Selective Synthesis of Bi₂Te₃/WS₂ Heterostructures with Strong Interlayer Coupling

The vertical integration of atomically thin-layered materials to create van der Waals heterostructures (vdWHs) has been proposed as a method to design nanostructures with emergent properties. In this work, epitaxial Bi₂Te₃/WS₂ vdWHs are synthesized via a two-step vapor deposition process. It is calculated that the vdWH has an indirect band gap with a valence band edge that bridges the vdW gap, resulting in a quenched photoluminescence (PL) from the WS₂ monolayer, reduced intensity of its resonance Raman vibrational peaks, improved vertical charge transport, and a decrease in the intensity of second harmonic generation (SHG). Furthermore, it is observed that induced defects strongly influence the nucleation and growth of vdWHs. By creating point defects in WS₂ monolayers, it is shown that the growth of Bi₂Te₃ platelets can be patterned. This work offers important insights into the synthesis, defect engineering, and moiré engineering of an emerging class of two-dimensional (2D) heterostructures.