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.