research Center, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650 (Korea, Republic of); Cho, W.J. [Semiconductor Materials Laboratory, Nano-Device Research Center, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650 (Korea, Republic of)

    2005-05-30

    The effects of annealing on the optical and the electronics properties of ZnO thin films grown on p-Si(1 0 0) substrates by using radio frequency magnetron sputtering were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence (PL), and X-ray photoelectron spectroscopy (XPS) measurements. The XRD patterns and pole figures showed that the crystallinity of the ZnO films grown on p-Si(1 0 0) substrates was improved by thermal treatment. XRD patterns, pole figures, and TEM images showed that the as-grown and the annealed ZnO films grown on Si(1 0 0) substrates had a c-axis preferential orientation in the [0 0 0 1] crystal direction. The PL spectra showed that luminescence peaks related to the free excitons and the deep levels appeared after annealing. The XPS spectra showed that the peak positions corresponding to the O 1s and the Zn 2p shifted slightly after thermal treatment. These results can help improve understanding of thermal effects on the optical and the electronic properties of ZnO thin films grown on p-Si(1 0 0) substrates.

  17. Cu-Doped ZnO Thin Films Deposited by a Sol-Gel Process Using Two Copper Precursors: Gas-Sensing Performance in a Propane Atmosphere

    Directory of Open Access Journals (Sweden)

    Heberto Gómez-Pozos

    2016-01-01

    Full Text Available A study on the propane gas-sensing properties of Cu-doped ZnO thin films is presented in this work. The films were deposited on glass substrates by sol-gel and dip coating methods, using zinc acetate as a zinc precursor, copper acetate and copper chloride as precursors for doping. For higher sensitivity values, two film thickness values are controlled by the six and eight dippings, whereas for doping, three dippings were used, irrespective of the Cu precursor. The film structure was analyzed by X-ray diffractometry, and the analysis of the surface morphology and film composition was made through scanning electron microscopy (SEM and secondary ion mass spectroscopy (SIMS, respectively. The sensing properties of Cu-doped ZnO thin films were then characterized in a propane atmosphere, C3H8, at different concentration levels and different operation temperatures of 100, 200 and 300 °C. Cu-doped ZnO films doped with copper chloride presented the highest sensitivity of approximately 6 × 104, confirming a strong dependence on the dopant precursor type. The results obtained in this work show that the use of Cu as a dopant in ZnO films processed by sol-gel produces excellent catalysts for sensing C3H8 gas.

  18. Synthesis of Colloidal ZnO Nanoparticles and Deposit of Thin Films by Spin Coating Technique

    Directory of Open Access Journals (Sweden)

    Jose Alberto Alvarado

    2013-01-01

    Full Text Available ZnO colloidal nanoparticles were synthesized, the average size of these nanoparticles is around 25 nm with hexagonal form. It was noted that stabilization depends directly on the purifying process; in this work we do not change the nature of the solution as a difference from Meulekamp's method, and we do not use any alkanes to remove the byproducts; only a centrifuge to remove those ones was used, thereby the stabilization increases up to 24 days. It is observed from the results that only three times of washing is enough to prevent the rapid aging process. The effect of annealing process on the composition, size, and geometrical shape of ZnO nanoparticles was studied in order to know whether the annealing process affects the crystallization and growth of the nanoparticles. After the synthesis, the colloidal nanoparticles were deposited by spin coating technique showing that the formed nanoparticles have no uniformly deposition pattern. But is possible to deposit those ones in glass substrates. A possible deposition process of the nanoparticles is proposed.

  19. Chemical-bath ZnO buffer layer for CuInS{sub 2} thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ennaoui, A.; Weber, M.; Scheer, R.; Lewerenz, H.J. [Hahn-Meitner-Institut, Abt. Grenzflaechen, Bereich Physikalische Chemie, Glienicker Strasse 100, D-14109 Berlin (Germany)

    1998-07-13

    ZnO buffer layers were grown by a chemical-bath deposition (CBD) in order to improve the interface quality in p-CuInS{sub 2} based solar cells, to improve the light transmission in the blue wavelength region, but also as an alternative to eliminate the toxic cadmium. The process consists of immersion of different substrates (glass, CIS) in a dilute solution of tetraamminezinc II, [Zn(NH{sub 2}){sub 4}]{sup 2+}, complex at 60-95C. During the growth process, a homogeneous growth mechanism which proceeds by the sedimentation of a mixture of ZnO and Zn(OH){sub 2} clusters formed in solution, competes with the heterogeneous growth mechanism. The mechanism consists of specific adsorption of a complex Zn(II) followed by a chemical reaction. The last process of growth results in thin, hard, adherent and specularly reflecting films. The characterization of the deposited CBD-ZnO layers was performed by X-ray diffraction (XRD), optical transmittance, scanning electron microscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The as-deposited films on glass show hexagonal zincite structure with two preferred orientations (1 0 0) and (1 0 1). High optical transmittance up to 80% in the near-infrared and part of the visible region was observed. The low growth rate of the films on CIS suggests an atomic layer-by-layer growth process.The device parameters and performance are compared to heterojunction with a standard CdS buffer layer

  20. Effect of atomic layer deposited Al2O3:ZnO alloys on thin-film silicon photovoltaic devices

    Science.gov (United States)

    Abdul Hadi, Sabina; Dushaq, Ghada; Nayfeh, Ammar

    2017-12-01

    In this work, we present the effects of the Al2O3:ZnO ratio on the optical and electrical properties of aluminum doped ZnO (AZO) layers deposited by atomic layer deposition, along with AZO application as the anti-reflective coating (ARC) layer and in heterojunction configurations. Here, we report complex refractive indices for AZO layers with different numbers of aluminum atomic cycles (ZnO:Al2O3 = 1:0, 39:1, 19:1, and 9:1) and we confirm their validity by fitting models to experimental data. Furthermore, the most conductive layer (ZnO:Al2O3 = 19:1, conductivity ˜4.6 mΩ cm) is used to fabricate AZO/n+/p-Si thin film solar cells and AZO/p-Si heterojunction devices. The impact of the AZO layer on the photovoltaic properties of these devices is studied by different characterization techniques, resulting in the extraction of recombination and energy band parameters related to the AZO layer. Our results confirm that AZO 19:1 can be used as a low cost and effective conductive ARC layer for solar cells. However, AZO/p-Si heterojunctions suffer from an insufficient depletion region width (˜100 nm) and recombination at the interface states, with an estimated potential barrier of ˜0.6-0.62 eV. The work function of AZO (ZnO:Al2O3 = 19:1) is estimated to be in the range between 4.36 and 4.57 eV. These material properties limit the use of AZO as an emitter in Si solar cells. However, the results imply that AZO based heterojunctions could have applications as low-cost photodetectors or photodiodes, operating under relatively low reverse bias.

  1. Influence of growth temperature on formation of continuous Ag thin film on ZnO surface by ultra-high vacuum deposition

    International Nuclear Information System (INIS)

    Zhang, T C; Mei, Z X; Guo, Y; Xue, Q K; Du, X L

    2009-01-01

    Growth of an Ag film on a ZnO (0 0 0 1) surface by ultra-high vacuum deposition has been investigated by field emission scanning electron microscopy. It is revealed that the growth temperature has a considerable effect on the formation of a continuous Ag thin film on a ZnO surface. At room temperature or above, the formation of continuous Ag films with small thickness was found to be difficult due to an upstepping mechanism, whereas a continuous Ag film as thin as 30 nm was achieved at 140 K, resulting from the reduced migration length of silver atoms and the increased saturated island density at low temperature. Coalescence between the islands occurred and predominated over upstepping during subsequent deposition, which is favourable for the formation of a continuous Ag film with a smaller thickness.

  2. Nanoscale determination of surface orientation and electrostatic properties of ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zuniga-Perez, J.; Munoz-Sanjose, V. [Universitat de Valencia, Departament de Fisica Aplicada i Electromagnetisme, Burjassot (Spain); Palacios-Lidon, E.; Colchero, J. [Universidad de Murcia, Departamento de Fisica, Facultad de Quimica, Campus Espinardo, Murcia (Spain)

    2007-07-15

    Scanning force microscopy related techniques are applied to study surface nanoscale properties. We show that nanogoniometry can be combined with local electrostatic measurements - electrostatic force microscopy and Kelvin probe microscopy - to identify surface planes families and to study their local electrical properties. The scanning force microscopy techniques employed are analyzed and the correct way of acquiring and interpreting data is discussed in detail. The experiments performed on ZnO films grown along the nonpolar [112 anti 0] direction show that these films completely facet into {l_brace}101 anti 11{r_brace} and {l_brace}10 anti 1 anti 1{r_brace} planes, which follow a well defined pattern of surface potential along the [0001 ] direction. This pattern is explained in terms of the different ionic termination - Zn or O ions - of the exposed facets. Finally, the presence of inversion domain boundaries is discussed. (orig.)

  3. Spectroscopy and control of near-surface defects in conductive thin film ZnO

    KAUST Repository

    Kelly, Leah L

    2016-02-12

    The electronic structure of inorganic semiconductor interfaces functionalized with extended π-conjugated organic molecules can be strongly influenced by localized gap states or point defects, often present at low concentrations and hard to identify spectroscopically. At the same time, in transparent conductive oxides such as ZnO, the presence of these gap states conveys the desirable high conductivity necessary for function as electron-selective interlayer or electron collection electrode in organic optoelectronic devices. Here, we report on the direct spectroscopic detection of a donor state within the band gap of highly conductive zinc oxide by two-photon photoemission spectroscopy. We show that adsorption of the prototypical organic acceptor C60 quenches this state by ground-state charge transfer, with immediate consequences on the interfacial energy level alignment. Comparison with computational results suggests the identity of the gap state as a near-surface-confined oxygen vacancy.

  4. Optoelectronic Characterization of Ta-Doped ZnO Thin Films by Pulsed Laser Deposition.

    Science.gov (United States)

    Koo, Horng-Show; Peng, Jo-Chi; Chen, Mi; Chin, Hung-I; Chen, Jaw-Yeh; Wu, Maw-Kuen

    2015-11-01

    Transparent conductive oxide of Ta-doped ZnO (TZO) film with doping amount of 3.0 wt% have been deposited on glass substrates (Corning Eagle XG) at substrate temperatures of 100 to 500 degrees C by the pulsed laser deposition (PLD) technique. The effect of substrate temperature on the structural, optical and electronic characteristics of Ta-doped ZnO (TZO) films with 3.0 wt% dopant of tantalum oxide (Ta2O5) was measured and demonstrated in terms of X-ray diffraction (XRD), ultraviolet-visible spectrometer (UV-Vis), four-probe and Hall-effect measurements. X-ray diffraction pattern shows that TZO films grow in hexagonal crystal structure of wurtzite phase with a preferred orientation of the crystallites along (002) direction and exhibits better physical characteristics of optical transmittance, electrical conductivity, carrier concentration and mobility for the application of window layer in the optoelectronic devices of solar cells, OLEDs and LEDs. The lowest electrical resistivity (ρ) and the highest carrier concentration of the as-deposited film deposited at 300 degrees C are measured as 2.6 x 10(-3) Ω-cm and 3.87 x 10(-20) cm(-3), respectively. The highest optical transmittance of the as-deposited film deposited at 500 degrees C is shown to be 93%, compared with another films deposited below 300 degrees C. It is found that electrical and optical properties of the as-deposited TZO film are greatly dependent on substrate temperature during laser ablation deposition.

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

    International Nuclear Information System (INIS)

    Phan, Duy-Thach; Chung, Gwiy-Sang

    2011-01-01

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

  6. Room temperature inorganic polycondensation of oxide (Cu2O and ZnO) nanoparticles and thin films preparation by the dip-coating technique

    International Nuclear Information System (INIS)

    Salek, G.; Tenailleau, C.; Dufour, P.; Guillemet-Fritsch, S.

    2015-01-01

    Oxide thin solid films were prepared by dip-coating into colloidal dispersions of oxide nanoparticles stabilized at room temperature without the use of chelating or complex organic dispersing agents. Crystalline oxide nanoparticles were obtained by inorganic polycondensation and characterized by X-ray diffraction and field emission gun scanning electron microscopy. Water and ethanol synthesis and solution stabilization of oxide nanoparticle method was optimized to prepare two different structural and compositional materials, namely Cu 2 O and ZnO. The influence of hydrodynamic parameters over the particle shape and size is discussed. Spherical and rod shape nanoparticles were formed for Cu 2 O and ZnO, respectively. Isoelectric point values of 7.5 and 8.2 were determined for cuprous and zinc oxides, respectively, after zeta potential measurements. A shear thinning and thixotropic behavior was observed in both colloidal sols after peptization at pH ~ 6 with dilute nitric acid. Every colloidal dispersion stabilized in a low cost and environmentally friendly azeotrope solution composed of 96 vol.% of ethanol with water was used for the thin film preparation by the dip-coating technique. Optical properties of the light absorber cuprous oxide and transparent zinc oxide thin solid films were characterized by means of transmittance and reflectance measurements (300–1100 nm). - Highlights: • Room temperature inorganic polycondensation of crystalline oxides • Water and ethanol synthesis and solution stabilization of oxide nanoparticles • Low cost method for thin solid film preparation

  7. Room temperature inorganic polycondensation of oxide (Cu{sub 2}O and ZnO) nanoparticles and thin films preparation by the dip-coating technique

    Energy Technology Data Exchange (ETDEWEB)

    Salek, G.; Tenailleau, C., E-mail: tenailleau@chimie.ups-tlse.fr; Dufour, P.; Guillemet-Fritsch, S.

    2015-08-31

    Oxide thin solid films were prepared by dip-coating into colloidal dispersions of oxide nanoparticles stabilized at room temperature without the use of chelating or complex organic dispersing agents. Crystalline oxide nanoparticles were obtained by inorganic polycondensation and characterized by X-ray diffraction and field emission gun scanning electron microscopy. Water and ethanol synthesis and solution stabilization of oxide nanoparticle method was optimized to prepare two different structural and compositional materials, namely Cu{sub 2}O and ZnO. The influence of hydrodynamic parameters over the particle shape and size is discussed. Spherical and rod shape nanoparticles were formed for Cu{sub 2}O and ZnO, respectively. Isoelectric point values of 7.5 and 8.2 were determined for cuprous and zinc oxides, respectively, after zeta potential measurements. A shear thinning and thixotropic behavior was observed in both colloidal sols after peptization at pH ~ 6 with dilute nitric acid. Every colloidal dispersion stabilized in a low cost and environmentally friendly azeotrope solution composed of 96 vol.% of ethanol with water was used for the thin film preparation by the dip-coating technique. Optical properties of the light absorber cuprous oxide and transparent zinc oxide thin solid films were characterized by means of transmittance and reflectance measurements (300–1100 nm). - Highlights: • Room temperature inorganic polycondensation of crystalline oxides • Water and ethanol synthesis and solution stabilization of oxide nanoparticles • Low cost method for thin solid film preparation.

  8. Enhancement of the Ultraviolet Photoresponsivity of Al-doped ZnO Thin Films Prepared by using the Sol-gel Spin-coating Method

    Science.gov (United States)

    Lee, Wookbin; Leem, Jae-Young

    2018-03-01

    We report the structural, morphological, optical, and ultraviolet (UV) photoresponse properties of Al-doped ZnO (AZO) thin films prepared on silicon substrates with different Al doping concentrations by using the sol-gel spin-coating method. An analysis of the X-ray diffraction patterns of the AZO thin films revealed that the average grain size decreased and the c-axis lattice constant increased with Al content. The field-emission scanning electron microscopy images showed that with Al doping, the grain size decreased, but the film density increased with increasing Al doping concentration from 0% to 3%. These results indicate that the surface area of the film increased with increasing Al doping. The absorbance spectra revealed that the UV absorbance of the AZO thin films increased with increasing Al doping concentration and that the absorption onset shifted towards lower energies. The photoluminescence spectra revealed that with increasing Al doping, the intensity of the visible emission greatly decreased and the visible emission peak shifted forward lower energy (a red shift). The UV sensor based on the AZO thin films exhibited a higher responsivity than that based on the undoped ZnO thin film. Therefore, this study provides a facile method for improving the photoresponsivity of UV sensors.

  9. CdTe Nanocrystal Hetero-Junction Solar Cells with High Open Circuit Voltage Based on Sb-doped TiO₂ Electron Acceptor Materials.

    Science.gov (United States)

    Li, Miaozi; Liu, Xinyan; Wen, Shiya; Liu, Songwei; Heng, Jingxuan; Qin, Donghuan; Hou, Lintao; Wu, Hongbin; Xu, Wei; Huang, Wenbo

    2017-05-03

    We propose Sb-doped TiO₂ as electron acceptor material for depleted CdTe nanocrystal (NC) hetero-junction solar cells. Novel devices with the architecture of FTO/ZnO/Sb:TiO₂/CdTe/Au based on CdTe NC and TiO₂ precursor are fabricated by rational ambient solution process. By introducing TiO₂ with dopant concentration, we are able to tailor the optoelectronic properties of NC solar cells. Our novel devices demonstrate a very high open circuit voltage of 0.74 V, which is the highest V oc reported for any CdTe NC based solar cells. The power conversion efficiency (PCE) of solar cells increases with the increase of Sb-doped content from 1% to 3%, then decreases almost linearly with further increase of Sb content due to the recombination effect. The champion device shows J sc , V oc , FF, and PCE of 14.65 mA/cm², 0.70 V, 34.44, and 3.53% respectively, which is prospective for solution processed NC solar cells with high V oc .

  10. Formation of ultrafast-switching viologen-anchored TiO{sub 2} electrochromic device by introducing Sb-doped SnO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hark Jin; Seo, Jung Kyu; Kim, Yong Joo; Jeong, Hyun Ki; Lim, Goo Il; Choi, Young S.; Lee, Wan In [Department of Chemistry, Inha University, Incheon 402-751 (Korea)

    2009-12-15

    Ultrafast-switching viologen-anchored TiO{sub 2} electrochromic device (ECD) was developed by introducing Sb-doped SnO{sub 2} (Sb{sub x}Sn{sub 1-x}O{sub 2}, ATO) as counter electrode (CE), and the switching behavior of the fabricated ECD was investigated as a function of Sb-doping concentration. About 9-nm-sized Sb{sub x}Sn{sub 1-x}O{sub 2} (x=0-0.3) nanoparticles were synthesized by a solvothermal reaction of tin (IV) chloride and antimony (III) chloride at 240 C, and employed to fabricate 2.4-{mu}m-thick transparent CE. Working electrode (WE) was formed from the 7-nm-sized TiO{sub 2} nanoparticle by a doctor blade method, and the thickness of the nanoporous TiO{sub 2} electrode was 4.5 {mu}m. The phosphonated viologen, bis(2-phosphonylethyl)-4,4'-bipyridinium dibromide, was then adsorbed on the prepared films for the construction of the ECD. The response time was strongly dependent on the doping concentration of Sb in ATO, and the fastest switching response was observed at 3 mol%. At this composition, the coloration time was 5.7 ms, and the bleaching time was 14.4 ms, which is regarded as one of the best results so far reported. (author)

  11. Temperature-dependent Hall effect studies of ZnO thin films grown by metalorganic chemical vapour deposition

    International Nuclear Information System (INIS)

    Roro, K T; Dangbegnon, J K; Sivaraya, S; Westraadt, J E; Neethling, J H; Leitch, A W R; Botha, J R; Kassier, G H

    2008-01-01

    The electrical properties of zinc oxide (ZnO) thin films of various thicknesses (0.3–4.4 µm) grown by metalorganic chemical vapour deposition on glass substrates have been studied by using temperature-dependent Hall-effect (TDH) measurements in the 18–300 K range. The high quality of the layers has been confirmed with x-ray diffraction, transmission electron microscopy, scanning electron microscopy and photoluminescence techniques. TDH measurements indicate the presence of a degenerate layer which significantly influences the low-temperature data. It is found that the measured mobility generally increases with increasing layer thickness, reaching a value of 120 cm 2 V −1 s −1 at room temperature for the 4.4 µm thick sample. The lateral grain size of the layers is also found to increase with thickness indicating a clear correlation between the size of the surface grains and the electrical properties of corresponding films. Theoretical fits to the Hall data suggest that the bulk conduction of the layers is dominated by a weakly compensated donor with activation energy in the 33–41 meV range and concentration of the order of 10 17 cm −3 , as well as a total acceptor concentration of mid-10 15 cm −3 . Grain boundary scattering is found to be an important limiting factor of the mobility throughout the temperature range considered

  12. Effect of sol concentration on the properties of ZnO thin films prepared by sol-gel technique

    International Nuclear Information System (INIS)

    Dutta, M.; Mridha, S.; Basak, D.

    2008-01-01

    ZnO thin films are deposited on the glass substrates by sol-gel drain coating technique by varying the concentration of the sol. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis were used to investigate the effect of sol concentration on the crystallinity and surface morphology of the films. The results show that with increase in sol concentration, the value of full width at half maximum (FWHM) of (0 0 2) peak decreases while the strain first increases and then decreases. The sol with higher concentration results in the increase in the grain size. The studies on the optical properties show that the band gap value increases from 3.27 to 3.3 eV when the sol concentration changes from 0.03 to 0.1 M. The photoconductivity studies reveal that the film for 0.05 M sol shows the maximum photoresponse for ultraviolet (UV) wavelength (<400 nm) which is co-related with the deep-level defects. The growth and decay of the photocurrent is found to be slowest for the same film

  13. Young's Modulus and Coefficient of Linear Thermal Expansion of ZnO Conductive and Transparent Ultra-Thin Films

    Directory of Open Access Journals (Sweden)

    Naoki Yamamoto

    2011-01-01

    Full Text Available A new technique for measuring Young's modulus of an ultra-thin film, with a thickness in the range of about 10 nm, was developed by combining an optical lever technique for measuring the residual stress and X-ray diffraction for measuring the strain in the film. The new technique was applied to analyze the mechanical properties of Ga-doped ZnO (GZO films, that have become the focus of significant attention as a substitute material for indium-tin-oxide transparent electrodes. Young's modulus of the as-deposited GZO films decreased with thickness; the values for 30 nm and 500 nm thick films were 205 GPa and 117 GPa, respectively. The coefficient of linear thermal expansion of the GZO films was measured using the new technique in combination with in-situ residual stress measurement during heat-cycle testing. GZO films with 30–100 nm thickness had a coefficient of linear thermal expansion in the range of 4.3 × 10−6 – 5.6 × 10−6 °C−1.

  14. Enhancement Of Free Exciton Peak Intensity In Reactively Sputtered ZnO Thin Films On (0001) Al2O3

    International Nuclear Information System (INIS)

    Tuezemen, S.; Guer, Emre; Yildirim, T.; Xiong, G.; Williams, R. T.

    2007-01-01

    Wide bandgap materials such as GaN with its direct bandgap structure have been developed rapidly for applications in short wavelength light emission. ZnO, II-VI oxide semiconductor, is also promising for various technological applications, especially for optoelectronic light emitting devices in the visible and ultraviolet (UV) range of the electromagnetic spectrum. Above-band-edge absorption spectra of reactively sputtered Zn- and O-rich samples exhibit free exciton (FX) and neutral acceptor bound exciton (A deg. X) features. It is shown that the residual acceptors which bind excitons with an energy of 75 meV reside about 312 meV above the valence band, according to effective mass theory. An intra-bandgap absorption feature peaking at 2.5 eV shows correlation with the characteristically narrow A-free exciton peak intensity. Relevant annealing processes are presented as a function of time and temperature dependently for both Zn- and O- rich thin films. Enhancement of the free exciton peak intensity is observed without disturbing the residual shallow acceptor profile which is necessary for at least background p-type conductivity

  15. Preparation of manganese-doped ZnO thin films and their ...

    Indian Academy of Sciences (India)

    Structural characterization by X-ray diffraction reveals that polycrystalline nature of the films increases with increasing ... SILAR; Mn:ZnO thin film; X-ray line broadening; SEM; optical bandgap. 1. Introduction. Zinc oxide is a II–IV ... potential in different applications in photo-thermal conver- sion systems, heat mirrors, ...

  16. Preparation of manganese-doped ZnO thin films and their ...

    Indian Academy of Sciences (India)

    Abstract. 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 ...

  17. Improved conductivity of ZnO thin films by exposure to an atmospheric hydrogen plasma

    NARCIS (Netherlands)

    Illiberi, A.; Kniknie, B.; Deelen, J. van; Steijvers, H.L.A.H.; Habets, D.; Simons, P.J.P.M.; Janssen, A.C.; Beckers, E.H.A.

    2012-01-01

    Aluminum-doped zinc oxide (ZnOx:Al) films have been deposited on a moving glass substrate by a high throughput metalorganic chemical vapor deposition process at atmospheric pressure. Thin (< 250 nm) ZnOx:Al films have a poor crystalline quality, due to a small grain size and the presence of

  18. Thin films of conductive ZnO patterned by micromolding resulting in nearly isolated features

    NARCIS (Netherlands)

    Göbel, Ole; Blank, David H.A.; ten Elshof, Johan E.

    2010-01-01

    Patterned and continuous thin films of conductive Al-doped zinc oxide (ZnO:Al) were prepared on different substrates from a polymeric precursor solution. Their electric conductivity and light transmittance (for visible and UV light) was measured at room temperature. By means of a simple device,

  19. Preparation of manganese-doped ZnO thin films and their ...

    Indian Academy of Sciences (India)

    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 ...

  20. Controlling the surface nanostructure of ZnO and Al-doped ZnO thin films using electrostatic spraying for their application in 12% efficient perovskite solar cells

    Science.gov (United States)

    Mahmood, Khalid; Swain, Bhabani Sankar; Jung, Hyun Suk

    2014-07-01

    In this paper, ZnO and Al-doped ZnO films were deposited using the electrospraying method and studied for the first time as photoanodes for efficient perovskite solar cells. Effects of substrate temperature, deposition time, applied voltage, substrate-to-nozzle distance and flow rate (droplet size) on the morphology of ZnO were studied with the help of FE-SEM images. The major factors such as the droplet size of the spray, substrate temperature and substrate-to-nozzle distance at deposition control the film morphology. Indeed, these factors determine the density of the film, its smoothness and the flow of solution over the substrate. The droplet size was controlled by the flow rate of the spray. The substrate-to-nozzle distance and flow rate will both regulate the solution amount deposited on the surface of the substrate. The most favorable conditions for a good quality ZnO thin film were a long substrate-to-nozzle distance and lower solution flow rates. In situ droplet size measurement shows that the size and dispersion of particles were narrowed. The method was shown to have a high deposition rate and efficiency relative to well-established thin film deposition techniques such as chemical and physical vapor deposition. In addition, it also allows easy control of the microstructure and stoichiometry of the deposits. The pure ZnO film produced under optimum conditions (440 nm thick) demonstrated a high power conversion efficiency (PCE) of 10.8% when used as a photoanode for perovskite solar cells, owing to its high porosity, uniform morphology and efficient electron transport. For thicker films a drastic decrease in PCE was observed due to their low porosity. We also observed that the open-circuit voltage increases from 1010 mV to 1045 mV and also the PCE increases from 10.8% to 12.0% when pure ZnO films were doped with aluminum (Al). Under atmospheric pressure, the electrospraying system produces the reasonably uniform-sized droplets of smaller size, so the films

  1. The structural and optical properties of Y (Y  =  Al, B, Si and Ti)-doped ZnO nano thin films from the first principles calculations

    Science.gov (United States)

    Zhang, Wenshu; Hu, Huijun; Zhang, Caili; Li, Jianguo; Li, Yuping; Ling, Lixia; Han, Peide

    2017-12-01

    Based on the density functional theory, the structural stability and optical properties of undoped and Y (Y  =  Al, B, Si and Ti)-doped ZnO nano thin films are investigated. The good stability of the films based on the ZnO (0 0 0 1) can be obtained when the layer is larger than 12. Moreover, the dielectric function, refractive index, absorption, and reflectivity of doped ZnO nano thin films have been analyzed in detail. In the visible light range, the values of ZnO films from 12 to 24 layers are all smaller than those of the bulk. And with the augment of the layers, the values keep increasing. All the results signify that the nano film of 12 layers possesses the lowest reflectivity and weakest absorption. In addition, there is an evident impact of some doped element on the properties of nano films. The absorption and reflectivity of Ti, Si-doped ZnO nano thin films are higher than those of the clean films, while Al, B-doped are lower, especially B-doped. Moreover, the conductivity of the doped structure is better than that of the bulk. Thus, the B-doped ZnO nano thin films could be potential candidate materials of transparent conductive films.

  2. Photoluminescence properties of ZnO thin films grown by using the hydrothermal technique

    International Nuclear Information System (INIS)

    Sahoo, Trilochan; Jang, Leewoon; Jeon, Juwon; Kim, Myoung; Kim, Jinsoo; Lee, Inhwan; Kwak, Joonseop; Lee, Jaejin

    2010-01-01

    The photoluminescence properties of zinc-oxide thin films grown by using the hydrothermal technique have been investigated. Zinc-oxide thin films with a wurtzite symmetry and c-axis orientation were grown in aqueous solution at 90 .deg. C on sapphire substrates with a p-GaN buffer layer by using the hydrothermal technique. The low-temperature photoluminescence analysis revealed a sharp bound-exciton-related luminescence peak at 3.366 eV with a very narrow peak width. The temperature-dependent variations of the emission energy and of the integrated intensity were studied. The activation energy of the bound exciton complex was calculated to be 7.35 ± 0.5 meV from the temperature dependent quenching of the integral intensities.

  3. Optical properties of the plasma hydrogenated ZnO thin films

    Czech Academy of Sciences Publication Activity Database

    Chang, Yu-Ying; Stuchlík, Jiří; Neykova, Neda; Souček, J.; Remeš, Zdeněk

    2017-01-01

    Roč. 68, č. 7 (2017), s. 70-73 ISSN 1335-3632 R&D Projects: GA ČR GC16-10429J Institutional support: RVO:68378271 Keywords : metal oxide * magnetron sputtering * thin films * reflectance interferometry * photothermal deflection spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 0.483, year: 2016

  4. Al-Sn doped ZnO thin film nanosensor for monitoring NO2 concentration

    Directory of Open Access Journals (Sweden)

    G.S. Hikku

    2017-07-01

    Full Text Available The metal oxide semiconductor gas sensor technology is robust and has quick response times. In this work, aluminium and tin co-doped zinc oxide (ASZO thin films were synthesized by a sol–gel dip-coating process as sensors for the greenhouse gas nitrogen dioxide (NO2. The prepared ASZO thin films were characterized using such techniques as X-ray diffraction (XRD, scanning electron microscopy (SEM, atomic force microscopy (AFM and photoluminescence (PL emission studies in order to analyze the elemental confirmation, particle size, surface roughness and optical emission properties, respectively. The XRD data reveals the hexagonal structure of ASZO and that the preferential orientation is along 2θ = 36.19°. SEM images of the ASZO thin film exhibit rod-like formations of ASZO on the substrate. The ASZO films show enhanced sensing behaviour, sensing NO2 gas even at 2 ppm at an operating temperature of 170 °C. The response and recovery times were determined to be 30 and 20 s, respectively.

  5. 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%)

  6. Correlation between electrical transport, microstructure and room temperature ferromagnetism in 200 keV Ni{sup 2+} ion implanted zinc oxide (ZnO) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, B. [Gautam Buddha University, Department of Applied Sciences, Greater Noida (India); Ghosh, S.; Srivastava, P. [Indian Institute of Technology Delhi, Nanostech Laboratory, New Delhi (India); Kumar, P.; Kanjilal, D. [Aruna Asaf Ali Marg, Inter University Accelerator Centre, New Delhi (India)

    2012-05-15

    We report variable temperature resistivity measurements and mechanisms related to electrical conduction in 200 keV Ni{sup 2+} ion implanted ZnO thin films deposited by vapor phase transport. The dc electrical resistivity versus temperature curves show that all polycrystalline ZnO films are semiconducting in nature. In the room temperature range they exhibit band conduction and conduction due to thermionic emission of electrons from grain boundaries present in the polycrystalline films. In the low temperature range, nearest neighbor hopping (NNH) and variable range hopping (VRH) conduction are observed. The detailed conduction mechanism of these films and the effects of grain boundary (GB) barriers on the electrical conduction process are discussed. An attempt is made to correlate electrical conduction behavior and previously observed room temperature ferromagnetism of these films. (orig.)

  7. Photoconductivity and surface chemical analysis of ZnO thin films deposited by solution-processing techniques for nano and microstructure fabrication

    International Nuclear Information System (INIS)

    Dwivedi, V. K.; Prakash, G. Vijaya; Srivastava, P.

    2013-01-01

    The fabrication of zinc oxide (ZnO) from inexpensive solution-processing techniques, namely, electrochemical deposition and electrospinning were explored on various conducting and mesoporous semiconducting surfaces. Optimised conditions were derived for template- and self-assisted nano/micro structures and composites. ZnO thin films were annealed at a fixed temperature under ambient conditions and characterised using physical and optical techniques. The photocurrent response in the UV region shows a fast rise and double decay behaviour with a fast component followed by a slow oscillatory decay. Photocurrent results were correlated with surface chemical analysis from X-ray photoelectron spectroscopy. Various characterisation details reveal the importance of fabrication parameter optimisation for useful low-cost optoelectronic applications. (semiconductor materials)

  8. Influence of Al concentration and annealing temperature on structural, optical, and electrical properties of Al co-doped ZnO thin films

    International Nuclear Information System (INIS)

    Gürbüz, Osman; Kurt, İsmail; Çalışkan, Serkan; Güner, Sadık

    2015-01-01

    Highlights: • RF magnetron sputtering technique seems to be very efficient method for fabrication of Al doped ZnO (AZO) films. • Long range single crystalline structure improves with annealing process. • Optical properties became much better after annealing process especially for the AZO films that include high Al concentration. • Much greater conductivity with increasing Al concentration and annealing process. • AZO films have potential applicability in spintronic devices. - Abstract: The pure ZnO and Al-doped ZnO (AZO) thin films (thickness: 200 nm) were prepared on both side polished silica (SiO 2 ) substrates via RF magnetron sputtering at room temperature by using 2.5 inches high-purity ZnO (99.9%) and Al (99.9%) targets. The samples were annealed at 300 °C, 400 °C and 500 °C for 45 min in N 2 ambient in quartz annealing furnace system, respectively. We investigated the effects of various Al concentrations and annealing treatment on the structural, electrical, and optical properties of films. The preferred crystallization was observed along c axis (single (0 0 2) diffraction peak) from substrate surface assigning the single crystalline Würtzite lattice for pure ZnO and AZO thin films. Although increasing Al concentration decreases the order of crystallization of as-grown films, annealing process increases the long range crystal order. The crystallite sizes vary between minimum 12.98 nm and maximum 20.79 nm for as-grown and annealed samples. The crystallite sizes decrease with increasing Al concentration but increase with increasing annealing temperature as general trend. The grain size and porosity of films change with annealing treatment. The smaller grains coalesce together to form larger grains for many films. However, a reverse behavior is seen for Al 2.23 ZnO and Al 12.30 ZnO samples. That is, Al concentration plays critical role as well as temperature on grain size. Low percent optical transmittance (T%) is observed due to higher Al

  9. Capacitive behavior of carbon nanotube thin film induced by deformed ZnO microspheres

    Science.gov (United States)

    Tripathi, Rahul; Naidu Majji, Shanmukh; Ghosh, Rituparna; Nandi, Sukanta; Boruah, Buddha D.; Misra, Abha

    2017-09-01

    Multiwalled carbon nanotubes (CNTs) are uniformly distributed with piezoelectric microspheres. This leads to a large strain gradient due to an induced capacitive response, providing a 250% enhancement in electromechanical response compared with pristine CNTs. The fabricated large-area flexible thin film exhibits excellent pressure sensitivity, which can even detect an arterial pulse with a much faster response time (˜79 ms) in a bendable configuration. In addition, the film shows a rapid relaxation time (˜0.4 s), high stability and excellent durability with a rapid loading-unloading cycle. The dominant contribution of piezoelectric microspheres in a CNT matrix as opposed to nanoparticles showed a much higher sensitivity due to the large change in capacitance. Therefore, hybrid microstructures have various potential applications in wearable smart electronics, including detection of human motion and wrist pulses.

  10. Influence of Codoping on the Optical Properties of ZnO Thin Films Synthesized on Glass Substrate by Chemical Bath Deposition Method

    Directory of Open Access Journals (Sweden)

    G. Shanmuganathan

    2014-01-01

    Full Text Available Fe and K simultaneously doped ZnO thin films Zn0.99 K0.01 (Fex O (x=1, 2, 3, and 4% were synthesized by chemical bath deposition method. The XRD investigation reveals that all the doped ZnO thin films are in hexagonal wurtzite crystal structure without impurity phases. With increase in Fe concentration, the growth of thin films along c axis is evident from the XRD which indicates the increase in intensity along (002 direction. The same is visible from the surface morphology which shows the formation of hexagonal structure for higher Fe concentration. The topography shows gradual variation with Fe incorporation. The optical energy band gap obtained from the transmittance spectrum decreases from 3.42 to 3.06 eV with increase in Fe concentration indicating the red shift and this trend is consistent with the earlier experimental results. The UV emission is centered around 3.59 eV. The optical constants such as refractive index, extinction coefficient, and absorption coefficient which are essential for the optoelectronic applications were also determined.

  11. Fabrication of the heterojunction diode from Y-doped ZnO thin films on p-Si substrates by sol-gel method

    Science.gov (United States)

    Sharma, Sanjeev K.; Singh, Satendra Pal; Kim, Deuk Young

    2018-02-01

    The heterojunction diode of yttrium-doped ZnO (YZO) thin films was fabricated on p-Si(100) substrates by sol-gel method. The post-annealing process was performed at 600 °C in vacuum for a short time (3 min) to prevent inter-diffusion of Zn, Y, and Si atoms. X-ray diffraction (XRD) pattern of as-grown and annealed (600 °C in vacuum) films showed the preferred orientation along the c-axis (002) regardless of dopant concentrations. The uniform surface microstructure and the absence of other metal/oxide peaks in XRD pattern confirmed the excellence of films. The increasing bandgap and carrier concentration of YZO thin films were interpreted by the BM shift, that is, the Fermi level moves towards the conduction band edge. The current-voltage characteristics of the heterojunction diode, In/n-ZnO/p-Si/Al, showed a rectification behavior. The turn-on voltage and ideality factor of n-ZnO/p-Si and n-YZO/p-Si were observed to be 3.47 V, 2.61 V, and 1.97, 1.89, respectively. Y-dopant in ZnO thin films provided more donor electrons caused the shifting of Fermi-energy level towards the conduction band and strengthen the interest for heterojunction diodes.

  12. Structural, optical and electrical properties of N-doped ZnO thin films prepared by thermal oxidation of pulsed filtered cathodic vacuum arc deposited Zn{sub x}N{sub y} films

    Energy Technology Data Exchange (ETDEWEB)

    Erdogan, N.H.; Kara, K.; Ozdamar, H. [Physics Department, Cukurova University, 01330 Adana (Turkey); Kavak, H., E-mail: hkavak@cu.edu.tr [Physics Department, Cukurova University, 01330 Adana (Turkey); Esen, R. [Physics Department, Cukurova University, 01330 Adana (Turkey); Karaagac, H. [Physics Department, Middle East Technical University, 06531 Ankara (Turkey)

    2011-09-08

    Graphical abstract: Highlights: > Thermal oxidation of Zn{sub x}N{sub y} method is used to obtain N doped ZnO. > N acceptors in ZnO is not sufficiently activated at oxidation temperature below 350 deg. C. > Oxidation treatment at 450 deg. C activates more N acceptors in ZnO. > Oxidation treatment at high temperatures above 550 deg. C reduces the N concentration in the ZnO thin film. - Abstract: In this study, N-doped ZnO thin films were fabricated by oxidation of Zn{sub x}N{sub y} films. The Zn{sub x}N{sub y} thin films were deposited on glass substrates by pulsed filtered cathodic vacuum arc deposition (PFCVAD) using metallic zinc wire (99.999%) as a cathode target in pure nitrogen plasma. The influence of oxidation temperature, on the electrical, structural and optical properties of N-doped ZnO films was investigated. P-type conduction was achieved for the N-doped ZnO obtained at 450 deg. C by oxidation of Zn{sub x}N{sub y}, with a resistivity of 16.1 {Omega} cm, hole concentration of 2.03 x 10{sup 16} cm{sup -3} and Hall mobility of 19 cm{sup 2}/V s. X-ray photoelectron spectroscopy (XPS) analysis confirmed the incorporation of N into the ZnO films. X-ray diffraction (XRD) pattern showed that the films as-deposited and oxidized at 350 deg. C were amorphous. However, the oxidized films in air atmosphere at 450-550 deg. C were polycrystalline without preferential orientation. In room temperature photoluminescence (PL) spectra, an ultraviolet (UV) peak was seen for all the samples. In addition, a broad deep level emission was observed.

  13. Area and energy efficient high-performance ZnO wavy channel thin-film transistor

    KAUST Repository

    Hanna, Amir

    2014-09-01

    Increased output current while maintaining low power consumption in thin-film transistors (TFTs) is essential for future generation large-area high-resolution displays. Here, we show wavy channel (WC) architecture in TFT that allows the expansion of the transistor width in the direction perpendicular to the substrate through integrating continuous fin features on the underlying substrate. This architecture enables expanding the TFT width without consuming any additional chip area, thus enabling increased performance while maintaining the real estate integrity. The experimental WCTFTs show a linear increase in output current as a function of number of fins per device resulting in (3.5×) increase in output current when compared with planar counterparts that consume the same chip area. The new architecture also allows tuning the threshold voltage as a function of the number of fin features included in the device, as threshold voltage linearly decreased from 6.8 V for planar device to 2.6 V for WC devices with 32 fins. This makes the new architecture more power efficient as lower operation voltages could be used for WC devices compared with planar counterparts. It was also found that field effect mobility linearly increases with the number of fins included in the device, showing almost \\\\(1.8×) enhancements in the field effect mobility than that of the planar counterparts. This can be attributed to higher electric field in the channel due to the fin architecture and threshold voltage shift. © 2014 IEEE.

  14. The effect of Al-doping on the structural, optical, electrical and cathodoluminescence properties of ZnO thin films prepared by spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Dghoughi, L. [Laboratoire d' Optoelectronique et de physico-chimie des Materiaux, Faculte des Sciences, Universite Ibn Tofail, Kenitra (Morocco); Ouachtari, F., E-mail: fouad489ou@gmail.co [Laboratoire de Physique Matiere et Rayonnement, Equipe de Spectroscopie Optique de la Matiere Solide, Faculte des Sciences, Universite Ibn Tofail, Kenitra (Morocco); Addou, M. [Laboratoire d' Optoelectronique et de physico-chimie des Materiaux, Faculte des Sciences, Universite Ibn Tofail, Kenitra (Morocco); Elidrissi, B.; Erguig, H.; Rmili, A.; Bouaoud, A. [Laboratoire de Physique Matiere et Rayonnement, Equipe de Spectroscopie Optique de la Matiere Solide, Faculte des Sciences, Universite Ibn Tofail, Kenitra (Morocco)

    2010-05-01

    Aluminum doped zinc oxide (Al-doped ZnO) thin films were deposited by the spray pyrolysis technique onto the glass substrates at 450 deg. C using anhydrous zinc chloride (ZnCl{sub 2}) and aluminum chloride (AlCl{sub 3}) as sources of zinc and aluminum ions, respectively. The effect of [Al]/[Zn] ratio in the solution on the structural, optical, electrical and cathodoluminescence properties of these films were investigated. XRD study revealed that both undoped and Al-doped ZnO films were polycrystalline with hexagonal structure and exhibited (0 0 2) preferential orientation. The optical and electrical studies showed that the film deposited with the [Al]/[Zn] ratio equal to 0.05 had high transmittance (of about 80% and 95% in the visible and near infra-red regions, respectively) and minimum resistivity of 1.4x10{sup -3} OMEGA cm, respectively. This resistivity value decreased with increase in temperature indicating the semiconducting nature of Al-doped ZnO films. The chemical composition analysis (EPMA) showed that this film was nearly stochiometric with a slight oxygen deficiency.

  15. Observation of dopant-profile independent electron transport in sub-monolayer TiOx stacked ZnO thin films grown by atomic layer deposition

    Science.gov (United States)

    Saha, D.; Misra, P.; Das, Gangadhar; Joshi, M. P.; Kukreja, L. M.

    2016-01-01

    Dopant-profile independent electron transport has been observed through a combined study of temperature dependent electrical resistivity and magnetoresistance measurements on a series of Ti incorporated ZnO thin films with varying degree of static-disorder. These films were grown by atomic layer deposition through in-situ vertical stacking of multiple sub-monolayers of TiOx in ZnO. Upon decreasing ZnO spacer layer thickness, electron transport smoothly evolved from a good metallic to an incipient non-metallic regime due to the intricate interplay of screening of spatial potential fluctuations and strength of static-disorder in the films. Temperature dependent phase-coherence length as extracted from the magnetotransport measurement revealed insignificant role of inter sub-monolayer scattering as an additional channel for electron dephasing, indicating that films were homogeneously disordered three-dimensional electronic systems irrespective of their dopant-profiles. Results of this study are worthy enough for both fundamental physics perspective and efficient applications of multi-stacked ZnO/TiOx structures in the emerging field of transparent oxide electronics.

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  17. Study of working pressure on the optoelectrical properties of Al–Y codoped ZnO thin-film deposited using DC magnetron sputtering for solar cell applications

    International Nuclear Information System (INIS)

    Hsu, Feng-Hao; Wang, Na-Fu; Tsai, Yu-Zen; Chuang, Ming-Chieh; Cheng, Yu-Song; Houng, Mau-Phon

    2013-01-01

    Low cost transparent conductive Al–Y codoped ZnO (AZOY) thin-films were prepared on a glass substrate using a DC magnetron sputtering technique with various working pressures in the range of 5–13 mTorr. The relationship among the structural, electrical, and optical properties of sputtered AZOY films was studied as a function of working pressure. The XRD measurements show that the crystallinity of the films degraded as the working gas pressure increased. The AZOY thin-film deposited at a working pressure of 5 mTorr exhibited the lowest electrical resistivity of 4.3 × 10 −4 Ω cm, carrier mobility of 30 cm 2 /V s, highest carrier concentration of 4.9 × 10 20 cm −3 , and high transmittance in the visible region (400–800 nm) of approximately 90%. Compared with Al doped ZnO (AZO) thin-films deposited using DC or RF magnetron sputtering methods, a high carrier mobility was observed in our AZOY thin-films. This result can be used to effectively decrease the absorption of near infrared-rays in solar cell applications. The mechanisms are attributed to the larger transition energy between Ar atoms and sputtering particles and the size compensation of the dopants. Finally, the optimal quality AZOY thin-film was used as an emitter layer (or window layer) to form AZOY/n-Si heterojunction solar cells, which exhibited a stable conversion efficiency (η) of 9.4% under an AM1.5 illumination condition.

  18. Study of working pressure on the optoelectrical properties of Al–Y codoped ZnO thin-film deposited using DC magnetron sputtering for solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Feng-Hao [Institute of Microelectronics, Department of Electrical Engineering, National Cheng Kung University, No. 1, Dasyue Road, East District, Tainan City 701, Taiwan (China); Wang, Na-Fu; Tsai, Yu-Zen; Chuang, Ming-Chieh; Cheng, Yu-Song [Department of Electronic Engineering, Cheng Shiu University, 840 Chengcing Road, Niaosong District, Kaohsiung City 833, Taiwan (China); Houng, Mau-Phon, E-mail: mphoung@eembox.ncku.edu.tw [Institute of Microelectronics, Department of Electrical Engineering, National Cheng Kung University, No. 1, Dasyue Road, East District, Tainan City 701, Taiwan (China)

    2013-09-01

    Low cost transparent conductive Al–Y codoped ZnO (AZOY) thin-films were prepared on a glass substrate using a DC magnetron sputtering technique with various working pressures in the range of 5–13 mTorr. The relationship among the structural, electrical, and optical properties of sputtered AZOY films was studied as a function of working pressure. The XRD measurements show that the crystallinity of the films degraded as the working gas pressure increased. The AZOY thin-film deposited at a working pressure of 5 mTorr exhibited the lowest electrical resistivity of 4.3 × 10{sup −4} Ω cm, carrier mobility of 30 cm{sup 2}/V s, highest carrier concentration of 4.9 × 10{sup 20} cm{sup −3}, and high transmittance in the visible region (400–800 nm) of approximately 90%. Compared with Al doped ZnO (AZO) thin-films deposited using DC or RF magnetron sputtering methods, a high carrier mobility was observed in our AZOY thin-films. This result can be used to effectively decrease the absorption of near infrared-rays in solar cell applications. The mechanisms are attributed to the larger transition energy between Ar atoms and sputtering particles and the size compensation of the dopants. Finally, the optimal quality AZOY thin-film was used as an emitter layer (or window layer) to form AZOY/n-Si heterojunction solar cells, which exhibited a stable conversion efficiency (η) of 9.4% under an AM1.5 illumination condition.

  19. Origin of high carrier mobility and low residual stress in RF superimposed DC sputtered Al doped ZnO thin film for next generation flexible devices

    Science.gov (United States)

    Kumar, Naveen; Dubey, Ashish; Bahrami, Behzad; Venkatesan, S.; Qiao, Qiquan; Kumar, Mukesh

    2018-04-01

    In this work, the energy and flux of high energetic ions were controlled by RF superimposed DC sputtering process to increase the grain size and suppress grain boundary potential with minimum residual stress in Al doped ZnO (AZO) thin film. AZO thin films were deposited at different RF/(RF + DC) ratios by keeping total power same and were investigated for their electrical, optical, structural and nanoscale grain boundaries potential. All AZO thin film showed high crystallinity and orientation along (002) with peak shift as RF/(RF + DC) ratio increased from 0.0, pure DC, to 1.0, pure RF. This peak shift was correlated with high residual stress in as-grown thin film. AZO thin film grown at mixed RF/(RF + DC) of 0.75 showed high electron mobility, low residual stress and large crystallite size in comparison to other AZO thin films. The nanoscale grain boundary potential was mapped using Kelvin Probe Force Microscopy in all AZO thin film and it was observed that carrier mobility is controlled not only by grains size but also by grain boundary potential. The XPS analysis confirms the variation in oxygen vacancies and zinc interstitials which explain the origin of low grain boundaries potential and high carrier mobility in AZO thin film deposited at 0.75 RF/(RF + DC) ratio. This study proposes a new way to control the grain size and grain boundary potential to further tune the optoelectronic-mechanical properties of AZO thin films for next generation flexible and optoelectronic devices.

  20. Studies on morphology, electrical and optical characteristics of Al-doped ZnO thin films grown by atomic layer deposition

    Science.gov (United States)

    Chen, Li; Chen, Xinliang; Zhou, Zhongxin; Guo, Sheng; Zhao, Ying; Zhang, Xiaodan

    2018-03-01

    Al doped ZnO (AZO) films deposited on glass substrates through the atomic layer deposition (ALD) technique are investigated with various temperatures from 100 to 250 °C and different Zn : Al cycle ratios from 20 : 0 to 20 : 3. Surface morphology, structure, optical and electrical properties of obtained AZO films are studied in detail. The Al composition of the AZO films is varied by controlling the ratio of Zn : Al. We achieve an excellent AZO thin film with a resistivity of 2.14 × 10‑3 Ω·cm and high optical transmittance deposited at 150 °C with 20 : 2 Zn : Al cycle ratio. This kind of AZO thin films exhibit great potential for optoelectronics device application. Project supported by the State Key Development Program for Basic Research of China (Nos. 2011CBA00706, 2011CBA00707) and the Tianjin Applied Basic Research Project and Cutting-Edge Technology Research Plan (No. 13JCZDJC26900).

  1. Effect of Sn-doped on microstructural and optical properties of ZnO thin films deposited by sol-gel method

    International Nuclear Information System (INIS)

    Tsay, C.-Y.; Cheng, H.-C.; Tung, Y.-T.; Tuan, W.-H.; Lin, C.-K.

    2008-01-01

    In this study, transparent thin films of Sn-doped ZnO (ZnO:Sn) were deposited onto alkali-free glass substrates by a sol-gel method; the effect of Sn doping on crystallinity, microstructural and optical properties was investigated. The atomic percentages of dopant in ZnO-based sols were Sn/Zn = 0, 1, 2, 3, and 5 at.%. The as-deposited films were pre-heated at 300 deg. C for 10 min and then annealed in air at 500 deg. C for 1 h. The results show that Sn-doped ZnO thin films demonstrate obviously improved surface roughness, enhanced transmittance in the 400-600 nm wavelength range and reduced average crystallite size. Among all of the annealed ZnO-based films in this study, films doped with 2 at.% Sn concentration exhibited the best properties, namely an average transmittance of 90%, an RMS roughness value of 1.92 nm and a resistivity of 9.3 x 10 2 Ω-cm

  2. Effect of the substrate temperature and acidity of the spray solution on the physical properties of F-doped ZnO thin films deposited by chemical spray

    Energy Technology Data Exchange (ETDEWEB)

    De la L. Olvera, M.; Maldonado, A.; Asomoza, R. [Depto de Ingenieria Electrica, CINVESTAV-IPN, Apdo. Postal 14-70, D.F. 07000 Mexico (Mexico); Melendez-Lira, M. [Depto de Fisica, CINVESTAV-IPN, Apdo. Postal 14-740, D.F. 07000 Mexico (Mexico)

    2002-01-31

    F-doped ZnO thin films were prepared by using the spray pyrolysis technique. The dependence of the electrical, optical, structural and morphological properties on the substrate temperature and spray solution acidity was studied. Additionally, aging of the spray solution presents a clear effect on the resistivity of ZnO thin films. The best films obtained show a resistivity, mobility and carrier concentration of the order of 1.5x10{sup -2}{omega}cm, 6cm{sup 2}/Vs and 2x10{sup 19}cm{sup -3}, respectively. Wurtzite hexagonal structure, with a preferential growth along the [002] direction for all substrate temperatures and acidities used, was obtained. From scanning electron microscopy and atomic force microscopy analysis, it was determined that the grain size of the films decreases and its homogeneity increases when the acidity of the starting solution is increased. High optical transmittances, in the order of 90%, were obtained in all the cases.

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

    Science.gov (United States)

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

    2017-05-01

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

  4. Nitrogen doping of ZnO thin films grown by plasma-assisted pulsed-laser deposition

    Czech Academy of Sciences Publication Activity Database

    Novotný, Michal; Duclére, J.-R.; McGlynn, E.; Henry, M.O.; O´Haire, R.; Mosnier, J.-P.

    2007-01-01

    Roč. 59, - (2007), s. 505-509 ISSN 0953-8984 Institutional research plan: CEZ:AV0Z10100522 Keywords : pulsed laser deposition * ZnO * doping * electron cyclotron resonance Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.886, year: 2007

  5. 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.

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

    International Nuclear Information System (INIS)

    Malek, M.F.; Mamat, M.H.; Khusaimi, Z.; Sahdan, M.Z.; Musa, M.Z.; Zainun, A.R.; Suriani, A.B.; Md Sin, N.D.; Abd Hamid, S.B.; Rusop, M.

    2014-01-01

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

  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. Synthesis of ZnO Nanoparticles to Fabricate a Mask-Free Thin-Film Transistor by Inkjet Printing

    Directory of Open Access Journals (Sweden)

    Chao-Te Liu

    2012-01-01

    Full Text Available We report a low-cost, mask-free, reduced material wastage, deposited technology using transparent, directly printable, air-stable semiconductor slurries and dielectric solutions. We have demonstrate an emerging process for fabricating printable transistors with ZnO nanoparticles as the active channel and poly(4-vinylphenol (PVP matrix as the gate dielectric, respectively, and the inkjet-printed ZnO TFTs have shown to exhibit the carrier mobility of 0.69 cm2/Vs and the threshold voltage of 25.5 V. We suggest that the printable materials and the printing technology enable the use of all-printed low-cost flexible displays and other transparent electronic applications.

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

    Directory of Open Access Journals (Sweden)

    Parta Mitra

    2009-09-01

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

  10. Photocatalytic activity of V doped ZnO nanoparticles thin films for the removal of 2- chlorophenol from the aquatic environment under natural sunlight exposure.

    Science.gov (United States)

    Salah, Numan; Hameed, A; Aslam, M; Babkair, Saeed S; Bahabri, F S

    2016-07-15

    Vanadium doped ZnO powders were used as precursors to deposit thin films of V(5+) incorporated ZnO nanoparticles on glass substrates by the pulsed laser deposition technique. The observed variations in Raman signals, visible region shift in the diffuse reflectance spectra along with a small shift in the (101) reflections of the X-ray diffraction (XRD) confirmed the insertion of V(5+) ions in ZnO lattice. No other additional reflection in the XRD results other than ZnO further endorsed the occupation of lattice positions by V entities rather than independent oxide formation. The asymmetric XPS peaks of Zn2p and V2p core levels confirmed the existence of both in the vicinity. The existence of minimal proportion of V(3+) along with V(5+) states varied the alteration of the oxidation states V in the synthetic route. The SEM images at various resolutions displayed the uniform distribution identical nanoparticles without the presence of additional phases in the deposited films. The SEM cross-section measurements revealed the uniform thickness of ∼90 nm of each film, whereas the surface studies of the films were performed by AFM. The as-synthesized films were tested for photocatalytic activity in sunlight illumination for the removal of 2-chlorophenol. The unique feature of the study was the estimation of the photocatalytic activity 20 ppm of 2-chlorophenol by exposing the low exposed area. The degradation of the substrate was measured by liquid phase UV-vis spectroscopy, whereas total organic carbon measurement revealed the mineralization of the substrate. The released Cl(-) ions were also measured by ion chromatography. The estimated flatband potentials and pHzpc values of the V doped materials, by Mott-Schottky analysis and zeta potential measurements respectively, were correlated with the photocatalytic activity. The kinetics of the photocatalytic degradation/mineralization process was estimated and results were correlated with the plausible mechanism. Copyright

  11. Annealing effects on electrical and optical properties of ZnO thin-film samples deposited by radio frequency-magnetron sputtering on GaAs (001) substrates

    International Nuclear Information System (INIS)

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

    2007-01-01

    The effects of thermal annealing on Hall-effect measurement and photoluminescence (PL) from undoped n-type ZnO/GaAs thin-film samples have been studied. The evolutions of carrier concentration, electrical resistivity, and PL spectrum at various annealing conditions reveal that the dominant mechanism that affects the electrical and PL properties is dependent on the amount of thermal energy and the ambient pressure applied during the annealing process. At low annealing temperatures, annihilation of native defects is dominant in reducing the carrier concentration and weakening the low-energy tail of the main PL peak, while the GaAs substrate plays only a minor role in carrier compensations. For the higher temperatures, diffusion of Ga atoms from the GaAs substrate into ZnO film leads to a more n-type conduction of the sample. As a result, the PL exhibits a high-energy tail due to the high-level doping

  12. Morphological variations of Mn-doped ZnO dilute magnetic semiconductors thin films grown by succesive ionic layer by adsorption reaction method.

    Science.gov (United States)

    Balamurali, Subramanian; Chandramohan, Rathinam; Karunakaran, Marimuthu; Mahalingam, Thayan; Parameswaran, Padmanaban; Suryamurthy, Nagamani; Sukumar, Arcod Anandhakrishnan

    2013-07-01

    Transparent conducting Mn-doped ZnO thin films have been prepared by successive ionic layer by adsorption reaction (SILAR) method. The deposition conditions have been optimized based on their structure and on the formation of smoothness, adherence, and stoichiometry. The results of the studies by X-ray diffraction, scanning electron microscope (SEM), reveal the varieties of structural and morphological modifications feasible with SILAR method. The X-ray diffraction patterns confirm that the ZnO:Mn has wurtzite structure. The interesting morphological variations with dopant concentration are observed and discussed. The films' quality is comparable with those grown with physical methods and is suitable for spintronic applications. Copyright © 2013 Wiley Periodicals, Inc.

  13. Physical Properties of ZnO Thin Films Codoped with Titanium and Hydrogen Prepared by RF Magnetron Sputtering with Different Substrate Temperatures

    Directory of Open Access Journals (Sweden)

    Fang-Hsing Wang

    2015-01-01

    Full Text Available Transparent conducting titanium-doped zinc oxide (TZO thin films were prepared on glass substrates by RF magnetron sputtering using 1.5 wt% TiO2-doped ZnO as the target. Electrical, structural, and optical properties of films were investigated as a function of H2/(Ar + H2 flow ratios (RH and substrate temperatures (TS. The optimal RH value for achieving high conducting TZO:H thin film decreased from 10% to 1% when TS increased from RT to 300°C. The lowest resistivity of 9.2×10-4 Ω-cm was obtained as TS=100°C and RH=7.5%. X-ray diffraction patterns showed that all of TZO:H films had a hexagonal wurtzite structure with a preferred orientation in the (002 direction. Atomic force microscopy analysis revealed that the film surface roughness increased with increasing RH. The average visible transmittance decreased with increasing RH for the RT-deposited film, while it had not considerably changed with different RH for the 300°C-deposited films. The optical bandgap increased as RH increased, which is consistent with the Burstein-Moss effect. The figure of merits indicated that TS=100°C and RH=7.5% were optimal conditions for TZO thin films as transparent conducting electrode applications.

  14. Growth stimulation of Bacillus cereus and Pseudomonas putida using nanostructured ZnO thin film as transducer element

    Energy Technology Data Exchange (ETDEWEB)

    Loukanov, Alexandre, E-mail: loukanov@mail.saitama-u.ac.jp [Saitama University, Department of Chemistry, Faculty of Science (Japan); Filipov, Chavdar [University of Forestry, Department of Infectious pathology, hygiene, technology and control of food stuffs of animal origin, Faculty of Veterinary Medicine (Bulgaria); Valcheva, Violeta [Bulgarian Academy of Science, Department of Infectious Diseases, Institute of microbiology (Bulgaria); Lecheva, Marta [University of Mining and Geology “St. Ivan Rilski”, Laboratory of Engineering NanoBiotechnology, Department of Engineering Geoecology (Bulgaria); Emin, Saim [University of Nova Gorica, Materials Research Laboratory (Slovenia)

    2015-04-15

    The semiconductor zinc oxide nanomaterial (ZnO or ZnO:H) is widely used in advanced biosensor technology for the design of highly-sensitive detector elements for various applications. In the attempt to evaluate its effect on common microorganisms, two types of nanostructured transducer films have been used (average diameter 600–1000 nm). They have been prepared by using both wet sol–gel method and magnetron sputtering. Their polycrystalline structure and specific surface features have been analyzed by X-ray diffraction (XRD), scanning electron microscope, and atomic force microscope. The assessment of growth stimulation of bacteria was determined using epifluorescent microscope by cell staining with Live/Dead BacLight kit. In our experiments, the growth stimulation of Gram-positive and Gram-negative bacteria on nanostructured ZnO film is demonstrated by Bacillus cereus and Pseudomonas putida. These two bacterial species have been selected, because they are well known and studied in biosensor technologies, with structural difference of their cell walls. These pathogens are easy for with common source in the liquid food or some commercial products. Our data has revealed that the method of transducer film preparation influences strongly bacterial inhibition and division. These results present the transforming signal precisely, when ZnO is used in biosensor applications.

  15. Growth stimulation of Bacillus cereus and Pseudomonas putida using nanostructured ZnO thin film as transducer element

    Science.gov (United States)

    Loukanov, Alexandre; Filipov, Chavdar; Valcheva, Violeta; Lecheva, Marta; Emin, Saim

    2015-04-01

    The semiconductor zinc oxide nanomaterial (ZnO or ZnO:H) is widely used in advanced biosensor technology for the design of highly-sensitive detector elements for various applications. In the attempt to evaluate its effect on common microorganisms, two types of nanostructured transducer films have been used (average diameter 600-1000 nm). They have been prepared by using both wet sol-gel method and magnetron sputtering. Their polycrystalline structure and specific surface features have been analyzed by X-ray diffraction (XRD), scanning electron microscope, and atomic force microscope. The assessment of growth stimulation of bacteria was determined using epifluorescent microscope by cell staining with Live/Dead BacLight kit. In our experiments, the growth stimulation of Gram-positive and Gram-negative bacteria on nanostructured ZnO film is demonstrated by Bacillus cereus and Pseudomonas putida. These two bacterial species have been selected, because they are well known and studied in biosensor technologies, with structural difference of their cell walls. These pathogens are easy for with common source in the liquid food or some commercial products. Our data has revealed that the method of transducer film preparation influences strongly bacterial inhibition and division. These results present the transforming signal precisely, when ZnO is used in biosensor applications.

  16. Photoluminescence and electrochemical properties of transparent CeO{sub 2}-ZnO nanocomposite thin films prepared by Pechini method

    Energy Technology Data Exchange (ETDEWEB)

    Sani, Z.K.; Ghodsi, F.E.; Mazloom, J. [University of Guilan, Department of Physics, Faculty of Science, Namjoo Ave, P.O. Box 41335-1914, Rasht (Iran, Islamic Republic of)

    2017-02-15

    Nanocomposite thin films of CeO{sub 2}-ZnO with different molar ratios of Zn/Ce (=0, 0.25, 0.5, 0.75 and 1) were prepared by the Pechini sol-gel route. Various spectroscopic and electrochemical techniques were applied to investigate the films. XRD patterns of all the samples exhibited the peaks corresponding to cubic fluorite structure of ceria and the (101) and (103) peaks of ZnO with hexagonal structure was just observed in the sample with molar ratio of 1. EDS confirmed the presence of constituent of element in the samples. FESEM images of the films showed a surface composed of nanograins. AFM analysis revealed that root mean square roughness was enhanced as molar ratio of Zn/Ce increased. Moreover, fractal dimension of surfaces were calculated by cube counting approach. Optical measurements indicated that the film with molar ratio of 1 has the highest transmission and lowest reflectivity. The optical band gap values varied between 2.95 and 3.42 eV. The compositional dependence of refractive index and extinction coefficient were reported. The UV and blue emission appeared in PL spectra. The highest photoluminescence emission intensity was observed in the 1:1 molar ratio sample. The cyclic voltammetry measurements indicated the highest charge density (9.75 mC cm{sup -2}) and diffusion coefficient (3.507 x 10{sup -17} cm{sup 2} s{sup -1}) belonged to the Ce/Zn (1:1) thin film. (orig.)

  17. Characterization of ZnO Interlayers for Organic Solar Cells: Correlation of Electrochemical Properties with Thin-Film Morphology and Device Performance.

    Science.gov (United States)

    Ou, Kai-Lin; Ehamparam, Ramanan; MacDonald, Gordon; Stubhan, Tobias; Wu, Xin; Shallcross, R Clayton; Richards, Robin; Brabec, Christoph J; Saavedra, S Scott; Armstrong, Neal R

    2016-08-03

    This report focuses on the evaluation of the electrochemical properties of both solution-deposited sol-gel (sg-ZnO) and sputtered (sp-ZnO) zinc oxide thin films, intended for use as electron-collecting interlayers in organic solar cells (OPVs). In the electrochemical studies (voltammetric and impedance studies), we used indium-tin oxide (ITO) over coated with either sg-ZnO or sp-ZnO interlayers, in contact with either plain electrolyte solutions, or solutions with probe redox couples. The electroactive area of exposed ITO under the ZnO interlayer was estimated by characterizing the electrochemical response of just the oxide interlayer and the charge transfer resistance from solutions with the probe redox couples. Compared to bare ITO, the effective electroactive area of ITO under sg-ZnO films was ca. 70%, 10%, and 0.3% for 40, 80, and 120 nm sg-ZnO films. More compact sp-ZnO films required only 30 nm thicknesses to achieve an effective electroactive ITO area of ca. 0.02%. We also examined the electrochemical responses of these same ITO/ZnO heterojunctions overcoated with device thickness pure poly(3-hexylthiophehe) (P3HT), and donor/acceptor blended active layers (P3HT:PCBM). Voltammetric oxidation/reduction of pure P3HT thin films on ZnO/ITO contacts showed that pinhole pathways exist in ZnO films that permit dark oxidation (ITO hole injection into P3HT). In P3HT:PCBM active layers, however, the electrochemical activity for P3HT oxidation is greatly attenuated, suggesting PCBM enrichment near the ZnO interface, effectively blocking P3HT interaction with the ITO contact. The shunt resistance, obtained from dark current-voltage behavior in full P3HT/PCBM OPVs, was dependent on both (i) the porosity of the sg-ZnO or sp-ZnO films (as revealed by probe molecule electrochemistry) and (ii) the apparent enrichment of PCBM at ZnO/P3HT:PCBM interfaces, both effects conveniently revealed by electrochemical characterization. We anticipate that these approaches will be

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  19. Self-compensation in ZnO thin films: An insight from X-ray photoelectron spectroscopy, Raman spectroscopy and time-of-flight secondary ion mass spectroscopy analyses

    International Nuclear Information System (INIS)

    Saw, K.G.; Ibrahim, K.; Lim, Y.T.; Chai, M.K.

    2007-01-01

    As-grown ZnO typically exhibits n-type conductivity and the difficulty of synthesizing p-type ZnO for the realization of ZnO-based optoelectronic devices is mainly due to the compensation effect of a large background n-type carrier concentration. The cause of this self-compensation effect has not been conclusively identified although oxygen vacancies, zinc interstitials and hydrogen have been suggested. In this work, typical n-type ZnO thin films were prepared by sputtering and investigated using X-ray photoelectron spectroscopy, Raman spectroscopy and time-of-flight secondary ion mass spectroscopy to gain an insight on the possible cause of the self-compensation effect. The analyses found that the native defect that most likely behaved as the donor was zinc interstitial but some contribution of n-type conductivity could also come from the electronegative carbonates or hydrogen carbonates incorporated in the ZnO thin films

  20. Effect of growth interruption on the crystalline quality and electrical properties of Ga-doped ZnO thin film deposited on quartz substrate by magnetron sputtering

    International Nuclear Information System (INIS)

    Lee, Geun-Hyoung

    2013-01-01

    Ga-doped ZnO(GZO) thin films were deposited on the quartz substrate by magnetron sputtering system with growth interruption technique. As the number of interruptions and interruption time increased, the carrier concentration and Hall mobility in GZO films significantly increased. As a result, the resistivity of GZO films decreased. The optical transmittance of GZO films also increased with the number of interruption and interruption time. The transmittance showed over 90% in visual region. Atomic force microscopy measurement showed that the film surface became smoother with an increase of the number of interruption. In addition, the crystalline quality and electrical properties of GZO films were more improved when the growth interruption was employed with a temperature gradient. - Highlights: • Ga-doped ZnO thin films were deposited with growth interruption technique. • The crystallinity of the films was improved with the number of interruptions. • The crystallinity of the films was improved as the interruption time increased. • The growth interruption with a temperature gradient more improved the film quality

  1. Suppression effect of silicon (Si on Er3+ 1.54μm excitation in ZnO thin films

    Directory of Open Access Journals (Sweden)

    Bo Xu

    2016-08-01

    Full Text Available We have investigated the photoluminescence (PL characteristics of ZnO:Er thin films on Si (100 single crystal and SiO2-on-silicon (SiO2 substrates, synthesized by radio frequency magnetron sputtering. Rutherford backscattering/channeling spectrometry (RBS, X-ray diffraction (XRD and atomic force microscope (AFM were used to analyze the properties of thin films. The diffusion depth profiles of Si were determined by second ion mass spectrometry (SIMS. Infrared spectra were obtained from the spectrometer and related instruments. Compared with the results at room temperature (RT, PL (1.54μm intensity increased when samples were annealed at 250°C and decreased when at 550°C. A new peak at 1.15μm from silicon (Si appeared in 550°C samples. The Si dopants in ZnO film, either through the diffusion of Si from the substrate or ambient, directly absorbed the energy of pumping light and resulted in the suppression of Er3+ 1.54μm excitation. Furthermore, the energy transmission efficiency between Si and Er3+ was very low when compared with silicon nanocrystal (Si-NC. Both made the PL (1.54μm intensity decrease. All the data in experiments proved the negative effects of Si dopants on PL at 1.54μm. And further research is going on.

  2. The preparation of Zn-ferrite epitaxial thin film from epitaxial Fe3O4:ZnO multilayers by ion beam sputtering deposition

    International Nuclear Information System (INIS)

    Su, Hui-Chia; Dai, Jeng-Yi; Liao, Yen-Fa; Wu, Yu-Han; Huang, J.C.A.; Lee, Chih-Hao

    2010-01-01

    A new method to grow a well-ordered epitaxial ZnFe 2 O 4 thin film on Al 2 O 3 (0001) substrate is described in this work. The samples were made by annealing the ZnO/Fe 3 O 4 multilayer which was grown with low energy ion beam sputtering deposition. Both the Fe 3 O 4 and ZnO layers were found grown epitaxially at low temperature and an epitaxial ZnFe 2 O 4 thin film was formed after annealing at 1000 o C. X-ray diffraction shows the ZnFe 2 O 4 film is grown with an orientation of ZnFe 2 O 4 (111)//Al 2 O 3 (0001) and ZnFe 2 O 4 (1-10)//Al 2 O 3 (11-20). X-ray absorption spectroscopy studies show that Zn 2+ atoms replace the tetrahedral Fe 2+ atoms in Fe 3 O 4 during the annealing. The magnetic properties measured by vibrating sample magnetometer show that the saturation magnetization of ZnFe 2 O 4 grown from ZnO/Fe 3 O 4 multilayer reaches the bulk value after the annealing process.

  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. Effect of an Sb-Doped SnO2 Support on the CO-Tolerance of Pt2Ru3 Nanocatalysts for Residential Fuel Cells

    Directory of Open Access Journals (Sweden)

    Yoshiyuki Ogihara

    2016-09-01

    Full Text Available We prepared monodisperse Pt2Ru3 nanoparticles supported on carbon black and Sb-doped SnO2 (denoted as Pt2Ru3/CB and Pt2Ru3/Sb-SnO2 with identical alloy composition and particle size distribution by the nanocapsule method. The activities for the hydrogen oxidation reaction (HOR of these anode catalysts were examined in H2-saturated 0.1 M HClO4 solution in both the presence and absence of carbon monoxide by use of a channel flow electrode at 70 °C. It was found that the CO-tolerant HOR mass activity at 0.02 V versus a reversible hydrogen electrode (RHE on the Pt2Ru3/Sb-SnO2 electrode was higher than that at the Pt2Ru3/CB electrode in 0.1 M HClO4 solution saturated with 1000 ppm CO (H2-balance. The CO tolerance mechanism of these catalysts was investigated by in situ attenuated total reflection Fourier transform infrared reflection-adsorption spectroscopy (ATR-FTIRAS in 1% CO/H2-saturated 0.1 M HClO4 solution at 60 °C. It was found, for the Pt2Ru3/Sb-SnO2 catalyst, that the band intensity of CO linearly adsorbed (COL at step/edge sites was suppressed, together with a blueshift of the COL peak at terrace sites. On this surface, the HOR active sites were concluded to be more available than those on the CB-supported catalyst surface. The observed changes in the adsorption states of CO can be ascribed to an electronic modification effect by the Sb-SnO2 support.

  5. Physical and photo-electrochemical characterizations of ZnO thin films deposited by ultrasonic spray method: Application to HCrO{sub 4}{sup −} photoreduction

    Energy Technology Data Exchange (ETDEWEB)

    Zebbar, N. [Department of Materials and Compounds, Faculty of Physics, USTHB, BP 32, Algiers 16111 (Algeria); Trari, M., E-mail: solarchemistry@gmail.com [Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry, USTHB, BP 32, Algiers 16111 (Algeria); Doulache, M. [Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry, USTHB, BP 32, Algiers 16111 (Algeria); Boughelout, A.; Chabane, L. [Department of Materials and Compounds, Faculty of Physics, USTHB, BP 32, Algiers 16111 (Algeria)

    2014-02-15

    ZnO thin films, prepared by ultrasonic spray onto glass substrate, crystallize in the wurtzite structure. The XRD pattern shows preferential orientation along the [0 0 2] direction. The films deposited at 350 °C consist of 60 nm crystallites with an average thickness of ∼150 nm and SEM images show rough surface areas. The gap increases with increasing the temperature of the substrate and a value of 3.25 eV is obtained for films deposited at 350 °C. ZnO is nominally non-stochiometric and exhibits n-type conduction because of the native defects such as oxygen vacancies (V{sub O}) and/or interstitial zinc atom (Zn{sub i}) which act as donor shallows. The conductivity is thermally activated and obeys to an exponential type law with activation energy of 57 meV and an electron mobility of 7 cm{sup 2} V{sup −1} s{sup −1}. The capacitance-voltage (C{sup −2} V) measurement in acid electrolyte (pH ∼ 3) shows a linear behavior with a positive slope, characteristic of n-type conduction. A flat band potential of −0.70 V{sub SCE} and a donors density of 5.30 × 10{sup 16} cm{sup −3} are determined. The Nyquist plot exhibits two semicircles attributed to a capacitive behavior with a low density of surface states within the gap region. The centre is localized below the real axis with a depletion angle of 16° ascribed to a constant phase element (CPE) due to the roughness of the film. The energy band diagram assesses the potentiality of ZnO films for the photo-electrochemical conversion. As application, 94% of chromate (3.8 × 10{sup −4} M) is reduced after 6 h under sunlight (AM 1) with a quantum yield of 0.06% and the oxidation follows a first order kinetic.

  6. Modelling the growth of ZnO thin films by PVD methods and the effects of post-annealing.

    Science.gov (United States)

    Blackwell, Sabrina; Smith, Roger; Kenny, Steven D; Walls, John M; Sanz-Navarro, Carlos F

    2013-04-03

    Results are presented for modelling of the evaporation and magnetron sputter deposition of Zn(x)O(y) onto an O-terminated ZnO (0001¯) wurtzite surface. Growth was simulated through a combination of molecular dynamics (MD) and an on-the-fly kinetic Monte Carlo (otf-KMC) method, which finds diffusion pathways and barriers without prior knowledge of transitions. We examine the effects of varying experimental parameters, such as substrate bias, distribution of the deposition species and annealing temperature. It was found when comparing evaporation and sputtering growth that the latter process results in a denser and more crystalline structure, due to the higher deposition energy of the arriving species. The evaporation growth also exhibits more stacking faults than the sputtered growth. Post-annealing at 770 K did not allow complete recrystallization, resulting in films which still had stacking faults where monolayers formed in the zinc blende phase, whereas annealing at 920 K enabled the complete recrystallization of some films to the wurtzite structure. At the latter temperature atoms could also sometimes be locked in the zinc blende phase after annealing. When full recrystallization did not take place, both wurtzite and zinc blende phases were seen in the same layer, resulting in a phase boundary. Investigation of the various distributions of deposition species showed that, during evaporation, the best quality film resulted from a stoichiometric distribution where only ZnO clusters were deposited. During sputtering, however, the best quality film resulted from a slightly O rich distribution. Two stoichiometric distributions, one involving mainly ZnO clusters and the other involving mainly single species, showed that the distribution of deposition species makes a huge impact on the grown film. The deposition of predominantly single species causes many more O atoms at the surface to be sputtered or reflected, resulting in an O deficiency of up to 18% in the

  7. Enhanced separation efficiency of photoinduced charges for antimony-doped tin oxide (Sb-SnO{sub 2})/TiO{sub 2} heterojunction semiconductors with varied Sb doping concentration

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhen-Long [School of Physics and Electronics, Henan University, Kaifeng 475004 (China); Ma, Wen-Hai [School of Physical Education, Henan University, Kaifeng 475004 (China); Mao, Yan-Li, E-mail: ylmao1@163.com [School of Physics and Electronics, Henan University, Kaifeng 475004 (China); Institute for Computational Materials Science, Henan University, Kaifeng 475004 (China)

    2014-09-07

    In this paper, antimony-doped tin oxide (Sb-SnO{sub 2}) nanoparticles were synthesized with varied Sb doping concentration, and the Sb-SnO{sub 2}/TiO{sub 2} heterojunction semiconductors were prepared with Sb-SnO{sub 2} and TiO{sub 2}. The separation efficiency of photoinduced charges was characterized with surface photovoltage (SPV) technique. Compared with Sb-SnO{sub 2} and TiO{sub 2}, Sb-SnO{sub 2}/TiO{sub 2} presents an enhanced separation efficiency of photoinduced charges, and the SPV enhancements were estimated to be 1.40, 1.43, and 1.99 for Sb-SnO{sub 2}/TiO{sub 2} composed of Sb-SnO{sub 2} with the Sb doping concentration of 5%, 10%, and 15%, respectively. To understand the enhancement, the band structure of Sb-SnO{sub 2} and TiO{sub 2} in the heterojunction semiconductor was determined, and the conduction band offsets (CBO) between Sb-SnO{sub 2} and TiO{sub 2} were estimated to be 0.56, 0.64, and 0.98 eV for Sb-SnO{sub 2}/TiO{sub 2} composed of Sb-SnO{sub 2} with the Sb doping concentration of 5%, 10%, and 15%, respectively. These results indicate that the separation efficiency enhancement is resulting from the energy level matching, and the increase of enhancement is due to the rising of CBO.

  8. Origins of Highly Stable Al-evaporated Solution-processed ZnO Thin Film Transistors: Insights from Low Frequency and Random Telegraph Signal Noise

    Science.gov (United States)

    Kim, Joo Hyung; Kang, Tae Sung; Yang, Jung Yup; Hong, Jin Pyo

    2015-01-01

    One long-standing goal in the emerging field of flexible and transparent electronic devices is to meet the demand of key markets, such as enhanced output performance for metal oxide semiconductor thin film transistors (TFTs) prepared by a solution process. While solution-based fabrication techniques are cost-effective and ensure large-area coverage at low temperature, their utilization has the disadvantage of introducing large trap states into TFTs. Such states, the formation of which is induced by intrinsic defects initially produced during preparation, have a significant impact on electrical performance. Therefore, the ability to enhance the electrical characteristics of solution-processed TFTs, along with attaining a firm understanding of their physical nature, remains a key step towards extending their use. In this study, measurements of low-frequency noise and random telegraph signal noise are employed as generic alternative tools to examine the origins of enhanced output performance for solution-processed ZnO TFTs through the control of defect sites by Al evaporation. PMID:26525284

  9. Influence of the substrate and nitrogen amount on the microstructural and optical properties of thin r.f.-sputtered ZnO films treated by rapid thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Nicolescu, Madalina [Institute of Physical Chemistry, Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania); Anastasescu, Mihai, E-mail: manastasescu@icf.ro [Institute of Physical Chemistry, Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania); Preda, S.; Stroescu, H.; Stoica, M. [Institute of Physical Chemistry, Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania); Teodorescu, V.S. [National Institute of Material Physics, 105 bis Atomistilor Street, 077125 Bucharest-Magurele (Romania); Aperathitis, E.; Kampylafka, V. [FORTH-IESL, Crete (Greece); Modreanu, M. [Tyndall National Institute, University College Cork, Cork (Ireland); Zaharescu, M.; Gartner, M. [Institute of Physical Chemistry, Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer ZnO:N films are crystallized in hexagonal wurtzite phase (XRD), (0 0 2) oriented. Black-Right-Pointing-Pointer The presence of the Nitrogen in the RTA films is confirmed by EDX and XPS. Black-Right-Pointing-Pointer All ZnO:N films are highly transparent (over 80%) in VIS to NIR spectral range. Black-Right-Pointing-Pointer The frequency of the phonon modes, E{sub 1}(TO) and A{sub 1}(LO), were obtained by IRSE. - Abstract: N-doped ZnO (ZnO:N) thin films, intended to be used as one of the layers in solar cell applications were deposited by r.f. sputtering, using ZnN target (99.9% purity), on silicon and fused silica substrates. In the gas flow composition, Ar was kept constant (50%) and the O{sub 2}/N{sub 2} ratio was varied as: 40%/10%, 25%/25% and 10%/40%. After deposition, rapid thermal annealing (RTA) at 400 and 550 Degree-Sign C for 1 min in N{sub 2} ambient has been performed. The RTA impact on the optical and microstructural properties of ZnO:N thin films have been investigated by X-ray diffraction (XRD), atomic force microscopy (AFM), transmission electron microscopy (TEM) coupled with selected area electron diffraction (SAED) and energy dispersive X-ray spectroscopy (EDX), UV-vis-NIR spectroscopy, UV-vis-NIR spectroscopic ellipsometry (SE) and infrared ellipsometry (IR-SE). The as-deposited (ad) ZnO:N films are polycrystalline with preferentially oriented columnar crystals. After RTA we found ZnO:N films with improved crystallinity and fewer boundary defects. We report optical constants of ZnO:N from UV to IR spectral range as well as the infrared active phononic modes.

  10. On X-ray diffraction study of microstructure of ZnO thin nanocrystalline films with strong preferred grain orientation

    Czech Academy of Sciences Publication Activity Database

    Kužel, R.; Čížek, J.; Novotný, Michal

    44A, č. 1 (2013), s. 45-57 ISSN 1073-5623 R&D Projects: GA ČR(CZ) GAP108/11/0958 Institutional support: RVO:68378271 Keywords : zinc oxide thin film * X-ray diffraction * Mg0 * fused silica Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.730, year: 2013

  11. Effect of disorder on carrier transport in ZnO thin films grown by atomic layer deposition at different temperatures

    Science.gov (United States)

    Saha, D.; Das, Amit. K.; Ajimsha, R. S.; Misra, P.; Kukreja, L. M.

    2013-07-01

    We have grown ˜200 nm thick ZnO films on (0001) sapphire substrates using atomic layer deposition at different substrate temperatures ranging from ˜150 to 350 °C. X-ray diffraction and photoluminescence spectra of these films showed that crystalline and compositional native defects were strongly dependent on the substrate temperature. Room temperature Hall measurement showed that all the films were degenerate with carrier concentration exceeding the Mott's critical density nc required for metallic conduction. The lowest value of room temperature resistivity ˜3.6 × 10-3 Ω cm was achieved for the film deposited at ˜200 °C, which had an estimated carrier concentration ˜5.7 × 1019 cm-3 and mobility ˜30 cm2/V s. The films deposited both below and above ˜200 °C showed increased resistivity and decreased mobility presumably due to the intensified defects and deteriorated crystalline quality of these films. To investigate the effect of disorder on the underlying charge transport mechanisms in these films, the electrical resistivity was measured in the temperature range of ˜4.2 to 300 K. The films grown at ˜150, 300, and 350 °C were found to be semiconducting in the entire range of the measurement temperature due to the intensified disorder which impeded the metallic transport in these films. However, the films grown at ˜200 and 250 °C showed a transition from metallic to semiconducting transport behaviour at lower temperatures due to the reduced defects and improved crystalline quality of these films. The observed semiconducting behaviour below the transition temperature for these films could be well explained by considering quantum corrections to the Boltzmann conductivity which includes the effect of disorder induced weak localization and coulomb electron-electron interactions.

  12. Study of sputtered ZnO thin films on SiO2 and GaP substrates

    International Nuclear Information System (INIS)

    Brath, T.; Buc, D.; Kovac, J.; Hrnciar, V.; Caplovic, L.

    2011-01-01

    We have investigated n-ZnO polycrystalline thin films prepared on SiO 2 and p-GaP substrate using magnetron sputtering technique. The structural and electrical properties of these structures were studied. The measured parameters give promising results with a possibility to utilize n-ZnO/p-GaP heterostructure for application in the solar cells development especially in the field of nanostructures. The prepared structures will be a subject of further research. (authors)

  13. Oxygen deficiency effects on recombination lifetime and photoluminescence characteristics of ZnO thin films; correlation with crystal structure

    Energy Technology Data Exchange (ETDEWEB)

    Guer, Emre; Tuezemen, S. [Ataturk University, Art and Science Faculty, Physics Department, Erzurum (Turkey); Meral, Kadem; Onganer, Y. [Ataturk University, Art and Science Faculty, Chemistry Department, Erzurum (Turkey)

    2009-03-15

    The photoluminescence (PL), recombination lifetime (RL), and X-ray diffraction (XRD) spectra of the samples grown at various O{sub 2} fractions of 0.290 (Zn-rich), 0.585 (moderate), and 0.836 (O-rich) over the total pressures in the growth chamber were investigated. XRD measurements revealed that all the films show highly preferred (0002) orientation. The PL measurements exhibit different dominant emissions in the ultraviolet (UV), violet and blue regions for Zn-rich, moderate and O-rich samples, respectively. Well-known green emission and high intensity of free exciton (FX) transition has been observed in Zn-rich sample after the sample is annealed at vacuum probably due to the oxygen deficiencies. Annealing the moderate sample gives rise to the UV emission at energy of 3.263 eV similar to the observed PL emission spectrum for the Zn-rich thin film. O-rich thin film exhibits a 338 meV acceptor level above the valance band maximum, most probably related to zinc vacancy (V{sub Zn}). Free exciton RL measurements result in 568.23, 397.65, and 797.46 ps for Zn-rich, moderate, and O-rich thin films, respectively. A good correlation was found between crystallite size and the lifetime values. (orig.)

  14. Development of Boron-Doped ZnO Films with Novel Thin Zn-Rich Film and Their Application to Solar Cells

    Science.gov (United States)

    Hongsingthong, Aswin; Wada, Hidetoshi; Moriya, Yuki; Sichanugrist, Porponth; Konagai, Makoto

    2012-10-01

    In this paper, we report newly developed high-haze glass/zinc oxide (ZnO) substrates with low resistivity by a combination of unique etched soda-lime glass and bilayered ZnO films with a Zn-rich (oxygen-poor) layer. The high mobility and low resistivity of bilayered ZnO films could be obtained with Zn-rich conditions. By depositing the ZnO films onto textured glass substrates, the obtained films exhibit an excellent light-scattering property, while their electrical property is still good. Furthermore, the bilayered ZnO films with a Zn-rich layer did not negatively affect the transparency of the films. Employing the bilayered ZnO films with a Zn-rich layer and an rms roughness of about 274 nm as the front transparent conductive oxide (TCO) in hydrogenated amorphous silicon (a-Si:H) solar cells, we improved the performance and quantum efficiency (QE) of the fabricated solar cells, particularly in the short-wavelength region without the deterioration of open-circuit voltage or fill factor. Thus, the developed glass/bilayered ZnO film with a Zn-rich layer is a new promising material since its resistivity is low while its light-scattering property is still high.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-07-25

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

  16. Effect of boric acid composition on the properties of ZnO thin film nanotubes and the performance of dye-sensitized solar cell (DSSC)

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, M.Y.A., E-mail: mohd.yusri@ukm.edu.my; Roza, L.; Umar, A.A., E-mail: akrajas@ukm.edu.my; Salleh, M.M.

    2015-11-05

    The effect of boric acid (H{sub 3}BO{sub 3}) composition at constant concentration of hexamethylenetetramine (HMT) and zinc nitrate (Zn(NO{sub 3}){sub 2}) on the morphology, thickness, elemental composition, optical absorption, structure, photoluminescence of ZnO nanotubes has been investigated. The performance of the DSSC utilizing the ZnO samples has also been studied. It was found that the structure, thickness, elemental composition, optical absorption and morphology of ZnO nanostructure are significantly affected by the concentration of H{sub 3}BO{sub 3}. The diameter and thickness of ZnO nanotubes decreases as the composition of H{sub 3}BO{sub 3} increases. The DSSC utilizing ZnO nanotubes synthesized at 2 wt. % H{sub 3}BO{sub 3} performs the highest J{sub SC} and η of 2.67 mA cm{sup −2} and 0.29%, respectively. The highest performance of the device is due to the highest optical absorption of ZnO nanotubes sample and lowest charge interfacial resistance. - Graphical abstract: Nyquist plots of the DSSCs utilizing ZnO nanotubes prepared at various boric acid compositions. - Highlights: • Boron was doped into ZnO films by adding H{sub 3}BO{sub 3} into the growth solution. • Diameter and thickness of ZnO nanotubes decreases with the composition of H{sub 3}BO{sub 3}. • The DSSC performs the highest J{sub SC} and η of 2.67 mA cm{sup −2} and 0.29%, respectively. • This is due to high specific surface area and low charge interfacial resistance.

  17. Nano-Floating Gate Memory Devices Composed of ZnO Thin-Film Transistors on Flexible Plastics

    Directory of Open Access Journals (Sweden)

    Park Byoungjun

    2011-01-01

    Full Text Available Abstract Nano-floating gate memory devices were fabricated on a flexible plastic substrate by a low-temperature fabrication process. The memory characteristics of ZnO-based thin-film transistors with Al nanoparticles embedded in the gate oxides were investigated in this study. Their electron mobility was found to be 0.18 cm2/V·s and their on/off ratio was in the range of 104–105. The threshold voltages of the programmed and erased states were negligibly changed up to 103 cycles. The flexibility, memory properties, and low-temperature fabrication of the nano-floating gate memory devices described herein suggest that they have potential applications for future flexible integrated electronics.

  18. On the investigation of electronic defect states in ZnO thin films by space charge spectroscopy with optical excitation

    Science.gov (United States)

    Schmidt, Matthias; Wenckstern, Holger von; Pickenhain, Rainer; Grundmann, Marius

    2012-09-01

    Electronic defect states in a n-type conducting zinc oxide thin film sample were investigated by means of space charge spectroscopy focussing on levels in the midgap region as well as on hole traps. To overcome the experimental difficulties arising from the wide bandgap and the lack of p-type conduction, optical excitation was employed to measure the emission of trapped charge carriers from these levels. Therefore - besides deep-level transient spectroscopy measurements - photo-capacitance, optically chopped photo-current, minority carrier transient spectroscopy, and optical capacitance-voltage experiments were conducted. In doing so, a midgap level labelled T4, and hole traps labelled TH1 and TH2 were detected. In the case of T4 and TH1 the photo-ionisation cross-section spectra were determined.

  19. Obtaining strong ferromagnetism in diluted Gd-doped ZnO thin films through controlled Gd-defect complexes

    KAUST Repository

    Roqan, Iman S.

    2015-02-21

    We demonstrate the fabrication of reproducible long-range ferromagnetism (FM) in highly crystalline GdxZn1-xO thin films by controlling the defects. Films are grown on lattice-matched substrates by pulsed laser deposition at low oxygen pressures (≤25 mTorr) and low Gd concentrations (x ≤ 0.009). These films feature strong FM (10 μB per Gd atom) at room temperature. While films deposited at higher oxygen pressure do not exhibit FM, FM is recovered by post-annealing these films under vacuum. These findings reveal the contribution of oxygen deficiency defects to the long-range FM. We demonstrate the possible FM mechanisms, which are confirmed by density functional theory study, and show that Gd dopants are essential for establishing FM that is induced by intrinsic defects in these films.

  20. Experiment and prediction on thermal conductivity of Al2O3/ZnO ...

    Indian Academy of Sciences (India)

    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 ...

  1. Experiment and prediction on thermal conductivity of Al2O3/ZnO ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. 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 ...

  2. Experiment and prediction on thermal conductivity of Al 2 O 3 /ZnO ...

    Indian Academy of Sciences (India)

    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 ...

  3. 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

  4. Fast Classification of Meat Spoilage Markers Using Nanostructured ZnO Thin Films and Unsupervised Feature Learning

    Directory of Open Access Journals (Sweden)

    John Bosco Balaguru Rayappan

    2013-01-01

    Full Text Available This paper investigates a rapid and accurate detection system for spoilage in meat. We use unsupervised feature learning techniques (stacked restricted Boltzmann machines and auto-encoders that consider only the transient response from undoped zinc oxide, manganese-doped zinc oxide, and fluorine-doped zinc oxide in order to classify three categories: the type of thin film that is used, the type of gas, and the approximate ppm-level of the gas. These models mainly offer the advantage that features are learned from data instead of being hand-designed. We compare our results to a feature-based approach using samples with various ppm level of ethanol and trimethylamine (TMA that are good markers for meat spoilage. The result is that deep networks give a better and faster classification than the feature-based approach, and we thus conclude that the fine-tuning of our deep models are more efficient for this kind of multi-label classification task.

  5. Enhancement of hole-injection and power efficiency of organic light emitting devices using an ultra-thin ZnO buffer layer

    International Nuclear Information System (INIS)

    Huang, H.-H.; Chu, S.-Y.; Kao, P.-C.; Chen, Y.-C.; Yang, M.-R.; Tseng, Z.-L.

    2009-01-01

    The advantages of using an anode buffer layer of ZnO on the electro-optical properties of organic light emitting devices (OLEDs) are reported. ZnO powders were thermal-evaporated and then treated with ultra-violet (UV) ozone exposure to make the ZnO layers. The turn-on voltage of OLEDs decreased from 4 V (4.2 cd/m 2 ) to 3 V (3.4 cd/m 2 ) and the power efficiency increased from 2.7 lm/W to 4.7 lm/W when a 1-nm-thick ZnO layer was inserted between indium tin oxide (ITO) anodes and α-naphthylphenylbiphenyl diamine (NPB) hole-transporting layers. X-ray and ultra-violet photoelectron spectroscopy (XPS and UPS) results revealed the formation of the ZnO layer and showed that the work function increased by 0.59 eV when the ZnO/ITO layer was treated by UV-ozone for 20 min. The surface of the ZnO/ITO film became smoother than that of bare ITO film after the UV-ozone treatment. Thus, the hole-injection energy barrier was lowered by inserting an ZnO buffer layer, resulting in a decrease of the turn-on voltage and an increase of the power efficiency of OLEDs.

  6. Properties of low-temperature deposited ZnO thin films prepared by cathodic vacuum arc technology on different flexible substrates

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Cheng-Tang [Department of Mechanical and Electron-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung City 804, Taiwan (China); Yang, Ru-Yuan, E-mail: ryyang@mail.npust.edu.tw [Graduate Institute of Materials Engineering, National Pingtung University of Science and Technology, Pingtung County 912, Taiwan (China); Weng, Min-Hang [Medical Devices and Opto-Electronics Equipment Department, Metal Industries Research and Development Center, Kaohsiung City 821, Taiwan (China); Huang, Chien-Wei [Department of Mechanical and Electron-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung City 804, Taiwan (China)

    2013-07-31

    Un-doped zinc oxide (ZnO) films were deposited on three different substrates (polyethylene terephthalate (PET), polyvinyl butyral (PVB) and polyimide (PI)) at a low temperature (< 75 °C) by cathode vacuum arc deposition. The microstructure, optical and electrical properties of the deposited films were investigated and discussed. All the deposited films reveal a preferred orientation with the c-axis perpendicular to the substrate, and an average transmittance of over 85% in the visible region. The calculated optical band gaps are around 2.6, 3.14 and 3.18 eV, respectively, for the ZnO films deposited on the PI, PVB and PET substrates. The lowest resistivity and the highest Hall mobility are 5.31 × 10{sup −3} Ω-cm and 15.16 cm{sup 2}/V-s for the ZnO film deposited on the PET substrate. - Highlights: • Polyethylene terephthalate, polyvinyl butyral and polyimide were used as substrates. • ZnO films were prepared by cathodic arc plasma deposition. • ZnO films have different properties due to different substrates. • The microstructure control of ZnO film on polymer substrate is important.

  7. Trajectory effect on the properties of large area ZnO thin films deposited by atmospheric pressure plasma jet

    International Nuclear Information System (INIS)

    Juang, Jia-Yang; Chou, Tung-Sheng; Lin, Hsin-Tien; Chou, Yuan-Fang; Weng, Chih-Chiang

    2014-01-01

    Highlights: • We develop a cost-effective technique, atmosphere pressure plasma jet (APPJ), to deposit gallium-doped zinc oxide (GZO) films on large area glass substrates in atmosphere. • Scanning trajectory has a significant impact on the pattern of sheet resistance distribution. • The primary root cause of the nonuniformity is the annealing effect of the deposited films in air while the nozzle scans over the rest of the substrate. • Equivalent circuits models considering only the resistance increase due to air annealing cannot explain the unexpected rise of resistance in the center of the substrate for multiple-pass samples. • Measurements of residual stress, carrier concentration and Hall mobility reveal that the residual stress is another factor that results in nonuniform resistance distribution. - Abstract: Large area (117 mm × 185 mm) gallium-doped zinc oxide (GZO) films are prepared on glass substrates by atmospheric pressure plasma jet (APPJ) technique. The uniformity of material properties, in particular the electrical resistivity, of the deposited film is of great importance in reducing design complexity of the electron devices. We investigate the effects of scanning trajectory recipe (speed, pitch and number of passes) on structural and electrical properties of GZO thin films. We find that the trajectory has significant effects on the magnitude and uniformity of sheet resistance over the glass substrates. For single pass, the resistance appears higher at the starting part of spray, whereas, for cases of multiple passes, the highest resistance appears in the central part of the substrate. XRD, SEM, Hall measurement and residual stress are used to study the film properties and identify root causes of the nonuniform distribution of sheet resistance. We conclude that annealing time is the dominant root cause of the nonuniform resistance distribution, and other factors such as residual stress and structural characteristics may also have

  8. High-Performance Spray-Deposited Indium Doped ZnO Thin Film: Structural, Morphological, Electrical, Optical, and Photoluminescence Study

    Science.gov (United States)

    Asl, Hassan Zare; Rozati, Seyed Mohammad

    2018-03-01

    In this study, high-quality indium doped zinc oxide thin films were deposited using the spray pyrolysis technique, and the substrate temperature varied from 450°C to 550°C with steps of 25°C with the aim of investigating the effect of substrate temperature. It was found that as the temperature increased, the resistivity of the films decreased to the extent that it was as low as 5.34 × 10-3 Ω cm for the one deposited at 500°C; however, it slightly increased for the resulting film at 550°C. Although the carrier concentration mostly increased with temperature, it appeared that the carrier mobility was the parameter mainly governing the conductivity variation. In addition, the average transparency of the deposited films at 500°C, 525°C and 550°C was around 87% (400-800 nm), which makes them outstanding transparent conductive oxide films. Moreover, the crystallite size and strain of the resulting films were estimated via the Williamson-Hall method. The results revealed a considerable reduction in the crystallite size and strain up to 500°C followed by a rise at higher substrate temperature. Based on both the surface and cross-section field emission scanning electron microscope images, the film resulting at 500°C was highly compacted and crack free, which can explain the enlargement of the carrier mobility (10.9 cm2 V-1 s-1) in this film. Finally, a detailed photoluminescence study revealed several peaks in the spectrum and the variation of the two major peaks appeared to have correlation with the carrier concentration.

  9. Pressure controlled tunable magnetic, electrical and optical properties of (Cu, Li)-codoped ZnO thin films

    Science.gov (United States)

    Zhang, Liqiang; Lu, Bin; Ye, Zhizhen; Lu, Jianguo; Huang, Jingyun

    2013-09-01

    Zn0.989Cu0.01Li0.001O thin films have been deposited on c-plane sapphire substrates by pulsed laser deposition (PLD). The films deposited at 500 °C and the oxygen pressures (PO2) ranging from 0.04 to 40 Pa were of good crystallinity with a (0002) preferential orientation. Three conductivity regimes were observed for the films with varying the PO2. The n-type film obtained at 0.04 Pa had a low resistivity of 1.95×10-2 Ω cm, Hall mobility of 14.8 cm2 V-1 s-1, and carrier concentration of 2.16×1019 cm-3. The p-type Zn0.989Cu0.01Li0.001O film could achieve when oxygen ambient reached as high as 40 Pa and with a hole concentration of 1.12×1018 cm-3. Films grown at PO2 between 0.4 and 4 Pa commonly exhibited insulating behavior. All the Zn0.989Cu0.01Li0.001O films had a high transmittance above 80% in visible regions and the red-shift in optical band gap (Eg) happened as the PO2 increased. Magnetic measurements showed that only the film fabricated at 0.04 Pa with n-type conduction exhibited room temperature ferromagnetism (RTFM) of 0.25μB/Cu while others obtained at higher PO2 were paramagnetic. Oxygen vacancies (VO) are speculated that would play a crucial role for the ferromagnetic behavior observed.

  10. Comparative investigation on cation-cation (Al-Sn) and cation-anion (Al-F) co-doping in RF sputtered ZnO thin films: Mechanistic insight

    Energy Technology Data Exchange (ETDEWEB)

    Mallick, Arindam; Basak, Durga, E-mail: sspdb@iacs.res.in

    2017-07-15

    Highlights: • Comparative study on Al, Al-Sn and Al-F doped ZnO films has been carried out. • High transparent Al-F co-doped film shows three times enhanced carrier density. • Al-F co-doped film shows larger carrier relaxation time. • Al-Sn co-doped films shows carrier transport dominated by impurity scattering. • Al-F co-doped ZnO film can be applied as transparent electrode. - Abstract: Herein, we report a comparative mechanistic study on cation-cation (Al-Sn) and cation-anion (Al-F) co-doped nanocrystalline ZnO thin films grown on glass substrate by RF sputtering technique. Through detailed analyses of crystal structure, surface morphology, microstructure, UV-VIS-NIR transmission-reflection and electrical transport property, the inherent characteristics of the co-doped films were revealed and compared. All the nanocrystalline films retain the hexagonal wurtzite structure of ZnO and show transparency above 90% in the visible and NIR region. As opposed to expectation, Al-Sn (ATZO) co-doped film show no enhanced carrier concentration consistent with the probable formation of SnO{sub 2} clusters supported by the X-ray photoelectron spectroscopy study. Most interestingly, it has been found that Al-F (AFZO) co-doped film shows three times enhanced carrier concentration as compared to Al doped and Al-Sn co-doped films attaining a value of ∼9 × 10{sup 20} cm{sup −3} due to the respective cation and anion substitution. The carrier relaxation time increases in AFZO while it decreases significantly for ATZO film consistent with the concurrence of the impurity scattering in the latter.

  11. Enhanced electrochemical oxidation of synthetic dyeing wastewater using SnO2-Sb-doped TiO2-coated granular activated carbon electrodes with high hydroxyl radical yields

    International Nuclear Information System (INIS)

    Li, Xinyang; Wu, Yue; Zhu, Wei; Xue, Fangqing; Qian, Yi; Wang, Chengwen

    2016-01-01

    Highlights: • We study granular activated carbon (GAC) electrodes coated with catalysts. • GAC coated with ATOT demonstrates an impressive ·OH yield. • This electrode can be used in continuous-flow three-dimensional electrode reactors. • We use Rhodamine B as a model organic compound for removal. • The GAC/ATOT performs better than all other electrodes examined. - Abstract: In this study, granular activated carbon (GAC) coated with SnO 2 -Sb doped TiO 2 (GAC/ATOT) with a high hydroxyl radical (·OH) yield is prepared via the sol-gel method. This material is utilized as a granular electrode in a continuous-flow three-dimensional electrode reactor (CTDER) for the enhanced treatment of synthetic dyeing wastewater containing Rhodamine B (RhB). We then characterize the physical properties, electrochemical properties, and electrochemical oxidation performance of the granular electrode. The results show that using the GAC/ATOT electrode in a CTDER significantly enhances the chemical oxygen demand (COD) removal, decreases the energy consumption, and improves the current efficiency of the wastewater. This is primarily attributed to the higher catalytic activity of GAC/ATOT for ·OH production compared to that of other candidates, such as TiO 2 coated GAC (GAC/T), Sb doped SnO 2 coated GAC (GAC/ATO), and pure GAC. The mechanism of the enhanced electrochemical oxidation afforded by using GAC/ATOT indicates that the high ·OH yield in the reactor packed with GAC/ATOT electrodes contributes to the enhanced electrochemical oxidation performance with respect to organic compounds.

  12. On the deactivation of the dopant and electronic structure in reactively sputtered transparent Al-doped ZnO thin films

    International Nuclear Information System (INIS)

    Horwat, David; Jullien, Maud; Capon, Fabien; Pierson, Jean-Francois; Andersson, Joakim; Endrino, Jose Luis

    2010-01-01

    We report on the possible origin of electrical heterogeneities in 4 at% Al-doped ZnO (AZO) reactively sputtered films. It is found through the Zn L 3 and Al K edge x-ray absorption near-edge structure that a fraction of the Al dopant is deactivated by its positioning in octahedral conformation with oxygen. This fraction as well as the conductivity, optical bandgap and c-axis parameter of ZnO wurtzite are all found to depend on the sample position during deposition. The present results suggest the formation of a metastable Al 2 O 3 (ZnO) m homologous phase that degrades the electrical conductivity. (fast track communication)

  13. ZnO Films with Very High Haze Value for Use as Front Transparent Conductive Oxide Films in Thin-Film Silicon Solar Cells

    Science.gov (United States)

    Hongsingthong, Aswin; Krajangsang, Taweewat; Afdi Yunaz, Ihsanul; Miyajima, Shinsuke; Konagai, Makoto

    2010-05-01

    We successfully increased the haze value of zinc oxide (ZnO) films fabricated using metal-organic chemical vapor deposition (MOCVD) by conducting glass-substrate etching before film deposition. It was found that with increasing the glass treatment time, the surface morphology of ZnO films changed from conventional pyramid-like single texture to greater cauliflower-like multi texture. Further, the rms roughness and the haze value of the films increased remarkably. Using ZnO films with a high haze value as front transparent conductive oxide (TCO) films in hydrogenated microcrystalline silicon (µc-Si:H) solar cells, we improved the quantum efficiency of these cells particularly in the long-wavelength region.

  14. ZnO nanocrystals and allied materials

    CERN Document Server

    Okada, Tatsuo

    2014-01-01

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

  15. Comparative investigation on cation-cation (Al-Sn) and cation-anion (Al-F) co-doping in RF sputtered ZnO thin films: Mechanistic insight

    Science.gov (United States)

    Mallick, Arindam; Basak, Durga

    2017-07-01

    Herein, we report a comparative mechanistic study on cation-cation (Al-Sn) and cation-anion (Al-F) co-doped nanocrystalline ZnO thin films grown on glass substrate by RF sputtering technique. Through detailed analyses of crystal structure, surface morphology, microstructure, UV-VIS-NIR transmission-reflection and electrical transport property, the inherent characteristics of the co-doped films were revealed and compared. All the nanocrystalline films retain the hexagonal wurtzite structure of ZnO and show transparency above 90% in the visible and NIR region. As opposed to expectation, Al-Sn (ATZO) co-doped film show no enhanced carrier concentration consistent with the probable formation of SnO2 clusters supported by the X-ray photoelectron spectroscopy study. Most interestingly, it has been found that Al-F (AFZO) co-doped film shows three times enhanced carrier concentration as compared to Al doped and Al-Sn co-doped films attaining a value of ∼9 × 1020 cm-3 due to the respective cation and anion substitution. The carrier relaxation time increases in AFZO while it decreases significantly for ATZO film consistent with the concurrence of the impurity scattering in the latter.

  16. Influence of substrate temperature and oxygen/argon flow ratio on the electrical and optical properties of Ga-doped ZnO thin films prepared by rf magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sookjoo; Jeon, Jinho; Kim, Hyoun Woo; Lee, Chongmu [Department of Materials Science and Engineering, Inha University, Incheon, 402-751 (Korea); Lee, Jae Gab [School of Advanced Materials Engeneering, Kukmin University, Seoul 136-702 (Korea)

    2006-12-15

    Effects of substrate temperature and atmosphere on the electrical and optical properties of Ga-doped ZnO thin films deposited by rf magnetron sputtering were investigated. The electrical resistivity of Ga-doped ZnO (GZO) films decreases as the substrate temperature increases from room temperature to 300 C. A minimum resistivity of 3.3 x 10{sup -4} {omega}cm is obtained at 300 C and then the resistivity increases with a further increase in the substrate temperature to 400 C. This change in resistivity with the substrate temperature is related to the crystallinity of the GZO film. The resistivity nearly does not change with the O{sub 2}/Ar flow ratio, R for R<0.25 but increases rapidly with R for R>0.25. This change in resistivity with R is also related to crystallinity. The crystallinity is enhanced as R increases, but if the oxygen partial pressure is higher than a certain level (R=0.25{+-}0.10) gallium oxides precipitate at grain boundaries, which decrease both carrier concentration and mobility. Optical transmittance increases as R increases for R<0.75. This change in transmittance with R is related to changes in oxygen vacancy concentration and surface roughness with R. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Manufacturing of patterned ZnO films with application for ...

    Indian Academy of Sciences (India)

    Patterned thin films, ZnO, are successfully prepared on glass substrates by the sol–gel method using dip-coating technique. The films, formed of ZnO nanocrystallites with hexagonal crystal structure, are characterized by means of scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction.

  18. Manufacturing of patterned ZnO films with application for ...

    Indian Academy of Sciences (India)

    Administrator

    Faculty of Chemistry, University of Sofia, 1 James Bourchier Blvd., 1164 Sofia, Bulgaria. MS received 30 December 2008; revised 11 July 2009. Abstract. 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 ...

  19. Enhancing Optical and Electrical Properties of La- and Al-Codoped ZnO Thin Films Prepared by Sol-Gel Method -La Codoping Effect.

    Science.gov (United States)

    He-Yan, Hai

    2017-07-10

    Backgroud: The transparent conductive ZnO film is widely used in solar cell. Enhancing the transmittance and electrical conductivity of the films is attracting many attentions to improve cell efficiency. This work focuses on the fabrication and potential application of the various cation-doped ZnO materials in recent patents and literature and then presents the La codoping effects of Al-doped ZnO films. Films were deposited by a sol-gel route and characterized by various techniques including X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, UV-vis and luminescent spectroscopies, and electrical conduction analysis. The UV-vis. transmittance and band gap increased and then decreased, whereas the resistivity decreased and then slightly increased with the increase in La/Al ratio. The La/Al ratio of 0.0105 led to a maximal transmittance, a widest band gap, and a minimal resistivity. The films also illustrated a near band gap emission and some intrinsic defect-related emissions with varied intensity with La/Al ratio. This work reveal that the electrical and optical properties of the ZnO:Al films can be well enhanced by La codoping. This is significant to the applications of the ZnO:Al materials. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  20. Sb-Doped SnO2 Nanorods Underlayer Effect to the α-Fe2 O3 Nanorods Sheathed with TiO2 for Enhanced Photoelectrochemical Water Splitting.

    Science.gov (United States)

    Han, Hyungkyu; Kment, Stepan; Karlicky, Frantisek; Wang, Lei; Naldoni, Alberto; Schmuki, Patrik; Zboril, Radek

    2018-04-14

    Here, a Sb-doped SnO 2 (ATO) nanorod underneath an α-Fe 2 O 3 nanorod sheathed with TiO 2 for photoelectrochemical (PEC) water splitting is reported. The experimental results, corroborated with theoretical analysis, demonstrate that the ATO nanorod underlayer effect on the α-Fe 2 O 3 nanorod sheathed with TiO 2 enhances the PEC water splitting performance. The growth of the well-defined ATO nanorods is reported as a conductive underlayer to improve α-Fe 2 O 3 PEC water oxidation performance. The α-Fe 2 O 3 nanorods grown on the ATO nanorods exhibit improved performance for PEC water oxidation compared to α-Fe 2 O 3 grown on flat fluorine-doped tin oxide glass. Furthermore, a simple and facile TiCl 4 chemical treatment further introduces TiO 2 passivation layer formation on the α-Fe 2 O 3 to reduce surface recombination. As a result, these unique nanostructures show dramatically improved photocurrent density (139% higher than that of the pure hematite nanorods). © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Influences of oxygen gas flow rate on electrical properties of Ga-doped ZnO thin films deposited on glass and sapphire substrates

    International Nuclear Information System (INIS)

    Makino, Hisao; Song, Huaping; Yamamoto, Tetsuya

    2014-01-01

    The Ga-doped ZnO (GZO) films deposited on glass and c-plane sapphire substrates have been comparatively studied in order to explore the role of grain boundaries in electrical properties. The influences of oxygen gas flow rates (OFRs) during the deposition by ion-plating were examined. The dependences of carrier concentration, lattice parameters, and characteristic of thermal desorption of Zn on the OFR showed common features between glass and sapphire substrates, however, the Hall mobility showed different behavior. The Hall mobility of GZO films on glass increased with increasing OFR of up to 15 sccm, and decreased with further increasing OFR. On the other hand, the Hall mobility of GZO films on c-sapphire increased for up to 25 sccm. The role of grain boundary in polycrystalline GZO films has been discussed. - Highlights: • Ga-doped ZnO films were deposited on glass and c-sapphire by ion-plating. • The epitaxial growth on c-sapphire was confirmed by X-ray diffraction. • Dependence of Hall mobility showed different tendency between glass and sapphire. • Grain boundaries influence transport properties at high O 2 gas flow rate

  2. Resistive Switching Characteristics in Electrochemically Synthesized ZnO Films

    Directory of Open Access Journals (Sweden)

    Shuhan Jing

    2015-04-01

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

  3. Effect of Cr{sub 2}O{sub 3} on the microstructure and non-ohmic properties of (Co, Sb)-doped SnO{sub 2} varistors

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar M, J. A. [Centro de Investigac ion en Materiales Avanzados, S. C., Alianza Norte No. 202, Parque de Investigacion e Innovacion Tecnologica, Nueva Carretera Aeropuerto Km. 10 Apodaca 66600, Nuevo Leon (Mexico); Pech C, M. I. [IPN, Centro de Investigacion y de Estudios Avanzados, Unidad Saltillo, Carretera Saltillo-Monterrey Km. 13, Saltillo 25900, Coahuila (Mexico); Hernandez, M. B.; Rodriguez, E.; Garcia O, L. [Universidad Autonoma de Nuevo Leon, Facultad de Ingenieria Mecanica y Electrica, San Nicolas de los Garza, Nuevo Leon (Mexico); Glot, A. B., E-mail: josue.aguilar@cimav.edu.mx [Universidad Tecnologica de la Mixteca, Division de Estudios de Posgrado, Carretera Acatlima Km. 2.5, Huajuapan de Leon 69000, Oaxaca (Mexico)

    2013-10-01

    The effect of Cr{sub 2}O{sub 3} addition on the physical characteristics, microstructure, and current-voltage properties of (Co-Sb)-doped SnO{sub 2} varistors was investigated. SnO{sub 2}-Co{sub 3}O{sub 4}-Sb{sub 2}O{sub 5} ceramics with additions of 0.0, 0.03, 0.05 and 0.07 mol % Cr{sub 2}O{sub 3} were sintered at 1350 C under ambient atmosphere and characterized micro structurally and electrically. The characterization by X-ray diffraction and scanning electron microscopy show that the microstructure remains as a single phase material with multimodal size distribution of SnO{sub 2} grains. The greatest effect of Cr{sub 2}O{sub 3} additions is manifested in the electric breakdown field. Additions of high levels (0.07 and 0.05 %) of this oxide promote and increase of approximately 55% in this parameter compared to the Cr{sub 2}O{sub 3}-free sample. Another physical property is affected: the measured density values decreases as the Cr{sub 2}O{sub 3} content increases. A change in the nonlinearity coefficient value is produced only at the highest Cr{sub 2}O{sub 3} content while at intermediate levels there is not change at all. Consequently, when seeking high nonlinearity coefficients, intermediate levels of Cr{sub 2}O{sub 3} are not recommended. (Author)

  4. Optical and Structural Properties of MEH-PPV: ZnO Nano composites

    International Nuclear Information System (INIS)

    Nurul Zayana Yahya; Mohamad Rusop; Mohamad Rusop

    2011-01-01

    Thin films of conducting unsaturated polymer of red color poly [2- methoxy-5(2-ethyl hexyloxy)-phenylene vinylene] (MEH-PPV) containing different weight percent of ZnO nanoparticles were deposited by spin coating techniques. The MEH-PPV: ZnO solutions were spin coated onto glass substrates. The spun MEH-PPV: ZnO thin films were used for investigating the optical properties by using Ultraviolet-Visible Spectrometer (UV-Vis). The structural properties of the thin films were investigated by Scanning Electron Microscopy (SEM). For MEH-PPV: ZnO nano composites, the UV-Vis absorption bands increases and showing slight blue shift compared to the pure MEH-PPV. From the SEM images of some MEH-PPV: ZnO nano composites, it can be seen that ZnO nanoparticles form aggregated regions. (author)

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  6. Spatial structure of radio frequency ring-shaped magnetized discharge sputtering plasma using two facing ZnO/Al2O3 cylindrical targets for Al-doped ZnO thin film preparation

    Directory of Open Access Journals (Sweden)

    Takashi Sumiyama

    2017-05-01

    Full Text Available Spatial structure of high-density radio frequency ring-shaped magnetized discharge plasma sputtering with two facing ZnO/Al2O3 cylindrical targets mounted in ring-shaped hollow cathode has been measured and Al-doped ZnO (AZO thin film is deposited without substrate heating. The plasma density has a peak at ring-shaped hollow trench near the cathode. The radial profile becomes uniform with increasing the distance from the target cathode. A low ion current flowing to the substrate of 0.19 mA/cm2 is attained. Large area AZO films with a resistivity of 4.1 – 6.7×10-4 Ω cm can be prepared at a substrate room temperature. The transmittance is 84.5 % in a visible region. The surface roughnesses of AZO films are 0.86, 0.68, 0.64, 1.7 nm at radial positions of r = 0, 15, 30, 40 mm, respectively, while diffraction peak of AZO films is 34.26°. The grains exhibit a preferential orientation along (002 axis.

  7. Study on Optoelectronic Characteristics of Sn-Doped ZnO Thin Films on Poly(ethylene terephthalate) and Indium Tin Oxide/Poly(ethylene terephthalate) Flexible Substrates

    Science.gov (United States)

    Cheng, Chi-Hwa; Chen, Mi; Chiou, Chin-Lung; Liu, Xing-Yang; Weng, Lin-Song; Koo, Horng-Show

    2013-05-01

    Transparent conductive oxides of Sn-doped ZnO (SZO) films with doping weight ratios of 2.0, 3.0, 4.0, and 5.0 wt % have been deposited on indium tin oxide (ITO)/poly(ethylene terephthalate) (PET) and PET flexible substrates at room temperature by pulsed laser deposition (PLD). Resultant films of SZO on ITO/PET and PET flexible substrates are amorphous in phase. It is found that undoped and SZO films on ITO/PET is anomalously better than films on PET in optical transmittance in the range of longer wavelength, possibly due to the refraction index difference between SZO, ITO films, and PET substrates, Burstein-Moss effect and optical interference of SZO/ITO bilayer films and substrate materials, and furthermore resulting in the decrement of reflection. The lowest electrical resistivity (ρ) of 4.0 wt % SZO films on flexible substrates of PET and ITO/PET are 3.8×10-2 and ρ= 1.2×10-2 Ω.cm, respectively. It is found that electrical and optical properties of the resultant films are greatly dependent on various amount of Sn element doping effect and substrate material characteristics.

  8. Optical and structural properties of nanostructured ZnO thin films deposited onto FTO/glass substrate by a solution-based technique

    CSIR Research Space (South Africa)

    Berruet, M

    2013-10-01

    Full Text Available Nanostructured zinc oxide thin films were spin coated on conductive glass substrates via a sol–gel based technique using zinc acetate dihydrate as precursor. The pH of the alkalis used as catalytic agents in the hydrolysis step is shown to have a...

  9. Intrinsic and extrinsic doping of ZnO and ZnO alloys

    Science.gov (United States)

    Ellmer, Klaus; Bikowski, André

    2016-10-01

    In this article the doping of the oxidic compound semiconductor ZnO is reviewed with special emphasis on n-type doping. ZnO naturally exhibits n-type conductivity, which is used in the application of highly doped n-type ZnO as a transparent electrode, for instance in thin film solar cells. For prospective application of ZnO in other electronic devices (LEDs, UV photodetectors or power devices) p-type doping is required, which has been reported only minimally. Highly n-type doped ZnO can be prepared by doping with the group IIIB elements B, Al, Ga, and In, which act as shallow donors according to the simple hydrogen-like substitutional donor model of Bethe (1942 Theory of the Boundary Layer of Crystal Rectifiers (Boston, MA: MIT Rad Lab.)). Group IIIA elements (Sc, Y, La etc) are also known to act as shallow donors in ZnO, similarly explainable by the shallow donor model of Bethe. Some reports showed that even group IVA (Ti, Zr, Hf) and IVB (Si, Ge) elements can be used to prepare highly doped ZnO films—which, however, can no longer be explained by the simple hydrogen-like substitutional donor model. More probably, these elements form defect complexes that act as shallow donors in ZnO. On the other hand, group V elements on oxygen lattice sites (N, P, As, and Sb), which were viewed for a long time as typical shallow acceptors, behave instead as deep acceptors, preventing high hole concentrations in ZnO at room temperature. Also, ‘self’-compensation, i.e. the formation of a large number of intrinsic donors at high acceptor concentrations seems to counteract the p-type doping of ZnO. At donor concentrations above about 1020 cm-3, the electrical activation of the dopant elements is often less than 100%, especially in polycrystalline thin films. Reasons for the electrical deactivation of the dopant atoms are (i) the formation of dopant-defect complexes, (ii) the compensation of the electrons by acceptors (Oi, VZn) or (iii) the formation of secondary phases, for

  10. Room temperature inorganic polycondensation of oxide (Cu2O and ZnO) nanoparticles and thin films preparation by the dip-coating technique

    OpenAIRE

    Salek, Guillaume; Tenailleau, Christophe; Dufour, Pascal; Guillemet-Fritsch, Sophie

    2015-01-01

    International audience; Oxide thin solid filmswere prepared by dip-coating into colloidal dispersions of oxide nanoparticles stabilized at room temperaturewithout the use of chelating or complex organic dispersing agents. Crystalline oxide nanoparticles were obtained by inorganic polycondensation and characterized by X-ray diffraction and field emission gun scanning electron microscopy. Water and ethanol synthesis and solution stabilization of oxide nanoparticle method was optimized to prepar...

  11. High rate (∼7 nm/s), atmospheric pressure deposition of ZnO front electrode for Cu(In,Ga)Se2 thin-film solar cells with efficiency beyond 15%

    NARCIS (Netherlands)

    Illiberi, A.; Grob, F.; Frijters, C.; Poodt, P.; Ramachandra, R.; Winands, H.; Simor, M.; Bolt, P.J.

    2013-01-01

    Undoped zinc oxide (ZnO) films have been grown on a moving glass substrate by plasma-enhanced chemical vapor deposition at atmospheric pressure. High deposition rates of ∼7 nm/s are achieved at low temperature (200°C) for a substrate speed from 20 to 60 mm/min. ZnO films are highly transparent in

  12. Preparation of electron buffer layer with crystalline ZnO nanoparticles in inverted organic photovoltaic cells

    Science.gov (United States)

    Lee, Donghwan; Kang, Taeho; Choi, Yoon-Young; Oh, Seong-Geun

    2017-06-01

    Zinc oxide (ZnO) nanoparticles synthesized through sol-gel method were used to fabricate the electron buffer layer in inverted organic photovoltaic cells (OPVs) after thermal treatment. To investigate the effect of thermal treatment on the formation of crystalline ZnO nanoparticles, the amorphous ZnO nanoparticles were treated via hydrothermal method. The crystalline phase of ZnO with well-ordered structure could be obtained when the amorphous phase of ZnO was processed under hydrothermal treatment at 170 °C. The crystalline structure of ZnO thin film in inverted organic solar cell could be obtained under relatively low annealing temperature by using thermally treated ZnO nanoparticles. The OPVs fabricated by using crystalline ZnO nanoparticles for electron buffer layer exhibited higher efficiency than the conventional ZnO nanoparticles. The best power conversion efficiency (PCE) was achieved for 7.16% through the ZnO film using the crystalline ZnO nanoparticles. The proposed method to prepared ZnO nanoparticles (NPs) could effectively reduce energy consumption during the fabrication of OPVs, which would greatly contribute to advantages such as lower manufacturing costs, higher productivity and application on flexible substrates.

  13. Effects of O2 plasma post-treatment on ZnO: Ga thin films grown by H2O-thermal ALD

    Science.gov (United States)

    Lee, Yueh-Lin; Chuang, Jia-Hao; Huang, Tzu-Hsuan; Ho, Chong-Long; Wu, Meng-Chyi

    2013-03-01

    Transparent conducting oxides have been widely employed in optoelectronic devices using the various deposition methods such as sputtering, thermal evaporator, and e-gun evaporator technologies.1-3 In this work, gallium doped zinc oxide (ZnO:Ga) thin films were grown on glass substrates via H2O-thermal atomic layer deposition (ALD) at different deposition temperatures. ALD-GZO thin films were constituted as a layer-by-layer structure by stacking zinc oxides and gallium oxides. Diethylzinc (DEZ), triethylgallium (TEG) and H2O were used as zinc, gallium precursors and oxygen source, respectively. Furthermore, we investigated the influences of O2 plasma post-treatment power on the surface morphology, electrical and optical property of ZnO:Ga films. As the result of O2 plasma post-treatment, the characteristics of ZnO:Ga films exhibit a smooth surface, low resistivity, high carrier concentration, and high optical transmittance in the visible spectrum. However, the transmittance decreases with O2 plasma power in the near- and mid-infrared regions.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-11-01

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

  15. High quality ZnO layers with adjustable refractive indices for integrated optics applications

    NARCIS (Netherlands)

    Heideman, Rene; Lambeck, Paul; Gardeniers, Johannes G.E.

    1995-01-01

    Thin (approx. 1 μm) crystalline ZnO films with a good optical quality and a good (0002) texture are grown under two considerably different process parameter sets using a r.f. planar magnetron sputtering unit. The optical parameters of the two corresponding ZnO layers are distinctly different: high

  16. Structural and optical properties of ZnO rods hydrothermally formed on polyethersulfone substrates

    International Nuclear Information System (INIS)

    Shin, Chang Mi; Jang, Jin Tak; Kim, Chang Yong; Ryu, Hyuk Hyun; Lee, Won Jae; Chang, Ji Ho; Son, Chang Sik; Choi, Hee Lack

    2012-01-01

    Various unique ZnO morphologies, such as cigar-like and belt-like structures and microrod and nanorod structures, were formed on flexible polyethersulfone (PES) substrates by using a low temperature hydrothermal route. The structural properties of ZnO depended highly on the precursor concentration. The effect of a thin ZnO seed layer deposited the on PES substrate by using atomic layer deposition on the structural and the optical properties of ZnO hydrothermally grown on the ZnO seed layer/PES substrates was studied. Field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and photoluminescence (PL) measurements were employed to analyze the characteristics of hydrothermally-grown ZnO. The diameter of the ZnO nanorods grown on the ZnO seed layer/PES substrates increased with increasing precursor concentration from 0.025 to 0.125 M due to the Ostwald ripening process. ZnO hydrothermally-grown on the ZnO seed layer/PES substrates at a low precursor concentration showed better structural properties than ZnO formed without a seed layer. Well-formed ZnO nanorods deposited on the ZnO seed layer/PES substrates showed two PL peaks, one in the ultraviolet and the other in the visible region, whereas horizontally positioned ZnO formed on the PES substrate in the absence of a seed layer emitted only one broad PL peak in the violet region. The ZnO grown on PES substrates in this work can be used as high-quality transparent electrodes for solar cells fabricated on flexible substrates.

  17. Effects of Rapid Thermal Annealing on the Structural, Electrical, and Optical Properties of Zr-Doped ZnO Thin Films Grown by Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Jingjin Wu

    2016-08-01

    Full Text Available The 4 at. % zirconium-doped zinc oxide (ZnO:Zr films grown by atomic layer deposition (ALD were annealed at various temperatures ranging from 350 to 950 °C. The structural, electrical, and optical properties of rapid thermal annealing (RTA treated ZnO:Zr films have been evaluated to find out the stability limit. It was found that the grain size increased at 350 °C and decreased between 350 and 850 °C, while creeping up again at 850 °C. UV–vis characterization shows that the optical band gap shifts towards larger wavelengths. The Hall measurement shows that the resistivity almost keeps constant at low annealing temperatures, and increases rapidly after treatment at 750 °C due to the effect of both the carrier concentration and the Hall mobility. The best annealing temperature is found in the range of 350–550 °C. The ZnO:Zr film-coated glass substrates show good optical and electrical performance up to 550 °C during superstrate thin film solar cell deposition.

  18. Synthesis and Characterization of Pb(Zr., Ti.)O-Pb(Nb/, Zn/)O Thin Film Cantilevers for Energy Harvesting Applications

    KAUST Repository

    Fuentes-Fernandez, E. M. A.

    2012-01-18

    A complete analysis of the morphology, crystallographic orientation, and resulting electrical properties of Pb(Zr0.53,Ti0.47) Pb(Nb1/3, Zn2/3)O3 (PZT-PZN) thin films, as well as the electrical behavior when integrated in a cantilever for energy harvesting applications, is presented. The PZT-PZN films were deposited using sol-gel methods. We report that using 20% excess Pb, a nucleation layer of PbTiO3 (PT), and a fast ramp rate provides large grains, as well as denser films. The PZT-PZN is deposited on a stack of TiO2/PECVD SiO2/Si3N4/thermal SiO2/Poly-Si/Si. This stack is designed to allow wet-etching the poly-Si layer to release the cantilever structures. It was also found that the introduction of the poly-Si layer results in larger grains in the PZT-PZN film. PZT-PZN films with a dielectric constant of 3200 and maximum polarization of 30 μC/cm2 were obtained. The fabricated cantilever devices produced ~300–400 mV peak-to-peak depending on the cantilever design. Experimental results are compared with simulations.

  19. Effect of solvents on sol-gel spin-coated nanostructured Al-doped ZnO thin films: a film for key optoelectronic applications

    Science.gov (United States)

    Kumar, K. Deva Arun; Valanarasu, S.; Kathalingam, A.; Ganesh, V.; Shkir, Mohd.; AlFaify, S.

    2017-12-01

    Aluminum-doped zinc oxide (AZO) thin films were deposited by sol-gel spin coating technique onto the glass substrates using different solvents such as 2-methoxyethanol, methanol, ethanol and isopropanol. Prepared films were characterized by XRD, Raman spectrum, SEM, UV-visible spectrophotometer, photoluminescence (PL) and electrical studies. XRD studies showed that all the prepared films are hexagonal wurtzite structure with polycrystalline nature oriented along (002) direction. SEM images showed uniform particles of size around 60 nm distributed regularly on to the entire glass substrate. EDX analysis confirmed the composition of grown AZO film consisting of Al, Zn and O elements. The prepared films showed highest optical transmittance 94% in the visible range and band gap 3.30 eV. PL spectra for all AZO films showed a strong UV emission peak at 387 nm. The AZO films prepared using isopropanol solvent showed high carrier concentration and low resistivity values as 1.72 × 1020 cm-3 and 2.90 × 10-3 Ω cm, respectively, with high figure of merit ( ϕ) value 8.42 × 10-3 (Ω/sq)-1.

  20. Effects of UV assistance on the properties of al-doped ZnO thin films deposited by sol-gel method

    Science.gov (United States)

    Tseng, Yung-Kuan; Pai, Feng-Ming; Chen, Yan-Cheng; Wu, Chao-Hsien

    2013-11-01

    We report here the preparation of aluminum doped zinc oxide transparent conductive thin films by a UV-assisted sol-gel method. It was found that UV irradiation creates ozone, which promotes the conductivity and transparency of the films. Boro-silicate glasses are used as substrates; an PGME is used as a solvent; after spin-coating, the films are dried and radiated with UV and then heated to 400°C for decarburization and 500°C for annealing under air. The surface morphologies of the prepared films are observed by FE-SEM and AFM. It was found that the films irradiated with UV-C are smoother and denser. An XRD analysis shows that the films have a typical wurtzite crystalline structure with a c-axis orientation normal to the surface. The electric resistance values measured with a four-point probe show that the films irradiated with UV have better conductivity (at approximately 3.4 × 10-3Ω-cm) than the films that did not undergo UV irradiation. An analysis by visible light spectrometry indicates that the AZO films irradiated with UV are more transparent than the films without UV-irradiation.

  1. Effects of Rapid Thermal Annealing on the Structural, Electrical, and Optical Properties of Zr-Doped ZnO Thin Films Grown by Atomic Layer Deposition.

    Science.gov (United States)

    Wu, Jingjin; Zhao, Yinchao; Zhao, Ce Zhou; Yang, Li; Lu, Qifeng; Zhang, Qian; Smith, Jeremy; Zhao, Yongming

    2016-08-13

    The 4 at. % zirconium-doped zinc oxide (ZnO:Zr) films grown by atomic layer deposition (ALD) were annealed at various temperatures ranging from 350 to 950 °C. The structural, electrical, and optical properties of rapid thermal annealing (RTA) treated ZnO:Zr films have been evaluated to find out the stability limit. It was found that the grain size increased at 350 °C and decreased between 350 and 850 °C, while creeping up again at 850 °C. UV-vis characterization shows that the optical band gap shifts towards larger wavelengths. The Hall measurement shows that the resistivity almost keeps constant at low annealing temperatures, and increases rapidly after treatment at 750 °C due to the effect of both the carrier concentration and the Hall mobility. The best annealing temperature is found in the range of 350-550 °C. The ZnO:Zr film-coated glass substrates show good optical and electrical performance up to 550 °C during superstrate thin film solar cell deposition.

  2. Laser-induced grating in ZnO

    DEFF Research Database (Denmark)

    Ravn, Jesper N.

    1992-01-01

    A simple approach for the calculation of self-diffraction in a thin combined phase and amplitude grating is presented. The third order nonlinearity, the electron-hole recombination time, and the ambipolar diffusion coefficient in a ZnO crystal are measured by means of laser-induced self-diffracti......A simple approach for the calculation of self-diffraction in a thin combined phase and amplitude grating is presented. The third order nonlinearity, the electron-hole recombination time, and the ambipolar diffusion coefficient in a ZnO crystal are measured by means of laser-induced self...

  3. Low temperature growth and optical properties of ZnO nanowires using an aqueous solution method.

    Science.gov (United States)

    Chu, Manh-Hung; Lee, Joon-Hyung; Kim, Jeong-Joo; Kim, Kyeong-Won; Norton, D P; Heo, Young-Woo

    2012-02-01

    ZnO nanowires were grown on indium tin oxide (ITO) coated glass substrates at a low temperature of 90 degrees C using an aqueous solution method. The ZnO seeds were coated on the ITO thin films by using a spin coater. ZnO nanowires were formed in an aqueous solution containing zinc nitrate hexahydrate (Zn(NO3)2 x 6H2O) and hexamethylenetetramine (C6H12N4). The pH value and concentration of the solution play an important role in the growth and morphologies of ZnO nanowires. The size of ZnO naonowires increased as the concentration of the solution increased. It was formed with a top surface of hexagonal and tapered shape at low and high pH values respectively. Additionally, the single crystalline structure and optical property of the ZnO nanowires were investigated using high-resolution transmission electron microscopy and photoluminescence spectroscopy.

  4. Luminescence properties of ZnO layers grown on Si-on-insulator substrates

    International Nuclear Information System (INIS)

    Kumar, Bhupendra; Gong, Hao; Vicknesh, S.; Chua, S. J.; Tripathy, S.

    2006-01-01

    The authors report on the photoluminescence properties of polycrystalline ZnO thin films grown on compliant silicon-on-insulator (SOI) substrates by radio frequency magnetron sputtering. The ZnO thin films on SOI were characterized by micro-Raman and photoluminescence (PL) spectroscopy. The observation of E 2 high optical phonon mode near 438 cm -1 in the Raman spectra of the ZnO samples represents the wurtzite crystal structure. Apart from the near-band-edge free exciton (FX) transition around 3.35 eV at 77 K, the PL spectra of such ZnO films also showed a strong defect-induced violet emission peak in the range of 3.05-3.09 eV. Realization of such ZnO layers on SOI would be useful for heterointegration with SOI-based microelectronics and microelectromechanical systems

  5. Photosensitivity of nanocrystalline ZnO films grown by PLD

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  6. Pulsed-laser deposited ZnO for device applications

    NARCIS (Netherlands)

    King, S.L.; Gardeniers, Johannes G.E.; Boyd, I.W.

    1996-01-01

    The study investigates the growth by pulsed-laser deposition (PLD) of ZnO thin films for the eventual incorporation into piezo-electric actuators and other sensors being developed at the University of Twente. All films are purely c-axis oriented, and results are presented which suggest the

  7. ZnO processing for integrated optic sensors

    NARCIS (Netherlands)

    Horsthuis, Winfried H.G.

    1986-01-01

    ZnO thin films were sputter deposited onto oxidized silicon wafers. The film quality increased with increasing applied r.f. power. Characterization of the films was performed by measurements of the attenuation of the transverse electric TE0 optical guided mode. For an applied r.f. power of 2000 W,

  8. The Strategy to Control the Morphology of ZnO Nanostructure UV Sensor

    International Nuclear Information System (INIS)

    Humayun, Q; Hashim, U; Foo, Kai Loong; Ruzaidi, C M

    2015-01-01

    The control morphology of ZnO nanostructures at specific area of electrodes by implemented a cost effective fabrication process, is extremely a challenging task. Rapid sensing, fast response and fast detection capability of the electronics devices is nowadays hot subject of keen interest. Our research is one of the successful attempts to achieve the desired goal at certain levels. Therefore in the current research article the ZnO thin film and ZnO nanorods were selectively deposited by low cost sol-gel and hydrothermal growth process at the selective area of microgap electrodes spacing and further the comparative study of ZnO thin film and ZnO nanorods were conducted electrically, for ultraviolet (UV) sensing application. On exposure to ultraviolet (UV) light the current gains, response/recovery times, repeatability, of the ZnO nanorods compared with ZnO thin film was improved probably due to the role of large surface area covered by the deposited nanostructures, and the most important is the bridging nanorods at the microgap electrodes tips. All the characterization including, surface, electrical and structural of the deposited nanostructures were completed by using SEM, sourcemeter and XRD respectively. (paper)

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

    KAUST Repository

    Kim, Hyunho

    2017-02-27

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

  10. ZnO film for application in surface acoustic wave device

    International Nuclear Information System (INIS)

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

    2007-01-01

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

  11. Atom probe microscopy of zinc isotopic enrichment in ZnO nanorods

    Directory of Open Access Journals (Sweden)

    C. N. Ironside

    2017-02-01

    Full Text Available We report on atomic probe microscopy (APM of isotopically enriched ZnO nanorods that measures the spatial distribution of zinc isotopes in sections of ZnO nanorods for natural abundance natZnO and 64Zn and 66Zn enriched ZnO nanorods. The results demonstrate that APM can accurately quantify isotopic abundances within these nanoscale structures. Therefore the atom probe microscope is a useful tool for characterizing Zn isotopic heterostructures in ZnO. Isotopic heterostructures have been proposed for controlling thermal conductivity and also, combined with neutron transmutation doping, they could be key to a novel technology for producing p-n junctions in ZnO thin films and nanorods.

  12. Self-assembled ZnO agave-like nanowires and anomalous superhydrophobicity

    Science.gov (United States)

    Yang, Y. H.; Li, Z. Y.; Wang, B.; Wang, C. X.; Chen, D. H.; Yang, G. W.

    2005-09-01

    Thin films of ZnO agave-like nanowires were prepared on amorphous carbon thin layers on silicon substrates using thermal chemical vapour transport and condensation without any metal catalysts. The unusual superhydrophobicity of the fabricated surface was measured; the water contact angle reaches 151.1°. On the basis of experimental and theoretical analyses, it appears likely that the biomimetic microcomposite and nanocomposite surfaces of the prepared thin films of ZnO agave-like nanowires are responsible for the excellent superhydrophobicity.

  13. Self-assembled ZnO agave-like nanowires and anomalous superhydrophobicity

    International Nuclear Information System (INIS)

    Yang, Y H; Li, Z Y; Wang, B; Wang, C X; Chen, D H; Yang, G W

    2005-01-01

    Thin films of ZnO agave-like nanowires were prepared on amorphous carbon thin layers on silicon substrates using thermal chemical vapour transport and condensation without any metal catalysts. The unusual superhydrophobicity of the fabricated surface was measured; the water contact angle reaches 151.1 deg. On the basis of experimental and theoretical analyses, it appears likely that the biomimetic microcomposite and nanocomposite surfaces of the prepared thin films of ZnO agave-like nanowires are responsible for the excellent superhydrophobicity

  14. Influence of substrate temperature on the properties of spray deposited nanofibrous zinc oxide thin films

    Science.gov (United States)

    Sharmin, Mehnaz; Bhuiyan, A. H.

    2018-01-01

    Zinc oxide (ZnO) thin films were deposited onto glass substrates by a spray pyrolysis technique at the substrate temperatures ( T S) between 250 and 500 °C. T S was observed to be one of the key parameters to influence the structural, surface morphological, optical and transport properties of ZnO thin films. X-ray diffraction patterns of the ZnO thin films showed polycrystalline hexagonal wurtzite structure and the preferred orientation was along (002) plane which got more prominent with the increase of T S. Field emission scanning electron microscopy of ZnO thin films showed the existence of nanofibers in the films with the average thickness ranging from 308 to 540 nm. Atomic force microscopy revealed that roughness of the ZnO thin film increased at higher T S. ZnO thin films were highly transparent in the visible to near infrared region with the maximum transmittance of 89% and the optical band gap was found from 3.23 to 3.31 eV. ZnO thin films showed n-type conductivity with the carrier concentrations ranging between 1019 and 1020 cm- 3. ZnO thin film deposited at the T S of 400 °C showed the highest mobility, highest carrier concentration and less resistivity.

  15. Transparent conducting zinc oxide thin film prepared by off-axis rf ...

    Indian Academy of Sciences (India)

    Unknown

    Keywords. Transparent conductors; ZnO thin films; photovoltaics. 1. Introduction. Zinc oxide is an n-type semiconductor with a wide direct band gap of 3⋅3 eV. Thin films of ZnO find application as transparent conducting electrode in photovoltaics, .... surface energy will become larger as the film grows. Then the growth ...

  16. Efficiency of Nb-Doped ZnO Nanoparticles Electrode for Dye-Sensitized Solar Cells Application

    Science.gov (United States)

    Anuntahirunrat, Jirapat; Sung, Youl-Moon; Pooyodying, Pattarapon

    2017-09-01

    The technological of Dye-sensitized solar cells (DSSCs) had been improved for several years. Due to its simplicity and low cost materials with belonging to the part of thin films solar cells. DSSCs have numerous advantages and benefits among the other types of solar cells. Many of the DSSC devices had use organic chemical that produce by specific method to use as thin film electrodes. The organic chemical that widely use to establish thin film electrodes are Zinc Oxide (ZnO), Titanium Dioxide (TiO2) and many other chemical substances. Zinc oxide (ZnO) nanoparticles had been used in DSSCs applications as thin film electrodes. Nanoparticles are a part of nanomaterials that are defined as a single particles 1-100 nm in diameter. From a few year ZnO widely used in DSSC applications because of its optical, electrical and many others properties. In particular, the unique properties and utility of ZnO structure. However the efficiency of ZnO nanoparticles based solar cells can be improved by doped various foreign impurity to change the structures and properties. Niobium (Nb) had been use as a dopant of metal oxide thin films. Using specification method to doped the ZnO nanoparticles thin film can improved the efficiencies of DSSCs. The efficiencies of Nb-doped ZnO can be compared by doping 0 at wt% to 5 at wt% in ZnO nanoparticles thin films that prepared by the spin coating method. The thin film electrodes doped with 3 at wt% represent a maximum efficiencies with the lowest resistivity of 8.95×10-4 Ω·cm.

  17. Electrodeposition of ZnO nano-wires lattices with a controlled morphology; Electrodepot de reseaux de nanofils de ZnO a morphologie controlee

    Energy Technology Data Exchange (ETDEWEB)

    Elias, J.; Tena-Zaera, R.; Katty, A.; Levy-Clement, C. [Centre National de la Recherche Scientifique (CNRS), Lab. de Chimie Metallurgique des Terres Rares, UPR 209, 94 - Thiais (France)

    2006-07-01

    In this work, it is shown that the electrodeposition is a changeable low cost method which allows, according to the synthesis conditions, to obtain not only plane thin layers of ZnO but different nano-structures too. In a first part, are presented the formation conditions of a compact thin layer of nanocrystalline ZnO electrodeposited on a conducing glass substrate. This layer plays a buffer layer role for the deposition of a lattice of ZnO nano-wires. The step of nano-wires nucleation is not only determined by the electrochemical parameters but by the properties of the buffer layer too as the grain sizes and its thickness. In this context, the use of an electrodeposition method in two steps allows to control the nano-wires length and diameter and their density. The morphology and the structural and optical properties of these nano-structures have been analyzed by different techniques as the scanning and transmission electron microscopy, the X-ray diffraction and the optical spectroscopy. These studies show that ZnO nano-structures are formed of monocrystalline ZnO nano-wires, presenting a great developed surface and a great optical transparency in the visible. These properties make ZnO a good material for the development of nano-structured photovoltaic cells as the extremely thin absorber cells (PV ETA) or those with dye (DSSC) which are generally prepared with porous polycrystalline TiO{sub 2}. Its replacement by a lattice of monocrystalline ZnO nano-wires allows to reduce considerably the number of grain boundaries and in consequence to improve the transport of the electrons. The results are then promising for the PV ETA cells with ZnO nano-wires. (O.M.)

  18. Influence Al doped ZnO nanostructure on structural and optical properties

    International Nuclear Information System (INIS)

    Ramelan, Ari Handono; Wahyuningsih, Sayekti; Chasanah, Uswatul; Munawaroh, Hanik

    2016-01-01

    The preparation of Al-doped ZnO (AZO) thin films prepared by the spin-coating method was reported. Preparation of AZO was conducted by annealing treatment at a temperature of 700°C. While the spin-coating process of AZO thin films were done at 2000 and 3000 rpm respectively. The structural properties of ZnO were determined by X- ray diffraction (XRD) analysis. ZnOnanostructure was formed after annealed at atemperature of 400°C.The morphology of ZnO was determined by Scanning Electron Microscopy (SEM) showed the irregular morphology about 30-50µm in size. Al doped on ZnO influenced the optical properties of those material. Increasing Al contain on ZnO cause of shifting to the lower wavelength. The optical properties of the ZnO as well as AZO films showed that higher reflectance on the ultraviolet region so those materials were used as anti-reflecting agent.Al addition significantly enhance the optical transparency and induce the blue-shift in optical bandgap of ZnO films.

  19. Tuning magnetism by biaxial strain in native ZnO.

    Science.gov (United States)

    Peng, Chengxiao; Wang, Yuanxu; Cheng, Zhenxiang; Zhang, Guangbiao; Wang, Chao; Yang, Gui

    2015-07-07

    Magnetic ZnO, one of the most important diluted magnetic semiconductors (DMS), has attracted great scientific interest because of its possible technological applications in optomagnetic devices. Magnetism in this material is usually delicately tuned by the doping level, dislocations, and local structures. The rational control of magnetism in ZnO is a highly attractive approach for practical applications. Here, the tuning effect of biaxial strain on the d(0) magnetism of native imperfect ZnO is demonstrated through first-principles calculations. Our calculation results show that strain conditions have little effect on the defect formation energy of Zn and O vacancies in ZnO, but they do affect the magnetism significantly. For a cation vacancy, increasing the compressive strain will obviously decrease its magnetic moment, while tensile strain cannot change the moment, which remains constant at 2 μB. For a singly charged anion vacancy, however, the dependence of the magnetic moment on strain is opposite to that of the Zn vacancy. Furthermore, the ferromagnetic state is always present, irrespective of the strain type, for ZnO with two zinc vacancies, 2VZns. A large tensile strain is favorable for improving the Curie temperature and realizing room temperature ferromagnetism for ZnO-based native semiconductors. For ZnO with two singly charged oxygen vacancies, 2Vs, no ferromagnetic ordering can be observed. Our work points the way to the rational design of materials beyond ZnO with novel non-intrinsic functionality by simply tuning the strain in a thin film form.

  20. Inverse spin Hall effect induced by spin pumping into semiconducting ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jung-Chuan [Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (China); Huang, Leng-Wei [Graduate Institute of Applied Physics, National Chengchi University, Taipei 11605, Taiwan (China); Hung, Dung-Shing, E-mail: dshung@mail.mcu.edu.tw [Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (China); Department of Information and Telecommunications Engineering, Ming Chuan University, Taipei 111, Taiwan (China); Chiang, Tung-Han [Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan (China); Huang, J. C. A., E-mail: jcahuang@mail.ncku.edu.tw [Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan (China); Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 70101, Taiwan (China); Liang, Jun-Zhi [Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 70101, Taiwan (China); Department of Physics, Fu Jen Catholic University, Taipei 242, Taiwan (China); Lee, Shang-Fan, E-mail: leesf@phys.sinica.edu.tw [Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (China); Graduate Institute of Applied Physics, National Chengchi University, Taipei 11605, Taiwan (China)

    2014-02-03

    The inverse spin Hall effect (ISHE) of n-type semiconductor ZnO thin films with weak spin-orbit coupling has been observed by utilizing the spin pumping method. In the ferromagnetic resonance condition, the spin pumping driven by the dynamical exchange interaction of a permalloy film injects a pure spin current into the adjacent ZnO layer. This spin current gives rise to a DC voltage through the ISHE in the ZnO layer, and the DC voltage is proportional to the microwave excitation power. The effect is sizeable even when the spin backflow is considered.

  1. Inverse spin Hall effect induced by spin pumping into semiconducting ZnO

    International Nuclear Information System (INIS)

    Lee, Jung-Chuan; Huang, Leng-Wei; Hung, Dung-Shing; Chiang, Tung-Han; Huang, J. C. A.; Liang, Jun-Zhi; Lee, Shang-Fan

    2014-01-01

    The inverse spin Hall effect (ISHE) of n-type semiconductor ZnO thin films with weak spin-orbit coupling has been observed by utilizing the spin pumping method. In the ferromagnetic resonance condition, the spin pumping driven by the dynamical exchange interaction of a permalloy film injects a pure spin current into the adjacent ZnO layer. This spin current gives rise to a DC voltage through the ISHE in the ZnO layer, and the DC voltage is proportional to the microwave excitation power. The effect is sizeable even when the spin backflow is considered

  2. Heteroepitaxial growth of ZnO on perovskite surfaces

    International Nuclear Information System (INIS)

    Wei, X H; Li, Y R; Jie, W J; Tang, J L; Zeng, H Z; Huang, W; Zhang, Y; Zhu, J

    2007-01-01

    The microstructural properties of heteroepitaxial ZnO thin films prepared by laser molecular beam epitaxy (L-MBE) were investigated on SrTiO 3 substrates and BaTiO 3 /SrTiO 3 pseudo substrates with different orientations. The interface characteristics were in situ monitored by reflection high-energy electron diffraction (RHEED), and the epitaxial orientation relations were reconfirmed by ex situ x-ray diffraction (XRD) measurements. ZnO films grown on SrTiO 3 (0 0 1) and BaTiO 3 /SrTiO 3 (0 0 1) contained a poly-domain structure. For the former, the lattice mismatch was about -1.7% by four types of domain growth with the epitaxial relation of ZnO(1 1 0) parallel SrTiO 3 (0 0 1) and ZnO[-1 1 1] parallel SrTiO 3 (100). For the latter, twin domains would result in a smaller mismatch of -0.8% by the epitaxial relation of ZnO(0 0 1) parallel BaTiO 3 (0 0 1) and ZnO[1 1 0] parallel BaTiO 3 (1 1 0). On SrTiO 3 (1 1 1) and BaTiO 3 /SrTiO 3 (1 1 1), single-domain films following the c-axial direction were observed with in-plane orientation ZnO[1 1 0] parallel SrTiO 3 [1 1 0] and ZnO[1 0 0] parallel BaTiO 3 [1 1 0], respectively. This 30 0 rotation in the in-plane direction of the ZnO epilayer with respect to the perovskite surfaces increased the lattice mismatch from about -2% to -14.5% after inserting BaTiO 3 layers. The orientation of ZnO films could be attributed to the characteristic difference of the interface energy. It is determined entirely by interface stress and crystallographic symmetry for the growth on nonpolar (0 0 1)-orientated perovskite surfaces while the competition between elastic energy and chemical energy plays an important role for that on polar (1 1 1)-surfaces

  3. Stability and electrorheology of ZnO nanofluids in the presence of anionic surfactants

    Science.gov (United States)

    Zaid, Hasnah Mohd; Adil, Muhammad; Chuan, Lee Kean; Latiff, Noor Rasyada Ahmad

    2016-11-01

    In this research, the preparation of stable ZnO nanofluids has been studied by the interaction of unmodified ZnO nanoparticles with anionic surfactant, and the impact of this on the electrorheological properties of nanofluid. Using laboratory experiments including measurement of sedimentation and adsorption of surfactant, the sedimentation behavior of ZnO nanoparticles was evaluated. The results show that the most stable aqueous dispersions of ZnO nanoparticles (calcined at 500 and 800°C) is obtained with the aid of 0.025 wt% sodium dodecylbenzenesulfonate (SDBS), at a fixed concentration of 0.1 wt% ZnO. The ZnO@500/SDBS dispersion exhibits better stability at high temperature of 95°C, with the percentage stability of 56.6% compare to 44.2% of ZnO@800/SDBS dispersion. The stabilized nanofluids were then subjected for measuring of electrorehological behaviour using a rotating viscometer attached to a custom-built solenoid coil. The rheological measurements indicated that all the nanofluids exhibit pseudoplastic (shear thinning) behavior. At a low shear rate, the viscosity of 0.1 wt% ZnO@500/SDBS dispersion provide an enhancement in the viscosity of nanofluid up to 133% compare to brine as a base fluid. Whereas, ZnO@800/SDBS dispersion shows an increment of 183% in its viscosity under electromagnetic waves. This depicts the role of stability in order to achieve an electrorheological effect by activating dielectric ZnO nanoparticles. Further these investigations explained how the polarization of induced dipoles affects the electrorheology of ZnO nanofluids, by creating chains that align with the applied electric field. Hence the mobility of a stabilized nanofluid can be efficiently controlled by regulating the applied field for EOR purposes.

  4. Electrical properties of Mg doped ZnO nanostructure annealed at different temperature

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, R., E-mail: ruziana12@gmail.com; Mamat, M. H., E-mail: hafiz-030@yahoo.com; Rusop, M., E-mail: nanouitm@gmail.com [NANO-ElecTronic Centre, Faculty of Electrical engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre, Institue of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Ismail, A. S., E-mail: kyrin-samaxi@yahoo.com [NANO-ElecTronic Centre, Faculty of Electrical engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Khusaimi, Z., E-mail: Zurai142@salam.uitm.edu.my [NANO-SciTech Centre, Institue of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia)

    2016-07-06

    In this work, ZincOxide (ZnO) nanostructures doped with Mg were successfully grown on the glass substrate. Magnesium (Mg) metal element was added in the ZnO host which acts as a doping agent. Different temperature in range of 250°C to 500°C was used in order to investigate the effect of annealing temperature of ZnO thin films. Field Emission Scanning Electron Microscopy (FESEM) was used to investigate the physical characteristic of ZnO thin films. FESEM results have revealed that ZnO nanorods were grown vertically aligned. The structural properties were determined by using X-Ray Diffraction (XRD) analysis. XRD results showed Mg doped ZnO thin have highest crystalinnity at 500°C annealing temperature. The electrical properties were investigating by using Current-Voltage (I-V) measurement. I-V measurement showed the electrical properties were varied at different annealing temperature. The annealing temperature at 500°C has the highest electrical conductance properties.

  5. Electrical properties of Mg doped ZnO nanostructure annealed at different temperature

    International Nuclear Information System (INIS)

    Mohamed, R.; Mamat, M. H.; Rusop, M.; Ismail, A. S.; Khusaimi, Z.

    2016-01-01

    In this work, ZincOxide (ZnO) nanostructures doped with Mg were successfully grown on the glass substrate. Magnesium (Mg) metal element was added in the ZnO host which acts as a doping agent. Different temperature in range of 250°C to 500°C was used in order to investigate the effect of annealing temperature of ZnO thin films. Field Emission Scanning Electron Microscopy (FESEM) was used to investigate the physical characteristic of ZnO thin films. FESEM results have revealed that ZnO nanorods were grown vertically aligned. The structural properties were determined by using X-Ray Diffraction (XRD) analysis. XRD results showed Mg doped ZnO thin have highest crystalinnity at 500°C annealing temperature. The electrical properties were investigating by using Current-Voltage (I-V) measurement. I-V measurement showed the electrical properties were varied at different annealing temperature. The annealing temperature at 500°C has the highest electrical conductance properties.

  6. Application of ZnO single-crystal wire grown by the thermal evaporation method as a chemical gas sensor for hydrogen sulfide.

    Science.gov (United States)

    Park, N K; Lee, S Y; Lee, T J

    2011-01-01

    A zinc oxide single-crystal wire was synthesized for application as a gas-sensing material for hydrogen sulfide, and its gas-sensing properties were investigated in this study. The gas sensor consisted of a ZnO thin film as the buffer layer and a ZnO single-crystal wire. The ZnO thin film was deposited over a patterning silicon substrate with a gold electrode by the CFR method. The ZnO single-crystal wire was synthesized over the ZnO thin film using zinc and activated carbon as the precursor for the thermal evaporation method at 800 degrees C. The electrical properties of the gas sensors that were prepared for the growth of ZnO single-crystal wire varied with the amount of zinc contained in the precursor. The charged current on the gas sensors increased with the increasing amount of zinc in the precursor. It was concluded that the charged current on the gas sensors was related to ZnO single-crystal wire growth on the silicon substrate area between the two electrodes. The charged current on the gas sensor was enhanced when the ZnO single-crystal wire was exposed to a H2S stream. The experimental results obtained in this study confirmed that a ZnO single-crystal wire can be used as a gas sensor for H2S.

  7. Catalytic growth of ZnO nanostructures by r.f. magnetron sputtering

    Directory of Open Access Journals (Sweden)

    Arroyo-Hernández María

    2011-01-01

    Full Text Available Abstract The catalytic effect of gold seed particles deposited on a substrate prior to zinc oxide (ZnO thin film growth by magnetron sputtering was investigated. For this purpose, selected ultra thin gold layers, with thicknesses close to the percolation threshold, are deposited by thermal evaporation in ultra high vacuum (UHV conditions and subsequently annealed to form gold nanodroplets. The ZnO structures are subsequently deposited by r.f. magnetron sputtering in a UHV chamber, and possible morphological differences between the ZnO grown on top of the substrate and on the gold are investigated. The results indicate a moderate catalytic effect for a deposited gold underlayer of 4 nm, quite close to the gold thin film percolation thickness.

  8. Electrodeposition of ZnO nano-wires lattices with a controlled morphology

    International Nuclear Information System (INIS)

    Elias, J.; Tena-Zaera, R.; Katty, A.; Levy-Clement, C.

    2006-01-01

    In this work, it is shown that the electrodeposition is a changeable low cost method which allows, according to the synthesis conditions, to obtain not only plane thin layers of ZnO but different nano-structures too. In a first part, are presented the formation conditions of a compact thin layer of nanocrystalline ZnO electrodeposited on a conducing glass substrate. This layer plays a buffer layer role for the deposition of a lattice of ZnO nano-wires. The step of nano-wires nucleation is not only determined by the electrochemical parameters but by the properties of the buffer layer too as the grain sizes and its thickness. In this context, the use of an electrodeposition method in two steps allows to control the nano-wires length and diameter and their density. The morphology and the structural and optical properties of these nano-structures have been analyzed by different techniques as the scanning and transmission electron microscopy, the X-ray diffraction and the optical spectroscopy. These studies show that ZnO nano-structures are formed of monocrystalline ZnO nano-wires, presenting a great developed surface and a great optical transparency in the visible. These properties make ZnO a good material for the development of nano-structured photovoltaic cells as the extremely thin absorber cells (PV ETA) or those with dye (DSSC) which are generally prepared with porous polycrystalline TiO 2 . Its replacement by a lattice of monocrystalline ZnO nano-wires allows to reduce considerably the number of grain boundaries and in consequence to improve the transport of the electrons. The results are then promising for the PV ETA cells with ZnO nano-wires. (O.M.)

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

    Indian Academy of Sciences (India)

    PPy/1-D ZnO nanocomposites with different 1-D ZnO nanorod weight ratios (15 and 25%) had better selectivity and sensitivity towards NH3 at room temperature. Keywords. 1-D ZnO nanorods; PPy/1-D ZnO nanocomposites; photocatalytic activity; sensitivity. 1. Introduction. The synthesis of zinc oxide (ZnO) nanostructures ...

  10. Role of SiNx Barrier Layer on the Performances of Polyimide Ga2O3-doped ZnO p-i-n Hydrogenated Amorphous Silicon Thin Film Solar Cells

    Directory of Open Access Journals (Sweden)

    Fang-Hsing Wang

    2014-02-01

    Full Text Available In this study, silicon nitride (SiNx thin films were deposited on polyimide (PI substrates as barrier layers by a plasma enhanced chemical vapor deposition (PECVD system. The gallium-doped zinc oxide (GZO thin films were deposited on PI and SiNx/PI substrates at room temperature (RT, 100 and 200 °C by radio frequency (RF magnetron sputtering. The thicknesses of the GZO and SiNx thin films were controlled at around 160 ± 12 nm and 150 ± 10 nm, respectively. The optimal deposition parameters for the SiNx thin films were a working pressure of 800 × 10−3 Torr, a deposition power of 20 W, a deposition temperature of 200 °C, and gas flowing rates of SiH4 = 20 sccm and NH3 = 210 sccm, respectively. For the GZO/PI and GZO-SiNx/PI structures we had found that the GZO thin films deposited at 100 and 200 °C had higher crystallinity, higher electron mobility, larger carrier concentration, smaller resistivity, and higher optical transmittance ratio. For that, the GZO thin films deposited at 100 and 200 °C on PI and SiNx/PI substrates with thickness of ~1000 nm were used to fabricate p-i-n hydrogenated amorphous silicon (α-Si thin film solar cells. 0.5% HCl solution was used to etch the surfaces of the GZO/PI and GZO-SiNx/PI substrates. Finally, PECVD system was used to deposit α-Si thin film onto the etched surfaces of the GZO/PI and GZO-SiNx/PI substrates to fabricate α-Si thin film solar cells, and the solar cells’ properties were also investigated. We had found that substrates to get the optimally solar cells’ efficiency were 200 °C-deposited GZO-SiNx/PI.

  11. Scaling up manufacturing of ZnO thin layers for application in flexible dye-sensitized solar cells; Aufskalierung der Herstellung von ZnO-Duennschichten fuer die Anwendung in flexiblen farbstoffsensibilisierten Solarzellen

    Energy Technology Data Exchange (ETDEWEB)

    Bittner, Florian

    2012-10-19

    Flexible solar cells possess good future prospects for versatile mobile applications and can provide an important environmental benefit. One of the technologies permitting flexible solar cells is that of dye-sensitized solar cells. Among other advantages the fabrication of these organic-inorganic hybrid solar cells promises to be inexpensive in comparison to other technologies. Nanoparticular TiO{sub 2} is used predominantly as the semiconducting photoanode material; however its preparation route contains a tempering step at about 450 C, which impedes the use of flexible plastic substrates - at least with the method established for dye-sensitized solar cells. An alternative to TiO{sub 2} is ZnO, which can be fabricated for example in an electrochemical process at temperatures of only 70 C in the form of porous quasicrystalline layers. To create porosity the dye eosin Y is used as structure-directing agent. In the context of this study layers prepared by this method were compared to ZnO layers prepared by screen printing. This was performed on glass based substrates. Better conversion efficiency has been determined for dye-sensitized solar cells based on electrochemical deposited layers, while other results indicated advantages for the screen printed layers. As the morphologies of the available screen printed layers proved to be unfavourable and poorly comparable, a concluding statement on the suitability of the different types of layers was eventually not possible. Furthermore a technical simple and inexpensive method for the platinum coating of plastic substrates, which are used as counter electrodes, was tried to be determined. However, layers prepared by technically relatively complex sputtering exhibited by far better properties than layers prepared by electrochemical deposition or by chemical reduction of platinum salts. Thus, the targeted objective has not been reached. The central scope of this study was the development of an electrochemical deposition setup

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-08-31

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

  13. Characterization of Zinc Oxide (ZnO piezoelectric properties for Surface Acoustic Wave (SAW device

    Directory of Open Access Journals (Sweden)

    Zakaria Mohd Rosydi

    2017-01-01

    Full Text Available In fabricating Surface Acoustic Wave (SAW biosensors device, the substrate is one of important factors that affected to performance device. there are many types of piezoelectric substrate in the markets and the cheapest is zinc Oxide substrate. Zinc Oxide (ZnO with its unique properties can be used as piezoelectric substrate along with SAW devices for detection of DNA in this research. In this project, ZnO thin film is deposited onto silicon oxide substrate using electron beam evaporation (E-beam and Sol-Gel technique. Different material structure is used to compare the roughness and best piezoelectric substrate of ZnO thin film. Two different structures of ZnO target which are pellet and granular are used for e-beam deposition and one sol-gel liquid were synthesize and compared. Parameter for thickness of ZnO e-beam deposition is fixed to a 0.1kÅ for both materials structure and sol-gel was coat using spin coat technique. After the process is done, samples are annealed at temperature of 500°C for 2 hours. The structural properties of effect of post annealing using different material structure of ZnO are studied using Atomic Force Microscopic (AFM for surface morphology and X-ray Diffraction (XRD for phase structure.

  14. Characterization of Zinc Oxide (ZnO) piezoelectric properties for Surface Acoustic Wave (SAW) device

    Science.gov (United States)

    Rosydi Zakaria, Mohd; Johari, Shazlina; Hafiz Ismail, Mohd; Hashim, Uda

    2017-11-01

    In fabricating Surface Acoustic Wave (SAW) biosensors device, the substrate is one of important factors that affected to performance device. there are many types of piezoelectric substrate in the markets and the cheapest is zinc Oxide substrate. Zinc Oxide (ZnO) with its unique properties can be used as piezoelectric substrate along with SAW devices for detection of DNA in this research. In this project, ZnO thin film is deposited onto silicon oxide substrate using electron beam evaporation (E-beam) and Sol-Gel technique. Different material structure is used to compare the roughness and best piezoelectric substrate of ZnO thin film. Two different structures of ZnO target which are pellet and granular are used for e-beam deposition and one sol-gel liquid were synthesize and compared. Parameter for thickness of ZnO e-beam deposition is fixed to a 0.1kÅ for both materials structure and sol-gel was coat using spin coat technique. After the process is done, samples are annealed at temperature of 500°C for 2 hours. The structural properties of effect of post annealing using different material structure of ZnO are studied using Atomic Force Microscopic (AFM) for surface morphology and X-ray Diffraction (XRD) for phase structure.

  15. Study of an antireflection surface constructed of controlled ZnO nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Ren-Jei, E-mail: rjchung@ntut.edu.tw [Department of Chemical Engineering and Biotechnology, National Taipei University of Technology (Taipei Tech), Taipei 10608, Taiwan, ROC (China); Lin, Zih-Cian [Department of Chemical Engineering and Biotechnology, National Taipei University of Technology (Taipei Tech), Taipei 10608, Taiwan, ROC (China); Lin, Chin-An; Lai, Kun-Yu [Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan, ROC (China); Department of Electrical Engineering, National Taiwan University, Taipei 10617, Taiwan, ROC (China)

    2014-11-03

    Zinc oxide (ZnO) nanostructures were fabricated on Si wafers using a hydrothermal method. By adjusting the spin-coating speed and annealing time for the zinc acetate thin films used as a seed layer, the density of ZnO nanorods (NRs) was controlled. In addition, it was found that the morphology of the NRs evolved from a wire-like geometry to a tower-like geometry with an increasing concentration of ascorbic acid. The surface reflectance of the ZnO NR layers with various textures was investigated. The results indicated that NRs effectively enhanced light trapping and further reduced Fresnel reflection due to the significant grading in the refractive index, avoiding the abrupt transition at the air/Si interface. The total reflectance on the coated surface can be as low as 11%, which is 3 times lower than that of polished Si. The optimized design of nanostructured ZnO surfaces for antireflection coatings will greatly improve the performance of optoelectronic devices. - Highlights: • Nanotructured ZnO was prepared to serve as an anti-reflection coating. • The geometries of sol–gel prepared ZnO were controlled. • ZnO nanorod, nanoneedle and nanotower arrays were fabricated. • The light reflectance of the nanostructures was much lower than that of bare Si.

  16. Hydrothermal Growth of ZnO Nanowires on UV-Nanoimprinted Polymer Structures.

    Science.gov (United States)

    Park, Sooyeon; Moore, Sean A; Lee, Jaejong; Song, In-Hyouk; Farshchian, Bahador; Kim, Namwon

    2018-05-01

    Integration of zinc oxide (ZnO) nanowires on miniaturized polymer structures can broaden its application in multi-functional polymer devices by taking advantages of unique physical properties of ZnO nanowires and recent development of polymer microstructures in analytical systems. In this paper, we demonstrate the hydrothermal growth of ZnO nanowires on polymer microstructures fabricated by UV nanoimprinting lithography (NIL) using a polyurethane acrylate (PUA). Since PUA is a siloxane-urethane-acrylate compound containing the alpha-hydroxyl ketone, UV-cured PUA include carboxyl groups, which inhibit and suppress the nucleation and growth of ZnO nanowires on polymer structures. The presence of carboxyl groups in UV-cured PUA was substantiated by Fourier transform infrared spectroscopy (FTIR), and a Ag thin film was deposited on the nanoimprinted polymer structures to limit their inhibitive influence on the growth of ZnO nanowires. Furthermore, the naturally oxidized Ag layer (Ag2O) reduced crystalline lattice mismatches at the interface between ZnO-Ag during the seed annealing process. The ZnO nanowires grown on the Ag-deposited PUA microstructures were found to have comparable morphological characteristics with ZnO nanowires grown on a Si wafer.

  17. Heat treatment effects on the surface morphology and optical properties of ZnO nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Zainizan Sahdan, M. [Faculty of Electrical Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Faculty of Electrical and Electronics Engineering, Universiti Tun Hussein onn Malaysia, 86400 Batu Pahat, Johor (Malaysia); Hafiz Mamat, M.; Salina, M.; Noor, Uzer M.; Rusop, Mohamad [Faculty of Electrical Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Khusaimi, Zuraida [Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia)

    2010-09-15

    Zinc oxide (ZnO) nanostructures have received broad attention due to its wide applications especially for thin-film solar cells and transistors. In this paper, we report the effects of heat treatment on the structural and optical properties of ZnO nanostructures. Zinc oxide nanostructures were synthesized using thermal chemical vapour deposition (CVD) method on glass substrate. The surface morphologies which were observed by scanning electron microscope (SEM) show that ZnO nanostructures change its shape and size when the annealing temperature increases from 400 C to 600 C. Structural measurement using X-ray diffraction (XRD) has shown that ZnO nanostructures have the highest crystallinity and smallest crystallite size (20 nm) when annealed at 550 C. Furthermore, the samples were optically characterized using Photoluminescence (PL) spectrometer. The PL spectra indicate that ZnO nanostructures have the highest peak at UV wavelength when annealed at 550 C. The mechanism of the PL properties of ZnO nanostructures is also discussed. We conclude that ZnO nanostructures deposited using thermal CVD have the optimum structural and PL properties when annealed at 550 C. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Characteristics of nanostructured ZnO layers deposited in spray plasma device.

    Science.gov (United States)

    Baba, K; Nikravech, M; Vrel, D; Kanaev, A; Museur, L; Chehimi, M

    2012-06-01

    ZnO and Al doped ZnO thin film have been deposited on glass substrate by "spray plasma" process using an aqueous solution of Zn(NO3)2. XRD patterns revealed polycrystalline character with the typical hexagonal würtzite structure. The preferential c-axis orientation of crystallites depends highly on the operating conditions. Willamson-Hall method and AFM photographs showed a size of crystallites ranging between 20 and 80 nm and a roughness between 6 and 50 nm. Films exhibit a transmittance between 65 and 90% in the visible region. XPS revealed that the stoichiometry of deposited ZnO is Zn/O = 0.93. Fluorescence spectroscopy showed the presence of two bands at 360 nm (UV) and at 410 nm (Blue). The UV band can be attributed to exiton emission. Another important result concerns the non-existence of a "green" band at 500 nm.

  19. Smoothing of ZnO films by gas cluster ion beam

    International Nuclear Information System (INIS)

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

    2005-01-01

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

  20. Fabrication Methods and Luminescent Properties of ZnO Materials for Light-Emitting Diodes

    Science.gov (United States)

    Lee, Ching-Ting

    2010-01-01

    Zinc oxide (ZnO) is a potential candidate material for optoelectronic applications, especially for blue to ultraviolet light emitting devices, due to its fundamental advantages, such as direct wide band gap of 3.37 eV, large exciton binding energy of 60 meV, and high optical gain of 320 cm−1 at room temperature. Its luminescent properties have been intensively investigated for samples, in the form of bulk, thin film, or nanostructure, prepared by various methods and doped with different impurities. In this paper, we first review briefly the recent progress in this field. Then a comprehensive summary of the research carried out in our laboratory on ZnO preparation and its luminescent properties, will be presented, in which the involved samples include ZnO films and nanorods prepared with different methods and doped with n-type or p-type impurities. The results of ZnO based LEDs will also be discussed.

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

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  2. Facile one-step synthesis of magnesium-doped ZnO nanoparticles: optical properties and their device applications

    International Nuclear Information System (INIS)

    Oh, Ji-Young; Lim, Sang-Chul; Ahn, Seong Deok; Lee, Sang Seok; Cho, Kyoung-Ik; Koo, Jae Bon; Choi, Rino; Hasan, Musarrat

    2013-01-01

    In this study, magnesium-doped (Mg-doped) zinc oxide (ZnO) nanoparticles were successfully synthesized by a sonochemical process under mild conditions. The x-ray diffraction pattern indicated that the Mg-doped ZnO nanoparticles maintain a wurtzite structure without impurities. We observed a blue-shift of the bandgap of the Mg-doped ZnO nanoparticles as the Mg-doping ratio increased. We also fabricated thin-film transistor (TFT) devices with the doped-ZnO nanoparticles. Devices using Mg-doped ZnO nanoparticles as a channel layer showed insensibility to white-light irradiation compared with undoped ZnO TFTs. (paper)

  3. 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.

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

    OpenAIRE

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

    2007-01-01

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

  5. 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.

  6. Use of ZnO as antireflective, protective, antibacterial, and biocompatible multifunction nanolayer of thermochromic VO2 nanofilm for intelligent windows

    International Nuclear Information System (INIS)

    Zhou, Huaijuan; Li, Jinhua; Bao, Shanhu; Li, Jian; Liu, Xuanyong; Jin, Ping

    2016-01-01

    Graphical abstract: - Highlights: • A multifunctional VO 2 /ZnO bilayer film is designed and deposited by magnetron sputtering apparatus. • The ZnO top layer can enhance the antireflective, antioxidative and anti-corrosion functions of the VO 2 film. • The ZnO top layer can endow VO 2 film with excellent antibacterial performance. • The ZnO top layer can attenuate the cytotoxicity of VO 2 thin film. - Abstract: A multifunctional VO 2 /ZnO bilayer film is designed and deposited by magnetron sputtering apparatus. The integration of the antireflective, antioxidative and anti-corrosion functions, and antibacterial performance makes the heterostructure film a promising candidate in the energy-saving smart window. The ZnO thin film as the antireflection layer can markedly boost the solar regulation efficiency (ΔT sol ) from 7.7% to 12.2% and possesses excellent luminous transmittance (T lum-L = 50.3%) in the low-temperature semiconductor phase. The ZnO layer as the protection barrier can not only protect VO 2 thin film from oxidation to much toxic V 2 O 5 , but also decrease the release of V ions. Besides, the synergistic effect of releasing killing by Zn 2+ ions and contact killing by ZnO NPs makes ZnO thin film an outstanding antibacterial coating. In terms of the biological safety, ZnO coating with appropriate film thickness can effectively attenuate the cytotoxicity of VO 2 on human HIBEpiC cells. We hope this work can provide new insights for better designing of novel multifunctional VO 2 -based intelligent energy-saving windows.

  7. Use of ZnO as antireflective, protective, antibacterial, and biocompatible multifunction nanolayer of thermochromic VO{sub 2} nanofilm for intelligent windows

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Huaijuan; Li, Jinhua [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Bao, Shanhu [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Li, Jian [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Liu, Xuanyong, E-mail: xyliu@mail.sic.ac.cn [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Jin, Ping, E-mail: p-jin@mail.sic.ac.cn [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Materials Research Institute for Sustainable Development, National Institute of Advanced Industrial Science and Technology, Nagoya 463-8560 (Japan)

    2016-02-15

    Graphical abstract: - Highlights: • A multifunctional VO{sub 2}/ZnO bilayer film is designed and deposited by magnetron sputtering apparatus. • The ZnO top layer can enhance the antireflective, antioxidative and anti-corrosion functions of the VO{sub 2} film. • The ZnO top layer can endow VO{sub 2} film with excellent antibacterial performance. • The ZnO top layer can attenuate the cytotoxicity of VO{sub 2} thin film. - Abstract: A multifunctional VO{sub 2}/ZnO bilayer film is designed and deposited by magnetron sputtering apparatus. The integration of the antireflective, antioxidative and anti-corrosion functions, and antibacterial performance makes the heterostructure film a promising candidate in the energy-saving smart window. The ZnO thin film as the antireflection layer can markedly boost the solar regulation efficiency (ΔT{sub sol}) from 7.7% to 12.2% and possesses excellent luminous transmittance (T{sub lum-L} = 50.3%) in the low-temperature semiconductor phase. The ZnO layer as the protection barrier can not only protect VO{sub 2} thin film from oxidation to much toxic V{sub 2}O{sub 5}, but also decrease the release of V ions. Besides, the synergistic effect of releasing killing by Zn{sup 2+} ions and contact killing by ZnO NPs makes ZnO thin film an outstanding antibacterial coating. In terms of the biological safety, ZnO coating with appropriate film thickness can effectively attenuate the cytotoxicity of VO{sub 2} on human HIBEpiC cells. We hope this work can provide new insights for better designing of novel multifunctional VO{sub 2}-based intelligent energy-saving windows.

  8. Study of the wettability of ZnO nanofilms

    Science.gov (United States)

    Subedi, Deepak Prasad; Madhup, Dinesh Kumar; Sharma, Ashish; Joshi, Ujjwal Man; Huczko, Andrzej

    2012-04-01

    Al-doped and un-doped ZnO thin films deposited on quartz substrates by the nebulized spray pyrolysis method were studied to investigate the wettability of the surface. The main objective of the present study was to investigate the wettability of ZnO thin film by changing the concentration of Al doping. Microstructure and water contact angles of the films were measured by scanning electron microscopy (SEM) and using a contact angle goniometer. SEM studies revealed that the grain size within the film increases with the doping concentration. The contact angles were studied to see the effect of aluminum doping on the hydrophilicity of the film. ZnO films were found to be hydrophobic in nature. A good correlation was observed between the SEM micrographs and contact angle results. The nature of the film was found to change from being hydrophobic to hydrophilic after the treatment in low-pressure DC glow discharge plasma, which, however, was reversible with the storage time.

  9. Retracted: Study of the wettability of ZnO nanofilms

    Directory of Open Access Journals (Sweden)

    Ujjwal M Joshi

    2012-04-01

    Full Text Available Al-doped and un-doped ZnO thin films deposited on quartz substrates by the nebulized spray pyrolysis method were studied to investigate the wettability of the surface. The main objective of the present study was to investigate the wettability of ZnO thin film by changing the concentration of Al doping. Microstructure and water contact angles of the films were measured by scanning electron microscopy (SEM and using a contact angle goniometer. SEM studies revealed that the grain size within the film increases with the doping concentration. The contact angles were studied to see the effect of aluminum doping on the hydrophilicity of the film. ZnO films were found to be hydrophobic in nature. A good correlation was observed between the SEM micrographs and contact angle results. The nature of the film was found to change from being hydrophobic to hydrophilic after the treatment in low-pressure DC glow discharge plasma, which, however, was reversible with the storage time.

  10. Effect of gamma radiation on the optical and structural properties of ZnO nanowires with various diameters

    Science.gov (United States)

    Reyhani, A.; Gholizadeh, A.; vahedi, V.; Khanlary, M. R.

    2018-01-01

    The effects of gamma-irradiation are studied on the morphology and structural properties of ZnO nanowire with various diameters. The ZnO nanowires are grown using Zn thin films at various initial thicknesses including 125, 250 and 500 nm in air ambient. The results illustrate dramatic effects of Gamma-irradiation on the deformation of ZnO nanowires. Thus, radiation induce ripple ZnO surfaces instead ZnO nanowires. Gamma-irradiation has also been effective on the optical and crystalline properties of the nanowires. X-ray diffraction attests that size of the ZnO nano-structures has changed and (l00) crystalline direction related to Zn metal has been created after irradiation. UV-Visible spectra display two areas for transmittance of irradiated ZnO nanowires, one in the Visible-light and the other in IR sub-region. In the Visible-light area, the layer gets thicker from 125 to 500 nm; the difference between the layer transmittance spectra is reduced before and after gamma irradiation. In the IR-light region, with increasing of ZnO initial thickness, the difference between the layer transmittance spectra is increased before and after gamma irradiation. The photoluminescence spectroscopy displays that intensity of green-yellow band improves in compared to near-band-edge emission due to formation of Zn metal and oxygen vacancies after gamma irradiation.

  11. Morphology and photoluminescence of ZnO nanorods grown on sputtered GaN films with intermediate ZnO seed layer

    Energy Technology Data Exchange (ETDEWEB)

    Nandi, R. [Department of Physics, Indian Institute of Technology Bombay, Mumbai, 400076 (India); Srinivasa, R.S. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai, 400076 (India); Major, S.S., E-mail: syed@iitb.ac.in [Department of Physics, Indian Institute of Technology Bombay, Mumbai, 400076 (India)

    2016-10-01

    ZnO nanorods (NRs) were grown by chemical bath deposition on sputtered GaN over Si with and without sputtered ZnO seed layers. The effect of ZnO seed layer thickness, precursor concentration and growth temperature on the morphology and photoluminescence (PL) of ZnO-NRs has been studied. Scanning electron microscopy studies at different stages of growth have shown that the thickness of ZnO seed layer is critically important for controlling the growth behavior, morphology and density of ZnO-NRs on GaN surface. ZnO-NRs on bare GaN/Si grow with a large diameter and small aspect ratio of ∼4, displaying the tendency of lateral growth. Introduction of a thin ZnO seed layer (10 nm) under optimized precursor concentration and temperature drastically increases the aspect ratio to ∼16, due to partial coverage of ZnO on GaN surface and a moderate density of nucleation with small critical size. ZnO seed layers of higher thickness (50 nm and 100 nm) result in reduced aspect ratio due to increase in nucleation density and limited availability of reacting species. Increase in precursor concentration results in pronounced lateral growth and the decrease in growth temperature also results in compact nanorods with reduced aspect ratios. Room temperature photoluminescence (PL) studies show that ZnO-NRs on GaN, grown with or without ZnO seed layer under optimized precursor concentration and temperature, display high near-band-edge luminescence and negligible defect emission, compared to the nanorods on a ZnO seed layer over Si, as well as those grown at higher precursor concentration and lower temperatures. The enhanced PL is attributed to the absence of crystalline defects at nanorod interfaces due to lateral coalescence, arising from the moderate density and slight misalignment of the nanorods. - Highlights: • ZnO nanorods grown on sputtered GaN film display strong tendency of lateral growth. • Nanorods grown on 10 nm ZnO/GaN display moderate density and high aspect ratios.

  12. Sensitivity enhancement of metal oxide thin film transistor with back gate biasing

    NARCIS (Netherlands)

    Dam, V.A.T.; Blauw, M.A.; Brongersma, S.H.; Crego-Calama, M.

    2011-01-01

    In this work, a room-temperature sensing device for detecting carbon monoxide using a ZnO thin film is presented. The ZnO layer (thickness close to the Debye length), which has a polycrystalline structure, is deposited with atomic-layer deposition (ALD) on an Al2O3/Si substrate. The operating

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

    Indian Academy of Sciences (India)

    Administrator

    power transistors and gas sensing (Özgür et al 2005;. Jagadish and Pearton 2006; Klingshirn 2007; Rout et al. 2007). In recent years, various forms of ZnO, such as thin films, nanorods, nanowires, nanobelts, nanorings, nano- cages, etc have been prepared by physical and chemical routes aiming at various applications ...

  14. Etude des propriétés physiques des couches minces de ZnO ...

    African Journals Online (AJOL)

    In this work, thin films of ZnO intrinsic and doped Al are prepared by sol-gel technique associated with spin-coating onto glass substrates. Zinc acetate dehydrate, ethanol and mono-ethanolamine were used as a starting material, solvent and stabilizer, respectively. The structural, electrical and optical properties of the ...

  15. Incorporation of graphene in quantum dot sensitized solar cells based on ZnO nanorods.

    Science.gov (United States)

    Chen, Jing; Li, Chu; Eda, Goki; Zhang, Yan; Lei, Wei; Chhowalla, Manish; Milne, William I; Deng, Wei-Qiao

    2011-06-07

    We demonstrate a novel architecture of solar cell by incorporating graphene thin film in a quantum dot sensitized solar cell. Quantum dot sensitized nanorods with a graphene layer exhibited a 54.7% improvement comparing a quantum dot sensitized ZnO nanorods without graphene layer. A fill factor as high as ∼62% was also obtained.

  16. Determination of the optimal parameters for the fabrication of ZnO ...

    Indian Academy of Sciences (India)

    In this work, ZnO thin films have been prepared by spray pyrolysis deposition method on the glass substrates. The effect of deposition parameters, such as deposition rate, substrate temperature and solution volume has been studied by X-ray diffraction (XRD) method, UV–Vis–NIR spectroscopy, scanning electron ...

  17. Determination of the optimal parameters for the fabrication of ZnO ...

    Indian Academy of Sciences (India)

    Abstract. In this work, ZnO thin films have been prepared by spray pyrolysis deposition method on the glass substrates. The effect of deposition parameters, such as deposition rate, substrate temperature and solution volume has been studied by X-ray diffraction (XRD) method, UV–Vis–. NIR spectroscopy, scanning electron ...

  18. ZnO UV Detectors Project

    Data.gov (United States)

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

  19. Highly stable thin film transistors using multilayer channel structure

    KAUST Repository

    Nayak, Pradipta K.

    2015-03-09

    We report highly stable gate-bias stress performance of thin film transistors (TFTs) using zinc oxide (ZnO)/hafnium oxide (HfO2) multilayer structure as the channel layer. Positive and negative gate-bias stress stability of the TFTs was measured at room temperature and at 60°C. A tremendous improvement in gate-bias stress stability was obtained in case of the TFT with multiple layers of ZnO embedded between HfO2 layers compared to the TFT with a single layer of ZnO as the semiconductor. The ultra-thin HfO2 layers act as passivation layers, which prevent the adsorption of oxygen and water molecules in the ZnO layer and hence significantly improve the gate-bias stress stability of ZnO TFTs.

  20. Modulation-Doped In2O3/ZnO Heterojunction Transistors Processed from Solution.

    Science.gov (United States)

    Khim, Dongyoon; Lin, Yen-Hung; Nam, Sungho; Faber, Hendrik; Tetzner, Kornelius; Li, Ruipeng; Zhang, Qiang; Li, Jun; Zhang, Xixiang; Anthopoulos, Thomas D

    2017-05-01

    This paper reports the controlled growth of atomically sharp In 2 O 3 /ZnO and In 2 O 3 /Li-doped ZnO (In 2 O 3 /Li-ZnO) heterojunctions via spin-coating at 200 °C and assesses their application in n-channel thin-film transistors (TFTs). It is shown that addition of Li in ZnO leads to n-type doping and allows for the accurate tuning of its Fermi energy. In the case of In 2 O 3 /ZnO heterojunctions, presence of the n-doped ZnO layer results in an increased amount of electrons being transferred from its conduction band minimum to that of In 2 O 3 over the interface, in a process similar to modulation doping. Electrical characterization reveals the profound impact of the presence of the n-doped ZnO layer on the charge transport properties of the isotype In 2 O 3 /Li-ZnO heterojunctions as well as on the operating characteristics of the resulting TFTs. By judicious optimization of the In 2 O 3 /Li-ZnO interface microstructure, and Li concentration, significant enhancement in both the electron mobility and TFT bias stability is demonstrated. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-04-30

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

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

  3. Modulation-Doped In2O3/ZnO Heterojunction Transistors Processed from Solution

    KAUST Repository

    Khim, Dongyoon

    2017-03-15

    This paper reports the controlled growth of atomically sharp In2 O3 /ZnO and In2 O3 /Li-doped ZnO (In2 O3 /Li-ZnO) heterojunctions via spin-coating at 200 °C and assesses their application in n-channel thin-film transistors (TFTs). It is shown that addition of Li in ZnO leads to n-type doping and allows for the accurate tuning of its Fermi energy. In the case of In2 O3 /ZnO heterojunctions, presence of the n-doped ZnO layer results in an increased amount of electrons being transferred from its conduction band minimum to that of In2 O3 over the interface, in a process similar to modulation doping. Electrical characterization reveals the profound impact of the presence of the n-doped ZnO layer on the charge transport properties of the isotype In2 O3 /Li-ZnO heterojunctions as well as on the operating characteristics of the resulting TFTs. By judicious optimization of the In2 O3 /Li-ZnO interface microstructure, and Li concentration, significant enhancement in both the electron mobility and TFT bias stability is demonstrated.

  4. Hydrogen-surfactant-assisted coherent growth of GaN on ZnO substrate

    Science.gov (United States)

    Zhang, Jingzhao; Zhang, Yiou; Tse, Kinfai; Zhu, Junyi

    2018-01-01

    Heterostructures of wurtzite based devices have attracted great research interest because of the tremendous success of GaN in light emitting diodes (LED) industry. High-quality GaN thin films on inexpensive and lattice matched ZnO substrates are both commercially and technologically desirable. Intrinsic wetting conditions, however, forbid such heterostructures as the energy of ZnO polar surfaces is much lower than that of GaN polar surfaces, resulting in 3D growth mode and poor crystal quality. Based on first-principles calculations, we propose the use of surfactant hydrogen to dramatically alter the growth mode of the heterostructures. Stable H-involved surface configurations and interfaces are investigated with the help of our newly developed modelling techniques. The temperature and chemical potential dependence of our proposed strategy, which is critical in experiments, is predicted by applying the experimental Gibbs free energy of H2. Our thermodynamic wetting condition analysis is a crucial step for the growth of GaN on ZnO, and we find that introducing H will not degrade the stability of ZnO substrate. This approach will allow the growth of high-quality GaN thin films on ZnO substrates. We believe that our new strategy may reduce the manufactory cost, improve the crystal quality, and improve the efficiency of GaN-based devices.

  5. 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.

  6. Porous Zinc Oxide Thin Films: Synthesis Approaches and Applications

    Directory of Open Access Journals (Sweden)

    Marco Laurenti

    2018-02-01

    Full Text Available Zinc oxide (ZnO thin films have been widely investigated due to their multifunctional properties, i.e., catalytic, semiconducting and optical. They have found practical use in a wide number of application fields. However, the presence of a compact micro/nanostructure has often limited the resulting material properties. Moreover, with the advent of low-dimensional ZnO nanostructures featuring unique physical and chemical properties, the interest in studying ZnO thin films diminished more and more. Therefore, the possibility to combine at the same time the advantages of thin-film based synthesis technologies together with a high surface area and a porous structure might represent a powerful solution to prepare ZnO thin films with unprecedented physical and chemical characteristics that may find use in novel application fields. Within this scope, this review offers an overview on the most successful synthesis methods that are able to produce ZnO thin films with both framework and textural porosities. Moreover, we discuss the related applications, mainly focused on photocatalytic degradation of dyes, gas sensor fabrication and photoanodes for dye-sensitized solar cells.

  7. Epitaxial growth of zinc oxide thin films on silicon

    International Nuclear Information System (INIS)

    Jin Chunming; Narayan, Roger; Tiwari, Ashutosh; Zhou Honghui; Kvit, Alex; Narayan, Jagdish

    2005-01-01

    Epitaxial zinc oxide thin films were grown on Si(111) using aluminum nitride and magnesium oxide/titanium nitride buffer layers. The resultant films were examined using transmission electron microscopy, X-ray diffraction, electrical conductivity, and photoluminescence spectroscopy. The following epitaxial relationships were observed in the ZnO/AlN/Si(111) heterostructure: ZnO[0001] parallel AlN[0001] parallel Si[111] along the growth direction, and ZnO[21-bar 1-bar 0] parallel AlN[21-bar 1-bar 0] parallel Si[011-bar] along the in-plane direction. Domain-matching epitaxial growth of TiN on Si(111) substrate allows successful epitaxial growth of MgO and ZnO layers in a ZnO/MgO/TiN/Si(111) heterostructure. The epitaxial relationships observed for this heterostructure were ZnO[0001] parallel MgO/TiN/Si[111] along the growth direction and ZnO[21-bar 1-bar 0] parallel MgO/TiN/Si[011-bar] along in-plane direction. The resultant ZnO films demonstrate excellent electrical and optical properties. ZnO thin films exhibit extremely bright ultraviolet luminescence with relatively weak green-band emission

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

    International Nuclear Information System (INIS)

    Alves, Marta M.; Santos, Catarina F.; Carmezim, Maria J.; Montemor, Maria F.

    2015-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-03-30

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

  10. ZnO Coated Nanospring-Based Gas Sensors

    Science.gov (United States)

    Bakharev, Pavel Viktorovich

    The current research demonstrates new techniques for characterization of electrical transport properties of the metal oxide polycrystalline structures, gas and vapor phase kinetics, surface processes such as gas-surface, vapor-surface interactions and redox processes by applying novel gas sensing devices. Real-time sensor electrical response characteristics obtained under highly controlled laboratory conditions have been used to characterize corresponding surface interactions and electrical properties of the gas sensitive structures. Novel redox chemical sensors (chemiresistors) have been fabricated with 3-D and 1-D ZnO coated nanospring (NS) structures. Silica NSs served as insulating scaffolding for a ZnO gas sensitive layer and has been grown via a vapor-liquid-solid (VLS) mechanism by using a chemical vapor deposition (CVD) technique. The NSs have been coated with polycrystalline ZnO by atomic layer deposition (ALD). The chemiresistor devices have been thoroughly characterized in terms of their crystal structures (by XRD, FESEM, TEM, and ellipsometry) and their electrical response properties. A 3-D gas sensor has been constructed from a xenon light bulb by coating it with a 3-D zinc oxide coated silica nanospring mat, where the xenon light bulb served as a sensor heater. This inexpensive sensor platform has been used to characterize gas-solid, vapor-solid, and redox processes. The optimal temperature of the gas sensitive ZnO layer, the temperature of the vapor-gas mixture and the crystal structure of the gas sensitive layer have been determined to reach the highest sensitivity of the gas sensors. The activation energy of toluene oxidation (Ed) on the ZnO surface and the activation energy of oxidation (Ea) of the depleted ZnO surface have been determined and analyzed. A 1-D chemiresistor has been fabricated with a single ZnO coated silica nanospring by photolithography. The question of sensor sensitivity of MOS nanomaterials and MOS thin films has been addressed

  11. ZnO: Hydroquinone superlattice structures fabricated by atomic/molecular layer deposition

    International Nuclear Information System (INIS)

    Tynell, Tommi; Karppinen, Maarit

    2014-01-01

    Here we employ atomic layer deposition in combination with molecular layer deposition to deposit crystalline thin films of ZnO interspersed with single layers of hydroquinone in an effort to create hybrid inorganic–organic superlattice structures. The ratio of the ZnO and hydroquinone deposition cycles is varied between 199:1 and 1:1, and the structure of the resultant thin films is verified with X-ray diffraction and reflectivity techniques. Clear evidence of the formation of a superlattice-type structure is observed in the X-ray reflectivity patterns and the presence of organic bonds in the films corresponding to the structure of hydroquinone is confirmed with Fourier transform infrared spectroscopy measurements. We anticipate that hybrid superlattice structures such as the ones described in this work have the potential to be of great importance for future applications where the precise control of different inorganic and organic layers in hybrid superlattice materials is required. - Highlights: • Inorganic–organic superlattices can be made by atomic/molecular layer deposition. • This is demonstrated here for ZnO and hydroquinone (HQ). • The ratio of the ZnO and HQ layers is varied between 199:1 and 14:1. • The resultant thin films are crystalline

  12. ZnO growth technologies: current status and perspectives

    International Nuclear Information System (INIS)

    Lupan, Oleg

    2011-01-01

    Development of new technologies for ZnO nano materials and thin films is of critical importance for further fundamental investigations and practical applications. We discuss on the main technical control of the synthesis of zinc oxide and its properties, which are of significance in understanding the growth mechanism and further developing ZnO-based devices. Next, we present a brief summary of recent research activities, current status and progress in developing improved control of technological processes for zinc oxide as advanced material.

  13. Electrical switching in Sb doped Al23Te77 glasses

    Science.gov (United States)

    Pumlianmunga; Ramesh, K.

    2017-08-01

    Bulk glasses (Al23Te77)Sbx (0≤ x≤10) prepared by melt quenching method show a change in switching type from threshold to memory for x≥5. An increase in threshold current (Ith) and a concomitant decrease in threshold voltage (Vth) and resisitivity(ρ) have been observed with the increase of Sb content. Raman spectra of the switched region in memory switching compositions show a red shift with respect to the as prepared glasses whereas in threshold switching compositions no such shift is observed. The magic angle spinning nuclear magnetic resonance (MAS NMR) of 27Al atom shows three different environments for Al ([4]Al, [5]Al and [6]Al). The samples annealed at their respective crystallization temperatures show rapid increase in [4]Al sites by annihilating [5]Al sites. The melts of threshold switching glasses (x≤2.5) quenched in water at room temperature (27 °C) show amorphous structure whereas, the melt of memory switching glasses (x>2.5) solidify into crystalline structure. The higher coordination of Al increases the cross-linking and rigidity. The addition of Sb increases the glass transition(Tg) and decreases the crystallization temperature(Tc). The decrease in the interval between the Tg and Tc eases the transition between the amorphous and crystalline states and improves the memory properties. The temperature rise at the time of switching can be as high as its melting temperature and the material in between the electrodes may melt to form a filament. The filament may consists of temporary (high resistive amorphous) and permanent (high conducting crystalline) units. The ratio between the temporary and the permanent units may decide the switching type. The filament is dominated by the permanent units in memory switching compositions and by the temporary units in threshold switching compositions. The present study suggests that both the threshold and memory switching can be understood by the thermal model and filament formation.

  14. Transparent conductive zinc oxide basics and applications in thin film solar cells

    CERN Document Server

    Klein, Andreas; Rech, Bernd

    2008-01-01

    Zinc oxide (ZnO) belongs to the class of transparent conducting oxides which can be used as transparent electrodes in electronic devices or heated windows. In this book the material properties of, the deposition technologies for, and applications of zinc oxide in thin film solar cells are described in a comprehensive manner. Structural, morphological, optical and electronic properties of ZnO are treated in this review. The editors and authors of this book are specialists in deposition, analysis and fabrication of thin-film solar cells and especially of ZnO. This book is intended as an overview and a data collection for students, engineers and scientist.

  15. Seedless Pattern Growth of Quasi-Aligned ZnO Nanorod Arrays on Cover Glass Substrates in Solution

    Science.gov (United States)

    Ahsanulhaq, Q.; Kim, Jin Hwan; Kim, Jeong Hyun; Hahn, Y. B.

    2010-03-01

    A hybrid technique for the selective growth of ZnO nanorod arrays on wanted areas of thin cover glass substrates was developed without the use of seed layer of ZnO. This method utilizes electron-beam lithography for pattern transfer on seedless substrate, followed by solution method for the bottom-up growth of ZnO nanorod arrays on the patterned substrates. The arrays of highly crystalline ZnO nanorods having diameter of 60 ± 10 nm and length of 750 ± 50 nm were selectively grown on different shape patterns and exhibited a remarkable uniformity in terms of diameter, length, and density. The room temperature cathodluminescence measurements showed a strong ultraviolet emission at 381 nm and broad visible emission at 585-610 nm were observed in the spectrum.

  16. Fabrication and characterization of novel transparent conducting oxide N-CNT doped ZnO for photovoltaic applications

    Science.gov (United States)

    Benyounes, Anas; Abbas, Naseem; Hammi, Maryama; Ziat, Younes; Slassi, Amine; Zahra, Nida

    2018-02-01

    The present research reports on the electrical and optical properties of N-CNT doped with ZnO, which is considered as wurtzite transparent and conducting oxide semiconductor structure. The thin films of N-doped carbon nanotubes/ZnO were prepared using sol-gel method, then we carried out investigations in optical and electrical point of view to extract their usefulness in photovoltaic applications. For this purpose, ZnO films were doped by several ratios of carbon nanotubes and N-doped carbon nanotubes. The electrical studies were performed over these two kinds of doped ZnO films, the electrical conductivity has found to be more important for ZnO films filled with N-CNTs. This finding is pretty explained by the electronic conduction hold by nitrogen as charge carriers within carbon nanotubes.

  17. Study of (1 0 0) orientated ZnO films by APCVD system

    Energy Technology Data Exchange (ETDEWEB)

    Pacio, M. [Centro de Investigacion en Dispositivos Semiconductores, Universidad Autonoma de Puebla, 14 Sur and Av. San Claudio, San Manuel 72000, Puebla (Mexico); Juarez, H., E-mail: hjuarez@cs.buap.mx [Centro de Investigacion en Dispositivos Semiconductores, Universidad Autonoma de Puebla, 14 Sur and Av. San Claudio, San Manuel 72000, Puebla (Mexico); Escalante, G.; Garcia, G.; Diaz, T.; Rosendo, E. [Centro de Investigacion en Dispositivos Semiconductores, Universidad Autonoma de Puebla, 14 Sur and Av. San Claudio, San Manuel 72000, Puebla (Mexico)

    2010-10-25

    ZnO thin films were grown on glass substrate by Atmospheric Pressure Chemical Vapor Deposition system (APCVD), using zinc acetate (Zn(CH{sub 3}COO){sub 2}) as precursor of Zn. The solution was prepared with zinc acetate in ammonium hydroxide (NH{sub 4}OH). Ozone was used as an oxidant agent to obtain ZnO films. The aqueous solution of zinc acetate was bubbled with nitrogen flow into the reaction chamber. The structural and optical properties of ZnO films were investigated in different deposition temperatures (300-375 deg. C in steps of 25 deg. C). X-ray diffraction results show that all deposited films were polycrystallined in (1 0 0) preferred orientation. Our samples showed a transmittance bigger or similar to 80% in the visible region. Preliminary studies show that the room-temperature photoluminescence spectrum of all films exhibits a strong peak in visible region at 492.31 nm.

  18. Double-layered ZnO nanostructures for efficient perovskite solar cells

    KAUST Repository

    Mahmood, Khalid

    2014-01-01

    To date, a single layer of TiO2 or ZnO has been the most successful implementations of any electron transport layer (ETL) in solution-processed perovskite solar cells. In a quest to improve the ETL, we explore a new nanostructured double-layer ZnO film for mesoscopic perovskite-based thin film photovoltaics. This approach yields a maximum power conversion efficiency of 10.35%, which we attribute to the morphology of oxide layer and to faster electron transport. The successful implementation of the low-temperature hydrothermally processed double-layer ZnO film as ETL in perovskite solar cells highlights the opportunities to further improve the efficiencies by focusing on the ETL in this rapidly developing field. This journal is

  19. Study of (1 0 0) orientated ZnO films by APCVD system

    International Nuclear Information System (INIS)

    Pacio, M.; Juarez, H.; Escalante, G.; Garcia, G.; Diaz, T.; Rosendo, E.

    2010-01-01

    ZnO thin films were grown on glass substrate by Atmospheric Pressure Chemical Vapor Deposition system (APCVD), using zinc acetate (Zn(CH 3 COO) 2 ) as precursor of Zn. The solution was prepared with zinc acetate in ammonium hydroxide (NH 4 OH). Ozone was used as an oxidant agent to obtain ZnO films. The aqueous solution of zinc acetate was bubbled with nitrogen flow into the reaction chamber. The structural and optical properties of ZnO films were investigated in different deposition temperatures (300-375 deg. C in steps of 25 deg. C). X-ray diffraction results show that all deposited films were polycrystallined in (1 0 0) preferred orientation. Our samples showed a transmittance bigger or similar to 80% in the visible region. Preliminary studies show that the room-temperature photoluminescence spectrum of all films exhibits a strong peak in visible region at 492.31 nm.

  20. Double-layered ZnO nanostructures for efficient perovskite solar cells

    Science.gov (United States)

    Mahmood, Khalid; S. Swain, Bhabani; Amassian, Aram

    2014-11-01

    To date, a single layer of TiO2 or ZnO has been the most successful implementations of any electron transport layer (ETL) in solution-processed perovskite solar cells. In a quest to improve the ETL, we explore a new nanostructured double-layer ZnO film for mesoscopic perovskite-based thin film photovoltaics. This approach yields a maximum power conversion efficiency of 10.35%, which we attribute to the morphology of oxide layer and to faster electron transport. The successful implementation of the low-temperature hydrothermally processed double-layer ZnO film as ETL in perovskite solar cells highlights the opportunities to further improve the efficiencies by focusing on the ETL in this rapidly developing field.

  1. Ferromagnetism in ZnO doped with Co by ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Borges, R.P. [CFMCUL, Ed. C8, Campo Grande, 1749-016 Lisbon (Portugal)]. E-mail: rpborges@fc.ul.pt; Pinto, J.V. [CFMCUL, Ed. C8, Campo Grande, 1749-016 Lisbon (Portugal); LFI, Departamento de Fisica, ITN, Estrada Nacional 10, 2695-953 Sacavem (Portugal); CFNUL, Av. Prof. Gama Pinto 2, 1649-003 Lisbon (Portugal); Silva, R.C. da [LFI, Departamento de Fisica, ITN, Estrada Nacional 10, 2695-953 Sacavem (Portugal); CFNUL, Av. Prof. Gama Pinto 2, 1649-003 Lisbon (Portugal); Goncalves, A.P. [CFMCUL, Ed. C8, Campo Grande, 1749-016 Lisbon (Portugal); Departamento de Quimica, ITN, Estrada Nacional 10, 2695-953 Sacavem (Portugal); Cruz, M.M. [CFMCUL, Ed. C8, Campo Grande, 1749-016 Lisbon (Portugal); Fac.Ciencias, Universidade de Lisboa, Dep. Fisica, Ed. C8, Campo Grande, 1749-016 Lisbon (Portugal); Godinho, M. [CFMCUL, Ed. C8, Campo Grande, 1749-016 Lisbon (Portugal); Fac.Ciencias, Universidade de Lisboa, Dep. Fisica, Ed. C8, Campo Grande, 1749-016 Lisbon (Portugal)

    2007-09-15

    The importance of doping ZnO with magnetic ions is associated with the fact that this oxide is a good candidate for the formation of a magnetic-diluted semiconductor. Most of the studies reported in Co-doped ZnO were carried out in thin films, but the understanding of the modification of the magnetic behaviour due to doping demands the study of single-crystalline samples. In this work, ZnO single crystals were doped at room temperature with Co by ion implantation with fluences ranging between 2x10{sup 16} and 1x10{sup 17} ions cm{sup -2} and implantation energy of 100 keV. As implanted samples show a superparamagnetic behaviour attributed to the formation of Co clusters, room temperature ferromagnetism is attained after annealing at 800 deg. C, but no magnetoresistance was detected in the temperature range from 10 to 300 K.

  2. "High Quantum Efficiency of Band-Edge Emission from ZnO Nanowires"

    Energy Technology Data Exchange (ETDEWEB)

    GARGAS, DANIEL; GAO, HANWEI; WANG, HUNGTA; PEIDONG, YANG

    2010-12-01

    External quantum efficiency (EQE) of photoluminescence as high as 20 percent from isolated ZnO nanowires were measured at room temperature. The EQE was found to be highly dependent on photoexcitation density, which underscores the importance of uniform optical excitation during the EQE measurement. An integrating sphere coupled to a microscopic imaging system was used in this work, which enabled the EQE measurement on isolated ZnO nanowires. The EQE values obtained here are significantly higher than those reported for ZnO materials in forms of bulk, thin films or powders. Additional insight on the radiative extraction factor of one-dimensional nanostructures was gained by measuring the internal quantum efficiency of individual nanowires. Such quantitative EQE measurements provide a sensitive, noninvasive method to characterize the optical properties of low-dimensional nanostructures and allow tuning of synthesis parameters for optimization of nanoscale materials.

  3. Study of zinc oxide thin film characteristics

    OpenAIRE

    Johari Shazlina; Muhammad Nazalea Yazmin; Zakaria Mohd Rosydi

    2017-01-01

    This paper presents the characterization of ZnO thin films with the thickness of 8nm, 30nm, and 200nm. The thin films were prepared using sol-gel method and has been deposited onto different substrate of silicon wafer, glass and quartz. The thin films were annealed at 400, 500 and 600°C. By using UV-Vis, the optical transmittance measurement were recorded by using a single beam spectrophotometer in the wavelength 250nm to 800nm. However, the transmittance in the visible range is hardly influe...

  4. Impact of strain on electronic defects in (Mg,Zn)O thin films

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Florian, E-mail: fschmidt@physik.uni-leipzig.de; Müller, Stefan; Wenckstern, Holger von; Benndorf, Gabriele; Pickenhain, Rainer; Grundmann, Marius [Universität Leipzig, Institut für Experimentelle Physik II, Linnéstraße 5, 04103 Leipzig (Germany)

    2014-09-14

    We have investigated the impact of strain on the incorporation and the properties of extended and point defects in (Mg,Zn)O thin films by means of photoluminescence, X-ray diffraction, deep-level transient spectroscopy (DLTS), and deep-level optical spectroscopy. The recombination line Y₂, previously detected in ZnO thin films grown on an Al-doped ZnO buffer layer and attributed to tensile strain, was exclusively found in (Mg,Zn)O samples being under tensile strain and is absent in relaxed or compressively strained thin films. Furthermore a structural defect E3´ can be detected via DLTS measurements and is only incorporated in tensile strained samples. Finally it is shown that the omnipresent deep-level E3 in ZnO can only be optically recharged in relaxed ZnO samples.

  5. Influence of oblique-angle sputtered transparent conducting oxides on performance of Si-based thin film solar cells

    International Nuclear Information System (INIS)

    Leem, Jung Woo; Yu, Jae Su

    2011-01-01

    The transparent conducting oxide (TCO) films with low-refractive-index (low-n) are fabricated by the oblique-angle sputtering method. By using the experimentally measured physical data of the fabricated low-n TCO films as the simulation parameters, the effect of low-n TCOs on the performance of a-Si:H/μc-Si:H tandem thin film solar cells is investigated using Silvaco ATLAS. The Al-doped zinc oxide, indium tin oxide (ITO), and Sb-doped tin oxide films are deposited at the flux incidence angles of θ i = 0 (normal sputtering) and θ i = 80 from the sputtering target during the sputtering process. The oblique-angle sputtered films at θ i = 80 show the inclined columnar nanostructures compared to those at θ i = 0 , modifying the optical properties of the films. This is caused mainly by the increase of porosity within the film which leads to its low-n characteristics. The a-Si:H/μc-Si:H tandem thin film solar cell incorporated with the low-n ITO film exhibits an improvement in the conversion efficiency of ∝1% under AM1.5g illumination because of its higher transmittance and lower absorption compared to that with the ITO film at θ i = 0 , indicating a conversion efficiency of 13.75%. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Influence of oblique-angle sputtered transparent conducting oxides on performance of Si-based thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Leem, Jung Woo; Yu, Jae Su [Department of Electronics and Radio Engineering, Kyung Hee University, 1 Seocheon-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of)

    2011-09-15

    The transparent conducting oxide (TCO) films with low-refractive-index (low-n) are fabricated by the oblique-angle sputtering method. By using the experimentally measured physical data of the fabricated low-n TCO films as the simulation parameters, the effect of low-n TCOs on the performance of a-Si:H/{mu}c-Si:H tandem thin film solar cells is investigated using Silvaco ATLAS. The Al-doped zinc oxide, indium tin oxide (ITO), and Sb-doped tin oxide films are deposited at the flux incidence angles of {theta}{sub i} = 0 (normal sputtering) and {theta}{sub i} = 80 from the sputtering target during the sputtering process. The oblique-angle sputtered films at {theta}{sub i} = 80 show the inclined columnar nanostructures compared to those at {theta}{sub i} = 0 , modifying the optical properties of the films. This is caused mainly by the increase of porosity within the film which leads to its low-n characteristics. The a-Si:H/{mu}c-Si:H tandem thin film solar cell incorporated with the low-n ITO film exhibits an improvement in the conversion efficiency of {proportional_to}1% under AM1.5g illumination because of its higher transmittance and lower absorption compared to that with the ITO film at {theta}{sub i} = 0 , indicating a conversion efficiency of 13.75%. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Genesis of flake-like morphology and dye-sensitized solar cell performance of Al-doped ZnO particles: a study

    International Nuclear Information System (INIS)

    Sengupta, D.; Mondal, B.; Mukherjee, K.

    2017-01-01

    In dye-sensitized solar cell (DSSC) application, the particulate morphologies of photo-anode facilitate efficient dye loading and thus lead to better photo-conversion efficiency than their thin film counterpart. However, till date, the electronic and optical properties as well as the DSSC application of Al-doped ZnO (AZO) particles as photo-anode material is studied less than thin films. Herein, phase formation behavior, morphology evolution, optical properties, and dye-sensitized solar cell performance of wet chemically prepared ZnO and AZO (dopant level: 1–4 mol%) particles are studied. It is found that Al doping modulates significantly the ZnO morphology which in turn results the maximum dye adsorption as well as best photo-conversion efficiency at optimum dopant concentration. Specifically, the nanoparticle of ZnO turns predominantly to flake-like morphology with a higher surface area when 2 mol% Al is doped. Such morphology modulation is expected, since the crystallinity, lattice parameters, and lattice strain of ZnO changes appreciably with Al doping. The variations of optical properties (absorbance, diffused reflectance, and band gap) of AZO materials as compared to primitive ZnO are also identified through UV-vis studies. An attempt is made here to correlate the structural features with the photovoltaic performances of ZnO and AZO.

  8. Genesis of flake-like morphology and dye-sensitized solar cell performance of Al-doped ZnO particles: a study

    Energy Technology Data Exchange (ETDEWEB)

    Sengupta, D.; Mondal, B.; Mukherjee, K., E-mail: kalisadhanm@yahoo.com [CSIR-Central Mechanical Engineering Research Institute, Centre for Advanced Materials Processing (India)

    2017-03-15

    In dye-sensitized solar cell (DSSC) application, the particulate morphologies of photo-anode facilitate efficient dye loading and thus lead to better photo-conversion efficiency than their thin film counterpart. However, till date, the electronic and optical properties as well as the DSSC application of Al-doped ZnO (AZO) particles as photo-anode material is studied less than thin films. Herein, phase formation behavior, morphology evolution, optical properties, and dye-sensitized solar cell performance of wet chemically prepared ZnO and AZO (dopant level: 1–4 mol%) particles are studied. It is found that Al doping modulates significantly the ZnO morphology which in turn results the maximum dye adsorption as well as best photo-conversion efficiency at optimum dopant concentration. Specifically, the nanoparticle of ZnO turns predominantly to flake-like morphology with a higher surface area when 2 mol% Al is doped. Such morphology modulation is expected, since the crystallinity, lattice parameters, and lattice strain of ZnO changes appreciably with Al doping. The variations of optical properties (absorbance, diffused reflectance, and band gap) of AZO materials as compared to primitive ZnO are also identified through UV-vis studies. An attempt is made here to correlate the structural features with the photovoltaic performances of ZnO and AZO.

  9. Photochemical Reaction Patterns on Heterostructures of ZnO on Periodically Poled Lithium Niobate.

    Science.gov (United States)

    Kaur, Manpuneet; Liu, Qianlang; Crozier, Peter A; Nemanich, Robert J

    2016-10-05

    The internal electric field in LiNbO 3 provides a driving force for heterogeneous photocatalytic reactions, where photoexcited holes or electrons can participate in redox reactions on positive (+c) and negative (-c) domain surfaces and at the domain boundaries. One method to characterize the surface chemical reactivity is to measure photoinduced Ag deposition by immersing the LiNbO 3 in an aqueous AgNO 3 solution and illuminating with above bandgap light. Reduction of Ag + ions leads to the formation of Ag nanoparticles at the surface, and a high density of Ag nanoparticles indicates enhanced surface photochemical reactions. In this study, an n-type semiconducting ZnO layer is deposited on periodically poled LiNbO 3 (PPLN) to modulate the surface electronic properties and impact the surface redox reactions. After plasma enhanced atomic layer deposition (PEALD) of 1, 2, 4, and 10 nm ZnO thin films on PPLN substrates, the substrates were immersed in aqueous AgNO 3 and illuminated with above band gap UV light. The Ag nanoparticle density increased for 1 and 2 nm ZnO/PPLN heterostructures, indicating an enhanced electron density at the ZnO/PPLN surface. However, increasing the ZnO thickness beyond 2 nm resulted in a decrease in the Ag nanoparticle density. The increase in nanoparticle density is related to the photoexcited charge density at the ZnO/PPLN interface and the presence of a weakly adsorbed Stern layer at the ZnO surface. The decrease in the nanoparticle density for thicker ZnO is attributed to photoexcited electron screening in the ZnO layer that suppresses electron flow from the LiNbO 3 to ZnO surface.

  10. Simple Preparation of ZnO Nano-layer by Sol-Gel Method as Active Electrode in P3HT/ZnO Heterojunction Solar Cell

    Science.gov (United States)

    Aprilia, Annisa; Herman, Hidayat, Rahmat

    2010-10-01

    Highly transparent undoped ZnO thin films have been prepared on glass and indium tin oxide substrates with simple process by sol-gel route and dip-coating deposition. Gel precursor of ZnO was prepared from zinc acetat dehydrate solution in methanol with the addition of trietylamine as stabilizing agent. Thin layer of gel precursor was prepared by dip coating and then followed by calcination at 400° C for 5 minute in air atmosphere. The thickness of the resulted ZnO thin film produced by ten times coating is about 150 nm. The films shows high transmittance larger than 98% in the visible region (400-800 nm). Absorption is observed in the UV region with absorption onset at about 390 nm indicating varying band gap between 3.18 eV until 3.23 eV depending on the number of coating layer. The AFM image shows that the films seems to be constructed from random stacking of nano-sized ZnO particle in the order of 50 nm. Among the prepared samples, the lowest resistivity is about 1.8×107 Ωm observed in the five-layer coating film. In order to fabricate solar cell structure, P3HT was deposited onto the ZnO thin film layer by spin casting technique and then followed by metal (Au) layer deposition by thermal evaporation. The formed solar cell has the inverted type solar cell with ITO/ZnO/P3HT/Au configuration. By the insertion ZnO layer, the photocurrent was improved by more than ten orders of magnitude in comparison to that of without ZnO layer. The measured photocurrent decreases at large number of coating layer which is supposed to be related with the current limitation by the effective carrier path length in ZnO layer.

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

    Directory of Open Access Journals (Sweden)

    Nur Azimah Abd Samad

    2015-01-01

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

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

    Science.gov (United States)

    Eom, Tae Hoon; Han, Jeong In

    2018-01-01

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

  13. N-doped ZnO nanosheets: towards high performance two dimensional catalysts

    Science.gov (United States)

    Guo, Na; Meng Yam, Kah; Wang, Xiaolu; Zhang, Chun

    2018-03-01

    Recently, catalytic activity of atomically thin two dimensional (2D) materials has attracted great interest. In this paper, via first principles calculations, we show for the first time that N-doped 2D one-atom-thick ZnO nanosheets exhibit high catalytic activity towards CO oxidation. A pristine 2D ZnO nanosheet is chemically inert and as a result, CO and O2 molecules do not chemically bind on the nanosheet. Our calculations predict that the N doping activates the ZnO sheet, leading to strong CO and O2 adsorptions. We further show that the CO oxidation catalyzed by the N-doped 2D ZnO sheet has a low reaction barrier around 0.5 eV. Besides high catalytic activity, the N-doped 2D ZnO sheet also demonstrates intriguing electronic and magnetic properties. These findings provide new opportunities for the future development of high performance 2D catalysts.

  14. 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.

  15. Wet chemically grown composite thin film for room temperature LPG sensor

    Science.gov (United States)

    Birajadar, Ravikiran; Desale, Dipalee; Shaikh, Shaheed; Mahajan, Sandip; Upadhye, Deepak; Ghule, Anil; Sharma, Ramphal

    2014-04-01

    We have synthesized thin film of zinc oxide-polyaniline (ZnO/PANI) composite using a simple wet chemical approach. As-synthesized ZnO/PANI composite thin film studied using different characterization techniques. The optical study reveals the penetration and interaction of PANI molecules with ZnO thin film. Prominent blue shift in UV-vis due to interaction between ZnO and PANI indicate presence of zinc oxide in polyaniline matrix. It is observed that ZnO thin film is not sensitive to LPG (liquefied petroleum gas) at room temperature. On the other hand ZnO/PANI composite thin film shows good response and recovery behaviors at room temperature.

  16. Determination of chemical state of Al doping element in ZnO layer

    International Nuclear Information System (INIS)

    Csik, A.; Toth, J.; Lovics, R.; Takats, V.; Hakl, J.; Vad, K.

    2011-01-01

    Complete text of publication follows. Transparent and conducting oxides (TCO) thin films are very important from the scientific and technological point of view. The coexistence of electrical conductivity and optical transparency in these materials makes it possible to use them in modern technologies: transparent electrodes for flat panel displays and photovoltaic cells, low emissivity windows, transparent thin films transistors, light emitting diodes. One of the important TCO semiconductors is the impurity-doped zinc-oxide (ZnO) layer, for example aluminium doped zinc-oxide layer (AZO), due to its unique physical and chemical properties. It has wide band gap (3.44 eV) and large exciton binding energy (60 meV). ZnO thin layers have a great interest for potential applications in optical and optoelectronic devices. Furthermore, high quality single crystal ZnO wafers has already been available as a result of new developments in ZnO growth technologies with the capability to scale up wafer size, which is an important factor for increasing efficiency of solar cells. Nonetheless, in order to enable the use of ZnO layers with enhanced electrical properties, higher conductivities can be obtained by doping with donor elements such as aluminium, gallium, indium, boron or fluorine. Investigation of p-type doping possibilities, diffusion processes and thermal stability of these layers are in the focus of interest in the interpretation of their optical and electrical properties, and the prediction of their lifetime. In our SNMS/SIMS-XPS laboratory, experiments on TCO layered structures were carried on. Depth profile and chemical state analyses of ZnO/AlO/ZnO layered structures were performed by Secondary Neutral Mass Spectrometry (SNMS) and X-ray photoelectron spectroscopy (XPS). The samples were produced by atomic layer deposition technique with the following layered structure: between a few hundred atomic layers of ZnO was an AlO atomic layer. The SNMS was used for depth

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

    Indian Academy of Sciences (India)

    The PPy/1-D ZnO nanocompositeswere used for the sensing of NH 3 , LPG, CO 2 and H 2 S gases, respectively, at room temperature. It was observed that PPy/1-D ZnO nanocomposites with different 1-D ZnO nanorod weight ratios (15 and 25%) had better selectivity and sensitivity towards NH3 at room temperature.

  18. Improving the Efficiency of Dye-Sensitized Solar Cells by Growing Longer ZnO Nanorods on TiO2 Photoanodes

    Directory of Open Access Journals (Sweden)

    Bao-gai Zhai

    2017-01-01

    Full Text Available By increasing the temperature of hydrothermal reactions from 70 to 100°C, vertically aligned ZnO nanorods were grown on the TiO2 thin film in the photoanode of dye-sensitized solar cells (DSSCs as the blocking layer to reduce the electron back recombinations at the TiO2/electrolyte interfaces. The length effects of ZnO nanorods on the photovoltaic performances of TiO2 based DSSCs were investigated by means of scanning electron microscope, X-ray diffractometer, photoluminescence spectrophotometer, and the photocurrent-voltage measurement. Under the illumination of 100 mW/cm2, the power conversion efficiency of DSSC with ZnO nanorods decorated TiO2 thin film as its photoanode can be increased nearly fourfold from 0.27% to 1.30% as the length of ZnO nanorods increases from 300 to 1600 nm. The enhanced efficiency of DSSC with ZnO nanorods decorated TiO2 thin film as the photoanode can be attributed to the larger surface area and the lower defect density in longer ZnO nanorods, which are in favor of more dye adsorption and more efficient transport in the photoanode.

  19. VLS-grown diffusion doped ZnO nanowires and their luminescence properties

    International Nuclear Information System (INIS)

    Roy, Pushan Guha; Dutta, Amartya; Das, Arpita; Bhattacharyya, Anirban; Sen, Sayantani; Pramanik, Pallabi

    2015-01-01

    Zinc Oxide (ZnO) nanowires were deposited by vapor–liquid–solid (VLS) method on to aluminum doped ZnO (AZO) thin films grown by sol-gel technique. For various device applications, current injection into such nanowires is critical. This is expected to be more efficient for ZnO nanowires deposited on to AZO compared to those deposited on to a foreign substrate such as silicon. In this work we compare the morphological and optical properties of nanowires grown on AZO with those grown under similar conditions on silicon (Si) wafers. For nanowires grown on silicon, diameters around 44 nm with heights around 2.2 μm were obtained. For the growth on to AZO, the diameters were around 90 nm while the heights were around 520 nm. Room temperature photoluminescence (RT-PL) measurements show improved near band-edge emission for nanowires grown on to AZO, indicating higher material quality. This is further established by low temperature photoluminescence (LT-PL) measurements where excitonic transitions with width as small as 14 meV have been obtained at 4 K for such structures. Electron energy loss spectroscopy (EELS) studies indicate the presence of Al in the nanowires, indicating a new technique for introduction of dopants into these structures. These results indicate that ZnO nanowires on sol-gel grown AZO thin films show promise in the development of various optoelectronic devices. (paper)

  20. Application of ZnO Nanoparticle as Sulphide Gas Sensor Using UV/VIS/NIR-Spectrophotometer

    Science.gov (United States)

    Juliasih, N.; Buchari; Noviandri, I.

    2017-04-01

    The nanoparticle of metal oxides has great unique characteristics that applicable to the wide industrial as sensors and catalysts for reducing environmental pollution. Sulphide gas monitors and detectors are required for assessing safety aspects, due to its toxicity level. A thin film of ZnO as the sulphide gas sensor was synthesised by the simple method of chemical liquid deposition with variation of annealing temperature from 200 ºC to 500 ºC, and characterised by Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), and UV/VIS/NIR-Spectrophotometer. Characterization studies showed nanoparticle size from the range 62 - 92 nm of diameters. The application this ZnO thin film to sulfide gas, detected by UV/VIS/NIR Spectrophotometer with diffuse reflectance, showed specific chemical reaction by the shifting of maximum % Reflectance peak. The gas sensing using this method is applicable at room.

  1. Synthesis and Characterization of Flower-Like Bundles of ZnO Nanosheets by a Surfactant-Free Hydrothermal Process

    Directory of Open Access Journals (Sweden)

    Jijun Qiu

    2014-01-01

    Full Text Available Flower-like bundles of ZnO nanosheets have been prepared by using preheating hydrothermal process without any surfactants. The flower-like bundles consist of many thin and uniform hexagonal-structured ZnO nanosheets, with a thickness of 50 nm. The selected area electronic diffraction (SAED and high-resolution transmission electron microscope (HRTEM images indicate that the ZnO nanosheets are single crystal in nature. The growth mechanism of the flower-like bundles of ZnO nanosheets is discussed based on the morphology evolution with growth times and reaction conditions. It is believed that the formation of flower-like bundles of ZnO nanosheets is related to the shielding effect of OH− ions and the self-assembly process, which is dominated by a preheating time. Room temperature photoluminescence spectra results show that the annealing atmosphere strongly affects the visible emission band, which is sensitive to intrinsic and surface defects, especially oxygen interstitials, in flower-like bundles of ZnO nanosheets.

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

    International Nuclear Information System (INIS)

    Sali, S.; Boumaour, M.; Kechouane, M.; Kermadi, S.; Aitamar, F.

    2012-01-01

    A ZnO thin film was successfully synthesized on glass, flat surface and textured silicon substrates by chemical spray deposition. The textured silicon substrate was carried out using two solutions (NaOH/IPA and Na 2 CO 3 ). Textured with Na 2 CO 3 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.

  3. Evaluation of Alternative Atomistic Models for the Incipient Growth of ZnO by Atomic Layer Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Manh-Hung; Tian, Liang; Chaker, Ahmad; Skopin, Evgenii; Cantelli, Valentina; Ouled, Toufik; Boichot, Raphaël; Crisci, Alexandre; Lay, Sabine; Richard, Marie-Ingrid; Thomas, Olivier; Deschanvres, Jean-Luc; Renevier, Hubert; Fong, Dillon; Ciatto, Gianluca

    2017-03-20

    ZnO thin films are interesting for applications in several technological fields, including optoelectronics and renewable energies. Nanodevice applications require controlled synthesis of ZnO structures at nanometer scale, which can be achieved via atomic layer deposition (ALD). However, the mechanisms governing the initial stages of ALD had not been addressed until very recently. Investigations into the initial nucleation and growth as well as the atomic structure of the heterointerface are crucial to optimize the ALD process and understand the structure-property relationships for ZnO. We have used a complementary suite of in situ synchrotron x-ray techniques to investigate both the structural and chemical evolution during ZnO growth by ALD on two different substrates, i.e., SiO2 and Al2O3, which led us to formulate an atomistic model of the incipient growth of ZnO. The model relies on the formation of nanoscale islands of different size and aspect ratio and consequent disorder induced in the Zn neighbors' distribution. However, endorsement of our model requires testing and discussion of possible alternative models which could account for the experimental results. In this work, we review, test, and rule out several alternative models; the results confirm our view of the atomistic mechanisms at play, which influence the overall microstructure and resulting properties of the final thin film.

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

    Science.gov (United States)

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

    2018-02-01

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

  5. Morphological Influence of Solution-Processed Zinc Oxide Films on Electrical Characteristics of Thin-Film Transistors

    Directory of Open Access Journals (Sweden)

    Hyeonju Lee

    2016-10-01

    Full Text Available We report on the morphological influence of solution-processed zinc oxide (ZnO semiconductor films on the electrical characteristics of ZnO thin-film transistors (TFTs. Different film morphologies were produced by controlling the spin-coating condition of a precursor solution, and the ZnO films were analyzed using atomic force microscopy, X-ray diffraction, X-ray photoemission spectroscopy, and Hall measurement. It is shown that ZnO TFTs have a superior performance in terms of the threshold voltage and field-effect mobility, when ZnO crystallites are more densely packed in the film. This is attributed to lower electrical resistivity and higher Hall mobility in a densely packed ZnO film. In the results of consecutive TFT operations, a positive shift in the threshold voltage occurred irrespective of the film morphology, but the morphological influence on the variation in the field-effect mobility was evident. The field-effect mobility in TFTs having a densely packed ZnO film increased continuously during consecutive TFT operations, which is in contrast to the mobility decrease observed in the less packed case. An analysis of the field-effect conductivities ascribes these results to the difference in energetic traps, which originate from structural defects in the ZnO films. Consequently, the morphological influence of solution-processed ZnO films on the TFT performance can be understood through the packing property of ZnO crystallites.

  6. Low temperature and rapid deposition of ZnO nanorods on Si(100) substrate with tunable optical emissions

    International Nuclear Information System (INIS)

    Brahma, Sanjaya; Huang, J.-L.; Liu, C.P.; Kukreja, L.M.; Shivashankar, S.A.

    2013-01-01

    This research article describes the large scale fabrication of ZnO nanorods of various shapes on Si(100) substrate, by using metalorganic precursor of Zn in solutions with microwave as the source of energy. This is a low temperature, environmental friendly and rapid thin film deposition process, where ZnO nanorods (1–3 μm length) were grown only in 1–5 min of microwave irradiation. All as-synthesized nanorods are of single crystalline grown along the crystallographic direction. The coated nanorods were found to be highly dense having a thickness of ∼1–3 μm over the entire area 20 mm × 20 mm of the substrate. The ZnO thin film comprising of nanorods exhibits good adhesion with the substrate. A possible mechanism for the initial nucleation and growth of ZnO is discussed. A cross over from a strong visible light emission to an enhanced UV emission is observed, when the nature of the surfactants are varied from polymeric to ionic and nonionic. The position of the chromaticity coordinates in yellow region of the color space gives an impression of white light generation from these coatings by exciting with a blue laser. - Graphical abstract: White light emission from ZnO nanorods deposited on Si(100) substrate excited by a blue laser. Display Omitted - Highlights: • ZnO coatings (1–3 μm) were achieved quickly (1–5 min) by a simple microwave process. • The coatings are uniform having high density of nucleation and excellent growth rate. • Luminescence could be tuned from strong visible light emission to an enhanced UV emission. • White light emission could be achieved from these ZnO coatings

  7. Low temperature and rapid deposition of ZnO nanorods on Si(100) substrate with tunable optical emissions

    Energy Technology Data Exchange (ETDEWEB)

    Brahma, Sanjaya, E-mail: sanjayaphysics@gmail.com [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India); Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 701, Taiwan (China); Huang, J.-L.; Liu, C.P. [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Kukreja, L.M. [Raja Ramanna Center for Advanced Technology, Indore 452013 (India); Shivashankar, S.A. [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India); Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore 560012 (India)

    2013-07-15

    This research article describes the large scale fabrication of ZnO nanorods of various shapes on Si(100) substrate, by using metalorganic precursor of Zn in solutions with microwave as the source of energy. This is a low temperature, environmental friendly and rapid thin film deposition process, where ZnO nanorods (1–3 μm length) were grown only in 1–5 min of microwave irradiation. All as-synthesized nanorods are of single crystalline grown along the <0001> crystallographic direction. The coated nanorods were found to be highly dense having a thickness of ∼1–3 μm over the entire area 20 mm × 20 mm of the substrate. The ZnO thin film comprising of nanorods exhibits good adhesion with the substrate. A possible mechanism for the initial nucleation and growth of ZnO is discussed. A cross over from a strong visible light emission to an enhanced UV emission is observed, when the nature of the surfactants are varied from polymeric to ionic and nonionic. The position of the chromaticity coordinates in yellow region of the color space gives an impression of white light generation from these coatings by exciting with a blue laser. - Graphical abstract: White light emission from ZnO nanorods deposited on Si(100) substrate excited by a blue laser. Display Omitted - Highlights: • ZnO coatings (1–3 μm) were achieved quickly (1–5 min) by a simple microwave process. • The coatings are uniform having high density of nucleation and excellent growth rate. • Luminescence could be tuned from strong visible light emission to an enhanced UV emission. • White light emission could be achieved from these ZnO coatings.

  8. doped ZnO thick film resistors

    Indian Academy of Sciences (India)

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

  9. ZnO UV Detectors Project

    Data.gov (United States)

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

  10. In-Situ Hydrothermal Growth of Bi-Hierarchical ZnO Nanoarchitecture with Surface Modification for Efficient Hybrid Solar Cells

    International Nuclear Information System (INIS)

    Zheng, Yan-Zhen; Ding, Haiyang; Liu, Yu; Tao, Xia; Cao, Guozhong; Chen, Jian-Feng

    2014-01-01

    Graphical abstract: ZnO nanoarchitecture was constructed on a bi-dimension seed layer via a facile chemical bath deposition method. ZnO nanoarchitecture with D205 modification as photoelectrode in organic-inorganic hybrid solar cell exhibits a high overall photoelectric conversion efficiency of ∼ 1.30% due to maximizing favorable characteristics including substantial carrier generation and efficient charge transport. - Highlights: • Hierarchical 1D ZnO nanoarchitecture is grown on a dual-dimension seeded layer. • Carrier generation and charge transport are simultaneously maximized. • D205 modification enhances cell power conversion efficiency up to 1.30%. - Abstract: The ability to fabricate hierarchical one-dimensional (1D) ZnO nanoarchitecture with a high degree of multifunctionalities by suitable synthetic strategies still represents a vital issue towards boosting the ultimate photoelectric conversion efficiency of organic-inorganic hybrid solar cells (HSCs). We herein synthesize a hierarchical 1D ZnO nanoarchitecture i.e. ZnO NAR/NR grown on a dual-dimension seeded layer via an all-solution chemical bath deposition process. It is found that ZnO NAR/NR nanoarchitecture can accelerate electron separation and the D205 dye uptake, and hence simultaneously maximizing the key features of photoelectrode in HSCs i.e. carrier generation and charge transport. A remarkable efficiency of 1.30% is achieved under 1 sun illumination for D205-modified hierarchical ZnO HSC fabricated with a very thin layer of ZnO NAR/NR (thickness ∼1 μm) and a significant improvement is evaluated with respect to a reference photoanode made from ZnO nanorods

  11. ZnO top-down structuring for UV photonic applications (Conference Presentation)

    Science.gov (United States)

    Nomenyo, Komla D.; Chevalier-César, Clotaire; Rumyantseva, Anna; Gokarna, Anisha; Gwiazda, Agnieszka; Lérondel, Gilles

    2016-09-01

    ZnO is a promising II-VI semiconductor for UV applications although p-type ZnO is not yet available. Nevertheless it remains an alternative material for GaN and its alloy InGaN. For example, the exciton binding energy of ZnO (60 meV) is higher than that of GaN (21 meV). This allows ZnO to emit light at ambient temperature and interestingly, it increases the device brightness. Besides promising intrinsic properties, light-matter control and especially in the UV relies on the ability of material nanostructuring. We present here two different kinds of top-down process in order to nanostructure ZnO. The first one relies on Electron Beam Lithography (EBL) combined with a lift-off process and inductively coupled plasma (ICP) reactive ion etching (RIE). Nickel (Ni) has been used as a mask in order to have a high selectivity in the presence of C2F6 and O2 ionized gases. The etching rate used was 26nm/s in order to avoid roughness. The second process is called Direct Holographic Patterning (DHP). ZnO thin films have been holographicaly patterned for the first time by direct photodissolution in NaCl solution using laser interference lithography. Application of an electrical potential strongly increases the dissolution rate and decreases the pattern formation time. Both processes will be discussed in terms of their respective potential for light confinement in the UV.

  12. Influence of substrate temperature and Zn-precursors on atomic layer deposition of polycrystalline ZnO films on glass

    International Nuclear Information System (INIS)

    Makino, Hisao; Miyake, Aki; Yamada, Takahiro; Yamamoto, Naoki; Yamamoto, Tetsuya

    2009-01-01

    Influence of substrate temperature and Zn-precursors on growth rate, crystal structure, and electrical property of undoped ZnO thin films grown by atomic layer deposition (ALD) have been studied. Differences between dimethylzinc (DMeZn) and diethylzinc (DEtZn) used as Zn-precursors were examined. The ZnO films grown using DMeZn showed higher electrical resistivity compared to that grown using DEtZn. However, the higher resistivity in the case of DMeZn was owing to much amount of residual impurities incorporated during the ALD growth

  13. Transparent conducting oxide layers for thin film silicon solar cells

    NARCIS (Netherlands)

    Rath, J.K.; Liu, Y.; de Jong, M.M.; de Wild, J.; Schuttauf, J.A.; Brinza, M.; Schropp, R.E.I.

    2009-01-01

    Texture etching of ZnO:1%Al layers using diluted HCl solution provides excellent TCOs with crater type surface features for the front contact of superstrate type of thin film silicon solar cells. The texture etched ZnO:Al definitely gives superior performance than Asahi SnO2:F TCO in case of

  14. Fabrication and characterization of ZnO nano wires/Cd Se/CuSCN eta-solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Tena-Zaera, R.; Ryan, M.A.; Abou, Katty; Hodes, G.; Bastide, St.; Levy-Clement, C. [LCMTR, Institut des sciences chimiques Seine-Amont, CNRS, 94 - Thiais (France); Tena-Zaera, R. [Valancia Univ., Dept. Fisica Aplicada i Electromagnetisme (Spain); Ryan, M.A. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA (United States); Hodes, G. [Weizmann Institute of Science, Dept. of Materials and Interfaces, Rehovot (Israel)

    2006-05-15

    ZnO/CdSe/CuSCN extremely thin absorber (eta)-solar cells based on ZnO nano-wires have been successfully realized using easily accessible electrochemical and solution deposition techniques. An n-type ZnO film consisting of free-standing single crystal nano-wires several microns high and 100-200 nm in diameter was-deposited on a conducting glass (SnO{sub 2}:F) substrate covered by a thin spray pyrolysis ZnO electronic blocking layer. A 30-40-nm-thin layer of CdSe absorber was electrodeposited, coating the ZnO nano-wires. The voids between the ZnO/CdSe nano-wires were filled with p-type CuSCN; the entire assembly formed a p-i-n junction. The ZnO/CdSe nano-wire layer exhibited a high light-trapping effect, with an effective absorbance of {approx}89% and effective reflectance of {approx}8% in the 400-800 nm region of the solar spectrum (AM1.5). The effects of an annealing process on the CdSe grain size and on the energy conversion efficiency of the eta-solar cell have been analyzed. The obtained efficiencies, for cells with annealed CdSe (1.5-2.3%) show that the ZnO/CdSe/CuSCN nano-heterostructure is an interesting option for developing new solar cell devices. (authors)

  15. Fabrication and characterization of ZnO nano wires/Cd Se/CuSCN eta-solar cell

    International Nuclear Information System (INIS)

    Tena-Zaera, R.; Ryan, M.A.; Abou, Katty; Hodes, G.; Bastide, St.; Levy-Clement, C.; Tena-Zaera, R.; Ryan, M.A.; Hodes, G.

    2006-01-01

    ZnO/CdSe/CuSCN extremely thin absorber (eta)-solar cells based on ZnO nano-wires have been successfully realized using easily accessible electrochemical and solution deposition techniques. An n-type ZnO film consisting of free-standing single crystal nano-wires several microns high and 100-200 nm in diameter was-deposited on a conducting glass (SnO 2 :F) substrate covered by a thin spray pyrolysis ZnO electronic blocking layer. A 30-40-nm-thin layer of CdSe absorber was electrodeposited, coating the ZnO nano-wires. The voids between the ZnO/CdSe nano-wires were filled with p-type CuSCN; the entire assembly formed a p-i-n junction. The ZnO/CdSe nano-wire layer exhibited a high light-trapping effect, with an effective absorbance of ∼89% and effective reflectance of ∼8% in the 400-800 nm region of the solar spectrum (AM1.5). The effects of an annealing process on the CdSe grain size and on the energy conversion efficiency of the eta-solar cell have been analyzed. The obtained efficiencies, for cells with annealed CdSe (1.5-2.3%) show that the ZnO/CdSe/CuSCN nano-heterostructure is an interesting option for developing new solar cell devices. (authors)

  16. CO2 gas sensitivity of sputtered zinc oxide thin films

    Indian Academy of Sciences (India)

    TECS

    Abstract. For the first time, sputtered zinc oxide (ZnO) thin films have been used as a CO2 gas sensor. Zinc oxide thin films have been synthesized using reactive d.c. sputtering method for gas sensor applications, in the deposition temperature range from 130–153°C at a chamber pressure of 8⋅5 mbar for 18 h. Argon and ...

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

    Directory of Open Access Journals (Sweden)

    Hua Zhang

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

  18. Efficient, Hysteresis-Free, and Stable Perovskite Solar Cells with ZnO as Electron-Transport Layer: Effect of Surface Passivation.

    Science.gov (United States)

    Cao, Jing; Wu, Binghui; Chen, Ruihao; Wu, Youyunqi; Hui, Yong; Mao, Bing-Wei; Zheng, Nanfeng

    2018-01-19

    The power conversion efficiency of perovskite solar cells (PSCs) has ascended from 3.8% to 22.1% in recent years. ZnO has been well-documented as an excellent electron-transport material. However, the poor chemical compatibility between ZnO and organo-metal halide perovskite makes it highly challenging to obtain highly efficient and stable PSCs using ZnO as the electron-transport layer. It is demonstrated in this work that the surface passivation of ZnO by a thin layer of MgO and protonated ethanolamine (EA) readily makes ZnO as a very promising electron-transporting material for creating hysteresis-free, efficient, and stable PSCs. Systematic studies in this work reveal several important roles of the modification: (i) MgO inhibits the interfacial charge recombination, and thus enhances cell performance and stability; (ii) the protonated EA promotes the effective electron transport from perovskite to ZnO, further fully eliminating PSCs hysteresis; (iii) the modification makes ZnO compatible with perovskite, nicely resolving the instability of ZnO/perovskite interface. With all these findings, PSCs with the best efficiency up to 21.1% and no hysteresis are successfully fabricated. PSCs stable in air for more than 300 h are achieved when graphene is used to further encapsulate the cells. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Synthesis of BiFeO3/ZnO core-shell hetero-structures using ZnO nanorod positive templates.

    Science.gov (United States)

    Chen, Shih-Wei; Lee, Chia-Ching; Chen, Ming-Teng; Wu, Jenn-Ming

    2011-03-18

    We report the synthesis, morphology, and magnetization characteristics of BiFeO(3) (BFO)-covered ZnO nanorod arrays (ZNAs). High quality and well-aligned ZNAs were grown by a hydrothermal method. BFO shells were deposited by sputtering at ambient temperature and then annealing in an oxygen atmosphere. The BFO shells crystallized to form a perovskite structure at 450 °C. Scanning electron microscopy and high resolution transmission electron microscopy demonstrated that the BFO shell was polycrystalline and randomly oriented, covering the ZnO nanorods well. The magnetization-magnetic field loops measured at 5 and 300 K indicate that the BFO/ZNA hetero-structure exhibits ferromagnetic order. The BFO/ZNA displays enhanced coercivity and saturated magnetization as compared with BFO thin films.

  20. Electrochemical fabrication of nanoporous polypyrrole thin films

    International Nuclear Information System (INIS)

    Li Mei; Yuan Jinying; Shi Gaoquan

    2008-01-01

    Polypyrrole thin films with pores in nanometer scale were synthesized by direct electrochemical oxidation of pyrrole in a mixed electrolyte of isopropyl alcohol, boron trifluoride diethyl etherate, sodium dodecylsulfonate and poly(ethylene glycol) using well-aligned ZnO nanowires arrays as templates. The thin films exhibit high conductivity of ca. σ rt ∼ 20.5 s/cm and can be driven to bend during redox processes in 1.0 M lithium perchlorate aqueous solution. The movement rate of an actuator based on this nanoporous film was measured to be over 90 o /s at a driving potential of 0.8 V (vs. Ag/AgCl)