Nea Gan Photocathode Photoelectric Emission Characteristic Research

Negative electron affinity(NEA) GaN photocathode has many advantages, such as high quantum efficiency, low dark current, concentrated electron energy distribution and good stability and so on. It’s widely used in ultraviolet vacuum detection and vacuum source electrons. In order to improve its photoemission property, the research of photoemission mechanism should be understand, and improve quantum efficiency is important.The systematic researches on the theory of photoemission, the photoemission mechanism and experiment of gradient-doping photocathode and the photoemissive property of different structures of GaN photocathode were carried out in this thesis. Firstly, the dissertation introduce you the development of NEA GaN photocathode and clear its research intent, deeply studied the process of photoelectron from excitation to emission, and analysed some important factors that influenced quantum efficiency of NEA GaN photocathode. Secondly, the dissertation studied the adsorbed property Cs/O on GaN(0001) surface, and used the double dipole layer model of GaN photocathode to calculate the emission electron energy distribute. Then, the dissertation studied the mechanization of gradient-doping GaN photocathode, and have experiments compared to uniform-doping GaN photocathode, also the Cs/O activation experiment of gradient-doping GaN photocathode was taken. Lastly, the comparative study of quantum efficiency properties was carried out among different structures of work mode and doping concentration. The influences of different work mode and doping concentration on GaN photocathode photoemission were experimentally investigated.