Synthesis of large monolayer single crystal MoS2 nanosheets with uniform size through a double-tube technology

Two-dimensional MoS2 attracts much attention because of its potential application in electronic and optoelectronic devices at present. However, the preparation of large and uniform single crystal MoS2 nanosheets is still a challenge, which restricts its further application. Herein, monolayer single crystal MoS2 nanosheets with large and uniform grain size have been synthesized by chemical vapor deposition using a double-tube system. Within the main growth area, the grain size reaches 146 μm on the substrate of SiO2/Si, and the portion of MoS2 nanosheets with grain size between 50 μm and 100 μm is up to 78%. Meanwhile, the grain size keeps constant in the direction perpendicular to the tubes and changes slightly in the parallel direction. This is attributed to the concentration distribution of intermediate product MoO3−x in the one-side sealed inner tube set in a quartz tube, i.e., the double-tube system, which provides a way to the controllable and uniform synthesis of large monolayer single crystal MoS2 ...