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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. 相似文献
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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. 相似文献
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(GaAl)As/GaAs质子轰击隔离条形双异质结构(DH)激光器是在(100)GaAs衬底上连续生长五层结构:n-GaAs;N-Al_(0.35)Ga_(0.65)As;p-GaAs(有源层);P-Al_(0.35)Ga_(0.65)AS和p-GaAs。p面浅扩Zn后利用质子浅轰击造成高阻隔离区,制成12微米宽的条形DH激光器。激光器管芯端面没有镀膜保护,但安装在充氮密封的可卸管壳内。 老化考验采用恒定功率(1毫瓦、2毫瓦和5毫瓦),考验环境温度分别为室温、50℃、70℃及80℃。考验结果表明,退化行为可分为快、慢两类。快退化激光器在工作期间阈电流不断显著上升,外微分量子效率迅速下降,激射时间都小于200小时。由电子束感生电流象可知,这是由于有源区内存在暗点、暗线或暗区之类的缺陷,在器件工作过程中这类缺陷不断扩大、增殖,器件很快就无法维持激射。暗点、暗线等是外延层内的位错网络缺陷。它来源于衬底原 相似文献