蓝延伸指数掺杂GaAlAs/GaAs光电阴极制备及其理论研究

Modern low-light-level night vision device is developed toward the features of high sensitivity and broadband spectral response, and the ability of detection, recognition and identification of targets in the desert terrain or marine environment is to be strengthened, therefore, the response in the blue-green waveband region serving as a transparent window should be improved. In this project, we will investigate the preparation and photoemission theory of blue-extended exponential-doping GaAlAs/GaAs photocathodes. Firstly, a proper and reasonable quantum efficiency model of the blue-extended exponential-doping GaAlAs/GaAs photocathode will be established. Then the structure of the blue-extended exponential-doping GaAlAs/GaAs photocathode will be optimized through overall consideration of band structure, optical property and quantum efficiency etc. Lastly, by the aid of cathode materials characterization and activation experiment, the discrepancy in the preparation craft and photoemission performance of the blue-extended exponential-doping GaAlAs/GaAs photocathodes grown by MOCVD and MBE will be investigated. Based on the above research results, we will provide theoretical guidance and experimental basis for the improvement of blue-extended effect of transmission-mode GaAlAs/GaAs photocathodes. Blue-extended exponential-doping GaAlAs/GaAs photocathodes have great potential for applications in the fields of marine exploration, high-energy physics and astronomy observations etc.

现代微光夜视器件正朝着高灵敏度、宽光谱响应的方向发展，为了提高微光夜视器件在沙漠地带或者海洋环境中景物的探测、识别和确认的能力，有必要进一步提高光电阴极在蓝绿光波段透光窗口的响应。本项目拟开展蓝延伸指数掺杂GaAlAs/GaAs光电阴极制备及其理论研究，通过建立正确合理的蓝延伸指数掺杂GaAlAs/GaAs光电阴极量子效率模型，从能带结构、光学性能、量子效率等多方面综合考虑优化设计蓝延伸指数掺杂GaAlAs/GaAs光电阴极结构，再通过材料性能表征和阴极激活实验比较MOCVD和MBE生长的蓝延伸指数掺杂GaAlAs/GaAs光电阴极制备工艺和光电发射性能的差异，从而为提高透射式GaAlAs/GaAs光电阴极的蓝延伸效果提供理论指导和实验依据。蓝延伸指数掺杂GaAlAs/GaAs光电阴极在海洋探测、高能物理、天文观测等领域具有很好的应用前景。

为了提高微光夜视器件在沙漠地带或者海洋环境中景物的探测、识别和确认能力，有必要研制蓝延伸的GaAlAs/GaAs光电阴极，使其光谱响应向短波长延伸。鉴于蓝延伸GaAlAs/GaAs光电阴极在海洋探测、高能物理、天文观测等领域具有很好的应用前景，本项目针对蓝延伸GaAlAs/GaAs光电阴极制备及理论进行了以下研究：建立了考虑GaAs层内建电场和GaAlAs层光电子的贡献作用的指数掺杂GaAlAs/GaAs光电阴极量子效率模型及光学性质计算模型，研究了阴极厚度和Al组分对阴极量子效率和光学性质的影响；建立了考虑二级电场作用的变组分指数掺杂GaAlAs/GaAs光电阴极量子效率模型及光学性质模型，分析了变组分指数掺杂结构对蓝延伸效果的作用，比较和分析了阴极相关性能参量对透射式变组分变掺杂GaAlAs/GaAs光电阴极光学性能的影响；编写了变组分变掺杂GaAlAs/GaAs光电阴极组件结构设计软件，实现了阴极组件结构的合理设计；建立了变组分变掺杂透射式GaAlAs/GaAs光电阴极的分辨力模型，分析了光电阴极内部电子输运情况；通过ECV、SEM测试对设计生长的变组分变掺杂GaAlAs/GaAs光电阴极进行了质量评估，优化了阴极结构；进行了GaAlAs/GaAs光电阴极的净化实验，确定了最佳化学清洗方法以及加热净化温度；通过一系列激活实验，验证了国产氧源满足GaAlAs/GaAs光电阴极激活要求，发现了激活过程中提高阴极量子效率和稳定性所需的光照条件和激活方法。目前研制的蓝延伸透射式光电阴极的最高灵敏度超过了2000μA/lm，在532nm和400nm处量子效率分别达到了30%和3%。本项目研究成果为进一步设计和制备高性能蓝延伸GaAlAs/GaAs光电阴极提供了理论指导和实验依据。