Abstract

The ternary nitride alloy InxGa1-xN, characterized by tunable band gap, can be used in photoelectric devices to achieve a wide spectrum response of UV-infrared light. A complete photoemission theoretical model of reflective InxGa1-xN thin film vacuum photocathode is established based on the “Spicer's model” and “Andachi model”. The simulation experiment of InxGa1-xN thin film photocathode is constructed by COMSOL Multiphysics software based on the finite element method. By analyzing the optical absorption and the distribution of photogenerated carrier concentration of photocathode, it is found that the photoconversion performance of photocathode can be enhanced by optimizing the thickness of emission layer and the angle of polarized light. The peak quantum efficiency and peak spectral responsivity of In0.5Ga0.5N photocathode with a thickness of 400 nm are 63.13% and 240.83 mA/W, respectively. The quantum efficiency of In0.5Ga0.5N photocathode with an incidence angle of 50° of TM mode polarized light can be increased to 65.99% compared with that with normal incidence. Therefore, the simulation results of this paper can provide reference for the design of wide spectrum photodetectors and vacuum electron sources.

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