Photoemission properties of triple-layer GaInAsSb heterojunction nanopillar array for infrared photocathode

The energy band structure of the heterojunction significantly affects the photoemission efficiency of the heterojunction nanopillar arrays negative electron affinity photocathode. To investigate the effect of different types of energy bands on the photoelectric emission characteristics of heterojunction nanopillar arrays (NPAs), a model of GaInAsSb heterojunction NPAs with a triple-layer component material is proposed in this work, and its optical and carrier distribution properties are investigated by the finite difference time domain method, and its emission efficiency is further calculated. Calculated results show that the stairs type energy band structure has a stronger photoelectric emission capability and the QE of the nanopillar array can reach more than 8% when the height of the bottom sublayer is higher. An external electric field similarly enhances the photoelectric emission from the top surface of the nanopillar arrays, but too high an electric field can breakdown the device and form fieldinduced emission. This study confirms the application value of heterojunction photocathodes and is instructive for the preparation of infrared photocathodes with high efficiency.