AlGaAs:Si中与DX中心有关的光生电子陷阱特性研究(英文)

A new electron trap state SD was found by DLTS measurement under light illumination in Si doped A.lxGa1-xAs. This new trap energy level ESD is shallower than the DX center energy in the gap and the concentration of SD is comparable to that of DX centers. The emission activation energy Ec=0.20±0.05eV and capture activation energy Ec= 0.17±0.05eV. The SD DLTS peak has never been detected previously because under dark and thermal equilibrium condition most of the electrons occupy the deeper DX states and most of SD states are empty. However, when the sample is illuminated by light, electrons are excited to the conduction band and then re-captured by SD since the deeper DX states have a slower electron capture rate, thus a new DLTS peak corresponding to SD appears. Constant temperature capacitance transient C-t and transient C-V measurements were also used to further confirm the existence of SD states.     

关于AlGaAs:Si中DX中心的新观点

本文给出DX中心为负U中心时所满足的统计规律。指出它与大量AlGaAs:Si的Hall实验不定量符合。为此我们提出,Si可能形成二种不同的施主NU和SD。NU是产生DX能级的负U中心。SD只形成浅施主能级或电激活中心。两种中心的浓度N~(NU)和N~(SD)可以比拟。且N~(SD)/N~(NU)随Si浓度增加而增加。SD中心作为一种电子源,向NU输送电子,放宽了费米能级钉扎于DX能级的条件,从而与Hall实验相符。并用此观点重新解释了过去的种种实验。     

瞬态C-V方法对Al_xGa_(1-x)As中DX中心的研究

本文指出DX中心电容测量中边区的重要性,提出一种新的瞬态C-V方法,可以用来测量DX中心浓度、导带电子浓度和边区的空间电荷分布及导带电子浓度随温度的变化关系,并由此导出测量DX中心热电离能的方法。另外,还对DX中心正∪和负∪两种模型的理论分析和实验结果进行了比较,得出不同模型所应满足的附加条件。     

Al_(0.35)Ga_(0.65)As中DX中心的俘获激活能(英文)

The capture, spectra in LPE-Ga0.35Al0.65As were studied. Two peaks of DX center is the capture spectra were obtained by a pulse with suitable duration, although there was one peak only in the emission spectra. It was possible thnt there were two deep levels about the different captures cross section and mar the emission rate. The unusual results of an emission activation energy of 0.31eV and a capture activation energy of 0.42eV were determined in the sample with NDX/Ns-1.7. Nonexponential single shot transient capacitance curves were imitated theoretically by using emission and capture equations for the high concentration of deep levels and by considering spreading factor of DX centers. Experimental curves were consistent with theoretical curves. The spreading factor of barrier was 40meV. Emission and capture activation energy were determined to be 0.3leV and 0.18eV, respectively.     

用C-V法同时测量半导体中深中心和浅杂质的浓度分布

测量半导体深中心浓度分布和测量浅杂质浓度分布一样,是一个十分重要的问题.本文提出用C-V 法同时确定半导体中深中心和浅杂质浓度分布的方法,在深中心浓度和浅杂质浓度可比的情况下,它的结果尤为精确.文中讨论了测试原理和测试方法并以掺金硅N~+-P结二极管和汽相外延N型砷化镓肖脱基二极管为例进行了测量.     

Al_x Ga_(1-x)As中DX中心的研究进展

<正> (一)DX中心与能带结构的关系 原来Lang等认为DX中心是AlxGa1-xAs中施主杂质与空位形成的络合物。奇怪的是它的浓度与Al的成分x有关。最近的实验彻底澄清了这个问题。因为AlxGa1-xAs能带结构随x的变化,与GaAs能带结构随压力p的变化相似,如果DX中心与能带结构有关,改变压力p与改变组分x应有相似效果。Mizuta等首先发现,对GaAs加压力到20多kbar时,DLTS测量出现一个峰。他们认为这个就是DX中心对应的峰。李名复等的进一步研究证实它     

Si(100)表面的TCS研究(英文)

Total current spectroscopy (TCS) is a newly developed method in detecting electronic properties of solid surfaces. In this work, a chemically cleaned Si(100) wafer was cleaned and annealed "by heating the sample up to about 850℃ in a UHV chamber with a pressure less than 1×10-7pa then the surface appeared a sharp 2×1 LEED pattern.In the TCS spectra both on cleaned and uncleaned surfaces, four peaks labeled A, B, C aad D appeared in 3.5, 6.4, 9.3, and 13.5eV, respectively, with respect to vacuum level. Among them peaks A,C,D remain unchanged while peak B is quite sensitive to gas absorption and the surface temperature, mainly by changing its intensity. The phenomena are explained by assuming that inelastic scattering of incident eletrons dominates the process. Peaks A,C, D were caused by interband transitions and peak B was attributed to the surface state. Further studies are in consideration.     

AlGaAs/GaAs太阳电池抗辐照性能的研究(英文)

The changes of performence of AlGaAs/GaAs heteroface solar cell after 1 -MeV electron irradiation has been studied by the experimental and numerical fitting. Using an improved damped least square method, the spectral response and dark J-V characteristic of the cells are fitted according to the various theoretical formulas. From the fitting calculation, a number of materials, structural and electric parameters of the cell are obtained. The experimental data and calculated results show that the critical irradiation flux of the cell is about 2.2×1014 cm-2, the damge constant KL for the minority carrier diffusion length in n-GaAs layer due to irradiation is found to be larger than that in p-GaAs, layer, they are about 7.0×10-3 and 2.2×10-7, respectively, the degradation of the minority carrier diffusion length in p-GaAs layer and the increase in the recombination velocity at interfaec are the majar reasons for the cell performence degradation. The cell with a shallow junction has higher irradiation resistance than the one with a deep junction. Based on the studies, the method for improving the irradiation resistance of the cell is discussed.     

Ce热引入Si单晶中及Ce在Si中的扩散系数(英文)

Ce has been introduced into the Si single crystal by means of vacuum deposition of Ce onto a Si wafer and then annealing at 1050℃ for 20 hours in vacuum.In the annealing process, Ce-Si alloy was formed on the surface at first, then Ce atoms were diffused into Si and produced a diffusion region with thickness about 4.5μm. The concentration profile of Ce was dedermined by SIMS. The diffusion coefficient of Ce in Si at 1050℃ was obtained as 3.9×10-13 cm2/s while the average resistivity P of the Ce diffusion layer was measured from 77K to 450K.     

利用瞬态热栅法测定固体材料的热扩散率

实验采用两束脉冲激光干涉形成瞬态热栅的方法，测量了半导体、金属和合金等固体材料的热扩散率。将实验测定值、理论预计值及公认值进行了比较，并对比较的结果进行了分析讨论，说明瞬态热栅法是定征固体热学性质及结构的灵敏且有效的方法。此外，在实验过程中还检测到固体材料表面附近空气中存在的界面波。     

微分C—V法和C—V法测量硅外延层杂质纵向分布的指数模型

提出了n/n~+或p/p~+硅外延层电荷密度ρ随x~(n-2)方式变化的正、负指数分布模型。导出了微分C—V法和C—V法杂质浓度纵向分布公式;也导出了两方法的耗尽层宽度公式。引入了n参数[logC—log(V_p—V)直线的斜率负倒数],可免去ASTMF419和SJl551—79逐点测量的麻烦,并使数据处理更为精确。还给出了硅外延层中杂质浓度纵向分布的规律。     

红外热像及比色测温技术在RH炉钢水温度检测中的应用

基于红外热像及比色测温技术的钢水温度检测可避免钢渣、钢水液面镜面效应等造成的测量误差。通过对红外热像的灰度分布特性、波动规律等的分析测算正向辐射概率,确定最佳采样区域,从而准确获取钢水温度。给出温度变化曲线,提高钢水温度数据测量的准确性和连续性,有利于精密炼钢的实现。     

Determination of carrier lifetime in Si by optical modulation

A contactless optical modulation technique for the determination of photogenerated carrier lifetime in silicon is presented. The method is based on the measurement of the optically modulated free-carrier absorption in Si at 10.6 µm. The fractional change in transmitted intensity of a dc below band-gap probe beam (with ħω_{p}<E_{g}) due to a modulated pump beam (with ħω_{p} > E_{g}) is proportional to the excess carrier lifetime. This optical modulation technique, which is relatively simple, contactless, and nondestructive, may have significant potential as a high-resolution high-sensitivity tool for Si wafer screening, crystal growth studies, and process evaluation.     

高能粒子辐射直拉硅中辐照缺陷的控制

受高能粒子辐射,在直拉硅中会产生各种辐照缺陷,对硅及硅基器件的性能产生不利的影响,对辐照缺陷的控制可以增加硅的辐照稳定性。     

Measurement of Deep Energy Level in InP：Fe by the Method of OTCS

We have measured the deep energy level of the InP:Fe which is semi -insulator through the method of OTCS.The effect of light intensity on OTCS measurement is mainly discussed. There are electron trap of ET=0.034 eV and hole trap of ET=1.13 eVin InP:Fe under the strong light and low temperature .The location of the OTCS peak of electron trap(ET=0.34 eV)moves towards the direction of high temperaturer,when the light intensity was increased,ET is different under different light intensity .It is corrected in terms of theory that the stuff ratio of the deep energy level is affected by the light intensity. The experiments show that the error is decreased greatly with the correction.