Comparative study of AlxGa1-xAs/GaAs photocathodes with different aluminum concentrations by surface photovoltage spectroscopy

摘要

The influence of aluminum concentration in an AlxGa1-xAs window layer on the performance of AlxGa1-xAs/GaAs photocathodes was investigated. Three types of transmission-mode photocathode materials with different aluminum concentrations were designed for the comparative research. The surface photovoltage technique was applied to prepare samples. After the Cs-O activation process, spectral response curves of AlxGa1-xAs/GaAs photocathodes were obtained. Comparative studies show that a higher aluminum composition in the window layer is beneficial to improve the response of AlxGa1-xAs/GaAs photocathodes in the short-wave region. The surface photovoltage calculation formula of photocathode materials was put forward and used to obtain key performance parameters of AlxGa1-xAs/GaAs photocathodes by fitting calculations. Through calculations, the AlxGa1-xAs/GaAs interface recombination velocity, the minority carrier diffusion length of the window layer, and the emission layer were deduced, and there is a positive correlation between the aluminum composition in the window layer and the AlxGa1-xAs/GaAs interface recombination velocity, which is negative with the performance of photocathodes. (C) 2015 Optical Society of America