Near-field nano-imaging of graphene Moiré superlattices (invited)

Two-dimensional materials with excellent photoresponse have presented high potential in new-type infrared photodetection technologies. Introducing a localized field into two-dimensional infrared photodetectors can greatly enhance their photodetection performance. An infrared detection technique is presented based on the photothermoelectric effect through twisted bilayer graphene Moiré superlattices. The formation of the Moire superlattice alters the Seebeck coefficient of the system and the concentration of hot carriers. Applying a high-resolution photocurrent tip is capable of detecting photoresponse of a single Moire unit cell, thereby obtaining a high-resolution photocurrent map of the whole twisted bilayer graphene system. This technique demonstrates the prospect of spintronics in the field of photodetection, and provides a novel pattern for designing future single-photon detectors.