Wafer-scale monolayer MoS₂ grown by chemical vapor deposition using a reaction of MoO₃ and H₂S

Monolayer MoS₂ nanosheets are potentially useful in optoelectronics, photoelectronics, and nanoelectronics due to their flexibility, mechanical strength, and direct band gap of 1.89 eV. Experimentalists have studied the synthesis of MoS₂ using chemical vapor deposition (CVD) methods in an effort to fabricate wafer-scale nanofilms with a high uniformity and continuity for practical electronic applications. In this work, we applied the CVD method to a reaction of MoO₃ powder and H₂S gas to grow high-quality polycrystalline monolayer MoS₂ sheets with unprecedented uniformity over an area of several centimeters. The monolayer MoS₂ was characterized using Raman spectroscopy, photoluminescence (PL) spectroscopy, atomic force microscopy (AFM), x-ray photoemission spectroscopy (XPS), and transmission electron microscopy (TEM). The top-gate field-effect transistor prepared with a 30 nm HfO₂ capping layer displayed an electrical mobility of 1 cm² v^-1 s^-1 and an I _on/off of ∼10⁵. This method paves the way for the development of practical devices with MoS₂ monolayers and advances fundamental research.