Experiment and analysis of (Cs,O) activation for NEA photocathode preparation

Xiaoqing Du; Benkang Chang; Guihua Wang

doi:10.1117/12.465816

20 September 2002 Experiment and analysis of (Cs,O) activation for NEA photocathode preparation

Xiaoqing Du, Benkang Chang, Guihua Wang

Proceedings Volume 4919, Advanced Materials and Devices for Sensing and Imaging; (2002) https://doi.org/10.1117/12.465816
Event: Photonics Asia, 2002, Shanghai, China

Abstract

On-line spectral response measurement technology and angular-dependent X-ray photoelectron spectroscopy (XPS) technology are firstly used to research the (Cs,O) activation of Gallium arsenide (GaAs) negative electron affinity (NEA) photocathode. Dynamic spectral response can be obtained from on-line spectral response measurement system and by use of the computer program for quantitative angular-dependent XPS, atom concentration and layer thickness of activation layer can be calculated. The photocathode properties for evaluating (Cs,O) activation, such as the surface electron escape probability, diffusion length and so on are also calculated by simulation method. From our experimental results, optimum cesium deposition quantity is obtained when photocurrent arrives at peak value and then decreases to 10% of the maximum, and optimum oxygen deposition quantity is obtained when photocurrent arrives at peak value and then decreases to 90% of the maximum. And the photoemission peaks at 0.71 monolayer of Cs coverage. In our experimental system the optimum thickness of activation layer is 0.82 nm and interfacial oxidation layer is 0.2 nm for successfully activated GaAs NEA photocathode. Mechanism of interfacial barrier formation and effect of oxygen on the surface of activation layer are explained.

Citation Download Citation

Xiaoqing Du, Benkang Chang, and Guihua Wang "Experiment and analysis of (Cs,O) activation for NEA photocathode preparation", Proc. SPIE 4919, Advanced Materials and Devices for Sensing and Imaging, (20 September 2002); https://doi.org/10.1117/12.465816

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