Two-Dimensional Monolayer MX₂ (M=Mo, W; X=S, Se) Synthesis, Characterization and Device Applications

Recently two-dimensional layered semiconductors with promising electronic and optical properties, have opened up a new way for applications in atomically thin electronics and optoelectronics. Here we demonstrate large area synthesis of monolayer MoS₂ and WSe₂ using a chemical vapor deposition method at ambient pressure. The atomic analysis of the as-grown monolayer was conducted by spherical-aberration-corrected high resolution scanning transmission electron microscopy and atomic force microscopy. Raman spectroscopy was utilized to identify the monolayer configuration of the as-grown samples. Strong photoluminescence peaks at a visible wavelength were observed at room temperature in the as-grown monolayer samples. The mobility and carrier concentrations were calculated in as-grown monolayer-based transistor devices. The emergency of these two dimensional materials provides grand possibilities for future semiconductor device applications.