Direct\nChemical Vapor Deposition Growth and Band-Gap\nCharacterization of MoS₂/<i>h</i>‑BN van der Waals Heterostructures on Au Foils

Abstract

Stacked transition-metal dichalcogenides\non hexagonal boron nitride\n(<i>h</i>-BN) are platforms for high-performance electronic\ndevices. However, such vertical stacks are usually constructed by\nthe layer-by-layer polymer-assisted transfer of mechanically exfoliated\nlayers. This inevitably causes interfacial contamination and device\nperformance degradation. Herein, we develop a two-step, low-pressure\nchemical vapor deposition synthetic strategy incorporating the direct\ngrowth of monolayer <i>h</i>-BN on Au foil with the subsequent\ngrowth of MoS₂. In such vertical stacks, the interactions\nbetween MoS₂ and Au are diminished by the intervening <i>h</i>-BN layer, as evidenced by the appearance of photoluminescence\nin MoS₂. The weakened interfacial interactions facilitate\nthe transfer of the MoS₂/<i>h</i>-BN stacks from\nAu to arbitrary substrates by an electrochemical bubbling method.\nScanning tunneling microscope/spectroscopy characterization shows\nthat the central <i>h</i>-BN layer partially blocks the\nmetal-induced gap states in MoS₂/<i>h</i>-BN/Au\nfoils. The work offers insight into the synthesis, transfer, and device\nperformance optimization of such vertically stacked heterostructures.