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Structural,Electrical,and Optical Properties of Transparent Conductive Al-Doped ZnO Films Prepared by RF Magnetron Sputtering

Yang Weifeng,Liu Zhuguang,Zhang Feng,Huang Huolin,Wu Zhengyun,

半导体学报 , 2008,
Abstract: 室温下采用RF磁控溅射技术在石英衬底上制备了多晶ZnO: Al (AZO)透明导电薄膜,通过XRD,AFM,AES,Hall效应及透射光谱等测试研究了RF溅射功率、氩气压强对薄膜的结构、电学和光学性能的影响. 分析表明:在最优条件下(溅射功率为250W,氩气压强为1.2Pa时), 180nm AZO薄膜的电阻率为2.68E-3 Ω· cm,可见光区平均透射率为90%,适合作为发光二极管和太阳能电池的透明电极. 所制备的AZO薄膜具有c轴择优取向,晶粒间界中的O原子吸附是限制薄膜电学性能的主要因素.
Influence of O2/Ar ratio on the properties of transparent conductive niobium-doped ZnO films
Feng Cao,YiDing Wang,KuiXue Liu,JingZhi Yin,BeiHong Long,Li Li,Yu Zhang,XiaMei Chen
Chinese Science Bulletin , 2009, DOI: 10.1007/s11434-009-0377-y
Abstract: Niobium-doped ZnO transparent conductive films are deposited on glass substrates by radio frequency sputtering at 300°C. The influence of O2/Ar ratio on the structural, electrical and optical properties of the as-deposited films is investigated by X-ray diffraction, Hall measurement and optical transmission spectroscopy. The lowest resistivity of 4.0×10 4 Ω·cm is obtained from the film deposited at the O2/Ar ratio of 1/12. The average optical transmittance of the films is over 90%.
Effects of Oxygen Partial Pressure on the Properties of Transparent Conductive ZnO:Ga Films Prepared by DC Reactive Magnetron Sputtering
氧分压对直流磁控溅射制备 ZnO:Ga透明导电薄膜特性的影响

MA Quan-Bao,YE Zhi-Zhen,HE Hai-Ping,ZHU Li-Ping,ZHANG Yin-Zhu,ZHAO Bing-Hui,

无机材料学报 , 2007,
Abstract: 通过直流反应磁控溅射法在玻璃衬底上制备了掺镓ZnO(ZnO:Ga)透明导电薄膜,研究了氧分压对ZnO:Ga透明导电薄膜结构和电光学性能的影响.X射线衍射结果表明所制备的薄膜具有c轴择优取向的六角多晶结构.ZnO:Ga透明导电薄膜的晶粒尺寸强烈依赖于氧分压的大小,随着氧分压的增大薄膜的晶粒尺寸先增大后减小,在氧分压为0.30Pa时沉积的ZnO:Ga薄膜半高宽最小,晶粒尺寸最大.薄膜的电阻率随着氧分压的增大先减小后增大,沉积薄膜的最低电阻率可达3.50×10^-4Ω·cm.此外,所有ZnO:Ga薄膜在可见光范围内的平均透射率均超过90%.
Effect of annealing on silicon heterojunction solar cells with textured ZnO:Al as transparent conductive oxide  [cached]
Salomon A.,Courtois G.,Charpentier C.,Labrune M.
EPJ Photovoltaics , 2012, DOI: 10.1051/epjpv/2012004
Abstract: We report on silicon heterojunction solar cells using textured aluminum doped zinc oxide (ZnO:Al) as a transparent conductive oxide (TCO) instead of flat indium tin oxide. Double side silicon heterojunction solar cell were fabricated by radio frequency plasma enhanced chemical vapor deposition on high life time N-type float zone crystalline silicon wafers. On both sides of these cells we have deposited by radio frequency magnetron sputtering ZnO:Al layers of thickness ranging from 800 nm to 1400 nm. These TCO layers were then textured by dipping the samples in a 0.5% hydrochloric acid. External quantum efficiency as well as I-V under 1 sun illumination measurements showed an increase of the current for the cells using textured ZnO:Al. The cells were then annealed at 150 °C, 175 °C and 200 °C during 30 min in ambient atmosphere and characterized at each annealing step. The results show that annealing has no impact on the open circuit voltage of the devices but that up to a 175 °C it enhances their short circuit current, consistent with an overall enhancement of their spectral response. Our results suggest that ZnO:Al is a promising material to increase the short circuit current (Jsc) while avoiding texturing the c-Si substrate.
Transparent conducting ZnO : Al films on different organic substrates deposited by r.f. sputtering
Transparent Conducting ZnO:Al Films on Different Organic Substrates Deposited by r.f. Sputtering

Yuan CHEN,Deheng ZHANG,Qingpo WANG,Jin MA,Tianlin YANG,

材料科学技术学报 , 2000,
Abstract: Transparent conducting ZnO:Al films with good adhesion, low resistivity and high transmittance have been prepared on polyptopylene adipate (PPA), polyisocyanate (PI) and polyester substrates by r.f. magnetron sputtering. The structural, electrical and optical properties of the obtained films were studied. The polycrystalline ZnO:Al films with resistivity as low as 5.76 x 10(-4) Omega.cm, carrier concentration 9.06 x 10(20) cm(-3) and Hall mobility 11.98 cm(2) V-1 s(-1) were produced on PPA substrate by controlling the deposition parameters. The average transmittance of films on PPA is similar to 80% in the wavelength range of visible spectrum. The films on PPA substrates have better electrical and optical properties compared with the films on other kinds of substrates.
Young's Modulus and Coefficient of Linear Thermal Expansion of ZnO Conductive and Transparent Ultra-Thin Films  [PDF]
Naoki Yamamoto,Hisao Makino,Tetsuya Yamamoto
Advances in Materials Science and Engineering , 2011, DOI: 10.1155/2011/136127
Abstract: 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. 1. Introduction Optically transparent and conductive ZnO films, such as Ga-doped Zinc oxide (GZO) or Al-doped ZnO films, are attracting attention as alternative electrode materials to indium tin oxide (ITO), with good optical transparency and electrical conductive properties for liquid crystal displays (LCDs), flexible displays, touch-screens, and solar cells. Motivations for the development of ZnO transparent electrodes include (a) the scarcity of indium natural resources and (b) the toxicity of indium. Indium is a rare element and ranks only 61st in abundance in the Earth's crust [1]. Also, in terms of toxicity, recently, indium was suspected to be a cause of pulmonary diseases [2]. ZnO electrodes need to endure against mechanical forces caused by the thermal processing steps during the manufacture of electronic devices such as flat panel displays, flexible displays, touch-screens, and LEDs, and by the expansion or shrinkage of parts caused by thermally severe circumstances (during summer and winter, e.g.) in the case of solar cells. These external forces could enhance the frequency of peeling or cracking in the elements composing the systems, such as transparent electrodes, during the fabrication or operation of the devices. It is desired that the films used to form such electrodes have mechanically soft properties, because soft materials can absorb external forces and avoid peeling and cracking of the films. To obtain such a film, various mechanical characteristics of the thin film, such as elasticity, plasticity, viscosity, brittleness, yield strength, and adhesiveness, should be evaluated and be analyzed. In these
ZnO:Al Grown by Sputtering from Two Different Target Sources: A Comparison Study  [PDF]
Abdalla A. Alnajjar
Advances in Condensed Matter Physics , 2012, DOI: 10.1155/2012/682125
Abstract: Al-doped ZnO thin films were deposited from two different targets. Ceramic targets were used in RF magnetron sputtering, whereas pulsed magnetron sputtering was used to grow films from powder targets. ZnO:Al films with different thicknesses were sputtered directly on soda-lime glass substrates. The film thickness was in the 0.04–2.0?μm range. The microstructure, such as the grain size and the texture, of the two differently grown ZnO:Al transparent conductive oxide films of different thickness, was studied using X-ray diffraction scans. The optical properties, such as the transmittance and reflectance, were measured using a UV-Vis-NIR spectrometer. Further, the sheet resistance, resistivity, carrier concentration, and Hall mobility of these ZnO:Al thin films were measured as a function of film thickness. These results obtained from the two different deposition techniques were compared and contrasted. 1. Introduction Recently, zinc oxide (ZnO) thin films have received increasing attention as an alternative window material for photovoltaic cell applications where low-resistance and transparent films are required. Aluminum-doped ZnO (ZnO:Al) thin-film transparent conductive oxides (TCOs) are excellent candidates for a transparent front contact for solar cells. Further, TCO films have found extensive applications in optoelectronic devices (e.g., solar cells, liquid-crystal displays, heat mirrors, and multiplayer photothermal conversion systems). Zinc oxide has attracted attention as a TCO because of its (i) large bandgap (3.3?eV), (ii) high conductivity, (iii) ease in doping, (iv) thermal stability when doped with group III elements, and (v) abundance in nature and nontoxicity. In addition to potential use as a TCO in optoelectronic devices, ZnO thin films also find application as gas sensors because of their high electrical resistivity. The optoelectronic properties of ZnO thin films depend on the deposition and postdeposition treatment conditions because these properties change significantly with the (i) nature of chosen doping element, (ii) adsorption of oxygen that occurs during film deposition, (iii) film deposition temperature, and (iv) desorption during annealing treatment in a reducing atmosphere. Several deposition techniques are used to grow ZnO:Al thin films, including chemical vapor deposition (CVD) [1], spray pyrolysis [2, 3], pulsed laser deposition (PLD) [4], and magnetron sputtering [5–7]. Compared to other techniques, magnetron sputtering has many advantages, such as (i) sputter cleaning of the substrate in vacuum prior to film deposition
Effects of substrate temperature on properties for transparent conducting ZnO: Al films on organic substrate deposited by r.f. sputtering
Effects of Substrate Temperature on Properties for Transparent Conducting ZnO:Al Films on Organic Substrate Deposited by r.f. Sputtering

Deheng ZHANG,Dejun ZHANG,Qingpu WANG,Tianlin YANG,

材料科学技术学报 , 2001,
Abstract: This paper presents the substrate temperature dependence of opto-electrical properties for transparent conducting Al-doped ZnO films prepared on polyisocyanate (PI) substrates by r.f. sputtering. Polycrystalline ZnO:Al films with good adherence to the substrates having a (002) preferred orientation have been obtained with resistivities in the range from 4.1 x 10(-3) to 5.3 x 10(-4) Ohm .cm, carrier densities more than 2.6 x 10(20) cm(-3) and Hall mobilities between 5.78 and 13.11 cm(2)/V/s for films. The average transmittance reaches 75% in the visible spectrum. The quality of obtained films depends on substrate temperature during film fabrication.
Fabrication of Transparent Conductive Zinc Oxide Co-Doped with Fluorine and Zirconium Thin Solid Films by Ultrasonic Chemical Pyrolysis: Effects of Precursor Solution Aging and Substrate Temperature  [PDF]
Luis Casta?eda
Journal of Coatings , 2013, DOI: 10.1155/2013/519140
Abstract: Highly transparent, conducting zinc oxide [ZnO] thin films co-doped with fluorine and zirconium have been deposited on glass substrates by the ultrasonic chemical spraying technique. The effects of aging of the starting solution and substrate temperature on the structural, morphological, and electrical properties of the ZnO:F:Zr films have been studied. The resistivity of the films decreases with the aging time of the starting solution until the seventeenth day reaching a minimum of about ???cm and then increases. Though all the samples are of polycrystalline hexagonal wurtzite type and grow preferentially with (002) plane parallel to the substrate, their morphology depends strongly on the aging time of the reaction solution. The optical transmittance of all the films remained around 80% in the visible spectral range. These highly transparent, low resistive thin films are expected to be highly useful as transparent electrodes in the fabrication of thin film solar cells. 1. Introduction The demand of low-cost and high-performance optoelectronic devices leads to the development of more efficient transparent conductive oxide (TCO) thin films. Among the popular TCOs, the last decade has seen the emergence of zinc oxide [ZnO] as one of the most important materials for manufacturing transparent electrodes utilized in the fabrication of amorphous silicon-based solar cells. Apart from their high optical transparency, the ZnO thin films are highly stable in the hydrogen-plasma environment commonly used for the fabrication of silicon-based p-i-n structures [1]. ZnO thin films have been deposited by a wide variety of techniques, like evaporation [2], sputtering [3], chemical vapor deposition [4, 5], sol-gel [6, 7], and chemical spray [8, 9], among others. Among those, the chemical spray technique has been successfully used for the deposition of conductive and transparent ZnO thin films. Keeping in mind the high optical transparency as one of the basic requirements, incorporation of several dopants has been tried to reduce the resistivity of ZnO films. On the other hand, like all the chemical deposition techniques, chemical spray technique involves several parameters or deposition conditions which control the physical properties of the fabricated thin films. However, a complete knowledge of the effect of deposition conditions on the physical characteristics of ZnO thin films is far from being reached. The spray pyrolysis technique is based on the pyrolytic decomposition of small droplets of a zinc-containing solution onto a heated substrate, under atmospheric
Fabrication of Transparent Conductive Al―doped ZnO Thin Films by Aerosol―assisted Chemical Vapour Deposition
QIN Xiu-Juan, HAN Si-Hui-Zhi, ZHAO Lin, ZUO Hua-Tong, SONG Shi-Tao
无机材料学报 , 2011, DOI: 10.3724/sp.j.1077.2011.00607
Abstract: Al―doped ZnO thin films were prepared by aerosol―assisted chemical vapour deposition (AACVD) on glass substrates. The effect of Al content (2at%―8at%) on the structural, optical and electrical properties of Al―doped ZnO thin films was investigated in detail. The samples were tested by XRD, SEM, EDAX and UV―Vis spectrophotometer. The results indicate that the AZO films have a hexagonal (wurtzite) structure without preferential orientation along c―axis, and however no Al related phases are observed. The average transmittances of the AZO film is over 72% in the visible regions. The optical band gap for the AZO films becomes narrow with the increasing Al dopant. The four―point probe technique is used to characterize thin films electrically. The data shows that Al dopant decrease the sheet resistance. The ZnO films doped with 6at% Al exhibit a minimum of sheet resistance (18Ω/ ).
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