Abstract

To obtain a high resolution of the reflection-mode AlGaN photocathode by establishing the modulation transfer function (MTF) model of this photocathode, the influence 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 for varied-doping and uniform-doping Al_0.42Ga_0.58N photocathodes have been given. The computational results suggest that varied-doping structure has great potentiality in improving both resolution and quantum efficiency of the reflection-mode Al_0.42Ga_0.58N photocathode. This improvement is mainly attributed to the reduced lateral diffusion of photoelectrons, which is caused by an electric field generated by the varied-doping structure, and hence the photoelectron transportation towards photocathode surface is promoted.

© 2021 Optical Society of America

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