Material Structure Design And Fabrication Technique Of GaN Ultraviolet Photocathode

Ultraviolet(UV) detection has important application in many fields, such as military, space astronomy, UV communication, environmental monitoring, industrial production and so on. As a UV detection material, GaN UV photocathode has been developed widely in recent years. It shows high quantum efficiency, low dark current, good stability and other advantages. UV vacuum detectors, which the core to GaN photocathode, can achieve high sensitivity and high stability UV detection in harsh physical and chemical environment.This dissertation focuses on how to obtain a high-performance GaN photocathode. The research work includes two important aspects: material structure design and fabrication technique. Firstly, the dissertation introduces the development of the GaN photocathode, and points out what contents need to explore and to research through comparing the performance differences of the GaN photocathodes. Secondly, the dissertation detailedly analyzes the influences of doping concentration, conductivity and cathode thickness on the quantum efficiency of GaN photocathode, and these parameters optimized guidelines have been established. Then, the emission layer thickness, optical properties and electrical properties of GaN photocathode material were tested and characterized. After repeated experiments, we ascertained the chemical cleaning steps, optimized heating purification process and the Cs, O activation technology of the photocathode. Finally, the comparative study of activation experiment and quantum efficiency properties was carried out among different doping concentration, variable doped structure and transmission-mode GaN photocathode material. The influences of doping concentration and photocathode thickness on GaN photocathode photoemission were experimentally investigated.