具有e指数内建电场的透射式GaAs光电阴极响应特性的理论分析

设计了具有e指数内建电场的透射式GaAs负电子亲和势阴极，利用数值计算方法研究了它的时间响应特性和量子效率特性。结果表明，当吸收区厚度L~0.2~1.5 μm时，阴极的响应时间和量子效率均随L的增大而增大；尤其当L~1.1 μm时响应时间达到10 ps，量子效率达到12.5%~20%，迄今为止，与其他GaAs光电阴极相比，在相同光谱响应条件下，该响应速度是最高的。另外，在不同L下，获得了平均时间衰减常数τ'的函数分布和能够获得最短响应时间的最优系数因子β分布，为新型高速响应GaAs光电阴极的时间响应和量子效率优化提供了必要的理论基础和数据支持。

Theoretical Study of Response Characteristics of Transmission-mode GaAs Photocathodes with Exponential Inner Electric Field

A new-type transmission-mode NEA GaAs photocathode with the exponential built-in electric field was designed. The two important features of the new-type GaAs photocathode, the time response and the quantum yield, were theoretically studied by numerical methods. The simulation results show that the response time and the quantum yield of the new-type photocathode gradually increase with the widths of absorption layer when the widths are 0.2-1.5 μm. Especially, when the width is 1.1 μm, the time responses are 10 ps, and the quantum yield is 12.5%-20%. So far, compare with previous GaAs photocathodes with other doping modes, this one has the shortest response time in the same condition of the spectral responses. Meanwhile, the two functions of the average decay time and optimal factor of the built-in electric field are obtained under different widths of absorption layers, the former is related to time responses, and under the latter condition the shortest response times are obtained. The above results provide the theoretical and data basis for the design to optimize new-type GaAs photocathodes with ultrafast response.