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ZnO Thin Films (zno + thin_film)
Selected AbstractsPhotoelectrochemical Study of Nanostructured ZnO Thin Films for Hydrogen Generation from Water SplittingADVANCED FUNCTIONAL MATERIALS, Issue 12 2009Abraham Wolcott Abstract Photoelectrochemical cells based on traditional and nanostructured ZnO thin films are investigated for hydrogen generation from water splitting. The ZnO thin films are fabricated using three different deposition geometries: normal pulsed laser deposition, pulsed laser oblique-angle deposition, and electron-beam glancing-angle deposition. The nanostructured films are characterized by scanning electron microscopy, X-ray diffraction, UV-vis spectroscopy and photoelectrochemical techniques. Normal pulsed laser deposition produces dense thin films with ca. 200,nm grain sizes, while oblique-angle deposition produces nanoplatelets with a fishscale morphology and individual features measuring ca. 900 by 450,nm on average. In contrast, glancing-angle deposition generates a highly porous, interconnected network of spherical nanoparticles of 15,40,nm diameter. Mott-Schottky plots show the flat band potential of pulsed laser deposition, oblique-angle deposition, and glancing-angle deposition samples to be ,0.29, ,0.28 and +0.20,V, respectively. Generation of photocurrent is observed at anodic potentials and no limiting photocurrents were observed with applied potentials up to 1.3,V for all photoelectrochemical cells. The effective photon-to-hydrogen efficiency is found to be 0.1%, 0.2% and 0.6% for pulsed laser deposition, oblique-angle deposition and glancing-angle deposition samples, respectively. The photoelectrochemical properties of the three types of films are understood to be a function of porosity, crystal defect concentration, charge transport properties and space charge layer characteristics. [source] Photocatalysis Using ZnO Thin Films and Nanoneedles Grown by Metal,Organic Chemical Vapor Deposition,ADVANCED MATERIALS, Issue 18 2004L. Yang Highly efficient photocatalytic ZnO nanoneedle arrays with a large surface/volume ratio were prepared on inexpensive, large-area substrates using metal,organic chemical vapor deposition. The photocatalytic activity of ZnO nanoneedle arrays is much enhanced due to their increased surface/volume ratio. It is believed that the "bottom,up" approach may be expanded to create many other one-dimensional oxide semiconductor nanostructures (see Figure). [source] Flux of Positive Ions and Film Growth in Reactive Sputtering of Al-Doped ZnO Thin FilmsPLASMA PROCESSES AND POLYMERS, Issue S1 2007Florian Ruske Abstract The reactive magnetron sputtering deposition of Al-doped zinc oxide thin films using a dual magnetron has been studied for a flux of positive ions and the total thermal load onto the substrate. The spatial distribution of both quantities has been studied using a thermal probe and a retarding field analyzer mounted onto a moveable carrier system. The positive ions were found to mostly originate from the plasma sheath at the substrate, with the spatial distribution determined by the plasma density distribution in the coating chamber. The total energy flux to the substrate mainly originated from the plasma, with positive ions only contributing a small part of the total plasma irradiation. In the tested conditions and with the coater examined, the quality of the deposited films mainly depends on oxygen distribution on the substrate and is not a direct consequence of the total energy flux to the substrate. [source] Preparation of ZnO thin film by the sol,gel method using low temperature ozone oxidationPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2010Takashi Ehara Abstract Zinc oxide thin films have been prepared by the sol,gel method from a 2-methoxyethanol solution of zinc acetate dihydrate on SiO2 substrates using air, pure oxygen, and 1% ozone in oxygen as oxygen source. In the cases where air or oxygen was used as the oxygen source for thermal annealing, samples annealed at 600 to 800,°C exhibit a (0002) peak in X-ray diffraction (XRD). A sample annealed at 700,°C exhibited the highest (0002) peak intensity in conventional thermal annealing. However, the case using 1% ozone in oxygen as the atmosphere presented different results. A sample treated in 1% ozone at 100,°C had peak intensity in XRD (0002) comparable with samples annealed at several hundreds of degree in air or oxygen. This result indicates that the high oxidation efficiency of ozone is useful in decreasing the processing temperature of the sol,gel method. [source] Interface properties and junction behavior of Pd contact on ZnO thin film grown by vacuum deposition techniquePHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2010Ghusoon M. Ali Abstract In this paper we explain the results of our experimental investigation on interface properties and junction behavior of Pd contact on ZnO thin film based Schottky diode. We used a conventional vacuum evaporation deposition unit for sequential deposition of ZnO film and metallic layer. For the first time a high quality Pd/ZnO Schottky diode is fabricated successfully in our laboratory by vacuum evaporation method. The I-V and C-V characteristics of the devices were studied by using microprobe arrangement. The parameter such as ideality factor, leakage current, resistance-area-product, carrier concentration and barrier height were extracted from the measured data. The surface morphological and the structural properties of thin film were studied by atomic force microscope. The optical band gap of thin film was determined using UV-visible spectrophotometer. The device fabricated by a simple technique exhibited excellent stability for use as an electronic or optoelectronic component. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Investigation on visible emission control of ZnO thin filmPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2004Hong Seong Kang Abstract ZnO thin films were deposited on various substrates and ZnO-Si-ZnO multi-layer thin films were fabricated by pulsed laser deposition (PLD). ZnO thin films showed the three photoluminescence bands centered at around ultraviolet (380 nm), green (490,530 nm) and orange (570,640 nm) region. The region and intensity of visible emission of ZnO thin films were controlled as substrate and annealing treatment. As-grown ZnO thin film showed strong ultraviolet (UV) emission. ZnO thin films on (001) Al2O3 showed the increase of green emission caused by oxygen vacancies in the range of 490 nm to 530 nm, those on (100) InP showed the increase of orange emission caused by oxygen interstitials in the range of 610 nm to 640 nm. The increase of orange emission caused by oxygen interstitials was also observed from ZnO-Si-ZnO multi-layer thin films. The visible emission mechanism of ZnO was investigated. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Properties of InAs co-doped ZnO thin films prepared by pulsed laser depositionCRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2009J. Elanchezhiyan Abstract InAs co-doped ZnO films were grown on sapphire substrates by pulsed laser deposition. The grown films have been characterized using X-ray diffraction (XRD), Hall effect measurements, Atomic force microscope (AFM) and Field emission scanning electron microscope (FESEM) in order to investigate the structural, electrical, morphological and elemental properties of the films respectively. XRD analysis showed that all the films were highly orientated along the c-axis. It was observed from Hall effect measurements that InAs co-doped ZnO films were of n-type conductivity. In addition, the presence of In and As has been confirmed by Energy dispersive X-ray analysis. AFM images revealed that the surface roughness of the films was decreased upon the co-doping. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Optical studies on ZnO films prepared by sol-gel methodCRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2009T. Ghosh Abstract A standard sol-gel method was used to deposit ZnO thin films of suitable thickness on glass substrate. The optical characteristics of the visible to infrared range on thermal stress were critically observed. Morphological signature of the films was detected by X-ray diffraction (XRD) and the crystallite size determined by Scherrer method from XRD data were consistent with grain size estimated from spectroscopic data through Meulenkamp equation. The optical band gap value from the transmission spectrum was found to corroborate with the existing works. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Optical and electrical studies on spray deposited ZnO thin filmsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 7 2007P. P. Sahay Abstract ZnO thin films were prepared by spray pyrolytic decomposition of zinc acetate onto a glass substrate. These films were analyzed for the optical and electrical properties. Optical studies show that in these films the electronic transition is of the direct transition type. The optical energy gap for the films of different thicknesses is estimated to be in the range 2.98 , 3.09 eV. Electrical studies indicate that the films exhibit thermally activated electronic conduction and the activation energies are found to be dependent on the film thickness. The complex impedance measurements were carried out over a wide range of frequencies at room temperature (300 K). All the impedance spectra contain only a single arc, but the arc has a non-zero intersection with the real axis in the high frequency region. Also, the arc has its centre lying below with the real axis which indicates the multirelaxation behavior of the films. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Preparation of undoped and indium doped ZnO thin films by pulsed laser deposition methodCRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2005B. Kotlyarchuk Abstract An original modification of the standard Pulse Laser Deposition (PLD) method for preparing both undoped and indium doped zinc oxide (ZnO:In) thin films at low substrate temperature is proposed. This preparation method does not demand any further post-deposition annealing treatment of the grown films. The developed method allows to grow thin films at low substrate temperature that prevents them from the considerable loss of their intrinsic electrical and optical properties. The influence of deposition parameters on the electrical and optical parameters of the undoped and the indium doped ZnO thin films is also analysed. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Fabrication and evaluation of complementary logic circuits using zinc oxide and pentacene thin film transistorELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 9 2009Hiroyuki Iechi Abstract We fabricated hybrid complementary inverters with n-channel zinc oxide (ZnO) transistors as the n-type inorganic material and p-channel organic transistors using pentacene as the p-type organic material. The complementary inverter exhibited a large voltage gain of 10 to 12 and a cutoff frequency of 0.5 kHz. ZnO thin film transistors show n-type semiconducting properties having field-effect mobility of 2.1×10,3 cm2/Vs. On the other hand, pentacene thin film transistors show p-type semiconducting properties having field-effect mobility of 3.2×10,2 cm2/Vs. We describe basic charge transfer characteristics of ZnO thin films. The results obtained here demonstrate that it is important for the transistor using ZnO to be injected charge from electrode to semiconducting material effectively. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(9): 36,42, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10085 [source] Photoelectrochemical Study of Nanostructured ZnO Thin Films for Hydrogen Generation from Water SplittingADVANCED FUNCTIONAL MATERIALS, Issue 12 2009Abraham Wolcott Abstract Photoelectrochemical cells based on traditional and nanostructured ZnO thin films are investigated for hydrogen generation from water splitting. The ZnO thin films are fabricated using three different deposition geometries: normal pulsed laser deposition, pulsed laser oblique-angle deposition, and electron-beam glancing-angle deposition. The nanostructured films are characterized by scanning electron microscopy, X-ray diffraction, UV-vis spectroscopy and photoelectrochemical techniques. Normal pulsed laser deposition produces dense thin films with ca. 200,nm grain sizes, while oblique-angle deposition produces nanoplatelets with a fishscale morphology and individual features measuring ca. 900 by 450,nm on average. In contrast, glancing-angle deposition generates a highly porous, interconnected network of spherical nanoparticles of 15,40,nm diameter. Mott-Schottky plots show the flat band potential of pulsed laser deposition, oblique-angle deposition, and glancing-angle deposition samples to be ,0.29, ,0.28 and +0.20,V, respectively. Generation of photocurrent is observed at anodic potentials and no limiting photocurrents were observed with applied potentials up to 1.3,V for all photoelectrochemical cells. The effective photon-to-hydrogen efficiency is found to be 0.1%, 0.2% and 0.6% for pulsed laser deposition, oblique-angle deposition and glancing-angle deposition samples, respectively. The photoelectrochemical properties of the three types of films are understood to be a function of porosity, crystal defect concentration, charge transport properties and space charge layer characteristics. [source] The effect of oxygen remote plasma treatment on ZnO TFTs fabricated by atomic layer depositionPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2010Seungjun Lee Abstract We deposited ZnO thin films by atomic layer deposition (ALD) and then investigated the chemical and electrical characteristics after plasma treatment. The chemical bonding states were examined by X-ray photoelectron spectroscopy (XPS). The XPS spectra of O 1s showed that the intensity of oxygen deficient regions of the ZnO film decreased from 27.6 to 19.4%, while the intensity of the oxygen bound on the surface of the ZnO film increased from 15.0 to 21.9% as plasma exposure times increased. The ZnO film exhibited a decrease in carrier concentration from 4.9,×,1015 to 1.2,×,1014,cm,3 and an increase in resistivity from 1.2,×,102 to 9.8,×,103,,,cm as the plasma exposure times increased. To verify the changes in the chemical and electrical properties of the ZnO films caused by the oxygen remote plasma treatment, ZnO thin film transistors were fabricated and their electrical properties were investigated. We found that the Ion/Ioff ratio increased from 7.3,×,104 to 8.6,×,106, the subthreshold swings improved from 1.67 to 0.45,V/decade, and the saturation mobility (µsat) decreased from 1.63 to 0.72,cm2/V,s as plasma exposure times were increased. [source] Spectroscopic ellipsometry studies of Mg-doped ZnO thin films prepared by the sol,gel methodPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2009Shenghong Yang Abstract Zn1,xMgx O (ZMO) thin films with x = 0, 0.1, 0.2, and 0.3 were prepared on Si(100) substrates by the sol,gel method. The influence of Mg content on the structural and the optical properties was studied by X-ray diffraction and spectroscopic ellipsometry (SE) in the UV,visible region. The measured SE spectra were analyzed with an appropriate procedure to accurately determine the thickness and the optical constants of the thin films. It was found that the optical constants of the ZMO films are functions of the film composition. The refractive indices of the ZMO films decrease with increasing Mg content, and the optical bandgap energy exhibits nonlinear behavior or a bowing effect with the change of Mg mole fraction. A maximum band gap of ,3.91 eV was achieved at x = 0.3. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Properties of post-annealed ZnO films grown with O3PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2008H. S. Kim Abstract The properties of ZnO thin films grown with ozone are examined. Annealing studies were performed on ZnO films grown by pulsed-laser deposition using either O2 and an O2/O3 gas mixture as the oxidant. The carrier density of ZnO films grown with pure O2 generally decreases upon annealing in 1 atm O2. In contrast, the n-type carrier density for ZnO films grown with O2/O3 mixture gas increased with O2 annealing. The results indicate that acceptor states, created via growth in ozone, are annihilated with post-annealing. This suggests that the ozone-related acceptor states are metastable. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Enhanced ultraviolet photoluminescence from V-doped ZnO thin films prepared by a sol,gel processPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2007Ling Wei Abstract Undoped and vanadium-doped ZnO thin films were prepared on single-crystalline p-type Si(100) substrates by a sol,gel process and further annealed in an oxygen atmosphere. The influence of vanadium doping on the structural, surface morphological and optical properties of ZnO thin films was investigated by X-ray diffraction, atomic force microscopy and photoluminescence measurements. Both the undoped and V-doped ZnO thin films were of polycrystalline hexagonal wurtzite structure with (002)-preferred orientation. The crystallite size and the root-mean-square roughness of V-doped ZnO are smaller than those of undoped ZnO. Vanadium doping could reduce deep level defects of ZnO and thus strengthen ultraviolet (UV) emission. The peak intensity of UV emission increased with increasing annealing temperature above 400 °C. After annealing at 800 °C, the UV emission for the V-doped ZnO films was largely enhanced, while the visible emission was distinctly weakened. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Improved electrical, optical, and structural properties of undoped ZnO thin films grown by water-mist-assisted spray pyrolysisPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 10 2006L. Martínez Pérez Abstract Undoped ZnO thin films were prepared using the ultrasonic spray pyrolysis deposition technique with zinc acetylacetonate dissolved in N,N-dimethylformamide as the source materials solution. The addition of water mist in a parallel flux to the spray solution stream was also used during deposition of the films. The addition of water mist improved the electrical characteristics of the ZnO films. Fresh ZnO samples were then thermally annealed in a H2 reducing atmosphere. X-ray diffraction patterns show mainly the wurzite crystalline ZnO phase in the films. An electrical resistivity (, ) of around 2.7 × 10,2 , cm was measured at room temperature for the best undoped ZnO film. , is approximately one order of magnitude lower than the resistivities found in undoped ZnO films obtained by means of similar non-vacuum deposition techniques. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Influence of annealing temperature on the structural and optical properties of sol,gel prepared ZnO thin filmsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 10 2006Mingsong Wang Abstract Zinc oxide thin films have been prepared via a sol,gel process. The influence of annealing temperature on the structural and optical properties of the ZnO thin films has been investigated. The prepared ZnO thin films had a polycrystalline hexagonal wurtzite structure with no preferred orientation. The annealing temperature had a great effect on the optical properties of the ZnO thin films: the optical band gap became narrow due to the increase in crystallite size and the reduction in amorphous phase amount with increasing annealing temperature. Absorption or desorption of oxygen in the annealing process caused the observed yellow or green emission. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth and characterization of Sn doped ZnO thin films by pulsed laser depositionPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2006E. López-Ponce Abstract Sn:ZnO thin films with different Sn concentrations were grown by pulsed laser deposition (PLD) onto single-crystal Si(001) substrates at an oxygen pressure of 2 × 10,2 mbar and substrate temperature of 600 °C. The targets used were high density Sn:ZnO pellets with different Sn concentrations produced by mixing ZnO and SnO2 by conventional ceramic routes. A deep structural and electrical characterization was carried out in order to determine the role of an increasing Sn nominal concentration on the ZnO film transport properties. Only films with a nominal 0.1 at% Sn show an improvement of the transport properties, lower resistivity and higher donor concentration, with respect to pure ZnO thin films. For films with larger Sn nominal concentrations segregated SnZnO phases appear that lead to larger film resistivities and no increase in donor concentration. The 0.1 at% Sn film is accordingly a good candidate to study the possible room temperature ferromagnetism when co doping with Mn. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effects of oxygen ion implantation in spray-pyrolyzed ZnO thin filmsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2006K. P. Vijayakumar Abstract ZnO thin films, prepared using the chemical spray pyrolysis technique, were implanted using 100 keV O+ ions. Both pristine and ion-implanted samples were characterized using X-ray diffraction, optical absorption, electrical resistivity measurements, thermally stimulated current measurements and photoluminescence. Samples retained their crystallinity even after irradiation at a fluence of ,1015 ions/cm2. However, at a still higher fluence of 2 × 1016 ions/cm2, the films became totally amorphous. The optical absorption edge remained unaffected by implantation and optical absorption spectra indicated two levels at 460 and 510 nm. These were attributed to defect levels corresponding to zinc vacancies (VZn) and oxygen antisites (OZn), respectively. Pristine samples had a broad photoluminescence emission centred at 517 nm, which was depleted on implantation. In the case of implanted samples, two additional emissions appeared at 425 and 590 nm. These levels were identified as due to zinc vacancies (VZn) and oxygen vacancies (VO), respectively. The electrical resistivity of implanted samples was much higher than that of pristine, while photosensitivity decreased to a very low value on implantation. This can be utilized in semiconductor device technology for interdevice isolation. Hall measurements showed a marked decrease in mobility due to ion implantation, while carrier concentration slightly increased. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Convertibility of conductivity type in reactively sputtered ZnO thin filmsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2003S. Tüzemen Abstract Possible negative- U behavior of the VO donor may explain rather unusual free carrier properties in as-sputtered ZnO thin films grown at extremely Zn-rich conditions. VO can act as a source of free electron concentration at sample temperatures above 210 K. Below this temperature it changes its charge state to an inactive neutral charge state where it cannot act as a donor because of a thermal barrier with a threshold temperature of 170,210 K. The thermal barrier for an electron to go to neutral charge state from positive charge state is approximately 162 meV. Material can be converted to p-type by annealing VO centers. O-rich growth conditions with low [VO] may result in p-type conductivity. [source] Photoconductivity of Ga doped polycrystalline ZnO films grown by reactive plasma depositionPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 5 2007Seiichi Kishimoto Abstract Photoconductivity and photo-absorption of polycrystalline Ga-doped ZnO (GZO) thin films with film thickness of 200 nm have evaluated compared with undoped ZnO films. The GZO and undoped ZnO thin films were deposited on alkali-free glass substrate at 200 °C by a reactive plasma deposition with DC arc discharge technique under an oxygen gas flow rate from 0 to 30 sccm. Undoped ZnO films with carrier concentration of 2.50 × 1018 and 7.96 × 1018 cm,3 have exciton absorption at about 3.28 eV. For these films, the photoconductivity peak is agreement with the photon-energy of exciton absorption in the optical-absorption. The optical band edge of undoped ZnO films estimated from the optical-absorption shows a shift to higher energy with increasing the carrier concentration. The increase of oxygen gas flow rate led to the resistivity change of GZO films from 2.15 × 10,4 to 4.54 × 10,3 , cm, corresponding to the carrier concentration change from 1.39 × 1021 to 1.05 × 1020 cm,3. The photoconductivity of GZO film is larger than that of undoped ZnO film. The peak energy of photoconductivity spectra of GZO films are seen to little shift to higher energy with increasing the carrier concentration. The GZO film exhibited the larger photoconductivity at the wavelength, ranging widely less than 380 nm. GZO film with carrier concentration more than 1 × 1021 cm,3 indicated much larger photoconductivity. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Preparation of ZnO thin films by MO-CVD method using bis(acetylacetonato) zinc(II) anhydrate fiberPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2010Shigeyuki Seki Abstract The MO-CVD method as a deposition process corresponding to the mass production of the high-quality ZnO film that can be used as an active layer in the thin film transistor is paid to attention. Bis(acetylacetonato) zinc(II) (Zn(acac)2) which has chemical stability and low toxicity is promising as the inexpensive raw material for CVD. The problem includes (1) pollution with water in process by character to easily take water of crystallization, and (2) the supply of the gas-phase raw material by sublimation should be not able to be controlled easily because it is a fine particle. In this study, Zn(acac)2 anhydrate fiber was prepared from Zn(acac)2 monohydrate powder by the sublimation process. Melting point of this fiber was almost same (,134 °C) as the monohydrate powder in N2 atmosphere. ZnO film was deposited on r-face sapphire substrate by MO-CVD process using Zn(acac)2 anhydrate fiber, successfully. RMS of the film flatness was 0.48 nm. This film had resistivity of 4.6 × 10,1 ,·cm, carrier electron density of 9.1 × 1017 cm,3 and Hall mobility of 15 cm2·V,1·s,1. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effect of deposition conditions on the growth rate and electrical properties of ZnO thin films grown by MOCVDPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2008K. T. Roro Abstract 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. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Investigations of p-type signal for ZnO thin films grown on (100) GaAs substrates by pulsed laser depositionPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2006D. J. Rogers Abstract In this work we investigated ZnO films grown on semi-insulating (100) GaAs substrates by pulsed laser deposition. Samples were studied using techniques including X-ray diffraction (XRD), scanning electron microscopy, atomic force microscopy, Raman spectroscopy, temperature dependent photoluminescence, C-V profiling and temperature dependent Hall measurements. The Hall measurements showed a clear p-type response with a relatively high mobility (,260 cm2/V s) and a carrier concentration of ,1.8 × 1019 cm,3. C-V profiling confirmed a p-type response. XRD and Raman spectroscopy indicated the presence of (0002) oriented wurtzite ZnO plus secondary phase(s) including (101) oriented Zn2As2O7. The results suggest that significant atomic mixing was occurring at the film/substrate interface for films grown at substrate temperatures of 450 ºC (without post-annealing). (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Investigation on visible emission control of ZnO thin filmPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2004Hong Seong Kang Abstract ZnO thin films were deposited on various substrates and ZnO-Si-ZnO multi-layer thin films were fabricated by pulsed laser deposition (PLD). ZnO thin films showed the three photoluminescence bands centered at around ultraviolet (380 nm), green (490,530 nm) and orange (570,640 nm) region. The region and intensity of visible emission of ZnO thin films were controlled as substrate and annealing treatment. As-grown ZnO thin film showed strong ultraviolet (UV) emission. ZnO thin films on (001) Al2O3 showed the increase of green emission caused by oxygen vacancies in the range of 490 nm to 530 nm, those on (100) InP showed the increase of orange emission caused by oxygen interstitials in the range of 610 nm to 640 nm. The increase of orange emission caused by oxygen interstitials was also observed from ZnO-Si-ZnO multi-layer thin films. The visible emission mechanism of ZnO was investigated. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Advances of pulsed laser deposition of ZnO thin filmsANNALEN DER PHYSIK, Issue 1-2 2004M. Lorenz Abstract Advances in Pulsed Laser Deposition (PLD) equipment and process design for the epitaxy of ZnO thin films on a-, and c-oriented sapphire substrates are reported. The achieved improvement of device relevant ZnO layer properties is directly related to our equipment design and novel process schemes. First results on growth and reflectivity of ZnO-MgO based dielectric Bragg resonators for future ZnO-based light emitter devices are shown. [source] | |||||||||||||||||||||||||