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A density functional theory research on Cs–O activation process of GaAlAs photocathodes

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Abstract

Using plane-wave ultrasoft pseudopotential based on first-principles, the Cs–O activation process of GaAlAs photocathodes is investigated. In the Cs–O alternate activation process, Cs–O unit is inclined to form the Cs-outer structure. After the adsorption of O atom, the additional O atoms weaken the dipole between Cs atoms and β 2 (2 × 4) surface and introduce additional dipole between Cs and O. Dual-dipole model is used to express the variation tendency of dipole moment and work function. During activation process, electrons of Cs atoms offset to the surface, the additional electrons at the surface cause n-type surface state, and result in downwards band bending; at the same time, the vacuum level is gradually lowered, forming two potential barriers. An experiment is performed and the photocurrent curve is well consistent with the calculation results. After Zn doping, the work function near Zn atoms is lower than surrounding, causing the scale-like effect.

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Acknowledgements

The authors would like to thank School of Information and Electrical Engineering, Ludong University for first-principles calculations. This work has been financially supported by the National Natural Science Foundation of China (No. 61572012) and the Key Natural Science Foundation of Hubei Province of China (No. 2014CFA055).

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  1. College of Information Engineering, Wuhan Technology and Business University, Wuhan, 430065, China

    Xiaohua Yu

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  1. Xiaohua Yu
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Yu, X. A density functional theory research on Cs–O activation process of GaAlAs photocathodes. J Mater Sci 51, 8259–8269 (2016). https://doi.org/10.1007/s10853-016-0103-5

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  • DOI: https://doi.org/10.1007/s10853-016-0103-5

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