Realizing Large-Scale, Electronic-Grade Two-Dimensional Semiconductors
Atomically thin transition metal dichalcogenides (TMDs) are of interest for next generation electronics and optoelectronics. Here, we demonstrate device-ready synthetic tungsten diselenide (WSe2) via metal-organic chemical vapor deposition and provide key insights into the phenomena that control the properties of large-area, epitaxial TMDs. When epitaxy is achieved, the sapphire surface reconstructs, leading to strong 2D/3D (i.e., TMD/substrate) interactions that impact carrier transport. Even with 2D/3D coupling, transistors utilizing transfer-free epitaxial WSe2/sapphire exhibit ambipolar behavior with excellent on/off ratios (~107), high current density (1-10 μA·μm-1) and good FET mobility (~ 30 cm2·V-1·s-1) at room temperature. This work establishes that realization of electronic-grade epitaxial TMDs must consider the impact of the substrate and 2D/3D interface as leading factors in electronic performance.