Enhanced photogalvanic effects in the two-dimensional [formula omitted] monolayer by vacancy- and substitution-doping

Abstract

The photogalvanic effect (PGE) enables the generation of photocurrent at zero bias and without the need of the p-n junction, and also offer a high polarization sensitivity in a broadband range, showing potential applications in the low-power 2D optoelectronics, however the PGE photocurrent is generally small. Here we studied the PGE in the 2D WTe2 monolayer using the quantum transport simulations, and proposed the mechanism to effectively enhance the PGE photocurrent by substitution-doping and vacancy-defects. The PGE photocurrent can be generated in the 2D WTe2 monolayer under the vertical illumination of linearly polarized light. The photocurrent can be enhanced evidently by creating the vacancy or Ga-substitution doping, and moreover a higher polarization sensitivity can be obtained. This performance is attributed to the reduced symmetry due to the doping, which increases the device asymmetry and therefore enhance the photocurrent. Our results propose the mechanism to effectively enhance the PGE by substitution doping and also show the promising applications of the 2D WTe2 monolayer in optoelectronics including the photodetections.