Electronic bandgap manipulation of monolayer WS2 by vertically coupled insulated Mg(OH)2 layers

Abstract

Searching for novel two-dimensional (2D) materials with tunable electrical and optical properties is significant to develop next-generation multifunctional nanoscale optoelectronic devices. The new insulated Mg(OH)2 is a promising and stable 2D material to construct heterojunction with transition metal dichalcogenides (TMDs). Here, WS2-Mg(OH)2 is experimentally designed and investigated. The similarity of lattice constants for the two materials is confirmed with selected area electron diffraction for the first time. By stacking Mg(OH)2 layers on WS2 monolayer, the Fermi level of WS2 is distinctly elevated, making the WS2-Mg(OH)2 a promising heterostructure for constructing and optimizing tunable electronic devices. We also showed the adjustable transition properties with enhanced coupling effect by thinning the Mg(OH)2 layers in the heterostructure. This study not only demonstrates the tunable Fermi levels and optical characteristics of WS2-Mg(OH)2, but also could promote the broad investigations of novel 2D materials for various optoelectronic device applications in nanoscale.