Tuning the band structure of monolayer WTe2 using back-gating in STM

Two-dimensional (2D) transition metal dichalcogenides are exciting systems potentially realizing toplogically protected edge states, topological superconductivity, and strong electron correlation physics. Monolayer 1T'-WTe₂ has been demonstrated to be a time-reversal-invariant 2D topological insulator that becomes a superconductor upon doping. Atomically-resolved scanning tunneling microscopy (STM) confirmed clear edge states on WTe₂ monolayer islands. Here, we report an STM study of back-gated monolayer 1T'-WTe₂. Along with topographical images, we present scanning tunneling spectroscopy of monolayer islands, performed while tuning the out-of-plane electric field and carrier concentration. The monolayer band structure and the edge states evolve in response to doping and back-gating. We use first principle calculations to explain the observed effects.