在激活过程中利用有利光照提高砷化镓光阴极的量子效率和稳定性。

Improved quantum efficiency and stability of GaAs photocathode using favorable illumination during activation.

作者信息

Feng Cheng, Zhang Yijun, Qian Yunsheng, Liu Jian, Zhang Jingzhi, Shi Feng, Bai Xiaofeng, Zou Jijun

机构信息

School of Electronic and Optical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China; School of Information and Communication Engineering, Nanjing Institute of Technology, Nanjing 211167, China.

School of Electronic and Optical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.

出版信息

Ultramicroscopy. 2019 Jul;202:128-132. doi: 10.1016/j.ultramic.2019.04.010. Epub 2019 Apr 23.

DOI:10.1016/j.ultramic.2019.04.010

PMID:31028974

Abstract

Considering that illumination using the light source is required to monitor the activation progress of negative-electron-affinity GaAs-based photocathodes, it is important to understand if and how the illumination affects the activation. To improve the photoemission performance of GaAs photocathode, epitaxial GaAs samples are Cs/O activated and recesiated under illumination of monochromatic light of blue (460 nm), green (532 nm), and red (633 nm) with approximately the same incident photons, and halogen tungsten lamp as white light source, respectively, to induce photoemission. The performance characteristics including quantum efficiency and photocurrent degradation among the samples treated by different illumination conditions are compared to investigate their photoemission capability and stability. The results show that GaAs photocathodes activated and recesiated under illumination of monochromatic red light, can obtain higher quantum efficiency, and better stability. This work provides a favorable illumination condition during activation for obtaining satisfactory capability of GaAs-based photocathodes, which will be propitious for applications as spin-polarized electron sources.

摘要

考虑到需要使用光源进行照明来监测基于负电子亲和势砷化镓的光电阴极的激活过程，了解照明是否以及如何影响激活过程非常重要。为了提高砷化镓光电阴极的光发射性能，分别在具有大致相同入射光子数的蓝色（460 nm）、绿色（532 nm）和红色（633 nm）单色光以及作为白色光源的卤钨灯照明下，对外延砷化镓样品进行铯/氧激活和再蒸发，以诱导光发射。比较不同照明条件处理的样品之间包括量子效率和光电流退化在内的性能特征，以研究它们的光发射能力和稳定性。结果表明，在单色红光照明下激活和再蒸发的砷化镓光电阴极可以获得更高的量子效率和更好的稳定性。这项工作为激活过程提供了有利的照明条件，以获得基于砷化镓的光电阴极的令人满意的性能，这将有利于其作为自旋极化电子源的应用。