Strain in a single wrinkle on an MoS2 flake for in-plane realignment of band structure for enhanced photo-response

Abstract

Since 2D transition metal dichalcogenides (TMDs) exhibit strain-tunable bandgaps, locally confining strain can allow lateral manipulation of their band structure, in-plane carrier transport and optical transitions. Herein, we show that a single wrinkle (width = 10 nm–10 μm) on an MoS₂ flake can induce confined uniaxial strain to reduce the local bandgap (40–60 meV per % deformation), producing a microscopic exciton funnel with an enhancement in photocurrent over flat MoS₂ devices. This study also shows that wrinkles can spatially reconfigure the distribution of dopants and enhance the light absorption in the MoS₂ layer via Fabry–Perot interference in its nanocavity. In the field-effect transistor studies on the MoS₂ flat–wrinkle-flat device-structure, a higher carrier mobility and an improvement in the on/off ratio were exhibited in the devices with a single wrinkle. This phenomenon is attributed to the built-in potential induced by the bandgap reduction at the wrinkle site and the change in doping of the suspended wrinkle. The wrinkle-induced tunability of the local bandgap and manipulation of the spatial transport barriers, and the enhanced light absorption can enable development of next-generation electronic and optoelectronic devices guided by in-plane deformation of 2D nanomaterials.