UC Berkeley

Transition metal dichalcogenides (TMDCs) have shown exceptional optoelectronic properties that can potentially substitute conventional silicon-based devices and be utilized in sensors and energy devices. To exploit their wide array of potential applications, it is necessary to develop methods capable of on demand, location selective, and tunable formation of structures of arbitrary shape. Here, we demonstrated high-speed direct writing of MoSe2 by laser-induced selenization process in vacuum or ambient environment. Laser irradiation on predeposited Se/Mo multilayer promptly forms polycrystalline MoSe2 in a site-selective manner without use of photomask and toxic gas. In situ reflectance measurement and temperature simulation identified distinct characteristic processing stages, revealing that the time required for synthesizing â20 nm-thick MoSe2 polycrystal film is of the order of 10-3s, which is significantly faster than the conventional selenization process using furnace annealing. We believe that the laser synthesis of MoSe2 demonstrated in this study is of general applicability and therefore offers a simple and straightforward route for obtaining arbitrary patterns in TMDCs.