传统的透射式GaAs基光电阴极由于窗口层存在短波阈值，难以实现紫外至近红外全波段响应特征，为了探索一种能够覆盖从紫外至近红外全波段响应的光电阴极，本项目根据光电阴极反射式工作模式特点，拟开展基于叠层复合结构的GaAs基光电阴极宽光谱响应增强研究，从光学吸收、能带结构、材料晶格匹配方面考虑，设计一种具有分布式布拉格反射超晶格结构、变组分变掺杂结构的反射式GaAs基光电阴极复合结构，建立综合光吸收增强和电场辅助特点的反射式GaAs基阴极光电发射模型，开展阴极材料外延生长和激活实验，优化制备工艺，从提高量子效率和增强稳定性两方面着手，研制出实现紫外至近红外宽光谱响应的反射式GaAs基光电阴极，并开展反射式原型真空光电器件研究。本项目是对高灵敏度、宽光谱响应反射式真空光电器件的一种探索。反射式叠层复合GaAs基光电阴极在微光夜视、太阳电池、高能物理、天文观测、环境监测等领域将具有广泛的应用前景。

Because of the shortwave threshold in window layer of traditional transmission-mode GaAs-based photocathode, it is difficult to achieve the broadband spectral response from ultraviolet to near-infrared. To explore a photocathode with spectral response covering the whole band from ultraviolet to near-infrared, we will investigate the enhancement of broadband spectral response for reflection-mode GaAs-based photocathode with the laminated composite structure in this project. Firstly, a laminated composite structure of reflection-mode GaAs-based photocathode with distributed Bragg reflector superlattice and graded-composition and graded-doping structure will be designed, through overall consideration of optical absorption, band structure and lattice matching. According to this structure, the photoemission model of reflection-mode GaAs-based photocathode with characteristics of the enhanced optical absorption and the assisted electric field will be established. Then, the epitaxial growth and activation experiment will be implemented, and the process of photocathode preparation will be optimized. Lastly, the reflection-mode GaAs-based photocathode with broadband spectral response from ultraviolet to near-infrared will be developed by improving the quantum efficiency and surface stability. Moreover, the research on the prototype of reflection-mode vacuum optoelectronic device will be carried out. This project is an exploration of reflection-mode vacuum optoelectronic devices with high sensitivity and broadband spectral response. The reflection-mode GaAs-based photocathodes with the laminated composite structure have great potential for applications in the fields of low-light-level night vision, solar cells, high-energy physics, astronomical observation and environmental monitoring etc.