Abstract: First-principles calculations of nonequilibrium Green's function combined with density functional theory are utilized to investigate the photogalvanic effects of α-Se photodetectors in the presence of single-atom vacancies,two-atom vacancies,and doping with Te,W,As,and Cd atoms.The results demonstrate that the single-atom vacancy can break the spatial symmetry of the device more greatly and generate stronger photocurrent.The maximum photoresponse of 32.61 a20/photon is obtained by doping with As atoms,and the extinction ratio of the device reaches 184.9 when Se atom are replaced by Cd atom,and the device possesses a more sensitive visible-light absorption along the y-direction,and the maximum photoresponse in y-direction is 1 369 times higher than that along the x-direction,showing an excellent anisotropic photoresponse.

Key words: α-Se, photodetectors, photogalvanic effects, anisotropic