n-Si/p-CuI异质结的制备及其光电特性研究

采用成本低廉的连续离子层沉积法通过在n型Si衬底上沉积γ相的多晶结构的CuI薄膜而制备了CuI/n-Si异质结。并通过测试其光照下的I-V、C-V特性对其光电特性、载流子输运特性及导电机理进行了研究。研究表明CuI/n-Si异质结存在良好的整流特性,由于在CuI/nSi异质结界面处的导带补偿与价带补偿相差较大,在正向电压、无光照下,导电机理为空间电荷限制电流导电,此时空穴电流主导;在光照下,异质结表现出良好的光电响应,因此可以广泛应用在光电探测和太阳电池等领域。     

ZnO/SiC/Si异质结的光电转换特性

我们利用直流溅射制备了一系列的n-ZnO/n-SiC/p-Si和n-ZnO/p-Si异质结,通过研究他们的结构、I-V曲线、光生伏特效应和光响应谱。并且研究了他们的光电转换特性。发现n-ZnO/n-SiC/p-Si异质结的光电转换效率大约是n-ZnO/p-Si异质结的四倍。n-ZnO/n-SiC/p-Si异质结的光响应曲线也比n-ZnO/p-Si异质结强,表明n-ZnO/p-Si异质结加入3C-SiC中间层后光响应明显增强。在表面光电流谱中n-ZnO/n-SiC/p-Si异质结观察到两个拐点,而n-ZnO/p-Si异质结只观察到一个。通过以上研究可以看出3C-SiC在n-ZnO/n-SiC/p-Si异质结的光电转换中起了很大的作用.     

CH3NH3PbI3/p-Si异质结的光电特性研究

利用一步溶液法在p型Si衬底上生长有机/无机杂化钙钛矿CH3NH3PbI3薄膜,构成CH3NH3PbI3/p-Si异质结。利用原子力显微镜(AFM)、扫描电子显微镜(SEM)对薄膜形貌和结构进行表征,通过无光照和有光照条件下的电流-电压(I-V)、电容-电压(C-V)测试对异质结的光电特性进行研究。I-V测试结果显示CH3NH3PbI3/p-Si异质结具有整流特性,正反偏压为±5V时,整流比大于70,并在此异质结上观察到了光电转换现象,开路电压为10mV,短路电流为0.16uA。C-V测试结果显示Ag/CH3NH3PbI3/p-Si异质结具有与MIS(金属-绝缘层-半导体)结构相似的C-V特性曲线,与理想MIS的C-V特性曲线相比,异质结的C-V曲线整体沿电压轴向正电压方向平移。C-V特性曲线的这种平移表明Ag/CH3NH3PbI3/p-Si异质结界面存在界面缺陷,CH3NH3PbI3层也可能存在固定电荷。这种界面缺陷是导致CH3NH3PbI3/p-Si异质结开路电压的大幅度降低的重要原因。此外,CH3NH3PbI3薄膜的C-V测试结果显示其具有介电非线性特性,其介电常数约为4.64。     

射频磁控溅射法制备AZO/p-Si异质结及其性能研究

利用射频磁控溅射法,在p-Si衬底上生长了Al掺杂的ZnO(AZO)薄膜,并进而制备了AZO/p-Si异质结。X射线衍射仪、紫外-可见光分光光度计、四探针测试仪和霍尔效应测试仪测量表明,AZO薄膜具有良好的结晶质量、光学和电学特性。暗态下的I-V测试表明,AZO/p-Si异质结具有较好的整流特性,反向饱和电流为1.29×10-6A,±2V处的正向和反向电流之比为229.41,计算得出异质结的理想因子为2.28。在标准光照下AZO/p-Si异质结呈现出明显的光生伏特效应,这种异质结太阳电池具有2.51%的光电转换效率。     

n-ZnO/p-Si异质结J-V特性的实验研究

本文首次报道n-ZnO/p-Si异质结J－V特性实验测量的初步结果－经退火处理的异质结反向饱和电流密度比未经退火的减少一个数量级,表明退火改善ZnO／Si晶格界面结构,提高了n-ZnO/p-Si异质结性能。     

（英）磁控溅射制备纳米晶GZO/CdS双层膜及GZO/CdS/p-Si异质结光伏器件的研究

本文中,采用磁控溅射制备Ga掺杂ZnO (GZO)/CdS双层膜在p型晶硅衬底上以形成GZO/CdS/p-Si异质结器件。纳米晶GZO/CdS双层膜的微结构、光学及电学特性,通过XRD、SEM、XPS、紫外-可见光分光光度计和霍尔效应测试系统表征。GZO/CdS/p-Si异质结J-V曲线显示良好的整流特性。在±3V时,整流比IF/IR(IF和IR分别表示正向和反向电流)已达到21。结果表明纳米晶GZO/CdS/p-Si异质结具有好的二极管特性,在反向偏压下获得高光电流密度。纳米晶GZO/CdS/p-Si异质结显示明显的光伏特性。由于CdS晶格常数在GZO和晶Si之间,它能作为一个介于GZO和晶Si之间的缓冲层,能有效地减少GZO和p-Si之间的界面态。因此,我们获得了GZO/CdS/p-Si异质结明显光伏特性。     

磁控溅射制备纳米晶GZO/CdS双层膜及GZO/CdS/p-Si异质结光伏器件的研究

采用磁控溅射制备Ga掺杂ZnO (GZO)/CdS双层膜在p型晶硅衬底上以形成GZO/CdS/p-Si异质结器件。纳米晶GZO/CdS双层膜的微结构、光学及电学特性,通过XRD、SEM、XPS、紫外-可见光分光光度计和霍尔效应测试系统表征。GZO/CdS/p-Si异质结J-V曲线显示良好的整流特性。在±3 V时,整流比IF/IR(IF和IR分别表示正向和反向电流)已达到21。结果表明纳米晶GZO/CdS/p-Si异质结具有好的二极管特性,在反向偏压下获得高光电流密度。纳米晶GZO/CdS/p-Si异质结显示明显的光伏特性。由于CdS晶格常数在GZO和晶Si之间,它能作为一个介于GZO和晶Si之间的缓冲层,能有效地减少GZO和p-Si之间的界面态。因此,我们获得了GZO/CdS/p-Si异质结明显光伏特性。     

ZnO/p-Si异质结的光电转换特性

通过直流反应溅射制备了整流特性良好的ZnO/p-Si异质结,并在该异质结上观察到了明显的光电转换特性.研究表明ZnO薄膜中的电子浓度在一个合适的数值(1.6×1015cm-3)时光电流最强,另外晶粒尺寸越大光电流越强.分析表明,电子浓度和晶粒直径对光电流的影响规律在很大程度上是载流子散射导致的.此外,还发现ZnO薄膜存在一个临界厚度,当薄膜厚度大于该临界厚度时,异质结的光电压和光电流都急剧衰减并很快接近于0.实验表明,这个临界厚度和ZnO薄膜(001)面最大晶粒直径一致.     

ZnO/p-Si异质结的光电转换特性

通过直流反应溅射制备了整流特性良好的ZnO/p-Si异质结,并在该异质结上观察到了明显的光电转换特性.研究表明ZnO薄膜中的电子浓度在一个合适的数值(1.6×1015cm-3)时光电流最强,另外晶粒尺寸越大光电流越强.分析表明,电子浓度和晶粒直径对光电流的影响规律在很大程度上是载流子散射导致的.此外,还发现ZnO薄膜存在一个临界厚度,当薄膜厚度大于该临界厚度时,异质结的光电压和光电流都急剧衰减并很快接近于0.实验表明,这个临界厚度和ZnO薄膜(001)面最大晶粒直径一致.     

Au/PZT/BIT/p-Si结构铁电 存储二极管I-V 特性

采用脉冲激光沉积方法（PLD）制备了Au/PZT/BIT/p-Si多层结构铁电存储二极管.对铁电存储二极管的P-E电滞回线、I-V特性曲线分别进行了测试与分析,并对其导电行为及基于I-V特性回滞现象的存储机理进行了讨论.实验表明,所制备的多层铁电薄膜具有较高的剩余极化（27μC/cm2）和较低的矫顽场（48kV/cm）,BIT铁电层有助于缓解PZT与Si衬底之间的界面反应和互扩散,减少界面态,与Au/PZT/p-Si结构相比,漏电流密度降低近两个数量级,I-V特性曲线回滞窗口明显增大.     

Photoelectric conversion characteristics of ZnO/SiC/Si heterojunctions

A series ofn-ZnO/n-SiC/p-Si and n-ZnO/p-Si heterojunctions were prepared by DC sputtering. Their struc-tural properties, Ⅰ-Ⅴ curves, photovoltaic effects and photo-response spectra were studied. The photoelectric conver-sion characteristics of n-ZnO/n-SiC/p-Si and n-ZnO/p-Si heterojunctions were investigated. It is found that the pho-toelectric conversion efficiency of the n-ZnO/n-SiC/p-Si heterojunction is about four times higher than that of the n-ZnO/p-Si heterojunction. The photovoltaic response spectrum indicated that the photoresponse curve of n-ZnO/n-SiC/p-Si increased more strongly than that of n-ZnO/p-Si with the wavelength increasing. It shows that the photore-sponse ofn-ZnO/p-Si can be enhanced when inserting a 3C-SiC layer between ZnO and Si. There is one inflexion in the photocurrent response curve of the n-ZnO/p-Si heterojunction and two inflexions in that of the n-ZnO/n-SiC/p-Si het-erojunction. It is clear that the 3C-SiC plays an important role in the photoelectric conversion of the n-ZnO/n-SiC/p-Si heterojunction.     

简易化学水浴法制备SnO2/p-Si异质结光电性能

SnO2薄膜沉积在晶硅衬底上通过一种简单化学水浴法以制备n-SnO2/p-Si异质结光电器件,该化学水浴法非常便宜和方便。采用XRD、XPS、紫外-可见光分光光度计和霍尔效应测试系统表征了SnO2薄膜的微结构、光学和电学性能,对SnO2/p-Si异质结的I-V曲线进行测试并分析,获得明显的光电转换特性。     

Electrical and optical properties of ZnO/Si heterojunctions as a function of the Mg dopant content

Undoped and Mg-doped ZnO thin films prepared by a sol–gel process were deposited on p-Si and glass substrates via spin coating. The electrical and optical properties of the films were investigated. Atomic force microscopy images revealed that the ZnO films are formed from fibers consisting of nanoparticles. The electrical conductivity mechanism of the films was investigated. The I–V characteristics of Al/ZnO/p-Si samples showed rectification behavior with a rectification ratio that depended on the applied voltage and the Mg doping ratio. ZnO/p-Si heterojunction diodes exhibited non-ideal behavior with an ideality factor greater than unity that could be ascribed to the interfacial layer, interface states, and series resistance. The barrier height for undoped and Mg-doped ZnO/p-Si diodes was in the range 0.78–0.84 eV. The results demonstrate that the electrical properties of ZnO/p-Si heterojunction diodes are controlled by the Mg dopant content and suggest that the optical bandgap of these ZnO films can be tuned using the Mg level.     

Semi-insulating polysilicon heterojunctions on silicon

The electrical characteristics of undoped semi-insulating polysilicon (SIPOS)/p-type crystalline silicon (p-Si) and N⁺-SIPOS/p-Si heterojunctions were investigated. The current-voltage characteristics of the undoped SIPOS/p-Si heterojunctions depart from a hyperbolic sine behavior as the refractive index of the SIPOS increases. Carrier conduction in the undoped heterojunctions is characterized by low- and high-temperature barrier heights, which also vary with refractive index. Current-voltage characteristics of the n⁺-SIPOS/p-Si structures were rectifying with a cut-in voltage of about 1 V, which decreased with increasing temperature. Increasing the SIPOS doping increased the current density for a given bias and reduced the cut-in voltage. The forward characteristic displayed both a low and a high field activation energy with the difference attributable to the presence of interface states at the junction. Consequently, carrier conduction in these doped and undoped SIPOS/p-Si heterojunctions appears to be controlled by the SIPOS/p-Si interface. However, hydrogen annealing passivates the interface states thereby altering the low field conduction region.     

Temperature coefficients of grain boundary resistance variations in a ZnO/p-Si heterojunction

Heteroepitaxial undoped ZnO films were grown on Si (100)substrates by radio-frequency reactive sput tering,and then some of the samples were annealed at N<,2>-800 ℃(Sample 1,S1)and O<,2>-800℃(Sample 2,S2)for 1 h,respectively.The electrical transport characteristics of a ZnO/p-Si heterojunction were investigated.We found two interesting phenomena.First,the temperature coefficients of grain boundary resistances of S1 were positive(positive temperature coefficients,PTC)while that of both the as-grown sample and S2 were negative(negative temperature coefficients,NTC).Second,the Ⅰ-Ⅴ properties of S2 were similar to those common p-n junctions while that of both the as-grown sample and S1 had double Schottky barrier behaviors,which were in contradiction with the ideal p-n heterojunction model.Combined with the deep level transient spectra results,this revealed that the concentrations of intrinsic defects in ZnO grains and the densities of interfacial states in ZnO/p-Si heterojunction varied with the different annealing ambiences,which caused the grain boundary barriers in ZnO/p-Si heterojunction to vary.This resulted in adjustment electrical properties of ZnO/p-Si heterojunction that may be suitable in various applications.     

Controlling of electrical and interface state density properties of ZnO:Co/p-silicon diode structures by compositional fraction of cobalt dopant

The heterojunction diodes based on cobalt doped zinc oxide (ZnO) were prepared by sol-gel deposition method. The compositional fraction of cobalt dopant was varied to control the electrical parameters of the diode. Atomic force microscopy was used to determine the structural properties of ZnO:Co films. The ZnO:Co films have a microfiber structure and the structure of microfibers was changed with the cobalt dopant. The ideality factor values of 5% and 15% Co doped ZnO:Co/p-Si diodes were determined to be 3.49 and 7.51, respectively. The barrier height of the ZnO:Co/p-Si diodes were found to vary from 0.75 eV to 0.78 eV.It is concluded that the electrical and interface state density properties of ZnO:Co/p-Si diodes can be controlled by compositional fraction of cobalt dopant.     

Electrical transport properties of crystalline siliconcarbide/silicon heterojunctions

The electrical transport properties of β-SiC/Si heterojunctions were investigated using current-voltage (I-V) and capacitance-voltage (C-V) characteristics. The heterojunctions were fabricated by growing n-type crystalline β-SiC films on p-type Si substrates by chemical vapor deposition (CVD). The I-V data measured at various temperatures indicate that at relatively high current, the heterojunction forward current is dominated by thermionic emission of carriers and can be expressed as exp(-qV_bi/kT ) exp(V/ηkT), where V_bi is the built-in voltage of the heterojunction and η(=1.3) is a constant independent of voltage and temperature. At lower current, defect-assisted multitunneling current dominates. The effective density of states and the density-of-states effective mass of electrons in the conduction band of SiC are estimated to be 1.7×10²¹ cm ^-3 and 0.78m₀, respectively. This study indicates that the β-SiC/Si heterojunction is a promising system for heterojunction (HJ) devices such as SiC-emitter heterojunction bipolar transistors (HBTs)