Point-defect improved photogalvanic effect in Janus WSSe monolayer

Abstract

Photogalvanic effect (PGE) occurs under polarization irradiation in a material without space inversion symmetry, yet the generated photocurrent is generally small. By imposing various species of point defects, we have studied the PGE in Janus WSSe using the quantum transport simulation. All the photocurrents show cosine dependence with the linear polarization angle when the photodetectors are built along the armchair direction. Effective improvements in photocurrent are detected with the maximum photocurrents of 4.55~6.33 a 0 2 /photon compared with 0.25 a 0 2 /photon in the pure one. The key cause for the improvement is the reduction of symmetry from C 3V to C S by the point defect. High polarization sensitivity is also achieved where the maximum extinction ratio of 1.37×10 4 is obtained in the Janus WSSe with one In substituted W. The point-defected Janus WSSe monolayer is a promising material for photodetectors with both high photocurrent and polarization sensitivity