Moiré Ferroelectricity-Enhanced Optoelectronic Response in an all-2D van der Waals Hybrid

Sliding ferroelectricity is an emergent phenomenon observed in twisted bilayers of boron nitride and twisted homobilayers of transition metal dichalcogenides (TMDs) arranged in a rhombohedral stacking configuration. While the signature of such a phenomenon is observed in several electronic devices through hysteretic transfer characteristics, nonlocality etc., the strong sensitivity of the TMDs to optical irradiation have neither been explored nor exploited in an optoelectronic architecture that also hosts sliding ferroelectricity. In this work, an edge-contacted encapsulated graphene-twisted WSe₂ heterostructure is created, in a dual-gated field-effect configuration to study the impact of the moiré polar domains on the optical response of the two dimenstional (2D) hybrid. A specific detectivity of 5.2 × 10¹³ Jones which is among the highest in all-2D optoelectronic architectures is observed. This is attributed to the polarization-induced electric field that facilitates charge-transfer across the graphene-ferroelectric interface. It is argued that compared to non-ferroelectric homobilayers and monolayers, the photoresponse in the minimally twisted layers is significantly enhanced due to large exciton lifetimes, staggered band alignment and a polarization-induced in-built electric field. This work highlights the functionality of the 2D ferroelectric, acting both as the photosensitive layer while effectively controlling the charge-transfer dynamics.