Comparison of structure and performance between extended blue and standard transmission-mode GaAs photocathode modules

摘要

Extended blue and standard transmission-mode GaAs photocathode modules were prepared, respectively, by metal organic chemical vapor deposition. The experimental reflectivity, transmissivity, and spectral response curves were measured and compared separately. The integral sensitivities are 1980 (mu)A/lm and 2022 (mu)A/lm for both the modules. By use of the revised quantum yield formula, the experimental spectral response curves are fitted to obtain the structure parameters. The fitted results show that the Ga_(1-x)Al_(x)As window layer with varied aluminum components is beneficial to improve extended blue GaAs photocathode module. In addition, the layer-thickness and aluminum component in the window layer determine the extended blue performance, while the thickness of the GaAs active layer settles the long-waveband performance for the transmission-mode GaAs photocathode module.