改进“yo-yo”Cs/O交替激活方法对GaAs光阴极稳定性影响  

Effect of Improved ’yo-yo’ Cs/O Alternate Activation Method on Stability of GaAs Photocathode

作　　者：焦岗成 张锴珉 张益军[2] 郭欣 石峰 程宏昌 闫磊 詹晶晶 JIAO Gangcheng;ZHANG Kaimin;ZHANG Yijun;GUO Xin;SHI Feng;CHENG Hongchang;YAN Lei;ZHAN Jingjing(Science and Technology on Low-Light-Level Night Vision Laboratory,Xi'an 710065,China;School of Electronic and Optical Engineering,Nanjing University of Science and Technology,Nanjing 210094,China)

机构地区：[1]微光夜视技术重点实验室,西安710065 [2]南京理工大学电子工程与光电技术学院,南京210094

出　　处：《光子学报》2022年第2期293-300,共8页Acta Photonica Sinica

基　　金：国家自然科学基金(Nos.U2141239,61771245);微光夜视技术重点实验室基金(Nos.J20200102,J20150102)。

摘　　要：为提高激活后GaAs光阴极的稳定性,延长微光夜视器件的工作寿命,围绕Cs/O激活方法和衰减特性进行实验研究。通过对比传统“yo-yo”激活法和改进“yo-yo”激活法在Cs/O激活光电流、光谱响应以及光照衰减方面的差异,发现采用改进“yo-yo”激活法的GaAs光阴极光谱灵敏度更高且稳定性更好。利用四极质谱仪监测真空腔内残气成分和分压强变化,基于衰减模型拟合光电流实验曲线,求得不同残气成分对GaAs光阴极性能衰减影响的权重因子。结果表明水蒸气和二氧化碳的影响最大,甲烷和一氧化碳次之,氢气几乎不产生影响,而其它碳氢有机分子也会产生负面影响。总体看来,改进的“yo-yo”激活法对GaAs光阴极表面吸附含氧气体分子造成的性能衰减具有明显的改善效果,这将有助于提高微光夜视器件中GaAs光阴极的稳定性。In modern low-light-level night vision devices,the negative-electron-affinity GaAs photocathode,as the photosensitive core component,is usually prepared by alternating Cs/O activation on the cleaned GaAs surface.Meanwhile,the stability of GaAs photocathode is directly affected by the quality of Cs/O activation process and the residual gases in the vacuum environment.In order to improve the stability of GaAs photocathodes after activation and prolong the operating lifetime of the low-light-level night vision devices,experimental researches were executed from the perspectives of Cs/O activation method and decay characteristic with the aid of the self-developed ultra-high vacuum photocathode preparation and multi-information on-line measurement and control system.Two different Cs-O activation methods,namely the traditional’yo-yo’method and the improved’yo-yo’activation method were performed on the p-type GaAs(100)substrates grown by the vertical gradient freeze method.During the traditional’yo-yo’activation process,the O source was introduced when the photocurrent dropped to 85%of the previous peak and the Cs source was kept continuously with a slight overdose,and then the O source was closed when the photocurrent reached a new peak.While in the process of the improved’yo-yo’activation,the Cs source was maintained continuously and the O source was introduced when the photocurrent dropped to the minimum with the complete Cs overdose in the Cs/O alternate activation cycles,and the O source was also closed when the photocurrent reached a new peak.The Cs/O activation results show that the improved’yo-yo’activation method with less alternate activation cycles can obtain a higher photocurrent peak and a higher spectral sensitivity than the traditional one with more alternate activation cycles.In addition,the photocurrent decay results under the long-time illumination of 633 nm demonstrate that the GaAs photocathode with the improved’yo-yo’activation method can achieve a longer operating lifetime an

关 键 词：GaAs光阴极 Cs/O激活 残余气体 稳定性 光谱响应 

分 类 号：TN223[电子电信—物理电子学]