Effects of doping Ti, Nb, Ni on the photoelectric properties of monolayer 2H–WSe2

Abstract

The photocurrent of Ti, Nb, Ni substitution-doped monolayer 2H–WSe 2 is calculated by the first-principles method based on the Keldysh nonequilibrium Green's function-density functional theory. The photogalvanic effect(PGE) photocurrent can be generated in the monolayer 2H–WSe 2 under the vertical irradiation of linear polarized light, However, it is generally very small. Calculation results show that the Nb and Ti-doped systems exhibit the characteristics of semi-metal, while the Ni-doped system tends to transform into metals. The substitutional doping of Nb, Ti, and Ni atoms can effectively enhance the photocurrent and the polarization sensitivity of monolayer 2H–WSe 2 .This excellent performance is mainly attributed to the fact that the doping introduces multiple impurity energy bands crossing the Fermi energy level, which becomes a bridge for electronic transitions, thus effectively enhancing the photocurrent. • Background and Significance: The research on the modification of monolayer 2H-WSe 2 by doping has become increasingly popular, and its doping system has shown great application potential. But the theoretical calculation of doped 2H-WSe 2 is relatively less in terms of the photogalvanic effect. Therefore, the photocurrent of Ti, Nb, and Ni-doped monolayer 2H-WSe 2 are calculated respectively. It is expected that the research in our work will provide some theoretical guidance for the application of 2H-WSe 2 in the field of optoelectronics. • Originality and Novelties: Our results show that doping Ti, Nb, and Ni atoms can effectively enhance the photocurrent and extinction ratio of the monolayer 2H-WSe 2 . The photocurrent functions are all proportional to COS2θ. The Ni-doped system can obtain the largest photocurrent (1.484) and the extinction ratio (23.2), which are mainly attributed to the fact that the doping introduces multiple impurity energy bands, which becomes a bridge for electronic transitions.