水平定向凝固法合成砷化镓多晶

采用水平定向凝固法合成砷化镓多晶,定向凝固炉分为3个温区,砷单质在低温区(约630℃)升华,通过中温区后在高温区(1 250~1 255℃)与镓逐渐化合为砷化镓多晶.石英变形、砷端杂质、多晶表面氧化以及多晶尾端富镓是合成砷化镓多晶过程中易出现的宏观缺陷.通过对原料配方设计、砷蒸气压控制以及炉子降温程序设计等进行优化,成功获得了完整性好且电学性能指标优异的砷化镓多晶.多晶的迁移率在4 800~5 400cm2/(V·s),载流子浓度为1015~1016 cm-3量级,完全满足砷化镓单晶制备要求.     

n型掺杂GaAs中电子与空穴的超快弛豫特性

研究了n型重掺杂GaAs中的光生电子与空穴的超快弛豫特性.在n型重掺杂情况下,由于费米面已进入导带之中,抑制了费米面附近光激发电子的弛豫过程对泵浦探测信号的贡献,而突出了空穴弛豫在饱和吸收谱中的地位.理论计算表明空穴通过吸收光声子在～300fs时间内达到与晶格热平衡,并由此所导出的材料光学形变势常数d0=31eV.计算值与实验测量结果相符合.     

Growth of AgGaS2 single crystal by descending crucible with rotation method and observation of properties

This note reports a new procedure of polycrystalline synthesis and a new technique of single crystal growth on AgGaS₂, i.e. two-zone temperature oscillation vapor transporting and descending crucible with rotation. A single phase dense AgGaS₂ polycrystalline ingot was synthesized, and a crack-free AgGaS₂ single crystal with 15 mm in diameter and 30 mm in length was grown by the techniques mentioned above. Structure integrity of the crystal was studied by the X-ray diffraction technique. Six order X-ray spectra from the 011 face of the crystal were obtained, and an anomalous phenomenon was observed for the first time that intensity of the higher order diffraction peak is much stronger than that of the lower order diffraction peak. Etch-pits of the crystal were observed by the scanning electron microscopy (SEM).     

GaAs红外发光管芯片的表面性质

利用扫描电子显微镜观察 Ｇａ Ａｓ 外延层及 Ｉ Ｒ Ｌ Ｅ Ｄ 芯片的表面，测量了输出辐射强度随芯片表面不同形貌的变化，讨论了 Ｇａ Ａｓ 红外发光二极管外延及芯片工艺对器件光学、电学性质的影响． 结果显示，芯片表面玷污、划伤，电极磨损，使输出辐射强度降低．     

Measurement of GaAs start duration in different solution concentration using infrared images

This paper proposes a new infrared method to measure the start duration of GaAs substrate in chemical etching. When etching starts, the temperature of liquid-film will change because of heat release in the chemical reaction. As a result, the start duration of GaAs can be tested by collecting real-time in-frared thermal images in the course of temperature variation. Both theoretical analysis and experi-mental results show that the line shape liquid film of a 2-mm width is a good monitoring subject. By making use of the grey distribution change of a certain cross section of the line shape liquid film, the start duration of reaction between GaAs and H2SO4-H202-H20 is obtained. The start durations of reac-tion between GaAs substrate and H2SO4： H202： H20 （=5：1：50 and 15：3：50） solution are about 0.2 s and 0.3-0.4 s, respectively. This result and relative method will impulse the research of wet chemical etching technology of GaAs and so on.     

GaAs：Cr中深能级俘获效应对电导的影响

本文报导半绝缘GaAs:Cr的低压和低频电流振荡现象,在室温下系统地测量电流和电压关系的伏安特性,并进一步研究在红外和可见光辐照下的振荡规律,分析了深能级俘获过程对导带内电子浓度和迁移率的影响。     

Polycrystalline Silicon Gettered by Porous Silicon and Heavy Phosphorous Diffusion

The biggest barrier for photovoltaic (PV) utilization is its high cost, so the key for scale PV utilization is to further decrease the cost of solar cells. One way to improve the efficiency, and therefore lower the cost, is to increase the minority carrier lifetime by controlling the material defects. The main defects in grain boundaries of polycrystaUine silicon gettered by porous silicon and heavy phosphorous diffusion have been studied. The porous silicon was formed on the two surfaces of wafers by chemical etching. Phosphorous was then diffused into the wafers at high temperature (900℃). After the porous silicon and diffusion layers were removed, the minority carrier lifetime was measured by photo-conductor decay. The results show that the lifetime‘s minority carriers are increased greatly after such treatment.     

定量测建丝材织构反极图的斜切组合试样法

为使丝材反极图的定量测建工作得以便捷地实行,本文发展了斜切组合试样法。整个方法包括样品制备、扫测实验和供立方系丝材使用的Fortran Ⅳ电算程序。理论和实算表明:本工作为丝织构的定量研究提供了一个简便、切实可行的方法。     

注入电流对MOVPE生长GaAs薄层光透射特性的影响

本文报道MOVPE生长不掺杂GaAs薄层对线偏振光和自然光的透射特性,详细介绍注入电流对光透射特性的影响。     

掺氧多晶硅薄膜退火特性的研究

掺氧多晶硅薄膜作为钝化膜己成功地应用于半导体器件。为了适应器件制造过程中的高温热处理,有必要探讨膜的高温热退火物理效应。本文从薄膜的腐蚀速率、膜的厚度以及膜的折射率随不同退火温度的变化,显示了掺氧多晶硅薄膜经高温退火的致密效应。而从膜的红外吸收谱测量表明膜中含氧量基本不变,但Si-O键吸收峰随着退火温度的升高向高频方向移动,并且愈益接近SiO_2的红外吸收谱。由此说明高温热退火使无定形的生长层薄膜再结构为Si多晶颗粒和SiO_2。使膜中SiO_2成份随着退火温度升高也跟着增加。