Spectral response and surface layer thickness of GaAs:Cs-O negative electron affinity photocathode

Benkang Chang; Wenli Liu; Rongguo Fu; Yunsheng Qian; Zhiyuan Zong; Guihua Wang

doi:10.1117/12.444934

19 October 2001 Spectral response and surface layer thickness of GaAs:Cs-O negative electron affinity photocathode

Benkang Chang, Wenli Liu, Rongguo Fu, Yunsheng Qian, Zhiyuan Zong, Guihua Wang

Proceedings Volume 4580, Optoelectronics, Materials, and Devices for Communications; (2001) https://doi.org/10.1117/12.444934
Event: Asia-Pacific Optical and Wireless Communications Conference and Exhibit, 2001, Beijing, China

Abstract

On-line spectral response curves of GaAs:Cs-O NEA photo- cathode of reflection model is first presented and the relation between spectral response curves and the thickness of Cs-O layer is discussed. When Cs and O is deposited on the surface of cleaning GaAs wafer, photo-cathode's spectral response rises sharply and long-wavelength threshold tends to a fixed value at the beginning of the activation. But, as Cs and O are deposited continually, spectral response rises slowly and the long-wavelength threshold tends to be shortened. When a fine thickness of Cs-O layer is reached, the optimum spectral response is obtained. As a quantity Cs-O is further increased, both the spectral response and the long-wavelength threshold decrease. The thickness of GaAs photo-cathode surface layer that consists of Cs-O layer and GaAs-O layer is researched by take-off angle XPS technology. Thickness of Cs-O layer is approximately equal to 0.7 nm, and the GaAs-O layer is approximately 0.2nm. Our experiments show when the thickness of Cs-O layer is approximately equal to 0.7nm, and the GaAs-O layer is approximately 0.2mm. Our experiments show when the thickness of Cs-O layer is 0.7nm or so and the GaAs-O layer tend to be disappeared, NEA photo-cathode with the optimum spectral response is achieved which can be used widely in low-light level imaging detectors.

Citation Download Citation

Benkang Chang, Wenli Liu, Rongguo Fu, Yunsheng Qian, Zhiyuan Zong, and Guihua Wang "Spectral response and surface layer thickness of GaAs:Cs-O negative electron affinity photocathode", Proc. SPIE 4580, Optoelectronics, Materials, and Devices for Communications, (19 October 2001); https://doi.org/10.1117/12.444934

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