Effect of electron lateral diffusion in transmission -mode varied-doping Al0.37Ga0.63N photocathode on resolution

To achieve a high resolution of transmission-mode Al0.37Ga0.63N photocathode, by establishing the modulation transfer function (MTF) model of this photocathode, we have researched the effect of emission layer thickness T-e, electron diffusion length L-d, recombination velocity at back-interface V-b, and optical absorption coefficient alpha on MTF of varied-doping and uniform-doping Al0.37Ga0.63N photocathodes. The computational results indicate that the varied-doping structure has a potential in improving both resolution and quantum efficiency of transmission-mode Al0.37Ga0.63N photocathode. This improvement is mainly attributed to the reduction of electron lateral diffusion caused by an electric field which is produced by the varied-doping structure, and thus electron transport towards photocathode surface is facilitated.