Preparation and characterization of transparent conducting ZnO:W films by DC magnetron sputtering

Tungsten-doped zinc oxide（ZnO:W） films with low resistivity and high transmittance were successfully deposited on glass substrates by direct current magnetron sputtering at low temperature.The deposition pressure is varied from 12 to 21 Pa.The X-ray diffraction results show that all of the deposited films are polycrystalline and have a hexagonal structure with a preferred c-axis orientation.The crystallinity,morphologies and resistivity of ZnO:W films greatly depend on deposition pressure while the optical properties including optical transmittance, optical band gap as well as refractive index are not sensitive to deposition pressure.The deposited films with an electrical resistivity as low as 1.5×10^-4Ω·cm,sheet resistance of 6.8Ω/□and an average transmittance of 91.3% in the visible range were obtained at a deposition pressure of 21 Pa and sputtering power of 130 W.     

Photoelectric properties of ITO thin films deposited by DC magnetron sputtering

As anti-reflecting thin films and transparent electrodes of solar cells,indium tin oxide（ITO） thin films were prepared on glass substrates by DC magnetron sputtering process.The main sputtering conditions were sputtering power,substrate temperature and work pressure.The influence of the above sputtering conditions on the transmittance and conductivity of the deposited ITO films was investigated.The experimental results show that, the transmittance and the resistivity decrease as the sputtering power increases from 30 to 90 W.When the substrate temperature increases from 25 to 150℃,the transmittance increases slightly whereas the resistivity decreases.As the work pressure increases from 0.4 to 2.0 Pa,the transmittance decreases and the resistivity increases.When the sputtering power,substrate temperature and work pressure are 30 W,150℃,0.4 Pa respectively,the ITO thin films exhibit good electrical and optical properties,with resistivity below 10^-4Ω·cm and the transmittance in the visible wave band beyond 80%.Therefore,the ITO thin films are suitable as transparent electrodes of solar cells.     

Low-temperature deposition of transparent conducting Mn-W co-doped ZnO thin films

Mn-W co-doped ZnO(ZMWO) thin films with low resistivity and high transparency were successfully prepared on glass substrate by direct current(DC) magnetron sputtering at low temperature.The sputtering power was varied from 65 to 150 W.The crystallinity and resistivity of ZMWO films greatly depend on sputtering power while the optical transmittance and optical band gap are not sensitive to sputtering power.All the deposited films are polycrystalline with a hexagonal structure and have a preferred orientat...     

Effect of deposition conditions on the physical properties of Sn_xS_y thin films prepared by the spray pyrolysis technique

Tin sulfide thin films（Sn_xS_y） with an atomic ratio of y/x = 0.5 have been deposited on a glass substrate by spray pyrolysis.The effects of deposition parameters,such as spray solution rate（R）,substrate temperature （T_s） and film thickness（t）,on the structural,optical,thermo-electrical and photoconductivity related properties of the films have been studied.The precursor solution was prepared by dissolving tin chloride（SnCl₄,5H₂O） and thiourea in propanol,and Sn_xS_y thin film was prepared with a mole ratio of y/x = 0.5.The prepared films were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM） and UV-vis spectroscopy. It is indicated that the XRD patterns of Sn_xS_y films have amorphous and polycrystalline structures and the size of the grains has been changed from 7 to 16 nm.The optical gap of Sn_xS_y thin films is determined to be about 2.41 to 3.08 eV by a plot of the variation of（αhv）² versus hv related to the change of deposition conditions.The thermoelectric and photo-conductivity measurement results for the films show that these properties are depend considerably on the deposition parameters.     

Development of aluminum-doped ZnO films for a-Si:H/μc-Si:H solar cell applications

This study deals with the optimization of direct current(DC) sputtered aluminum-doped zinc oxide (AZO) thin films and their incorporation into a-Si:H/μc-Si:H tandem junction thin film solar cells aiming for high conversion efficiency.Electrical and optical properties of AZO films,i.e.mobility,carrier density,resistivity, and transmittance,were comprehensively characterized and analyzed by varying sputtering deposition conditions, including chamber pressure,substrate temperature,and sputtering power.The correlations between sputtering processes and AZO thin film properties were first investigated.Then,the AZO films were textured by diluted hydrochloric acid wet etching.Through optimization of deposition and texturing processes,AZO films yield excellent electrical and optical properties with a high transmittance above 81%over the 380-1100 nm wavelength range,lowsheet resistance of 11Ω/□and high haze ratio of 41.3%.In preliminary experiments,the AZO films were applied to a-Si:H/μc-Si:H tandem thin film solar cells as front contact electrodes,resulting in an initial conversion efficiency of 12.5%with good current matching between subcells.     

Effect of thickness on optoelectrical properties of Nb-doped indium tin oxide thin films deposited by RF magnetron sputtering

Niobium-doped indium tin oxide （ITO:Nb） thin films are prepared on glass substrates with various film thicknesses by radio frequency （RF） magnetron sputtering from one piece of ceramic target material. The effects of thickness （60-360 nm） on the structural, electrical and optical properties of ITO: Nb films are investigated by means of X-ray diffraction （XRD）, ultraviolet （UV）-visible spectroscopy, and electrical measurements. XRD patterns show the highly oriented （400） direction. The lowest resistivity of the films without any heat treatment is 3.1×10^-4 Ω·cm^-1, and the resistivity decreases with the increase of substrate temperature. The highest Hall mobility and carrier concentration are 17.6 N·S and 1.36×10²¹ cm^-3, respectively. Band gap energy of the films depends on substrate temperature, which varies from 3.48 eV to 3.62 eV.     

Structural and optoelectronic properties of sprayed Sb:SnO_2 thin films:Effects of substrate temperature and nozzle-to-substrate distance

The influence of substrate temperature and nozzle-to-substrate distance（NSD） on the structural,morphological, optical and electrical properties of Sb:SnO₂ thin films prepared by chemical spray pyrolysis has been analyzed.The structural,morphological,optical and electrical properties were characterized by using XRD,SEM, UV-visible spectrophotometry and Hall effect measurement techniques.It was seen that the films are polycrystalline, having a tetragonal crystal structure with strong orientation along the（200） reflection.The pyramidal crystallites formed due to coalescence were observed from SEM images.The values of highest conductivity,optical transmittance and figure of merit of about 1449（Ω·cm）^-1,70%and 5.2×10^-3□/Ω,respectively,were observed for a typical film deposited using optimal conditions（substrate temperature = 500℃and NSD = 30 cm）.     

Effect of substrate temperature on the properties of deep ultraviolet transparent conductive ITO/Ga2O3 films

正ITO/Ga_2O_3 bi-layer films were deposited on quartz glass substrates by magnetron sputtering.The effect of substrate temperature on the structure,surface morphology,optical and electrical properties of ITO/Ga_2O_3 films was investigated by an X-ray diffractometer,a scanning electron microscope,a double beam spectrophotometer and the Hall system,respectively.The structural characteristics showed a dependence on substrate temperature. The resistivity of the films varied from 6.71×10~(-3) to 1.91×10~3Ω·cm as the substrate temperature increased from 100 to 350℃.ITO(22 nm)/Ga_2O_3(50 nm) films deposited at 300℃exhibited a low sheet resistance of 373.3Ω/□and high deep ultraviolet transmittance of 78.97%at the wavelength of 300 nm.     

Properties of ITO：Zr films deposited by co-sputtering

ITO：Zr films were deposited on glass substrate by co-sputtering with an ITO target and a Zirconium target. Substrate temperature and oxygen flow rate have important influences on the properties of ITO：Zr films. ITO：Zr films show better crystalline structure and lower surface roughness. Better optical-electrical properties of the films can be achieved at low substrate temperature. The certain oxygen flow rates worsen the electrical properties but can enhance the optical properties of ITO：Zr films. The variation in optical band gap can be explained on the basis of Burstin-Moss effect.     

Metal Oxide Transistors via Polyethylenimine Doping of the Channel Layer: Interplay of Doping,Microstructure, and Charge Transport

Polymer doping of solution‐processed In₂O₃ with small amounts of the electron‐rich polymer, polyethylenimine (PEI), affords superior transistor performance, including higher electron mobility than that of the pristine In₂O₃ matrix. PEI doping of In₂O₃ films not only frustrates crystallization and controls the carrier concentration but, more importantly, acts as electron dopant and/or scattering center depending on the polymer doping concentration. The electron donating capacity of PEI combined with charge trapping and variation in the matrix film microstructure yields, for optimum PEI doping concentrations of 1.0%–1.5%, electron mobilities as high as ≈9 cm² V^?1 s^?1 on a 300 nm SiO₂ gate dielectric, an excellent on/off ratio of ≈10⁷, and an application optimal V _T. Importantly, these metrics exceed those of the pure In₂O₃ matrix with a maximum mobility ≈4 cm² V^?1 s^?1. Furthermore, we show that this approach is extendible to other oxide compositions such as IZO and the technologically relevant IGZO. This work opens a new means to fabricate amorphous semiconductors via solution processing at low temperatures, while preserving or enhancing the mobility of the pristine polycrystalline semiconductor.     

Continuous hydrothermal processing of nano-crystalline particulates for chemical-mechanical planarization

A wide range of nano-crystalline, single and multi-component oxide/oxyhydroxide particulates, which may be potentially useful as abrasives for chemical-mechanical planarization (CMP) processes, have been produced using a novel, flow-through hydrothermal technology previously developed at the Pacific Northwest National Laboratory. The process, termed rapid thermal decomposition of precursors in solution (RTDS), converts aqueous feed stock solutions containing metal salts and other thermally activated reactants into suspensions or slurries of nano-crystals (with diameters of generally less than 30 nm) by continuous flow through a heated, high pressure reaction pipe (typically, 200–400°C, 6000–8000 psi). Flow at pressure is maintained using a nozzle at the down-stream end of the reaction tube. Crystallite formation occurs during the solution’s brief residence time (<30 s) in the reaction pipe. Control over crystalline phase and, in some cases, particle morphology can be tailored by selecting the appropriate feed chemistry and processing conditions. Using bench-scale equipment, RTDS is capable of producing nano-crystalline particulate material at rates of up to ≈500 gm of solids per hour. The RTDS processing and characterization of nano-crystalline zirconium-, titanium-, and iron-based oxide and oxyhydroxide particulates are reviewed.     

氧化钌在法拉第准电容器中的应用研究进展

介绍氧化钌法拉第准电容器的工作原理、特点和制造方法,还对近年来这类电容器的发展状况和存在问题进行了评述。     

Dye-sensitized solid-state photovoltaic cells: Suppression of electron-hole recombination by deposition of the dye on a thin insulating film in contact with a semiconductor

The heterojunction n-SnO₂/Ru-dye/p-CuI prepared by deposition of the ruthernium bipyridyl dye on a meso-porous film of SnO₂ followed by deposition of p-CuI was found to be inactive with respect to visible light photoresponse and dark current rectification. However, n-SnO₂/Al₂O₃/Ru-dye/p-CuI where the dye is coated on a thin film on Al₂O₃ first deposited on SnO₂, delivered a short-circuit current density of 1.7 mAcm⁻² and an open-circuit voltage of 350 mV, behaving as a dye-sensitized solid-state photovoltaic cell. This result is explained as a transfer of energetic electrons released by excitation of the dye molecules to the conduction band of SnO₂ via tunneling across the thin layer of Al₂O₃. The implications of the result on suppression of recombination in dye-sensitized photovoltaic cells are discussed.     

Zr掺杂的SnO_2瓷的压敏和介电性质

目前电子陶瓷工艺普遍采用ZrO2球作为磨介。为了弄清ZrO2球磨损对压敏瓷性能的作用,系统研究了ZrO2对(Co,Nb)掺杂SnO2瓷的压敏和介电性质的影响。当ZrO2的含量(摩尔分数)从0.00增加到1.00%时,(Co,Nb)掺杂的SnO2压敏电阻的击穿电压从345 V/mm增大到485 V/mm,1 kHz时的相对介电常数从1 590减小到1 120。晶界势垒高度测量表明:在实验范围内,Zr的含量对势垒高度的影响较小。SnO2的晶粒尺寸的迅速减小是击穿电压增高和介电常数迅速减小的主要原因。对Zr掺杂量增加引起SnO2晶粒减小的根源进行了解释。     

掺氟氧化锡(SnO_2:F)纳米粉末的制备

以SnCl4.5H2O、氨水和HF酸为主要原料,用化学方法制取了掺氟氧化锡(FTO)纳米粉末。用XRD、SEM分别研究了FTO粉末的相结构和形貌,用比表面仪测定了粉末比表面积,同时测试了FTO粉末的电阻率。结果表明:FTO粉末是四方晶系金红石结构;在500℃下焙烧制取的粉末电阻率最低,为50?.m,比表面积为61.00m2/g。采用无水酒精球磨分散等步骤,可有效防止粉末团聚。     

(Li,Nb)掺杂SnO_2压敏材料的电学非线性研究

研究了掺锂对 Sn O2 压敏电阻器性能的影响。研究发现 L i 对 Sn4 的取代能明显提高陶瓷的烧结速度和致密度 ,且能大幅度改善材料的电学非线性性能。掺入 x(L i2 CO3)为 1.0 %的陶瓷样品具有最高的密度 (ρ=6 .77g/ cm3)、最高的介电常数 (ε=185 1)、最低的视在势垒电场 (EB=6 8.86 V/ mm)和最高的非线性常数 (α=9.9)。对比发现 ,Na 由于具有较大的离子粒半径 ,其掺杂改性性能相对较差。提出了 Sn O2 · L i2 CO3· Nb2 O5晶界缺陷势垒模型     

(Cd,Co,Nb)掺杂的SnO2压敏材料的电学性质

研究了Cd对(Co，Nb)掺杂SnO2压敏材料电学性质的影响。组分为97．65％SnO2 O．75％Co2O3 0．10％Nb2O5 1．50％CdO的压敏电阻具有最大非线性系数(a=22．2)和最高的势垒(ψB=0．761eV)．当CdO的摩尔分数从0增加到3％时，(Co，Nb)掺杂SnO2压敏电阻的击穿电压从366V／mm增大到556V／mm，1kHz时的相对介电常数从1429减小到1108。晶界势垒高度测量揭示，SnO2的晶粒尺寸的减小是击穿电压增高和介电常数减小的主要原因。对Cd掺杂量增加引起SnO2晶粒减小的根源进行了解释。     

溶剂热法制备氧化亚铜纳米晶粒

以甘油和氧化铜为原料,采用溶剂热法制备了纳米氧化亚铜粉体。将甘油和氧化铜按一定的摩尔比混合并加入适量的分散剂(PVP+SDBS),然后快速搅拌、加热并在430～440 K反应一定时间,随后在继续搅拌情况下冷却至室温,然后静置抽滤,在把过滤产物用无水乙醇洗涤数次并400 K真空干燥4 h后,得到了红色纳米氧化亚铜粉体。XRD和SEM分析结果表明,所制纳米氧化亚铜粉体属立方晶系,粒子呈球形,粒径约40 nm。