将In0.53Ga0.47As吸收层设计为多个薄层, 通过不同浓度掺杂实现吸收层杂质指数分布, 建立了InP/In0.53Ga0.47As/InP红外光电阴极模型, 在皮秒级响应时间的前提下模拟了吸收层厚度、掺杂浓度和阴极外置偏压对阴极内量子效率的影响, 给出了光电子在吸收层和发射层的一维连续性方程和边界条件, 计算了光电子克服激活层势垒发射到真空中的几率, 进而获得阴极外量子效率随上述三个因素的变化规律, 结果表明, 吸收层掺杂浓度在1015~1018 cm-3范围内变化时, 内量子效率变化很小; 随着吸收层厚度在0.09~0.81 μm内增大, 内量子效率随之增大; 随着外置偏压升高, 内量子效率先增大后趋于平稳。文中给出一组既能获得高量子效率又能有快时间响应的阴极设计参数, 理论上1.55 μm入射光可以获得8.4%的外量子效率, 此时响应时间为49 ps。

An InP/In0.53Ga0.47As/InP infrared photocathode model was established. The In0.53Ga0.47As absorber layer was designed as a multi-layer structure, the impurities of it were exponentially distributed by doping with different concentrations of the thin layers. The one-dimensional continuity equations and boundary conditions of the photoelectron in the absorber layer and the emissive layer were given and the probability that photoelectrons overcome the launch of the active layer barrier into the vacuum was calculated. The effects of absorber layer thickness, doping concentration and cathode bias voltage on the internal quantum efficiency of the cathode was simulated under the condition of picosecond response time, and then the law of the external quantum yield of the cathode was obtained with the above three factors. The results show that, when the doping concentration of the absorber layer changes within the range of 1015-1018 cm-3, The internal quantum efficiency change is very small; as the thickness of the absorber layer increases within 0.09-0.81 μm, the internal quantum efficiency increases. As the external bias voltage increases, the internal quantum efficiency increases first and then tends to be stable. A set of cathode design parameters that could achieve both high quantum efficiency and fast time response were presented. Theoretically, an external quantum yield of 8.4% can be obtained for 1.55 μm incident light, and the response time is 49 ps.