Enhancement of near-infrared response for GaAs-based photocathode with laminated graded-bandgap structure: theory and experiment

• DOI: 10.1016/j.jmrt.2022.05.099
• Publication Date: 2022-05-21T05:26:56Z
• Authors: Ziheng Wang; Yijun Zhang; Shiman Li; Shan Li; Jingjing Zhan; Yunsheng Qian; Feng Shi; Hongchang Cheng; Gangcheng Jiao; Yugang Zeng
• Keywords: Photocathode; Quantum Efficiency; Molar absorptivity; Reflection

To enhance the quantum efficiency of GaAs-based photocathode in near-infrared range, a laminated graded-bandgap structure consisting distributed Bragg reflection layer and emission is proposed. The theoretical optical properties this proposed are simulated based on finite-different time-domain method one-dimensional continuity equations, respectively. absorptivity at 1064 nm can be significantly increased for new-type because secondary absorption caused by layer. With improvement nm, specific wavelength enhanced significantly. contribution DBR built-in electric field to investigated According design, cathode samples grown epitaxial technique prepared verify prediction enhancement. After treatment surface cleaning Cs/NF3 activation, experimental results show that minimum reflectivity realized, sample with ten times than without nm. This research provides guidance design novel structures response special wavelength.