| As a new type ultraviolet (UV) photocathode, negative electron affinity (NEA) gallium nitride (GaN)/gallium aluminium nitride(GaAlN) photocathode has many good performance characteristics, such as high quantum efficiency, low dark current and concentrated electron energy distribution and so on.GaN/GaAIN photocathode has important application in many fields, such as military, space astronomy, UV communication, environmental monitoring, industrial production and so on.The researches were made on such aspects as photoelectric characteristics test and evaluation for transmission-mode GaN/GaAIN photocathode material and component.Through this research, innovative research result is following:(1) For our country, there has been no test and evaluation of the photoelectric characteristics of transmission-mode GaN/GaAIN photocathode material, which is growing on sapphire substrate with 0.5mm thickness, had been conducted. Based on this work, test methods for material structureã€optics and electrics properties about transmission-mode GaN/GaAIN photocathode materials were developed. These methods involve High Resolution X-Ray Diffractometer(HRXRD), Atomic Force Microscope(AFM), transmissivity, reflectivity, photoluminescence, and the like.The rationality of test method was validated by analysis.The results are important reference data for the further development and application of the said photocathode material.(2) Test methods and evaluation means of the optical properties for transmission-mode GaN/GaAIN photocathode component were introduced. Transmission-mode GaN/GaAIN photocathode was made from growing directly GaAIN epitaxial layer on 1.5mm thickness sapphire substrate. The components qualities and optical property of the photocathode had been characterized and the effective measure methods were also developed. Based these methods, the properties of transmittance, reflectivity, doping concentration, minority carrier diffusion length were studied. The results are important reference data for the structure design and materials growth of photocathode.(3) Test methods and evaluation means of the surface condition for transmission-mode GaN/GaAIN photocathode component were introduced. The surface condition of the diffirent stages (the surface cleaned by the semiconductor wahing liquid, corroded by the H2SO4/H2O2 solution and high temperature annealing of the photocathode) are characterized and compared.With these results,we evaluated the effection of the chemical treatment and validated the qualities of material production and the stabilities of GaN/GaAIN on the technical process.This achievement could be used to conduct the designs and technics of Transmission-mode GaN/GaAIN photocathode structure, and provide the technical surports of the formation of NEA. |
