Enhanced blue-green response of nanoarray AlGaAs photocathodes for underwater low-light detection

• DOI: 10.1364/oe.495599
• Publication Date: 2023-07-13T12:00:07Z
• Authors: Shiman Li; Yijun Zhang; Ziheng Wang; Dongzhi Wang; Song Tang; Junju Zhang; Feng Shi; Gangcheng Jiao; Hongchang Cheng; Guanghui Hao
• Keywords: Green-light

Underwater optical communication and low-light detection are usually realized via blue-green laser sources light-sensitive detectors. Negative-electron-affinity AlGaAs photocathode is an ideal photosensitive material for ocean exploration due to its adjustable spectrum range, long working lifetime, easy epitaxy of materials. However, compared with other photocathodes, the main problem low quantum efficiency. Based on Spicer’s three-step photoemission model, nanoarray structures designed surface improve efficiency from two aspects absorption photoelectron transport. Through simulation, it concluded that cylinder diameter 120 nm height 600 best structure, absorptance always greater than 90% in 445∼532 range. Moreover, less affected by incident angle. When angle light reaches 70°, minimum still 64.6% 24.9%. In addition, square or hexagonal arrangement pattern has little effect absorptance, however, a reduction overall emission layer thickness will decrease near 532 nm.