指数掺杂反射式GaAlAs和GaAs光电阴极比较研究

采用指数掺杂技术, 通过金属有机化学气相沉积法外延生长了反射式GaAlAs和GaAs光电阴极, GaAlAs发射层的Al组分设计为0.63. 在超高真空系统中分别对两种阴极进行激活实验, 得到激活后的光谱响应曲线. 利用指数掺杂反射式光电阴极量子效率公式对实验曲线进行拟合并分析了电子漂移扩散长度、后界面复合速率、表面电子逸出几率等性能参数对光电发射性能的影响. 结果表明, 与GaAs光电阴极相比, GaAlAs光电阴极的Al组分虽然在一定程度上不利于光电发射, 但是解决了GaAs光电阴极由于响应波段宽而不能很好地用于窄波段可见光探测领域的问题, 制备出只对蓝绿光响应的反射式GaAlAs光电阴极.

Comparison between exponential-doping reflection-mode GaAlAs and GaAs photocathodes

A reflection-mode GaAlAs photocathode and a reflection-mode GaAs photocathode using exponential-doping technique are prepared by metal organic chemical vapor deposition, and the Al content of GaAlAs emission layer is 0.63. The two photocathodes are activated in an ultra-high vacuum system, and the spectral response curves are measured after activation. The quantum efficiency formula for exponential-doping reflection-mode photocathode is used to fit the experimental curves of the two photocathodes respectively, and the effects of some performance parameters on photoemission are analyzed, such as electron diffusion and drift length, back-interface recombination velocity, surface electron escape probability, etc. The results show that the Al content of the GaAlAs photocathode plays a bad role in the photoemission compared with that the GaAs photocathode, but it solves the problem that the GaAs photocathode cannot be well used in the area of detecting the narrow wavelength light due to the broad spectral response. The reflection-mode GaAlAs photocathode prepared is responsive to the blue and green light.