梯度掺杂GaN光电阴极的光谱响应测试与分析

用光谱响应测试仪得到了反射式梯度掺杂GaN光电阴极在激活和衰减过程中的光谱响应曲线，发现此曲线不断发生变化。在激活过程中光谱响应不断提高，且长波响应提高较快；衰减过程中光谱响应不断下降，长波响应下降得更快。结果表明：光谱响应曲线的变化与光电阴极高能光电子的逸出有关。GaN光电阴极发射的电子能量分布随入射光子能量升高而向高能端偏移，阴极表面势垒形状的变化对低能光激发电子的影响更大，导致光谱响应曲线随入射光波长改变而产生了不同的变化。

Spectral response measurement and analysis of gradient-doping GaN photocathode

The spectral response curves of reflection-type gradient-doping GaN photocathode in the process of activation and attenuation are obtained with the spectral response measurement instrument. It’s found that the curve is constantly changing. The spectral response improves continuously in the process of activation, and the long wave response increases faster. The spectral response decreases continuously in the process of attenuation, and the long wave response decreases faster. Results show that the variation of spectral response curve is related to the escape of the high energy photoelectron of photoelectric cathde. The electron energy distribution of GaN photocathode is shifted to the high energy side with increasing of the incident photon energy. Influence of cathode surface potential barrier shape change on low energy light excited electrons is even greater, which leads to different change in spectral response curve with incident light wavelength.