透射式蓝延伸GaAs光电阴极的光电发射特性研究

Photoemission Characteristic of Transmission-Mode Extended Blue GaAs Photocathodes

利用计算光学性能、量子效率和积分灵敏度的理论模型,分别研究比较了我国和ITT典型透射式蓝延伸GaAs光阴极的光电发射特性,包括阴极的光学性质和性能参数。结果表明我国的透射式蓝延伸光阴极积分灵敏度已经达到2 100μA.lm-1,但与ITT的2 750μA.lm-1相比还存在一定的差距。分析的主要原因是一方面是GaAlAs窗口层的厚度和Al组分大小对于短波响应,特别是对蓝延伸起着决定的作用;另一方面阴极性能参数电子扩散长度和后界面复合速率的大小对长波响应和短波响应也有着重要的影响,这些因素都受制于基础工业制造水平的落后。

Based on the theoretical models of computing the photocathode optical performance,quantum yield and integral sensitivity,the photoemission characteristics of the domestic and ITT＇s transmission-mode extended blue GaAs photocathodes,namely the cathode optical properties and performance parameters,were respectively investigated.The compared results show that the integral sensitivity of the domestic transmission-mode extended blue photocathode has achieved 2 100 μA·lm-1,still falling behind the ITT＇s integral sensitivity of 2 750 μA·lm-1.The reasons for the difference in quantum yield curves are that,on one hand,the thickness of GaAlAs window-layer and the Al mole fraction play a critical role in the short-wavelength response,especially in the extended blue region.On the other hand,the cathode performance parameters such as electron diffusion length and back interface recombination velocity work on the long-wavelength and short-wavelength response.All these factors are subject to the backwardness of basic industrial manufacturing level.