铟封前后透射式GaAs光电阴极光谱响应特性的测试与分析

利用自行研制的光谱响应测试仪工程化样机,对透射式GaAs光电阴极在高温激活结束、低温激活结束以及铟封成管后的光谱响应特性进行了测试。结果显示,铟封后阴极整个响应波段的光谱响应下降,长波响应受到最显著的影响,表现为800~815 nm之间长波响应大幅度衰减,截止波长和峰值波长向短波移动,峰值响应和积分灵敏度减小,最终的光谱响应曲线变得平坦。阴极参量的计算结果反映铟封后阴极的表面逸出几率降低,说明铟封引起阴极表面激活层发生变化,使得能量较低的长波段光生电子不容易逸出,阴极长波响应和灵敏度随之降低。进一步分析了铟封过程中影响阴极表面激活层的因素。

Measurement and Analysis of Spectral Response Characteristic of Transmission-Mode GaAs Photocathode before and after Indium Seal

Spectral response characteristics of transmission-mode GaAs photocathode after high-temperature activation, low-temperature activation and indium sealed into intensifier are measured by use of the home-made prototype of spectral response measurement instrument. The results show that spectral response curve in the whole response waveband decreases after indium seal, and long-wave responsibility is most obviously influenced. The long- wave response 800-815 nm decreases largely, cut-off wavelength and peak value wavelength move towards shortwave, peak response value and integral sensitivity decrease, and the final spectral response curve becomes flat. The calculation results of photocathode parameters reflect that surface escape probability decreases after indium seal, which indicates that indium seal leads to the variations of surface activation layers of photocathode, low-energy photoelectrons under long-wave are difficult to escape, and the long-wave response and sensitivity decrease accordingly. The influencing factors on the surface activation layers during indium seal are also analyzed.