Theoretical exploration of quantum efficiency ofAlxGa1 −xNmonolayer photocathode with varying Al contents and ultra‐thin emission layer

To obtain high-efficiency AlGaN monolayer photocathode, the quantum efficiency formulas of reflection-mode and transmission-mode AlxGa1 − xN monolayer photocathode with varying Al contents and ultra-thin emission layer are derived in this article. Based on the formulas, we have simulated quantum efficiency of AlxGa1 − xN monolayer photocathode under different conditions. The results reveal that built-in electric field caused by varying Al contents can significantly promote quantum efficiency of photocathode. If difference in Al contents between adjacent AlxGa1 − xN monolayer enlarges, quantum efficiency will decrease. At the same time, built-in electric field also plays a great impact in stabilizing quantum efficiency and photoelectric emission performance of AlxGa1 − xN monolayer photocathode. The ideal quantum efficiency and photoelectric emission performance can be obtained when buffer layer thickness is about 50 to 75 nm. In addition, when emission layer is composed of a larger number of AlxGa1 − xN monolayers with varying Al contents, the more number of monolayers with high Al contents are, the higher the quantum efficiency is. This study can give useful help for design and preparation of AlxGa1 − xN monolayer photocathodes with varying Al contents.