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。     

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.     

MBE MD AlGaAs/GaAs调制反射谱及其与2DEG浓度的关系(英文)

The two-dimensional electron gas concentration dependence of photore-flectance of n-AlGaAs/GaAs heterostructures is reported and explained by analysing the physical process induced by photo-modulation. Comparison of the experimental results and energy level calculations based on a triangular potential well approximation shows good agreement.     

瞬态C-V法测量AlGaAs:Si中DX中心的电离能(英文)

The thermal ionization energy ET of DX centers in AlxGa1-xAs and its dependence with the value of x and the pressure are very important for estab- lishing the model of DX centers. The conventional DLTS and Hall methods used to DX center measurement have some ambiguities in theoretical analysis and experiments and the values of ET determined are different with those methods. The new constant temperature transient C-V measurement is based on the fact that at low temperature both electron capture and emission rates of DX centers are very slow. During the transient C-V measurement, change; of bias voltages and capacitance measurements are completed in a time duration much shorter than the electron capture and emission time constants, therefore the electrons occupied on the DX centers are considered to be frozen. The density of DX centers, the distribution profile of electrons on DX centers in the depletion region of a Schottky diode at a constant reverse bias, and the density of free electrons in conduction band in the bulk and their temperature dependence have been measured.     

Al_xGa_(1-x)As-GaAs多层量子阱结构的流体静压光荧光研究

本文对Al_xGa_(1-x)As-GaAs多层量子阱结构的子带间跃迁能的压力关系做了77K低温下的光荧光光谱研究.实验结果表明,未掺杂的量子阱的非本征发光主要来自缺陷的束缚激子d~ox.d~ox束缚激子态在量子阱中的压力系数(5meV/kbar)与体材料中的压力系数(2.7meV/kbar)的比较表明,在量子阱中深中心发生了浅化.通过对不同子带间跃迁能的压力关系测量给出了GaAs Γ谷相应能量点的压力系数,结果表明Γ谷并不是以同一压力系数移动的刚性球.最后测量了量子阱的发光强度随压力的变化.     

量子阱中δ掺杂的光谱特性

用δ掺杂的方法实现了Be受主在量子阱边界和阱中央的分布,并用光致发光实验证实了这种掺杂的实际效果。第一次用人为的实验方法证实了量子阱中杂质态密度分布的有关理论计算结果。     

分子束外延高性能P型GaAs单晶薄膜

用国产分子束外延设备生长出性能优良、表面平整光洁的GaAs。不掺杂的P型GaAs空穴浓度为 2-8×10~(14)cm~(-3),室温迁移率为360-400cm~2/V·s.使用国产材料,纯度为 2N5并经我们“提纯”的 Be作为 P型掺杂剂.掺 Be的 P型GaAs空穴浓度范围从1.0 × 10~(15)至6×10~(15)cm~(-3).其室温迁移率与空穴浓度的关系曲线与国外文献的经验曲线相符.当空穴浓度为1—2 ×10~(15)cm~(-3)时,室温迁移率达 400cm~2/V·s.低温(77K)迁移率为 3500—7000cm~2/V·s.在4.2K下对不同空穴浓度的P型GaAs样品进行了光荣光测量和分析.     

分子束外延反射式高能电子衍射的强度振荡采集系统及其应用

在分子束外延(MBE)设备上设计和装配了一套反射式高能电子衍射(RHEED)强度振荡的采集系统。用本系统在MBE生产GaAs和Al_xGa_(1-x)As材料时观察了RHEED强度振荡现象。并“在位”得到GaAs和Al_xGa_(1-x)As材料的生长速率和Al_xGa_(1-x)As材料的AlAs摩尔分数,即x值。     

级联布喇格声光互作用的频移与光束偏转分析

声光器件在设计和制作中,由于器件结构和功能上的需要,常采用级联形式的声光互作用。根据声光互作用的一般理论,对不同的声光互作用条件下,级联布喇格声光互作用的频移和光束偏转进行了分析。当组合两次不同的声光互作用,可以得到不同的频移和光束偏转。并指出,通过调节两声波的频率,可以使输出光波的传播方向不随声波频率的改变而变化。     

GaAs／AlGaAs多量子阱二维面阵红外探测器

本文报道１０×１６元二维面阵ＧａＡｓ／ＡｌＧａＡｓ多量子阱红外探测器的研究进展．通过表面光栅耦合，采用垂直入射的工作模式，在Ｔ＝８０Ｋ时探测率为２．９e１０ｃｍ·Ｈｚ（１／２）／Ｗ，电压响应率为１．３e４Ｖ／Ｗ．各测试单元间探测率和电压响应率的偏差小于１８％，串音小于０．４５％，在最大探测率偏置条件下，器件的暗电流密度为６．２e－）Ａ／ｃｍ２．