Modulating the periods and electronic properties of striped moiré superstructures for monolayer WSe2 on Au(100) by varied interface coupling

Abstract

Moiré superlattices formed by the stacking of two-dimensional (2D) transition metal dichalcogenide lattices on substrate lattices have been reported to imply a crucial effect on the electronic properties of 2D materials (e.g., band gap, doping level) and their physical properties. Herein, we report the direct observation of various striped moiré superstructures for monolayer WSe₂ on the Au(100) facet, due to the lattice symmetry difference and relative rotation. The periodicities or the inter-stripe distances for striped superstructures fall in a range of 0–15 nm or 0–3 nm after relatively low or high temperature annealing processes, respectively. The diverse striped moiré superstructures then served as perfect platforms for examining the electronic band gap tunability for monolayer WSe₂/Au(100) by using scanning tunneling microscopy/spectroscopy (STM/STS), which increases from ∼1.59 eV to ∼1.90 eV with increasing moiré periods from ∼1.62 to ∼11.58 nm. The coupling strength of monolayer WSe₂/Au(100) with various striped patterns is thus proposed to be modulated by the different relative orientations. This work should hereby provide some fundamental references for the domain orientation control, interface coupling strength, and application explorations of two-dimensional layered materials in future electronics and optoelectronics.