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

Moire 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 moire 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 moire 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 similar to 1.59 eV to similar to 1.90 eV with increasing moire periods from similar to 1.62 to similar 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.

Automated summary

The formation of various striped moire superstructures on the Au(100) facet has been observed for monolayer WSe2, leading to tunability of the electronic band gap for monolayer WSe2/Au(100). The coupling strength between monolayer WSe2/Au(100) and different striped patterns can be modulated by the relative orientations, providing a fundamental reference for future applications in electronics and optoelectronics.