Comparative study of cesium adsorption on GaN planar and nanowire photocathodes

Abstract

Using first-principle calculations, we compare the quantum efficiency and stability of Cs-GaN planar model and Cs-GaN nanowire model. The results show that the work function of GaN nanowire photocathodes decreases continuously with the increase of θCs, the “Cs-kill” phenomenon disappears, resulting in a lower work function (1.76 eV) than the conventional GaN planar photocathodes (1.82 eV). However, we find that the nanowire GaN photocathodes had a lower stability by calculating the adsorption energy. In addition, the surface atomic structures of both kinds of photocathodes are almost identical, which account for the similarity of their best adsorption sites. Our study is helpful to the growth of GaN nanowire materials in the future and can be used to guide the improvements of GaN-based equipment photoelectric efficiency.