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Proceedings Paper

Improved performance of GaAs photocathodes using effective activation technique
Author(s): Yijun Zhang; Jingzhi Zhang; Cheng Feng; Hongchang Cheng; Xiang Zhang; Yunsheng Qian
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Paper Abstract

To achieve negative-electron-affinity state, the atomically clean surface of GaAs-based photocathode is usually activated by cesium and oxygen in the ultrahigh vacuum environment. In view of the required computer-control of evaporation flow rates, the solid oxygen dispenser instead of gaseous oxygen is urgently needed just as the regular cesium dispenser. Accordingly, the solid cesium and oxygen dispensers were applied to activate epitaxial GaAs cathode samples. Two types of solid oxygen dispensers composed of barium peroxide powder and silver oxide powder respectively are employed to improve cathode photoemission performance. The experimental results show that the barium peroxidebased oxygen dispenser can release more oxygen and bring in higher activation photocurrent and spectral response than the silver oxide-based one. The unsatisfactory feature is that the silver oxide-based oxygen dispenser released effectual oxygen gas more slowly than the barium peroxide-based oxygen dispenser. Therefore, an effective activation technique was proposed to ameliorate this unfavorable phenomenon for the silver oxide-based dispenser, which can bring out the desired symmetry of photocurrent curve shape during the Cs/O alternate activation process. The improved activation technique would provide guidance for the optimization of activation craft.

Paper Details

Date Published: 7 September 2017
PDF: 6 pages
Proc. SPIE 10404, Infrared Sensors, Devices, and Applications VII, 104040Y (7 September 2017); doi: 10.1117/12.2272958
Show Author Affiliations
Yijun Zhang, Nanjing Univ. of Science and Technology (China)
Jingzhi Zhang, Nanjing Univ. of Science and Technology (China)
Cheng Feng, Nanjing Univ. of Science and Technology (China)
Hongchang Cheng, Science and Technology on Low-Light-Level Night Vision Lab. (China)
Xiang Zhang, Nanjing Univ. of Science and Technology (China)
Yunsheng Qian, Nanjing Univ. of Science and Technology (China)

Published in SPIE Proceedings Vol. 10404:
Infrared Sensors, Devices, and Applications VII
Paul D. LeVan; Ashok K. Sood; Priyalal Wijewarnasuriya; Arvind I. D'Souza, Editor(s)

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