Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5026424 | Optik - International Journal for Light and Electron Optics | 2016 | 6 Pages |
Abstract
In order to study the cause of the longer-wavelength threshold of GaN and GaAlN photocathodes, three GaN photocathodes and two GaAlN photocathodes were designed and prepared by Cs/O activation following MOCVD, and first-principles calculations about the GaN(0001), Ga0.75Al0.25N(0001), and Ga0.625Al0.375N(0001) surfaces were performed. Results show that the calculated band gap values of the bulk GaN, Ga0.75Al0.25N, and Ga0.625Al0.375N are 1.630Â eV, 2.261Â eV, and 2.272Â eV respectively. Meanwhile the band gap of GaN(0001), Ga0.75Al0.25N(0001) and Ga0.625Al0.375N(0001) surfaces are much smaller than 1Â eV. The relation of the smaller surface band gap and the longer-wavelength threshold was discussed. We found that the lattice parameters of the surfaces are larger than those of bulk GaN and GaAlN, which results in the decrease of the band gap. So the phenomenon about the longer wavelength threshold is theoretically explained.
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Authors
Mingzhu Yang, Benkang Chang, Weifeng Rao,