To optimize the structure design and preparation technology of NEA GaN photocathode, considering the cathode quantum efficiency formula and the factors that influence the quantum efficiency, the surface reflectivity, optical refractive index, spectral absorption coefficient and transmission spectra of GaN photocathode material were studied theoretically and experimentally. As a direct influencing factor of the quantum efficiency, the surface reflectivity is relatively steady in the waveband from 250 nm to 365 nm. The optical refractive index influences the quantum efficiency indirectly by the electronic surface escape probability. The characteristics of uniform doping GaN photocathode spectral absorption coefficient were given. According to the structure characteristics of variable doping NEA GaN photocathode, the concept of spectrum average absorption coefficient and the equivalent formula were given. The spectral absorption coefficients of the uniform doping and the variable doping of NEA GaN photocathode were compared.%针对NEA GaN光电阴极结构设计和制备工艺需进一步优化的问题,结合阴极量子效率表达式和影响量子效率的因素,采用理论和实验相结合的方法,分别研究了GaN光电阴极材料的表面反射率、光学折射率、光谱吸收系数以及透射光谱等光学参数.结果表明在250 nm到365 nm的波长范围内,表面反射率相对平稳,是影响量子效率的直接因素,而光学折射率则通过电子表面逸出几率间接影响着量子效率.给出了均匀掺杂GaN光电阴极的光谱吸收系数的特点,根据变掺杂NEA GaN光电阴极的结构特点,给出了光谱平均吸收系数的概念和等价计算公式,并对均匀掺杂与变掺杂NEA GaN光电阴极光谱吸收系数进行了对比.
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