Strain-Controlled Growth of Transition Metal Dichalcogenides and its Influence on Ultrafast Exciton Dynamics

Monolayer transition metal dichalcogenides (TMDs) exhibit direct bandgap characteristics despite their ultrathin structure and have drawn considerable interest due to their exceptional electrical and optical properties. Researchers have extensively investigated methods to control these properties, particularly through the application of mechanical strain, motivated by the sensitivity of their electronic band structure to lattice deformation [1]. While most studies have concentrated on tensile strain, which enhances electrical properties, compressive strain has been comparatively understudied because of its adverse effects on carrier mobility. Nevertheless, recent findings suggest that compressive strain can significantly enhance certain optical properties such as photoluminescence (PL). To fully harness this enhancement for practical applications, it is essential to gain a deeper understanding of carrier dynamics in compressively strained lattices, an area that remains underexplored. In this work, we investigate the effects of compressive strain on hot carrier dynamics in monolayer molybdenum disulfide (ML MoS<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>) through steady-state PL measurements and ultrafast optical pump-probe (OPP) spectroscopy.