分子束外延碲镉汞薄膜中VOID缺陷的研究

HgCdTe薄膜中的Void缺陷严重影响面阵器件的有效元数。对用分子束外延法在GaAs衬底上生长的HgCdTe薄膜中的Void缺陷进行了形貌、剖面观测和能谱分析。衬底表面状况和HgCdTe生长过程中的Hg/Te束流比及衬底温度决定了Void缺陷的密度和尺寸。在比较优化的条件下，可将Void缺陷密度降到5×102cm－2以下。     

不同生长条件对CdTe/GaAs外延薄膜表面形貌和光学性质的影响

本文利用分子束外延技术在GaAs（211）B衬底上外延CdTe（211）薄膜,系统研究不同工艺条件对CdTe 外延薄膜的表面形貌和光学性质的影响。研究表明,在一定的生长温度下,在Te气氛下生长CdTe薄膜,增加CdTe：Te的束流比,可显著降低CdTe表面金字塔缺陷的尺寸和密度,当CdTe 和Te束流比为6.5时,金字塔缺陷几乎消失,材料的表面平整度显著改善,X射线衍射（XRD）也表明CdTe晶体质量显著提高。进一步的拉曼光谱表明,随着CdTe和Te束流比的增加,Te的A₁峰减弱,CdTe LO和TO声子峰强度比增强。低温光致发光光谱（PL）研究也表明随着CdTe和Te束流比的增加,Cd空位的减少可以使与杂质能级相关的深能级区域的峰强降低,与此同时和晶体质量相关的自由激子峰半峰宽减少,材料的光学质量明显改善。该研究为探索CdTe/GaAs外延材料的理想的工艺窗口以及相关机理,并为进一步以此为缓冲层外延高质量HgCdTe材料提供基础。     

HgCdTe液相外延薄膜表面缺陷的控制

研究了HgCdTe液相外延薄膜表面两类宏观缺陷的形成原因.研究表明,大部分表面凹陷点(void)缺陷的形成是由衬底的蜡沾污所引入的,而表面凸起点(hill-like)是由衬底边缘脱落的CdZnTe微颗粒造成的,通过控制外延生长前的衬底处理过程,可以抑制这两类缺陷,从而生长出零(宏观)缺陷密度的优质HgCdTe外延薄膜.     

CdZnTe(211)B衬底对MBE外延碲镉汞材料的影响分析

碲锌镉 CdZnTe（211）B 衬底广泛应用于碲镉汞（HgCdTe）分子束外延生长,其性能参数在很大程度上决定了碲镉汞分子束外延材料的质量。主要讨论了 CdZnTe（211）B 衬底几个关键性能参数对碲镉汞外延材料的影响,包括 Zn 组分及均匀性、缺陷（位错、孪晶及晶界和碲沉淀）以及表面状态（粗糙度和化学组成）,并且分析了对 CdZnTe（211）B 衬底进行筛分时各性能参数的评价方法和指标。     

HgCdTe外延材料批量化生产及其质量控制

经过多年研发,我司的碲镉汞(HgCdTe)红外焦平面探测器已达到批量生产的水平。优异性能的红外探测器离不开高质量的HgCdTe外延材料,外延材料的厚度及组分均匀性、表面缺陷的控制以及HgCdTe外延/CdZnTe衬底晶格匹配度是批量化生产中需要控制的关键性因素,红外探测器的批量化生产也给HgCdTe外延材料质量稳定性以及一致性的控制提出了更高的要求。本文介绍了HgCdTe外延材料批量化生产中这几项关键指标的控制,以及外延质量优化后红外焦平面性能的提升。Abstract:关键词:     

基于HgCdTe薄膜和GaAs／AlGaAs多量子阱的红外光电探测器列阵

俄罗斯科学院西伯利亚分院半导体物理研究所设计并制作了若干用于3μm～12μm光谱范围的光电探测器组件.这些光电探测器组件都是以用分子束外延方法生长的Hg1-xCdxTe/GaAs异质结构和GaAs/AlGaAs多量子阱结构为基础的,其HgCdTe光敏层长在带CdZnTe中间缓冲层的GaAs衬底上.为了减少表面对复合过程的影响,生长了增加表面组分的渐变带隙HgCdTe层.     

液相外延HgCdTe薄膜组分的均匀性

利用水平推舟液相外延法,以CdZnTe作为衬底,固态HgTe作为Hg补偿源,从富Te-HgCdTe溶液中外延生长大面积HgCdTe薄膜.通过选择合适的温度和生长速率,获得了组分均匀性和重复性较好的大面积长波HgCdTe薄膜.     

分子束外延HgCdTe表面缺陷研究

采用GaAs作为衬底研究了HgCdTe MBE薄膜的表面缺陷,借助SEM分析了不同缺陷的成核机制,确定了获得良好表面所需的最佳生长条件。发现HgCdTe外延生长条件、衬底表面处理等因素与外延层表面各种缺陷有关,获得的外延层表面缺陷（尺寸大于2μm）平均密度为300cm^-2,筛选合格率为65％。     

采用(211)碲锌镉衬底制备碲镉汞液相外延薄膜

文中对(211)晶向的CdZnTe衬底进行液相外延生长HgCdTe。获得的碲镉汞液相外延材料的组分为0. 30 ～0. 33,薄膜厚度为10 ～15μm,表面缺陷密度为500cm- 2 ,材料的FWHM达到24弧秒,位错腐蚀坑密度约为2 ×105 cm- 2 ,该材料的表面形貌与采用(111)晶向衬底的HgCdTe外延材料有较大区别。     

不同钝化层结构对HgCdTe热退火Hg空位调控影响

对不同钝化层结构的分子束外延（MBE）生长的HgCdTe外延材料的Hg空位浓度控制进行研究。获得了更高Hg空位浓度调控范围的外延材料,为后续新型焦平面器件的研发提供基础。研究发现,在热退火过程中,HgCdTe外延材料的Hg空位浓度的变化随着钝化层结构的不同而发生改变。且这种改变是因为HgCdTe表层的钝化层的存在改变了原始热退火的平衡态过程。同时,通过二次离子质谱（SIMS）测试以及相应的理论拟合进行了验证。     

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.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

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.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

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.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

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.     

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.