Substrate-Induced Strain Upshot on the Optical and Optoelectronic Properties of Trilayer MoS₂

The characteristics of 2D layered MoS₂ film are highly dependent on the substrate it is grown on which leaves us privileged to achieve unique and tunable properties. In this study, trilayer MoS₂ films have been grown on fused quartz, crystalline quartz (z-cut), sapphire (0001), and silicon (100) substrates. MoS₂ film grows as freestanding on amorphous fused quartz, while it experiences an in-plane tensile strain on the sapphire and silicon. Unprecedentedly we show that due to a large mismatch in the lattice parameter as well as in the thermal expansion coefficient, MoS₂ grows with a significant compressive strain both along both in-plane on the crystalline quartz. The developed strain causes an alteration in its electronic structure, causing a 30 meV blue shift in the photoluminescence peak and an increased band gap in addition to fewer sulphur vacancies. Comparatively, the film on sapphire having tensile strain along the in-plane exhibits more sulphur vacancies increasing the electron density. The photoresponse time, photosensitivity, and charge separation distinctly vary for the MoS₂ films depending on the substrates. This study underscores the influence of substrate on MoS₂ film opening further research scopes on tunable properties owing to 2D layer-substrate interactions.