Large-Area Synthesis of Highly Crystalline WSe2 Monolayers and Device Applications

摘要

The monolayer transition metal dichalcogenides have recently attracted much attention owing to their potential in valleytronics, flexible and lowpower electronics, and optoelectronic devices. Recent reports have demonstrated the growth of large-size two-dimensional MoS_2 layers by the sulfurization of molybdenum oxides. However, the growth of a transition metal selenide monolayer has still been a challenge. Here we report that the introduction of hydrogen in the reaction chamber helps to activate the selenization of WO_3, where large-size WSe_2 monolayer flakes or thin films can be successfully grown. The top-gated field-effect transistors based on WSe_2 monolayers using ionic gels as the dielectrics exhibit ambipolar characteristics, where the hole and electron mobility values are up to 90 and 7 cm~2/Vs, respectively. These films can be transferred onto arbitrary substrates, which may inspire research efforts to explore their properties and applications. The resistor-loaded inverter based on a WSe_2 film, with a gain of ～13, further demonstrates its applicability for logic-circuit integrations.