Epitaxial Intercalation Growth of Scalable Hexagonal Boron Nitride/Graphene Bilayer Moiré Materials with Highly Convergent Interlayer Angles

Abstract

Vertically stacked two-dimensional van der Waals (vdW) heterostructures with specific interlayer angles exhibit peculiar physical properties. Nowadays, most of the stacked layers are fabricated by mechanical exfoliation followed by precise transfer and alignment with micrometer spatial accuracy. This stringent ingredient of sample preparation limits the productivity of device fabrication and the reproducibility of device performance. Here, we demonstrate the one-pot chemical vapor deposition growth of hexagonal boron nitride (hBN)/graphene bilayers with a high-purity moiré phase. The epitaxial intercalation of graphene under a hydrogen-terminated hBN template leads to convergent interlayer angles of less than 0.5°. The near 0° stacking angle shows almost 2 orders of magnitude higher likelihood of occurrence compared with angles larger than 0.5°. The bilayers show a substantial enhancement of carrier mobility compared with monolayer graphene owing to protection from the top hBN layer. Our work proposes a large-scale fabrication method of hBN/graphene bilayers with a high uniformity and controlled interlayer rotation and will promote the production development for high-quality vdW heterostructures.

Growth Mechanism of High-Quality hBN Monolayers on Cu through Chemical Vapor Deposition with Inductively Coupled Plasma

“…Since hydrogen stabilizes the edges of hBN grains rather than the Cu surface, the energy is low enough for the B and N adatoms to locate between the Cu surface and hBN layers. Hence, they can diffuse underneath the as-grown hBN layer to form the multilayer hBN . So far, the growth mechanism of multilayer hBN still needs to be further explored.…”

“…Hence, they can diffuse underneath the as-grown hBN layer to form the multilayer hBN. 32 So far, the growth mechanism of multilayer hBN still needs to be further explored.…”

Challenges and opportunities in 2D heterostructures for electronic and optoelectronic devices

“…However, the progress in this direction is not promising as most of the structures obtained either have the R-type (0°) stacking orientations or the H-type (60°) stacking orientations, as they are energetically favorable in the CVD growth process ( Liu et al., 2014 ). Few strategies, including heterosite nucleation ( Sun et al., 2021 ), temperature triggered misalignment ( Omambac et al., 2019 ), metal-semiconductor stacking ( Li et al., 2020a ), epitaxial intercalation of graphene under hydrogen-terminated hBN template ( Wang et al., 2021a ), are recently reported that showed the potential of CVD to generate moiré phase. Still, stringent control on interlayer twist angle is challenging and needs to be encountered soon.…”

Stacking Order Effects on the Energetic Stability and Electronic Properties of $N$-Doped Graphene/H-Bn Van Der Waals Heterostructures on Sic(0001)

“…It is worth noting that intercalation has also been observed during epitaxial growth of h-BN/graphene heterostructures on metals. [9,10] If, on the one hand, intercalation during vdW epitaxy is unwanted, it also represents a very promising path for the controlled synthesis of novel material systems. In fact, Al Balushi et al [11] developed an experimental scheme that enhanced the intercalation of Ga and N species below epitaxial graphene on SiC(0001), which allowed for the realization of a 2D-like GaN phase encapsulated between graphene and SiC(0001).…”