  Assembling two-dimensional van der Waals layered materials into
heterostructures is an exciting development that sparked the discovery of rich
correlated electronic phenomena and offers possibilities for designer device
applications. However, resist residue from fabrication processes is a major
limitation. Resulting disordered interfaces degrade device performance and mask
underlying transport physics. Conventional cleaning processes are inefficient
and can cause material and device damage. Here, we show that thermal scanning
probe based cleaning can effectively eliminate resist residue to recover
pristine material surfaces. Our technique is compatible at both the material-
and device-level, and we demonstrate the significant improvement in the
electrical performance of 2D WS2 transistors. We also demonstrate the cleaning
of van der Waals heterostructures to achieve interfaces with low disorder. This
enables the electrical formation and control of quantum dots that can be tuned
from macroscopic current flow to the single-electron tunnelling regime. Such
material processing advances are crucial for constructing high-quality vdW
heterostructures that are important platforms for fundamental studies and
building blocks for quantum and nano-electronics applications.
