Structural and Electrical Characterization of the CdTe/SnO2 Heterojunction for Solar Cell Application

Thin film heterojuction of the type CdTe/SnO2 was prepared by spray pyrolysis and electron beam evaporation technique, respectively. The structural and electrical properties of the CdTe/SnO2 heterojunction are investigated by X-ray diffraction （XRD）, Hall and current-voltage （I-V） measurements. The XRD spectrum of SnO2 film is indicated that it has a rutile tetragonal structure with a preferred orientation along （l 10） plane. XRD pattern of CdTe thin film is shown that it has a cubic structure with a preferred orientation along （111 ） plane. Hall measurements demonstrate the firm p-type conductivity of the CdTe film and n-type conductivity of the SnO2 film. The Hall mobility and carrier density were determined from the combined measurements of resistivity and Hall coefficient at room temperature. The current-voltage curve of the heterojunction demonstrates obvious rectifying diode behavior in the dark and under illumination conditions. The ideality factor of the heterojunction was determined in case of forward bias at low voltages and it was found to be 7.08. The turn-on voltage appears at about 0.6 V under forward-biased voltage, and the reverse breakdown voltage is about 1 V. It was found that the forward current of the heterojunction was 160 × 10^-6 A with ＋1 V applied bias, while the reverse leakage current was 37 × 10^-6 A when -1V was applied.     

Study on variable capacitance diode of (p)nc-Si:H/(n)c-Si heterojunction

Hydrogenated nanocrystalline silicon (nc-Si:H) layers of boron-doped increasing step by step was deposited on n-type crystalline silicon substrate using Plasma Enhanced Chemical Vapor Deposition (PECVD) system. After evaporating Ohm contact electrode on the side of substrate and on the side of nc-Si:H film, a structure of electrode/(p)nc-Si:H/(n)c-Si/electrode was obtained. It is confirmed by electrical measurement such as I-V curve, C-V curve and DLTS that this is a variable capacitance diode.     

水热合成Bi2WO6/ZnO异质结型光催化剂及其光催化性能

在不同温度下(120～220℃),利用水热法制备了含1wt%、2wt%、4wt%和8wt%Bi2WO6的异质结型Bi2WO6/ZnO复合光催化剂,采用X射线粉末衍射(XRD)、扫描电镜(SEM)、傅里叶变换红外光谱(FT-IR)、紫外可见漫反射(UV-Vis)吸收光谱及光致发光光谱(PL)等系列手段对所制备的光催化剂进行了表征,并以紫外光(365nm)为光源,酸性橙II为降解对象,进行光催化活性测试,考察了不同Bi2WO6复合量及不同水热温度对ZnO光催化剂反应活性的影响.研究表明,异质结型Bi2WO6/ZnO复合光催化剂的光催化活性明显优于纯ZnO和Bi2WO6.当复合4wt%Bi2WO6水热处理温度为150℃时,所制备的复合光催化剂的光催化活性最佳,为纯ZnO的2.6倍.活性提高的主要原因是形成的Bi2WO6/ZnO异质结能显著降低光生电子和空穴对的复合几率,并改善了异质结型Bi2WO6/ZnO复合光催化剂的表面性能.     

基于p+-Si与n-ZnO纳米线的p-n异质结的制备及其性质研究

利用CVD蒸汽俘获法，在p^＋硅片上制备了垂直生长的n型ZnO纳米线阵列，用XRD和SEM分析了样品的结构与形貌。测试发现样品的I-V曲线符合典型的p-n异质结特性，正向开启电压为0．5V，反向饱和电流为0．02mA。计算了异质结的理想因子η，发现当异质结两端偏压在0V-0．3V的低压区域，理想因子为1．85，而在0．3v-0．8v的高偏压区域，理想因子为8．36。解释了理想因子偏高的原因是由于金属一半导体接触以及ZnO纳米线与p^＋-si界而存在缺陷。     

S掺杂ZnO薄膜光电特性的研究

采用射频磁控溅射法,在玻璃基片上生长了ZnO∶S薄膜.XRD测试表明所制薄膜为六角纤锌矿结构,具有明显的(002)衍射峰.室温下的透射光谱测量结果表明,随着S掺入量的增加,ZnO∶S合金薄膜的吸收边向长波长方向移动,但在可见光部分有较高的透过率.在此基础上计算了各样品的禁带宽度,结果表明,在S掺入量小于8％的范围内,随着S掺入量的增加,禁带宽度减小.样品紫外光电导特性明显,在波长365nm、功率4000μW/cm2紫外光源照射下,紫外光与可见光所对应光电流响应之比可达3.     

掺氮ZnO薄膜的制备及其光电性能

在保持氩气流量一定,通过改变O2与N2的流量比,以高纯锌为靶材,通过射频磁控溅射技术在石英玻璃衬底上生长氮掺杂ZnO薄膜。采用XRD、荧光光谱、扫描电镜及皮安表对薄膜的晶体结构、光学性能、表面和截面形貌及电学性能进行了表征。结果表明：氮掺杂ZnO薄膜仍具有高度的c轴择优取向;氮以受主杂质形式存在可有效降低薄膜的电阻率;薄膜中氮含量的相对变化是影响ZnO薄膜晶体质量和光电性质的重要因素。     

纳米Ag夹层ZnO薄膜的光电性能

用射频磁控溅射ZnO陶瓷靶、直流磁控溅射Ag靶的方法在室温下制备了Ag纳米夹层结构ZnO薄膜．用X射线衍射仪、紫外一可见分光光度计、四探针电阻测量仪和原子力显微镜对薄膜样品的结构、光学透过率、面电阻和表面形貌进行表征．结果表明,ZnO衬底有利于Ag夹层形成连续膜．随着Ag层厚度的增加,Ag夹层ZnO薄膜呈现多晶结构,Ag（111）衍射峰强度增强,面电阻先迅速下降后缓慢下降．随着ZnO膜厚度的增加,Ag夹层ZnO薄膜的透射峰红移．制得样品的最佳可见光透过率高达92．3％,面电阻小于4．2Ω／□．     

Thermal and Doping Effect on Sn/(n)ZnO Schottky Junction and Its Performance as a <Emphasis Type="Italic">PV</Emphasis> Effect

Thin film Sn/(n)ZnO Schottky junctions with different doping concentrations were prepared by vacuum evaporation. Different junction parameters such as ideality factor, barrier height, Richardson’s constant, short-circuit current, etc. were determined from I–V characteristics. These parameters were found to change significantly with variations of doping concentration and temperature. The structures showed the change of the PV effect, giving a fill factor of 0.42 (efficiency of 0.39 %) with an open-circuit voltage of 124mV and a short-circuit current density of 113 × 10⁻⁵ A ·cm⁻² for a doping concentration, N _d = 3.88 × 10¹⁵ cm ⁻³(2.74 % Al-doped ZnO). However, by increasing the doping concentration, the efficiency was found to increase by up to 4.54 % for doping concentration, N _d = 2.28 × 10¹⁷ cm ⁻³. The conversion efficiencies varied with temperature and were observed to have an overall improvement up to 343 K. Proper doping, annealing, and hydrogenation are necessary to reduce the series resistance so as to achieve an ideal and high efficiency PVconverter.     

Mg-Al共掺杂ZnO薄膜的制备及其光学特性

采用溶胶-凝胶（sol—gel）旋涂法在载玻片上制备了不同A1掺杂量的Mg—Al共掺杂ZnO薄膜．在室温下利用X射线衍射仪（XRD）、扫描电子显微镜（SEM）和光致发光（PL）谱仪等手段分析了Mg—Al共掺杂Zn0薄膜的微结构、形貌和发光特性．XRD结果表明Mg．AI＆掺杂zn0薄膜具有六角纤锌矿结构;随着Al掺杂量的增加,共掺杂薄膜呈C轴取向生长．由SEM照片可知薄膜表面形貌随Al掺杂量的增加由颗粒状结构向纳米棒状结构转变．透射光谱表明共掺杂薄膜在可见光区内的透射率大于50％,紫外吸收边发生蓝移．在室温下的PL谱表明Mg—Al共掺杂zn0薄膜的紫外发射峰向短波长方向移动：Al掺杂摩尔分数为1％和3％的Mg—Al共掺杂ZnO薄膜的可见发射峰分别为596nm的黄光和565nm的绿光．黄光主要与氧间隙有关,而绿光主要与氧空位有关．     

射频磁控溅射法制备的ZnO:Al薄膜在不同偏压下的光电特性

采用RF磁控溅射法在玻璃衬底和PET衬底上沉积了Al掺杂的ZnO(AZO)薄膜,衬底的直流偏压为0～50V.主要研究了薄膜的结构、光学和电学特性.在玻璃衬底上制备AZO薄膜的沉积速率随偏压的升高而增大,然而再增加偏压时反而下降.当偏压为30V时,在玻璃衬底上制备的薄膜的最低电阻率为6.5×10-4Ω·cm,在波长450～800nm内的平均透射率大于80%;在PET衬底上制备的薄膜也有相似的特性,但没有在玻璃衬底上制备的好.     

溶胶凝胶法制备ZnO:Ga作为电流扩散层的LED光电性能研究

采用溶胶凝胶法制备了ZnO:Ga(GZO)透明导电薄膜,并用做GaN基LED的电流扩散层。研究表明,GZO薄膜为多晶薄膜,透光率大于80%,粗糙度为Ra 4.6nm,制备的LED的开启电压为2.4V,并成功的点亮LED芯片。     

退火温度对ZnO/Mo/ZnO透明导电薄膜结构及光电性能的影响

采用电子束蒸发法成功制备了透明导电的ZnO/Mo/ZnO(ZMZ)复合薄膜,研究了不同的退火温度对其电学和光学性质的影响规律。利用X射线衍射仪、扫描电子显微镜、X射线能谱仪、紫外可见分光光度计和四探针测试仪等检测手段对样品的性能进行了分析。实验结果表明:随着退火温度的升高,薄膜的结晶程度提高,晶粒尺寸增大;薄膜的电阻率先降低后升高;薄膜的光学透过率先升高后降低。当退火温度为250℃时,ZnO/Mo/ZnO薄膜具有最佳的综合光电性能,在400nm~900nm波长范围内最高透过率为81.4%,平均透过率高于80%,最低电阻率为1.71×10-4Ω·cm,表面电阻为15.5Ω/sq。研究表明所制备的ZMZ复合透明导电薄膜可应用于太阳能电池、液晶显示器等领域。     

磁控溅射制备银掺杂ZnO薄膜结构及光电性质研究

利用磁控溅射法在玻璃衬底上制备了银掺杂ZnO薄膜,通过改变制备条件生长了一系列样品,样品退火后呈现P型导电特性.测量了样品的结构特性、光学性质和电学性质,实验表明薄膜厚度与淀积时间、溅射功率分别呈近似线性关系;薄膜晶体质量随溅射功率、背景气压的增加而降低;退火过程是银元素形成受主的重要环节,且退火能有效提高薄膜晶体质量,改善薄膜的光学性质和电学性质.分析了这些影响的机理和来源.     

The Electrical and Optical Properties of Organometal Halide Perovskites Relevant to Optoelectronic Performance

Organometal halide perovskites are under intense study for use in optoelectronics. Methylammonium and formamidinium lead iodide show impressive performance as photovoltaic materials; a premise that has spurred investigations into light‐emitting devices and photodetectors. Herein, the optical and electrical material properties of organometal halide perovskites are reviewed. An overview is given on how the material composition and morphology are tied to these properties, and how these properties ultimately affect device performance. Material attributes and techniques used to estimate them are analyzed for different perovskite materials, with a particular focus on the bandgap, mobility, diffusion length, carrier lifetime, and trap‐state density.     

退火条件对Sn掺杂ZnO薄膜光电性能的影响

采用溶胶-凝胶法在普通载玻片上制备Sn掺杂ZnO薄膜(SZO薄膜)。研究空气退火、低真空退火、高真空退火、氮气退火、三高退火、循环退火6种不同退火条件对SZO薄膜光电性能的影响。结果表明:6种不同的退火条件制备的SZO薄膜均为纤锌矿结构且具有c轴择优取向生长的特性。高真空退火下,SZO薄膜的结晶状况和电学性质最优,最低电阻率可达到5.4×10~(-2)Ω·cm。薄膜的可见光区平均透过率均大于85%。薄膜在390nm和440nm附近(325nm光激发下)都出现光致发光峰,在空气、氮气、低真空中退火后薄膜440nm处发光强度最为显著。     

多孔硅与聚乙烯咔唑复合光电性能研究

用旋涂法实现了多孔硅与聚乙烯咔唑(PVK)的复合，研究了多孔硅／PVK复合体系的光学性能和电学性能。PL谱的测试发现，复合体系的PL同时具有多孔硅和PVK的峰。此外，在485nm的位置出现了一个新峰，讨论了这个峰的来源。I-V特性测试表明，多孔硅/PVK异质结与多孔硅相比。I-V曲线呈现更好的整流特性，讨论了其原因。     

射频溅射氧化锌薄膜晶体结构和电学性质

利用射频磁控溅射ZnO:Al(3wt%)陶瓷靶材制备ZAO薄膜,利用X射线衍射仪和霍尔测试仪分析了不同衬底温度和工作压强对薄膜结构和电学性能的影响.结果表明,随工作压强的降低,薄膜(002)优先取向增强,迁移率逐渐增大,当工作压强为0.2 Pa、衬底温度为200℃时,薄膜的电阻率为1.4×10-3Ω·cm.     

衬底温度对Sn掺杂ZnO薄膜结构、电学和光学性能的影响

采用射频磁控溅射技术在石英衬底上制备了掺杂浓度为0.5％(原子分数)的ZnO∶Sn(TZO)薄膜,研究了不同衬底温度下薄膜的结构、形貌、电学和光学的性能.研究发现,TZO薄膜沿着C轴择优生长,在400℃时结晶度最好,最低电阻率为2.619×10-2Ω·cm,在可见光范围内具有较好的透光率.