Enhanced Photoluminescence and Optoelectronic Performance for Wrinkled 2D MoS2 Through Strain Regulation

Abstract

Strain regulation for 2D molybdenum disulfide (MoS₂) has become an active topic. Here, the pre-stretching method fabricates wrinkled 2D MoS₂ field-effect transistors (FETs), which exhibit an ultra-high on/off ratio (8.3 × 10⁷). The impacts of wrinkles on enhanced photoluminescence (PL) and optoelectronic performance are systematically investigated by experiments and simulations. High-resolution transmission electron microscopy (HRTEM) and Raman spectroscopy results indicate that the wrinkled 2D MoS₂ is subjected to a compressive strain (layer space decreases from 6.2 to 6.1 Å), alongside a redshift in the Raman signals. The PL intensity of wrinkled 2D MoS₂ shows a significant enhancement of up to 133% at the strain of 1.683%. Furthermore, the PL results suggest that the wrinkles can effectively adjust the bandgap (30 meV/%). The on/off ratio of the wrinkled FET is an order of magnitude higher than that of flat FET (2.0 × 10⁶). Photoelectric measurements show that the dark and photocurrents of the wrinkled FET are enhanced by 200% and 47% at a gate voltage of 40 V, meanwhile, the response time is increased by 70%. Density-functional theory (DFT) and technology computer-aided design (TCAD) simulation are closely aligned with the experimental results for wrinkled 2D MoS₂.