Direct reversible writing of nanoscale doping patterns in van der Waals heterostructures*

Spatially controlled modification of charge density is essential to explore exotic physics and enable new device applications. Conventionally, this has been achieved using lithographically defined local gates or by employing molecular self-assemblies on surfaces. However, these methods face limitations in applications necessitating spatial re-writability and complex circuit designs. Recent progress has demonstrated alternative ways to induce rewritable doping patterns in van der Waals (vdW) heterostructures without complex processing masks or resist by optical illumination or applying an STM tip voltage pulse. In this work we introduce a more flexible electron beam doping technique to induce controllable and erasable doping effect in (vdW) heterostructures. With this new doping technique, we can accumulate high carrier density and reversibly write complex doping patterns with nanoscale spatial resolution while preserving the high quality of the vdW heterostructures. The technique can be an ideal approach to study a variety of superlattice physics in vdW heterostructures and to create on-demand circuits for device applications.