Geometrically Confined Strain Engineering of MoS

Transition metal dichalcogenides (TMDs) are promising materials for next-generation electronics due to their atomically thin body and exceptional optoelectronic properties. Their ultrathin and stiff nature make them highly sensitive to strain, enabling modulation of lattice and band structures and enhancing carrier mobility via tensile strain. While uniform strain degrades optical properties of MoS2 due to the indirect bandgap, localized strain enhances them through the funnel effect, highlighting the importance of localized strain engineering. In this study, localized strain is achieved in monolayer MoS2 using geometrically confined quasi-van der Waals (qvdW) recrystallization of patterned gold nanopillars. After transferring hBN-encapsulated MoS2 onto the pillars and annealing, the gold recrystallizes into thicker, more crystalline structures, inducing ≈0.15% local tensile strain. This results in a 65-fold increase in photoluminescence (PL) intensity due to the funnel effect, Fabry-Pérot interference, and Purcell effect. Additionally, field-effect mobility is significantly enhanced to 100 cm2V-1s-1, a two-order of magnitude improvement. The work shows a way to apply local strain in MoS2 using geometrically confined gold pillars via qvdW recrystallization, offering a possibility for advanced optoelectronic devices.