Quantitative study on the photoemission of AlGaN nanoarrays based on the three-dimensional transportation within a four-step process

Abstract

Photocathodes play a crucial role in photoelectronic imaging and vacuum electronic devices. The quantum efficiency of photocathodes, which determines their performance, can be enhanced through materials engineering. However, the quantum efficiency of conventional planar photocathodes remains consistently low, at around 25%. In this paper, we propose what we believe is a novel structure of AlGaN nanowire array to address this issue. We investigate the photoemission characteristics of the nanowire array using the "four-step" process, which takes into account optical absorption, electron transportation, electron emission, and electron collection. We compare the quantum efficiency of nanowire arrays with different structure sizes and Al components. After studying the effect of incident light at various angles on the nanowire array photocathode, we identify the optimal dimensional parameters: a height of 400∼500 nm and a wire width of 200∼300 nm. Furthermore, we improved the collection efficiency of the photocathode by introducing a built-in/external electric field, and obtained a 104.4% enhancement of the collection current with the built-in electric field, meanwhile the photocurrent was increased by 87% compared to the case without the external electric field. These findings demonstrate the potential of optimizing photocathode performance through the development of a novel model and adjustment of parameters, offering a promising approach for photocathode applications.