Direct Chemical Vapor Deposition Growth and Band-Gap Characterization of MoS₂/<i>h</i>-BN van der Waals Heterostructures on Au Foils

Abstract

Stacked transition-metal dichalcogenides on hexagonal boron nitride (h-BN) are platforms for high-performance electronic devices. However, such vertical stacks are usually constructed by the layer-by-layer polymer-assisted transfer of mechanically exfoliated layers. This inevitably causes interfacial contamination and device performance degradation. Herein, we develop a two-step, low-pressure chemical vapor deposition synthetic strategy incorporating the direct growth of monolayer h-BN on Au foil with the subsequent growth of MoS₂. In such vertical stacks, the interactions between MoS₂ and Au are diminished by the intervening h-BN layer, as evidenced by the appearance of photoluminescence in MoS₂. The weakened interfacial interactions facilitate the transfer of the MoS₂/h-BN stacks from Au to arbitrary substrates by an electrochemical bubbling method. Scanning tunneling microscope/spectroscopy characterization shows that the central h-BN layer partially blocks the metal-induced gap states in MoS₂/h-BN/Au foils. The work offers insight into the synthesis, transfer, and device performance optimization of such vertically stacked heterostructures.