Real time optical observation and control of transition metal dichalcogenide synthesis

Synthesis of atomically thin transition metal dichalcogenide (TMC) crystals have attracted tremendous amount of attention in the past few years. The common technique for the synthesis is to use a tubular split furnace with gas and exhaust connections. The precursors and the target substrate are placed in the hot zone of the furnace. The major shortcoming of the setup is the inaccessibility of the growth for real time characterizations. Thus, the growth has to be shut down blindly and the intermediate products that may lead to the growth has to be analysed later. Here, we developed a compact CVD chamber that allows real time optical observation of the crystal synthesis. Among our findings, for the first time we observed the formation of the atomically thin TMCs in real time, and characterized the various synthesis routes for several TMCs. By using the unique abilities we have with our chamber, we also observed the formation of the heterostructures. Furthermore, we demonstrated a directed synthesis of TMCs with prepatterned structures on a substrate.