电场下GaAs/Ga1-xAlxAs量子阱中的子带和激子

本文利用有限势垒模型,研究电场对GaAs/Ga_1-xAl_xAs量子阱中子带和激子的影响。对阱宽为105?的GaAs/Ga_0.66Al_0.34As量子阱,电场由0—1.2×10⁵V/cm,我们计算了电子和空穴的子带以及激子的结合能。基于上述计算结果,所得电子-空穴重叠函数和激子峰的能量移动与实验测量符合得较好。 关键词：     

正切平方势单量子阱的本征值和本征函数

鉴于“方形”势阱描述量子阱中的电子运动行为过于简单、过于理想,引入了正切平方势来代替,使结果得到了改善。在量子力学框架内,利用正切平方势把电子的Schrdinger方程化为超几何方程,利用系统参数和超几何函数严格地求解了电子的本征值和本征函数,并以Ga_1-xAl_xAs-GaAs-Ga_1-xAl_xAs量子阱为例计算了电子的能级和能级之间的跃迁。结果表明,电子在量子阱中的能量是量子化的,而相邻能级之间的跃迁给出与实验进一步符合的结果。     

浅杂质势与窄量子阱的耦合作用

本文采用一种新的变分波函数描述GaAs/Ga_1-xAl_xAs窄量子阱中的浅施主基态,并计算了杂质基态波函数和结合能。计算所得数值结果表明正确考虑窄量子阱与杂质势间的耦合作用是极为重要的。 关键词：     

高性能透射式GaAs光电阴极量子效率拟合与结构研究

为了探索高性能透射式GaAs光电阴极的特征结构,对光电阴极量子效率公式进行了光谱反射率与短波截止限的修正,并利用修正后的公式对ITT透射式GaAs光电阴极量子效率(≈43%)曲线进行了拟合,得到拟合相对误差小于5%时的结构参数为:窗口层Ga_1-xAl_xAs的厚度介于0.3-0.5 μm,Al组分x值为0.7,发射层GaAs的厚度介于1.1-1.4 μm.另外,根据拟合结果讨论了均匀掺杂透射式GaAs光电阴极的优化结构参数,如果光电阴极具有0.4 μm厚的Ga_1-xAl_xAs(x=0.7)窗口层和1.1-1.5 μm厚的GaAs发射层,则积分灵敏度可以达到2350 μA/lm以上. 关键词： 透射式GaAs光电阴极 量子效率 积分灵敏度 光学性能     

准一维电子通道中声电电流的理论计算

表面声波在GaAs/Al _x Ga_1-x As异质结表面上沿由分裂门产生的准一维电子通道方向传 播时，在通道中诱导产生声电电流.采用WKB近似，计算了只有一个电子被量子阱俘获时的声电电流；并在此基础上，详细讨论了表面声波的频率和功率，以及门电压和源漏偏压对声电电流的影响. 关键词： 表面声波 准一维电子通道 量子阱 声电电流     

分子束外延生长的(GaAs1－xSbx/InyGa1－yAs)/GaAs量子阱光致发光谱研究

报道了(GaAs_1-xSb_x/In_yGa_1-yAs)/Ga As量子阱结构的分子束外延生长与光致发光谱研究结果.变温与变激发功率光致发光谱的研究表明了此结构 为二型量子阱发光性质.讨论了光谱双峰结构的跃迁机制.通过优化生长条件，获得了室温1 31μm发光. 关键词： 分子束外延 量子阱 二型发光     

In0.53Ga0.47As/InP量子阱与体材料的1 MeV电子束辐照光致发光谱研究

为获得对In_0.53Ga_0.47As/InP材料在电子束辐照下的光致发光谱变化规律, 开展了1 MeV电子束辐照试验, 注量为 5×10¹²-9×10¹⁴ cm^-2. 样品选取量子阱材料和体材料, 在辐照前后, 进行了光致发光谱测试, 得到了不同结构In_0.53Ga_0.47As/InP材料在1 MeV电子束辐照下的不同变化规律; 对比分析了参数退化的物理机理. 结果显示: 试验样品的光致发光峰强度随着辐照剂量增大而显著退化. 体材料最先出现快速退化, 而五层量子阱在注量达到6×10¹⁴ cm^-2时, 就已经退化至辐照前的9%. 经分析认为原因有: 1)电子束进入样品后, 与材料晶格发生能量传递, 破坏晶格完整性, 致使产生的激子数量减少, 光致发光强度降低; 电子束辐照在材料中引入缺陷, 增加了非辐射复合中心密度, 导致载流子迁移率降低. 2)量子阱的二维限制作用使载流子运动受限, 从而能够降低载流子与非辐射复合中心的复合概率; 敏感区域截面积相同条件下, 体材料比量子阱材料辐射损伤更为严重. 3)量子阱的层数越多, 则异质结界面数越多, 相应的产生的界面缺陷数量也随之增多, 辐射损伤越严重.     

PbTe/PbSrTe半导体非对称量子阱中的Rashba效应

窄带隙半导体异质结构的自旋效应最近受到了国际上的很大关注.Ⅳ-Ⅵ族半导体具有各向异性和多能谷的特征,因此可以预期Rashba自旋效应在不同取向的Ⅳ-Ⅵ族半导体量子阱结构中存在显著差异.计算了多个取向的Pb_1-ySr_yTe/PbTe/Pb_1-xSr_xTe非对称量子阱中的Rashba分裂能,结果表明［100］取向的PbTe量子阱的Rashba分裂能在阱宽为5.0nm时 关键词： Ⅳ-Ⅵ族半导体 非对称量子阱 Rashba效应 自旋-轨道耦合分裂     

量子阱半导体激光器阈值的理论分析

分析了单量子阱(SQW)、多量子阱(MQW)和分别限制异质结构量子阱(SCH-SQW)半导体激光器的阈值.求出了表示光增益随注入载流子密度变化的方程.利用这个结果,得到了上述三种量子阱半导体激光器的阈值电流密度的表达式.     

超晶格中GaAs/InGaAs界面与InGaAs/GaAs界面的特性差异

In_xGa_1-xAs缓冲层上生长In_yGa_1-yAs/GaAs超晶格（x＜y）．阱层处于压缩应变，垒层处于伸张应变，其厚度均小于Mathews-Blakeslee（M-B）平衡理论计算的临界厚度．透射电子显微镜及俄歇电子能谱、二级离子质谱测试发现，GaAs/In_yGa_1-yAs界面铟组分过渡区比In_yGa_1-yAs/GaAs界面铟组 关键词：     

Effects of Coupling Lens on Optical Refrigeration of Semiconductors

Optical refrigeration of semiconductors is encountering efficiency difficulties caused by nonradiative recombination and luminescence trapping. A commonly used approach for enhancing luminescence efficiency of a semiconductor device is coupling a lens with the device. We quantitatively study the effects of a coupling lens on optical refrigeration based on rate equations and photon recycling, and calculated cooling emciencies of different coupling mechanisms and of different lens materials. A GaAs/GalnP heterostructure coupled with a homo-epitaxial GalnP hemispherical lens is recommended.     

一种微型温差电制冷器建模与性能分析

温差电制冷技术广泛应用在半导体的降温和制冷中,但由于半导体器件的尺寸越来越小,导致传统的温差电制冷理论和方法不再适用新的环境,尤其是在微型半导体器件中,非线性的热传导规律导致制冷模型和分析方法都发生了改变.文中在深入研究了微型半导体器件中,温差电制冷技术的工作原理和过程.在此基础上,提出了一种微型温差电制冷器的建模方法...     

Radiative and nonradiative recombination times in semiconducting films

The radiation emitted spontaneously by a semiconductor which has been excited for a very short time decays exponentially with a time constant that depends on the recombination rate of electrons and holes. This recombination rate is the combination of radiative and nonradiative transition rates between conduction and valence bands of the semiconductor. The radiative recombination rate depends on the density of states of the electromagnetic field, which can be made to be dependent on the geometry. In this paper, we report on the dependence of the fluorescence lifetime upon the thickness of active thin films. For systems in which the radiative recombination rate is dominant over the nonradiative ones, the total recombination time can be changed by suitable modifications of the thickness of the film. In this situation, the nonradiative rate can be evaluated. We present experimental results for the case of cadmium sulphide (CdS) thin films.     

Modeling of gain and phase dynamics in quantum dot amplifiers

By means of an electron hole rate equation model we explain the phase dynamics of a quantum dot semiconductor optical amplifier and the appearance of different decay times observed in pump and probe experiments. The ultrafast hole relaxation leads to a first ultrafast recovery of the gain, followed by electron relaxation and, in the nanosecond timescale, radiative and non-radiative recombinations. The phase dynamics is slower and is affected by thermal redistribution of carriers within the dot. We explain the ultrafast response of quantum dot amplifiers as an effect of hole escape and recombination without the need to assume Auger processes.     

半导体制冷演示实验

研制了可用于物理教学演示的半导体制冷演示仪，半导体制冷器是纯固体制冷源，既能制冷又能制热，体积小，重量轻，使用方便，无污染，有广泛的应用前景，本仪器着重演示半导体制冷的优点。     

新型热驱动半导体制冷器性能的优化分析

提出一种新型的热驱动半导体制冷器模型 ,以制冷系数和制冷率为目标函数分析其性能特性。计算在不同情况下热驱动半导体制冷器的最大制冷系数和制冷率。进而优化工作电流的最佳范围 ,从而确定热驱动半导体制冷器的内部结构参数。所得结果可为新型的热驱动半导体制冷器的优化设计和最佳运行提供有价值的理论指导 ,可促进热驱动半导体制冷器的开发和在不同高新科技领域中的应用。     

The effect of temperature on the recombination rate of AlGaN/GaN light emitting diodes

Nitride semiconductors and their alloys recently have versatile applications as high-power and high-efficiency electro optical devices duo to their high thermal stability, direct transition and wide bang-gap. Nanostructure light emitting diodes of these materials have an emission spectrum from infrared to ultraviolet. In this paper, besides simulating a nanostructure nitride semiconductor LED, such as multi quantum well nitride LEDs, the effect of temperature on the recombination rate has been investigated.     

半导体制冷及其在物理实验中的应用

半导体制冷是通过空穴和电子在运动中直接传递热量的固体致冷方式.本文通过半导体致冷型恒温量热器和半导体热电特性实验为例,说明在物理实验中应用半导体制冷技术的设计思路及优势.     

Optical evaluation of radiative recombination in III–V compound semiconductors

This paper reviews experimental techniques and recent results concerning the evaluation of AIII–BV compound semiconductor materials by means of analysis of radiative recombination processes. Photoluminescence is a particularly sensitive and informative technique to reveal low concentrations of impurity, admixtures and fine details of their, electronic structure. The technologically important materials GaAs and GaP have most thoroughly been investigated. The application of external perturbations lifts degeneracies and indicates the structure of exciton-binding centers. Time-resolved spectroscopy down to the picosecond-regime has been utilized to directly measure phonon lifetimes, energy relaxation, and other phenomena. Photoluminescence scanning with high spatial resolution yields information about dopant incorporation and the effects of line defects and interfaces on recombination. Excitation spectroscopy, an important variant of luminescence spectroscopy, is reviewed.     

Auger relaxation processes in semiconductor nanocrystals and quantum wells

Auger recombination rates in mesoscopic semiconductor structures have been studied as a function of energy band parameters and heterostructure size. It is shown that nonthreshold Auger processes stimulated by the presence of heteroboundaries become the dominant nonradiative recombination channel in nanometer size semiconductor structures. The size dependence of luminescence quantum yields in nanostructures and microcrystals are discussed. Auger-like collisions of electrons and heavy holes are shown to serve as “accelerators” of thermalization processes in semiconductor quantum dots.