Scalable Growth of High-Quality Polycrystalline MoS₂ Monolayers on SiO₂ with Tunable Grain Sizes

We report a scalable growth of monolayer MoS2 films on SiO2 substrates by chemical vapor deposition. As-grown polycrystalline MoS2 films are continuous over the entire substrate surface with a tunable grain size from ∼20 nm up to ∼1 μm. An obvious blue-shift (up to 80 meV) of photoluminescence peaks was observed from a series samples with different grain sizes. Back-gated field effect transistors based on a polycrystalline MoS2 film with a typical grain size of ∼600 nm shows a field mobility of ∼7 cm(2)/(V s) and on/off ratio of ∼10(6), comparable to those achieved from exfoliated MoS2. Our work provides a route toward scaled-up synthesis of high-quality monolayer MoS2 for electronic and optoelectronic devices.