Controlling Grain Size and Continuous Layer Growth in Two-Dimensional MoS2 Films for Nanoelectronic Device Application

We report that control over the grain size and lateral growth of monolayer MoS₂ film, yielding a uniform large-area monolayer MoS₂ film, can be achieved by submitting the SiO₂ surfaces of the substrates to oxygen plasma treatment and modulating substrate temperature in chemical vapor deposition (CVD) process. Scanning electron microscopy and atomic force microscopy images and Raman spectra revealed that the MoS₂ lateral growth could be controlled by the surface treatment conditions and process temperatures. Moreover, the obtained monolayer MoS₂ films showed excellent scalable uniformity covering a centimeter-scale SiO₂ /Si substrates, which was confirmed with Raman and photoluminescence mapping studies. Transmission electron microscopy measurements revealed that the MoS₂ film of the monolayer was largely single crystalline in nature. Back-gate field effect transistors based on a CVD-grown uniform monolayer MoS₂ film showed a good current on/off ratio of ~10⁶ and a field effect mobility of 7.23 cm²/V·s. Our new approach to growing MoS₂ films is anticipated to advance studies of MoS₂ or other transition metal dichalcogenide material growth mechanisms and to facilitate the mass production of uniform high-quality MoS₂ films for the commercialization of a variety of applications.