中文摘要：

通过求解扩散方程，推导了含有后界面复合速率的反射式GaAs光电阴极量子效率公式，并利用MBE在GaAS（100）衬底上外延生长了发射层厚度分别为1．6μm、2．0μm和2．6μm，掺杂浓度为1×10^19cm^-3的三个反射式GaAs阴极样品，进行了激活实验．实验结果显示：随着发射层厚度的增加，阴极的长波量子效率和灵敏度都有所提高，而这种提高与阴极电子扩散长度的增长有关．同时，理论仿真研究发现．当后界面复合速率小于或等于10^8cm／s时，阴极发射层有一个最佳厚度，此时阴极灵敏度最高．后界面复合速率对阴极灵敏度在发射层厚度较小时影响较大．而随着厚度的增大阴极灵敏度最终趋于稳定．

英文摘要：

The quantum-efficiency equation of the reflection-mode GaAs photocathode with back-interface recombination velocity is solved from the diffusion equation. Three reflection-mode cathode materials are grown on a GaAs wafer （100） by molecular beam epitaxy,the active-layer thickness of which are 1.6μm, 2.0 μm and 2.6 μm, respectively,and the doping concentration is 1×10^19cm^-3. The results of activation experiments show that the quantum efficiency of long-wavelength photons and the integral sensitivity for cathodes increase with the increase in active-layer thickness, which is due to the increase of electron diffusion length. Through the theoretical simulation, it is found, as the back-interface recombination velocity is less than or equal to 105cm/s, the active-layer thickness has an optimum value in which the cathodes achieve the maximum sensitivity. The influence of recombination velocity on cathodes with a small active-layer thickness is great ,and with the increase in thickness, the sensitivity of cathodes finally tends to a stable value.