Research on quantum efficiency of GaN monolayer reflection-mode photocathode with atomically ultra-thin emission layer

Abstract

The excitonic effects of GaN will be enhanced by quantum confinement effect when it has only an atomic layer, which can greatly enhance strength of electron–hole interaction and lead to a higher carrier concentration, so GaN monolayer can be used to prepare photocathode to achieve higher quantum efficiency. In this paper, we put forward GaN monolayer reflection-mode photocathode Considering electrons generated both in buffer layer and each GaN monolayer, we propose a revised quantum efficiency (QE) formula for ultra-thin GaN ML photocathode. And based on the quantum efficiency formula, back interface recombination rate, surface escape probability and surface reflectivity are simulated when emission layer is 1 ML GaN. Furthermore, we also simulate back interface recombination rate, recombination rate of the GaN ML/GaN ML interface and number of GaN monolayers when emission layer are few GaN monolayers. The simulated results show that the number of monolayer can affect QE of GaN ML photocathode, and QE would depend largely on back interface recombination rate and recombination rate of the GaN ML/GaN ML interface. Our simulation results are expected to provide theoretical guidance for the preparation of GaN photocathodes with a certain number of GaN ML as emission layers.