Strain Driven Electrical Bandgap Tuning of Atomically Thin WSe2

Tuning electrical properties of 2D materials through mechanical strain has predominantly focused on n-type 2D materials like MoS₂ and WS₂, while p-type 2D materials such as WSe₂ remain relatively unexplored. Here, the impact of controlled mechanical strain on the electron transport characteristics of both mono and bi-layer WSe₂ is studied. Through coupling atomic force microscopy (AFM) nanoindentation techniques and conductive AFM, the ability to finely tune the electronic band structure of WSe₂ is demonstrated. The research offers valuable mechanistic insights into understanding how WSe₂'s electronic properties respond to mechanical strain, a critical prerequisite for the development of flexible photoelectronic devices. It is also observed that under high pressure, the AFM tip/monolayer WSe₂/metal substrate junction transitions from Schottky to Ohmic contact, attributed to significant charge injection from the substrate to the WSe₂. These findings are significant for designing efficient metal/semiconductor contact in thin and flexible PMOS (p-type Metal–Oxide–Semiconductor) devices.