Abstract
Vertically stacked hexagonal boron nitride (h-BN)/graphene heterostructures present potential applications in electronic, photonic, and mechanical devices, and their interface interaction is one of the critical factors that affect the performances. In this work, the vertical h-BN/graphene heterostructures with high coverage are synthesized by chemical vapor deposition (CVD) of h-BN on Ni substrates followed by segregation growth of graphene at the h-BN/Ni interfaces, which are monitored by in situ surface microscopy and surface spectroscopy. We find that h-BN overlayers can be decoupled from Ni substrates by the graphene interlayers. Furthermore, the h-BN domain boundaries exhibit a confinement effect on the graphene interlayer growth and the lower graphene domains are limited within the upper h-BN domains. This work provides new insights into the formation mechanism and interface interaction of the vertical heterostructures.
Highlights
Graphene shows promising applications in electronic, photonic and mechanical devices due to its excellent physical and chemical properties [1,2,3,4]
Graphene overlayers were synthesized on the Ni substrates by surface segregation of near-surface carbon species as the temperature was decreased from 900 to 650 ◦ C (Figure 1a). μ-LEED patterns acquired from the forming graphene domains display a typical six-fold symmetric structure (Figure 1b) due to the 2D hexagonal lattice [22]
All the results indicate that graphene can be prepared through the surface segregation of carbon species from near-surface regions of the Ni substrates
Summary
Graphene shows promising applications in electronic, photonic and mechanical devices due to its excellent physical and chemical properties [1,2,3,4]. Graphene overlayers need to be transferred onto SiO2 surfaces for device applications, while performances of the graphene-based devices are often limited by the SiO2 surfaces such as surface roughness and charging effect [5,6,7]. Integration of h-BN and graphene in a vertically stacked way may achieve high-performance graphene-based devices, in which the atomically flat and dangling-bond-free h-BN surface enables them to avoid the charge trapping at the interfaces [10,11]. Construction of well-defined h-BN/graphene heterostructures becomes critical for future potential applications. Growing h-BN and graphene in sequence on Cu or Ni substrate has been attempted [12,13,14,15,16]
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