光伏碲镉汞探测器在波段内连续激光辐照下的非线性响应机理研究

利用波段内连续激光, 辐照禁带宽度为0.33 eV的中波光伏碲镉汞探测器. 实验结果表明, 随着辐照激光光强的逐渐增大, 探测器从线性响应过渡为非线性响应. 当探测器进入非线性状态, 探测器的开路电压随激光光强的增大而减小, 且在激光开启辐照时开路电压信号迅速下跳, 在激光停止辐照时开路电压信号迅速上跳. 通过考虑激光辐照下探测器的温度场分布以及温度对p-n结内建电场的影响, 结合考虑机械快门在开启和关闭时对激光光强变化的影响, 建立了光伏探测器在波段内连续激光辐照下的解析模型, 模型计算结果与实验结果吻合得较好. 研究表明, 激光辐照过程中的非线性响应, 主要由温度对p-n结内建电场的影响决定, 激光开启和关闭时的开路电压的幅值是由光强和温度共同决定.     

p-n结二极管结区边界附近的交流电特性

基于p-n结二极管的理想工作状态的基本假定,推导了二极管在交流电下工作时其基区和p-n结分界面附近上的时间常数与二极管空间尺寸、扩散长度、载流子寿命和外加交流电频率等的依赖关系.结果发现高频和低频两种状态下二极管各类特征参量对时间常数的作用不一样.低频条件下,二极管的时间常数由材料本身来决定,与外加电流频率无关.高频情况下,时间常数则与半导体材料性质无关,只由外加交流电的频率来决定. 关键词： p-n结二极管 时间常数 载流子 分界面     

p-n结二极管结区边界附近的交流电特性

基于p-n结二极管的理想工作状态的基本假定，推导了二极管在交流电下工作时其基区和p-n结分界面附近上的时间常数与二极管空间尺寸、扩散长度、载流子寿命和外加交流电频率等的依赖关系.结果发现高频和低频两种状态下二极管各类特征参量对时间常数的作用不一样.低频条件下，二极管的时间常数由材料本身来决定，与外加电流频率无关.高频情况下，时间常数则与半导体材料性质无关，只由外加交流电的频率来决定.     

氧非正分La0.9Ba0.1MnO3-δ/SrTiO3:Nb p-n异质结的整流特性研究

利用脉冲激光沉积技术在掺Nb的SrTiO3衬底上制备了氧非正分La0.9Ba0.1MnO3-δ/SrTiO3:Nb p-n异质结.在20-300 K这一较宽的温度范围内获得了光滑的整流曲线.整流实验表明:该p-n异质结的正向扩散电压V0随着温度升高在薄膜金属-绝缘转变温度附近出现极大值,表现出与氧正分La0.9Ba0.1MnO3-δ/SrTiO3:Nb p-n结截然不同的温度特性.结合薄膜的电阻-温度实验和能带计算结果,对这一奇异的现象进行了解释.     

Graphene/Ag2ZnSnSe4诱导p-n结薄膜太阳电池数值模拟

银锌锡硒(Ag2ZnSnSe4)是一种禁带宽度为1.4 eV的n型半导体材料.本文提出一种由n型Ag2ZnSnSe4与石墨烯(Graphene)组成的Graphene/Ag2ZnSnSe4诱导p-n结薄膜太阳电池,并借助wxAMPS软件对电池的物理机理和性能影响因素进行模拟研究.模拟结果表明,高功函数的石墨烯与n型Ag2ZnSnSe4半导体接触时,Ag2ZnSnSe4吸收层的前端能带向上弯曲,在n型Ag2ZnSnSe4吸收层表面诱导形成p型Ag2ZnSnSe4反型层,p型Ag2ZnSnSe4和n型Ag2ZnSnSe4组成p-n同质结.模拟发现石墨烯和背接触的功函数会影响载流子的分离、输运和收集,严重影响器件性能,石墨烯功函数达到5.5 eV,背接触功函数不高于4.4 eV,都有利于提高器件性能.Ag2ZnSnSe4吸收层的掺杂浓度主要影响器件的短路电流,而Ag2ZnSnSe4吸收层的体内缺陷对器件整体性能产生影响.在石墨烯和背接触功函数分别为5.5和3.8 eV,Ag2ZnSnSe4吸收层的掺杂浓度和缺陷密度分别为1016和1014 cm–3时,Graphene/Ag2ZnSnSe4诱导p-n结薄膜太阳电池能够取得高达23.42%的效率.这些模拟结果为设计新型高效低成本太阳电池提供了思路和物理阐释.     

GaInP/GaAs/Ge三结太阳电池不同能量质子辐照损伤模拟

以GaInP/GaAs/Ge三结太阳电池为研究对象,开展了能量为0.7, 1, 3, 5, 10 MeV的质子辐照损伤模拟研究,建立了三结太阳电池结构模型和不同能量质子辐照模型,获得了不同质子辐照条件下的I-V曲线,光谱响应曲线,结合已有实验结果验证了本文模拟结果,分析了三结太阳电池短路电流、开路电压、最大功率、光谱响应随质子能量的变化规律,利用不同辐照条件下三结太阳电池最大输出功率退化结果,拟合得到了三结太阳电池最大输出功率随位移损伤剂量的退化曲线.研究结果表明,质子辐照会在三结太阳电池中引入位移损伤缺陷,使得少数载流子扩散长度退化幅度随质子能量的减小而增大,从而导致三结太阳电池相关电学参数的退化随质子能量的减小而增大.相同辐照条件下,中电池光谱响应退化幅度远大于顶电池光谱响应退化幅度,中电池抗辐照性能较差,同时中电池长波范围内光谱响应的退化幅度比短波范围更大,表明中电池相关电学参数的退化主要来源于基区损伤.     

在蓝宝石衬底上生长的氧化锌p-n同质结发光二极管

用等离子体辅助的分子束外延的方法在蓝宝石衬底上生长了氧化锌的p-n同质结发光二极管。在实验中p型ZnO层是采用NO等离子体作为掺杂剂生长的。在低温下,二极管的I-V特性曲线显示了典型的p-n结整流特性,并且具有很低的开启电压（4V）。在实验中得到了位于蓝紫区的电致发光。     

立方氮化硼单晶-金刚石薄膜异质p-n结

 在Si中掺杂N型片状立方氮化硼单晶的(111)面上,利用热灯丝化学气相沉积方法生长了掺B的p型金刚石薄膜,从而制得了立方氮化硼单晶-金刚石薄膜异质p-n结,测试了该p-n结的V-A特性,结果表明其整流特性良好。     

基于双极性二维晶体的新型p-n结

二维晶体的特殊结构和新奇物理性能为构建新型纳米结构和器件,实现半导体领域的突破性进展提供了可能.本文首先介绍了双极性二维晶体的基本物理性能和相关范德瓦耳斯异质结的制备方法.在此基础上,主要综述了双极性二维晶体在新型电场调制二维晶体p-n结与异质p-n结以及非易失性可存储二维晶体p-n结等方面的应用、相关结构设计、电子和光电子等物理性能.然后进一步介绍了该类新型p-n结在逻辑整流电路、场效应光电子晶体管、多模式非易失性存储器、整流存储器、光电子存储器、光伏器件等方面的潜在应用.最后总结展望了该种新型p-n结在相关领域的可能发展方向.     

氧非正分La0.9Ba0.1MnO3-δ/SrTiO3:Nb p-n异质结的整流特性研究

利用脉冲激光沉积技术在掺Nb的SrTiO₃衬底上制备了氧非正分La_0.9Ba_0.1MnO_3-δ/SrTiO₃:Nb p-n异质结.在20—300K这一较宽的温度范围内获得了光滑的整流曲线.整流实验表明：该p-n异质结的正向扩散电压V_D随着温度升高在薄膜金属—绝缘转变温度附近出现极大值,表现出与氧正分La_0.9Ba_{0. 关键词： 0.9}Ba_0.1MnO_3-δ薄膜')" href="#">La_0.9Ba_0.1MnO_3-δ薄膜 锰氧化物p-n结 整流性质     

描述光伏效应的新解析模型

 对陆启生等人提出的描述光伏效应的解析模型涉及的边界条件进行了讨论，提出了一个适用性更宽的解析模型。通过对新模型、陆的模型以及另一个解析模型的比较，对前两个模型能够描述光伏型光电探测器在强光辐照时的信号饱和效应的原因进行了解释。     

高择优取向铌酸锶钡薄膜的射频磁控溅射制备

采用溶胶-凝胶法在(100)Si单晶上预先制备出掺钾(K)的铌酸锶钡(SBN)缓冲层,利用射频磁控溅射法在缓冲层KSBN上沉积出高择优取向的铌酸锶钡薄膜,获得了磁控溅射法制备择优取向铌酸锶钡薄膜的相关工艺参数,研究发现,KSBN缓冲层能够很有效地克服衬底与SBN薄膜之间较大的晶格失配,在氧气氩气的比例为1∶2,工作气压为10 Pa,溅射功率300 W,衬底温度300℃,退火温度为800℃的工艺条件下,能够获得c轴高度择优取向的铌酸锶钡铁电薄膜.利用X射线衍射仪,原子力显微镜等仪器分析了薄膜 关键词： 磁控溅射 高择优取向 p-n结效应     

The study of a new n/p tunnel recombination junction and its application in a-Si：H/μc-Si：H tandem solar cells

This paper reports that a double N layer (a-Si:H/μc-Si:H) is used to substitute the single microcrystalline silicon n layer (n-μc-Si:H) in n/p tunnel recombination junction between subcells in a-Si:H/μc-Si:H tandem solar cells. The electrical transport and optical properties of these tunnel recombination junctions are investigated by current-voltage measurement and transmission measurement. The new n/p tunnel recombination junction shows a better ohmic contact. In addition, the n/p interface is exposed to the air to examine the effect of oxidation on the tunnel recombination junction performance. The open circuit voltage and FF of a-Si:H/μc-Si:H tandem solar cell are all improved and the current leakage of the subcells can be effectively prevented efficiently when the new n/p junction is implemented as tunnel recombination junction.     

Nanosecond photoelectric effects in all-oxide p-n junction of La_(0.9)Sr_(0.1)MnO_3/SrNb_(0.01)Ti_(0.99)O_3

Since the discoveries of high Tc superconductors and colossal magnetoresistance, enormous efforts have been devoted to investigating the perovskite oxide materials. The fabrication of artificial crystalline materials through layer-by-layer epitaxial growth with full control over the composition and structure at the atomic level has become one of the most exciting areas of research in condensed matter physics and materials science. In related research, much attention has been paid to the new de…     

硅太阳能电池的调制载流子红外辐射动态响应与参数分析

建立了调制激光诱发硅太阳能电池的少数载流子密度波数学模型,并利用光致载流子辐射检测掺杂浓度、阻抗及载流子输运参数. 对频域响应曲线中的双弯曲效应进行了研究,构建了小交流信号作用的太阳能电池等效电路拓扑结构,仿真分析了不同掺杂浓度、阻抗电阻和载流子传输参数对频响曲线拐点的影响. 通过光致载流子辐射频域扫描实验与多参数拟合检测了单晶硅太阳电池的施/受主浓度、并联电阻和载流子输运参数. 结果表明：光致载流子辐射技术检测大面积太阳能电池频响曲线的双弯曲是由电容效应所引起的,建立的数学模型可定量描述和预测检测结果,并用于测量太阳能电池的掺杂浓度、电阻和载流子输运参数. 关键词： 调制自由载流子辐射 扫频检测 PN结电容 参数测量     

An n—n type heterojunction enabling highly efficientcarrier separation in inorganic solar cells

Carrier separation in a solar cell usually relies on the p—n junction. Here we show that an n—n type inorganic semiconductor heterojunction is also able to separate the exciton for efficient solar cell applications. The n—n type heterojunction was formed by hydrothermal deposition of Sb₂(S,Se)₃ and thermal evaporation of Sb₂Se₃. We found that the n—n junction is able to enhance the carrier separation by the formation of an electric field, reduce the interfacial recombination and generate optimized band alignment. The device based on this n—n junction shows 2.89% net efficiency improvement to 7.75% when compared with the device consisted of semiconductor absorber—metal contact. The study in the n—n type solar cell is expected to bring about more versatile materials utility, new interfacial engineering strategy and fundamental findings in the photovoltaic energy conversion process.     

Solar cells as pseudo-Josephson junctions

We have identified pseudo-Josephson effects within currents in solar cells. Compared to the original Josephson junction of superconductors, we were able to obtain theoretical results in one-to-one correspondence with experimental observation of solar cell currents. We applied a pseudo-Josephson junction to the current along the axis of energy, that is, the momentum space. The theoretical form of DC-type currents before integration over frequency was also found to be of the tan-function. This pseudo-Josephson junction is, however, not in real space but in momentum space. Currents of solar cells were not formulated in terms of the unique semiconductor differences between electrons and holes but with our pseudo-Josephson junction in terms of conduction band electrons, energy gap, and valence band electrons in the solar cell materials. The mechanism of solar cell function is thus ascribed to a pseudo-Josephson effect in our scheme.     

Nanosecond photoelectric effects in all-oxide p-n junction of La<Subscript>0.9</Subscript>Sr<Subscript>0.1</Subscript>MnO<Subscript>3</Subscript>/SrNb<Subscript>0.01</Subscript>Ti<Subscript>0.99</Subscript>O<Subscript>3</Subscript>

Nanosecond (ns) photoelectric effects have been observed in all-oxide p-n junctions of La_0.9Sr_0.1MnO₃/SrNb_0.01Ti_0.99O₃ for the first time. The rise time was about 23 ns and the full width at half maximum was about 125 ns for the open-circuit photovoltaic pulse when the La_0.9Sr_0.1MnO₃ thin film in the p-n junction was irradiated by a laser of ≈20 ns pulse duration and 308 nm wavelength. The photovoltaic sensitivity was 80 mV/MJ for a 308 nm laser pulse.     

Numerical simulation of the magnetoresistance effect controlled by electric field in p–n junction

The magnetoresistance effect of a p–n junction under an electric field which is introduced by the gate voltage at room temperature is investigated by simulation. As auxiliary models, the Lombardi CVT model and carrier generationrecombination model are introduced into a drift-diffusion transport model and carrier continuity equations. All the equations are discretized by the finite-difference method and the box integration method and then solved by Newton iteration.Taking advantage of those models and methods, an abrupt junction with uniform doping is studied systematically, and the magnetoresistance as a function of doping concentration, SiO_2 thickness and geometrical size is also investigated. The simulation results show that the magnetoresistance(MR) can be controlled substantially by the gate and is dependent on the polarity of the magnetic field.     

Solar cells

Solar cells are based on the photovoltaic effect of converting solar energy into electric energy. The mechanism for solar cells is divided into steps, that is, electron-hole pair generation by absorption of light in semiconductors, separation of electron-hole pairs by built-in potential, electron-hole recombination, collection of charge carriers by metal electrodes, etc. In this article, the principle and the theories of these basic steps are presented. On the basis of these steps, methods to improve the efficiency for solar cells are discussed. The fabrication process and the situation of currently produced solar cells are also presented. Solar cells having no p-n junction, that is, photoelectrochemical solar cells and MIS solar cells, are discussed from the perspective of low-cost solar cells.