Microwave-assisted synthesis of group 5 transition metal dichalcogenide thin films†
Layer-structured transition metal dichalcogenide (TMDC) thin films have recently emerged as a new class of materials holding great promise as novel catalytic materials and for other electronic applications. Although many successes in the synthesis of group 6 TMDCs have been reported, the synthesis of group 5 TMDCs has rarely been investigated. In this study, we have developed a one-step solution phase synthesis of group 5 TMDC films directly grown on a substrate. As example materials, we synthesized NbS2, NbSe2, VSe2, and VTe2 films directly on Si wafers. We used microwave-assisted synthesis employing thermolysis of the precursors exclusively at the surface of the electrically conductive Si wafer substrate. Microwave absorption and heat loss of the substrate was experimentally and theoretically analyzed, and the microwave conditions for the synthesis are clarified. We have performed the elemental and structural analysis of the synthesized films, and investigated the growth kinetics of the synthesized films. This study paves a robust way for the synthesis of various group 5 TMDC films in solution phases.