Tunable chemical vapor transport growth of 2D Bi2Te3/MoS2 van der Waals heterostructures.

The design of van der Waals (vdW) heterostructures by integrating distinct two-dimensional (2D) materials remains a central strategy for tailoring novel functionalities or enhancing intrinsic properties beyond those of their individual components. In this work, direct epitaxial Bi2Te3/MoS2 vdW heterostructures are synthesized via a sequential chemical vapor transport (CVT) approach. By optimizing the growth parameters, it was observed that the deposition of Bi2Te3 crystals is highly substrate-dependent, with preferential nucleation occurring on MoS2 rather than directly on the sapphire substrate. This selective nucleation may be related to the different surface diffusion characteristics of MoS2 and sapphire. Compared with sapphire, the MoS2 surface provides more favorable diffusion and nucleation conditions for Bi-Te species, promoting preferential lateral growth of Bi2Te3 on MoS2. Furthermore, the lateral size and thickness of Bi2Te3 crystals vary over a broad range as a function of the growth conditions. These findings provide practical insights into parameter-controlled growth of Bi2Te3/MoS2 vdW heterostructures using sequential CVT and highlight their potential for applications in electronic and optoelectronic devices.