Near field study of twisted transition metal dichalcogenide bilayers

Twistronics has recently emerged as a novel tuning knob to engineer the properties of electrons and excitons in two dimensional van der Waals heterostructures. However, directly probing the properties of vdW heterostructures within a single moiré unit cell remains elusive. In this talk, we utilize near-field optical microscopy to explore twisted transition metal dichalcogenides (TMD) bilayers. The atomically thin vertical p-n junction of WSe₂/MoSe₂ bilayer is fabricated by mechanical exfoliation and stacking. The type-II band alignment of the WSe₂/MoSe₂ facilitates electron-hole separation permitting photocurrent measurements at the nanoscale. Features with ~100 nm periodicity are observed and show systematic evolution under electro-static gating. More experiments are carrying out to conclusively assign these features to the moiré. Our study demonstrates a viable pathway towards probing and manipulating moiré patterned TMD heterostructures at the nanoscale.