Controllable One-Pot Growth of MoSe₂/WSe₂ Lateral and Vertical Heterostructures by Facile Chemical Vapor Deposition

The controllable growth of single-crystal lateral and vertical heterostructures based on two-dimensional transition metal dichalcogenides (TMDs) is more difficult than the preparation of ordinary TMDs. In this study, we develop a facile chemical vapor deposition (CVD) scheme for the preparation of large-area and single-crystal WSe2/MoSe2 heterostructures on amorphous SiO2/Si substrates. In addition to using a customized temperature profile and introducing H-2 flow, we also make a facile placement for the transition metal precursors: the Mo and W sources are placed on either side below the growing substrate for the growth of lateral heterostructures, while the Mo source is stacked with the W source for the growth of vertical heterostructures. The combination of these strategies helps the controllable lateral (or vertical) epitaxy of different TMD materials. Both lateral and vertical WSe2/MoSe2 heterostructures are of high quality and homogeneity, as revealed by optical and structural characterizations. The photodetectors based on lateral heterostructures at self-driven mode exhibit a maximum photoresponsivity of 45 A/W, a detectivity of 9.4 x 10(14) Jones, and a fast response time of 22.5 ms. This one-pot and facile CVD epitaxy strategy may pave the way to fabricating large-area and high-quality lateral and vertical TMD heterostructures, which are of great importance in electronics and optoelectronics.