Performance enhancement in MoS2/CuInP2S6 photodetectors via topography-designed flexoelectric fields

Abstract

Flexoelectricity, driven by strain gradients, offers a mechanical route to manipulate ferroelectric polarization and electronic states for nanoscale applications. In this work, we demonstrate topography-induced flexoelectric engineering to modulate the energy band structure of the MoS2/CuInP2S6 (CIPS) heterostructure for high-performance optoelectronics. By deforming CIPS flakes over designed topographical variations, controlled strain gradients can be induced to pin the ferroelectric polarization via a flexoelectric potential field. This locally defined polarization serves as an effective modulation for the MoS2 band structure. By utilizing a nanowire to induce local curvature, a potential barrier is created in the MoS2 channel without requiring doping or electrostatic gating, which suppresses thermally excited carriers while simultaneously promoting the separation of photogenerated carriers. The curved MoS2/CIPS photodetector exhibits a significant performance enhancement. Under 450 nm illumination, the responsivity increases from 0.93 to 4.74 A/W, and the specific detectivity reaches 2.22 × 1012 Jones, a tenfold enhancement over regular devices. These results establish a direct link between topography-controlled flexoelectric modulation and device functionality, providing a versatile route for designing energy landscapes for 2D devices.