Abstract
We have investigated the stability and electronic properties of GaN nanowires photocathode based on first-principle calculations. The most stable adsorption configuration of Cs adatoms on the (001) surface of [001]-oriented GaN nanowires changes accordingly as Cs coverage increases. The work function of Cs-only-covered surface falls off with increasing Cs coverage. For the nanowire surface covered with either excessive or minor Cs coverage, the work function surprisingly increases slightly after O activation; however, for Cs coverage of 0.5 (monolayer) ML and 0.75 ML, O activation process still works for the nanowires photocathode. A downward band bending region is formed after Cs adsorption and will further bend downward after O adsorption only for models with Cs coverage of 0.5 ML and 0.75 ML. The optimized atomic ratio of Cs/O is 3:1. The diversification of the band structures is mainly attributed to the orbital hybridization between Cs-5 s, Cs-5p, O-2p states and Ga-4 s, N-2p states.
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Acknowledgements
We would like to appreciate Meishan Wang of Ludong University for the first-principle calculations. This work is supported by the Natural Science Foundation of Jiangsu Province-China (Grant No. BK20130767), the Fundamental Research Funds for the Central Universities-China (Grant No. 30916011206) and the Six Talent Peaks Project in Jiangsu Province-China (Grant No. 2015-XCL-008).
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Xia, S., Liu, L., Diao, Y. et al. Cs and Cs/O adsorption mechanism on GaN nanowires photocathode. J Mater Sci 52, 5661–5671 (2017). https://doi.org/10.1007/s10853-017-0801-7
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DOI: https://doi.org/10.1007/s10853-017-0801-7