Numerical analysis of temporal response of a large exponential-doping transmission-mode GaAs photocathode

The theory of temporal response properties for a large exponential-doping transmission mode GaAs photocathode is discussed in detail. By the introduction of a new concept referred to as “average decay time”, the deficiency usually caused by the boundary condition in the previous calculations is effectively eliminated. The analytical results show that the response time of the new GaAs photocathode can be significantly reduced to several picoseconds in the absence of bias. In addition, the thickness of the GaAs absorption layer we obtained is much larger than that of traditional GaAs photocathodes with the same response time, which means that the novel photocathode with ultrafast time response will have higher yield, especially in near-infrared region.