Band type engineering using different stacking configurations of anisotropic and isotropic monolayer transition metal dichalcogenides

Abstract This work demonstrates the band-type engineering and the detailed charge transport mechanism upon visible light illumination for various configurations of vertically stacked monolayers of MoS₂-ReS₂ grown by a two-step chemical vapour deposition method. In order to understand the stacking order of both materials has a direct impact on the band alignment arrangements, we investigate the optical properties of both ReS₂–MoS₂ stacking configurations using micro-photoluminescence and interestingly observed the change in the band alignment upon changing the stacking order (ReS₂–MoS₂ and MoS₂–ReS₂). The formation of the vertically stacked heterostructure is further validated by observing its morphology by HR-TEM. The MoS₂ on top of ReS₂ yielded Type II and ReS₂ on top of MoS₂ yielded type I band alignment. The fabricated photodetector exhibits responsivities of 152 A W⁻¹ for pristine ReS₂, 72 A W⁻¹ for MoS₂ on top, and 400 A W⁻¹ for ReS₂ on top respectively for visible light illumination of 554 nm suggesting that the stacking configuration of the monolayer TMDs play a vital role in the performance of the optoelectronic properties. The detailed study of such configurations of vertically stacked 2D heterostructure is essential to better understand the optimal configuration for the development of highly responsive photodetectors.