Comparative study of Cs,O coadsorption on Ga0.75Al0.25N (0001) and (001) surfaces
- 7 Downloads
Based on first principle calculations, we carried out comparative research of Cs,O coadsorption on Ga0.75Al0.25N (0001) surface and Ga0.75Al0.25N (001) (2 × 2) reconstruction surface. On the (0001) surface, the average coordinate difference between Cs and O atoms along  direction is obviously smaller than that along  direction on (001) (2 × 2) reconstruction surface. This is due to the existence of dimers and trenches on the (001) (2 × 2) reconstruction surface. Cs atoms are favored to locate on the dimers while O atoms are favored to locate in the trenches. As a result, Cs–O dipoles on (001) (2 × 2) reconstruction surface make an important contribution on lowering work function. For both (0001) and (001) (2 × 2) reconstruction surface, work function values fluctuate up and down at the stage of Cs,O alternative adsorption, and the valley values are smaller and smaller. The site of Mg dopant has an influence on work function of the surfaces, which results in the “fish scale field” effect.
KeywordsGa0.75Al0.25N (0001) surface Ga0.75Al0.25N (001) (2 × 2) reconstruction surface Work function Cs–O dipole “Fish scale field” effect
This study was funded by Natural Science Foundation of Jiangsu Province (Grant No. BK20170959), National Natural Science Foundation of China (Grant Nos. 61705108, 61704075 and 61601198), and the startup foundation for introducing talent of NUIST (Grant No. 2016r039). The authors acknowledge National Supercomputing Center in Shenzhen for providing the computational resources.
- Ainbund, M.R., Alekseev, A.N., Alymov, O.V., Jmerik, V.N., Lapushkina, L.V., Mizerov, A.M., Ivanov, S.V., Pashuk, A.V., Petrov, S.I.: Solar-blind UV photocathodes based on AlGaN heterostructures with a 300- to 330-nm spectral sensitivity threshold. Tech. Phys. Lett. 5, 439–442 (2012)ADSCrossRefGoogle Scholar
- Hogan, C., Paget, D., Garreau, Y., Sauvage, M., Onida, G., Reining, L., Chiaradia, P., Corradini, V.: Early stages of cesium adsorption on the As-rich c(2 × 8) reconstruction of GaAs (001): adsorption sites and Cs-induced chemical bonds. Phys. Rev. B 68, 2053131–20531311 (2003)Google Scholar
- Reverchon, J.L., Mazzeo, G., Dussaigne, A., Duboz, J.Y.: Status of AlGaN based focal plane arrays for UV solar blind detection. Proc. SPIE 5964, 596420–596431 (2005)Google Scholar
- Segall, M.D., Lindan, P.J.D., Probert, M.J., Pickard, C.J., Hasnip, P.J., Clark, S.J., Payne, M.C.: First-principles simulation: ideas, illustrations and the CASTEP code. J. Phys.: Condens. Matter 14, 2017–2044 (2002)Google Scholar
- Sumiya, M., Kamo, Y., Ohashi, N., Takeguchi, M., Heo, Y.U., Yoshikawa, H., Ueda, S., Kobayashi, K., Nihashi, T., Hagino, M.: Others, fabrication and hard X-ray photoemission analysis of photocathodes with sharp solar-blind sensitivity using AlGaN films grown on Si substrates. Appl. Surf. Sci. 256, 4442–4446 (2010)ADSCrossRefGoogle Scholar
- Wang, X.H., Chang, B.K., Ren, L., Gao, P.: Influence of the p-type doping concentration on reflection-mode GaN photocathode. Appl. Phys. Lett. 98, 08210901–08210903 (2011)Google Scholar
- Xue, Z.Q.: Polycrystalline photoelectric emission films with negative electron affinity. Appl. Opt. 5, 251–255 (1984). (in Chinese) Google Scholar
- Zhang, E.Q.: Some properties of the work function. J. Electron. 11(3), 244–249 (1989). (in Chinese) Google Scholar
- Zhang, E.Q., Liu, X.Q.: On the emission mechanism of barium containing thermionic cathodes. J. Electron. 6(2), 89–95 (1984). (in Chinese) Google Scholar