Spatially Textured Strained Engineering of WSe₂ on Dielectric Silk Fibroin for Enhanced Optoelectronic Performance.

Abstract

Nanostrain patterning in two-dimensional transition metal dichalcogenides can enhance electrical and optoelectronic performance. However, from the viewpoint of device configurations, existing strategies cannot obtain controllable localized strain distribution with high-density integration capability nor effectively integrate with field effect transistors (FETs) for efficient electric field tunability. In this work, by leveraging both thermal scanning probe lithography and silk fibroin (SF), we achieved controllable nanostrain patterning in monolayer and bilayer WSe₂ FETs for enhanced carrier mobility and photocurrent. First, we confirmed the presence of nanostrain and investigated its effect on the electronic structure and optical properties. Notably, bilayer WSe₂ FET on SF dielectric exhibited enhanced carrier mobility after nanostrain patterning compared to pristine devices, attributed to strain-induced band gap narrowing and suppression of nonradiative recombination. Additionally, nanostrain reduced the binding energy of excitons and induced a built-in electric field, which drove electrons toward the strained area, facilitating trion formation and exciton multiplication. Consequently, the photocurrent was significantly enhanced in the patterned regions of the device, which can be efficiently tuned by electrostatic gating. These findings offer a blueprint for advanced nanoscale strain strategies aimed at miniaturizing and integrating multifunctional devices.