Feng Cheng, Zhang Yijun, Liu Jian, Qian Yunsheng, Liu Xinxin, Shi Feng, Cheng Hongchang
Appl Opt. 2017 Nov 10;56(32):9044-9049. doi: 10.1364/AO.56.009044.
The graded bandgap AlGaAs/GaAs photocathode with graded composition and exponential doping structure has shown great potential for improving photoemission capability. In order to better study the performance of transmission-mode AlGaAs/GaAs photocathode with the complex graded bandgap structure, the experimental optical properties and quantum efficiency are measured by comparison with uniform composition and exponential doping AlGaAs/GaAs photocathode. The theoretical optical properties of the multilayer AlGaAs/GaAs photocathode modules are calculated by matrix formula on the basis of thin-film optical principles. The effect of cathode thickness and aluminum proportion on optical properties are analyzed by simulation. The results show that these parameters have complicated effects on the optical properties. Different parameters are presented as the changes of peak and valley of the optical property curves. Meanwhile, the emission layer has a significant effect on the absorptivity values of the photocathode modules, which will obviously influence photoemission performance. By using the optical properties via calculation, a better fit of the experimental data with the theoretical model can be achieved, which would make reasonable guidance for further investigation of these complex graded bandgap photoemitters.
具有渐变成分和指数掺杂结构的渐变带隙AlGaAs/GaAs光电阴极在提高光发射能力方面显示出巨大潜力。为了更好地研究具有复杂渐变带隙结构的透射模式AlGaAs/GaAs光电阴极的性能，通过与均匀成分和指数掺杂的AlGaAs/GaAs光电阴极进行比较，测量了实验光学性质和量子效率。基于薄膜光学原理，利用矩阵公式计算了多层AlGaAs/GaAs光电阴极模块的理论光学性质。通过模拟分析了阴极厚度和铝比例对光学性质的影响。结果表明，这些参数对光学性质有复杂的影响。不同参数表现为光学性质曲线的峰谷变化。同时，发射层对光电阴极模块的吸收率值有显著影响，这将明显影响光发射性能。通过计算光学性质，可使实验数据与理论模型更好地拟合，这将为进一步研究这些复杂渐变带隙光发射体提供合理指导。
