光伏法测量AlAs/GaAs超晶格子带间光跃迁

采用电容耦合法,在18—300K温度范围内测量了AlAs/GaAs超晶格的光伏谱.在100K以下,光伏曲线反映了台阶式二维状态密度分布,可观测到6个信号峰.采用Kronig-Penney模型计算势阱中导带和价带子带的位置和带宽,共有3个导带子带,6个重空穴子带和3个轻空穴子带.根据宇称守恒确定光跃迁选择定则,对6个峰进行指认.实验结果与理论计算的结果基本相符合.     

GaInAs／AlInAs调制掺杂结构材料的光学性质研究

研究了ＧａＩｎＡｓ／ＡｌＩｎＡｓｎ型调制掺杂结构样品的光致发光及其激发光谱。当空穴态被局域化后．二维电子气的发光线形反映了导带二维态密度的填充效应：导带两个子带填充电子。发光强度则表明，导带第二子带电子波函数在空间上更扩展，与空间分离的空穴产生发光复合的几率较大。激发光谱提供了样品中异质结结构直接带边附近光吸收过程的信息。     

n-InSb的纵向磁阻振荡

在测量磁阻振荡的直流法中,加一级差分放大,可显著提高分辨振荡峰的本领,因而可以用较低的磁场研究电子浓度为 10~(15)cm~(-3)数量级的 n-InSb的磁阻振荡.这一方法适用于纵向磁阻振荡的研究.在液氦温度到10K的范围内,测量了四个n-InSb样品.从振荡频率得到载流子浓度,与霍尔效应的结果相符.从振荡峰的幅度-温度关系得到导带底的电子有效质量m~*=0.0137m_o. 从振荡峰与温度及外加电场的变化关系中,可求得样品的 Dingle温度及过热电子温度.在4.2K-7.2K温度范围内Dingle温度不变.在实验所用的电场下过热电子温度可达到14K.     

GaAs-Al_xGa_(1-x)As n-N异质结的光伏特性

测量了液相外延生长的GaAs-Al_xGa_(1-x)As n -N异质结 300K和 77K下的光伏响应的光谱分布,证明异质结界面上存在着较多的界面能级.能带形状在界面上有两个背对背的势垒.在禁带中离AlxGa_(1-x)As导带边 0.7-0.8eV处有一个类受主界面能级.在某些特定条件下,这种n-N异质结在光照和温度作用下可具有多态变化,它和界面态上电子的捕获和释放有关.     

In_xGa_(1-x)As/GaAs应变单量子阱结构的静压光致发光研究

在室温和液氮温度下,0-60kbar范围内对In_xGa(1-x)As/GaAs应变单量子阱结构进行了静压光致发光研究.在室温下,量子阱中发光峰随压力的变化是亚线性的,而在液氮温度下是线性的.阱中发光峰的压力系数比GaAs势垒的小约10％左右.发现对应于导带第二子带的发光峰的压力系数略大于第一子带的.此结果与GaAs/Al_xGa_(1-x)As量子阱的情况正好相反.     

窄禁带半导体Pb_(1-x)Sn_xTe的带间磁光光谱及其能带参数的研究

用选支连续CO_2激光器为光源,首次对x=0.2 组分的n型Pb_(1-x)Sn_xTe 单晶进行了法拉第构象下圆偏振光的磁光反射光谱的测量.样品温度在10—50K范围内,磁光反射谱的振荡峰值对应L_1~6价带到L_3~(6＇)导带朗道能级间的跃迁. 采用k·p微扰理论模型,用上述峰位,经过拟合计算得到了该模型下此x值处能带边有效质量、g因子、各向异性因子、能隙等参数.结果发现,远带对有效质量贡献较大,特别是对纵向有效质量的贡献可达到30％,并带来一定程度的导带、价带不对称.相比之下,远带对g因子则影响很小.x=0.2时各向异性因子为10的量级,并随能隙而变化,远带作用使它有所降低.     

Hg_(0.656)Cd_(0.344)Te本征吸收光谱和Kane模型

本文描述在80K到300K温度范围,利用PE580B型红外分光光度计测量厚度为6.5μm的Hg_(0.656)Cd_(0.344)Te薄样品的本征吸收光谱。测得最高吸收系数达10~4cm~(-1)。由吸收曲线确定了该样品在不同温度下的禁带宽度以及吸收边所符合的规律,与参考文献[3]的经验公式一致。本文还利用Kane模型计算了吸收系数的理论曲线,取动量矩阵元P=8×10~(-8)eV-cm,重空穴有效质量m_(hh)=0.55m_0时,理论曲线与实验曲线符合较好。但Kane理论不能解释吸收边。根据指数吸收边可以推测,在导带底存在一个指数型带尾。     

低温强磁场测量下N-InSb材料的补偿度

在温度4.2～77K、磁场强度0～5T、不同电场强度条件下,对不同参数材料的样品进行了物理测试。在低温、弱电场下即欧姆电场区,以横向磁场和温度作为可变外界条件,采用平衡法,测得N型InSb样品在“磁冻出”状态下霍尔电压和电阻电压随温度的变化,利用“磁冻出”区的磁阻和霍尔效应求得导带电子浓度随温度的变化。且利用Putley的导带电子浓度与温度、磁场强度和材料掺杂量的关系式,求得N型InSb材料的补偿度。     

In0.4Ga0.6As/GaAs自组织量子点的光伏谱温度特性

自组织生长方法作为一种有效而直接的制备半导体量子点的方法受到重视。本文采用无需在样品上制备电极的电容耦合的光伏谱方法,实验测量了Ｉｎ０．４Ｇａ０．６Ａｓ／ＧａＡｓ自组织量子点在不同的温度下的光伏谱,对测量谱峰进行了指认,研究了量子点谱峰能量位置随温度的依赖关系,实验结果表明,量子点具有与体材料及二维体系不同的温度特性,对实验所测样品,其激子峰能量随温度增加而红移的速率约为ＧａＡｓ体材料带隙变化的１     

钒受主能级在n型4H-SiC中的深能级瞬态傅里叶谱和光致发光

借助深能级瞬态傅里叶谱研究了钒离子注入在SiC中引入的深能级陷阱.掺人的钒在4H-SiC中形成两个深受主能级,分别位于导带下0.81和1.02eVt处,其电子俘获截面分别为7.0 × 10-16和6.0×10-16cm2.对钒离子注入4H-SiC样品进行低温光致发光测量,同样发现两个电子陷阱,分别位于导带下0.80和1.6eV处.结果表明,在n型4H-SiC掺入杂质钒可以同时形成两个深的钒受主能级,分别位于导带下0.8±0.01和1.1±0.08eV处.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.