Enhanced photogalvanic effect in the two-dimensional MgCl2/ZnBr2 vertical heterojunction by inhomogenous tensile stress
Liyu Qian , Juan Zhao , Yiqun Xie
Front. Phys. ›› 2022, Vol. 17 ›› Issue (1) : 13502
The photogalvanic effect (PGE) occurring in noncentrosymmetric materials enables the generation of a dc photocurrent at zero bias with a high polarization sensitivity, which makes it very attractive in photodetection. However, the magnitude of the PGE photocurrent is usually small, leading to a low photoresponsivity, and therefore hampers its practical application in photodetection. Here, we propose an approach to largely enhancing the PGE photocurrent by applying an inhomogenous me-chanical stretch, based on quantum transport simulations. We model a two-dimensional photodetector consisting of the wide-bandgap MgCl2/ZnBr2 vertical van der Waals heterojunction with the noncen-trosymmetric C3v symmetry. Polarization-sensitive PGE photocurrent is generated under the vertical illumination of linearly polarized light. By applying inhomogenous mechanical stretch on the lattice, the photocurrent can be largely increased by up to 3 orders of magnitude due to the significantly in-creased device asymmetry. Our results propose an effective way to enhance the PGE by inhomogenous mechanical strain, showing the potential of the MgCl2/ZnBr2 vertical heterojunction in the low-power UV photodetection.
photogalvanic effect / mechanical stretch / polarization-sensitive / vertical heterojunction / ultraviolet photodetection
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Higher Education Press
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