Improvement of quantum efficiency of field-assisted GaN monolayer photocathode

Abstract

In this paper, in order to explore quantum efficiency of field-assisted GaN monolayer photocathode, uniform-doping and exponential-doping reflection-mode GaN monolayer photocathode model with an external electric field have been established, and quantum efficiency formulas have been derived. We simulate the quantum efficiency of photocathode with uniform-doping and exponential-doping structure under different external electric fields, number of monolayers in emission layer, thickness of buffer layer and interface recombination velocity. The results show that quantum efficiency enhances with increase of external electric field. As the thickness of emission layer increases, the quantum efficiency decline, while as the thickness of buffer layer increases, the quantum efficiency improves. At the same time, an appropriate interface recombination velocity can improve the quantum efficiency of photocathode. When back surface recombination velocity and GaN ML/GaN ML interface recombination velocity are 8 × 106 cm/s and 108 cm/s, respectively, the optimal quantum efficiency can be obtained.