Scanning Tunneling Microscopy Study of Gated Monolayer WSe2/RuCl₃ Heterostructure

The extreme 2D nature of monolayer transition metal dichalcogenides (TMDs) creates opportunities for manipulating their properties outside of conventional chemical doping. Electrostatic doping and substrate engineering are commonly used strategies to induce carriers into monolayers. In this work, we investigate nanoscale p-n junctions created using a combination of these strategies. We start with a flux-grown WSe₂ monolayer that has a small extrinsic carrier density, and place it across a RuCl₃ layer on hexagonal boron nitride (hBN). RuCl₃ has been shown to transfer substantial charge due to the work function mismatch with WSe₂. Using this device geometry, we can therefore create sharp doping gradients across the boundary. We will describe scanning tunneling microscopy and spectroscopy (STM/S) measurements of the interface to quantify the local band diagram in these devices.