Large scale graphene/h-BN heterostructures obtained by direct CVD growth of graphene using high-yield proximity-catalytic process

Abstract

We present a transfer-free process for the rapid growth of graphene on hexagonal boron nitride (h-BN) flakes via chemical vapor deposition. The growth of graphene on top of h-BN flakes is promoted by the adjacent copper catalyst. Full coverage of half-millimeter-sized h-BN crystals is demonstrated. The proximity of the copper catalyst ensures high-yield with a growth rate exceeding 2 μm min −1 , which is orders of magnitude above what was previously reported on h-BN and approaches the growth rate on copper. Optical and electron microscopies along with Raman mapping indicates a two-step growth mechanism, leading to the h-BN being first covered by discontinuous graphitic species prior to the formation of a continuous graphene layer. Electron transport measurements confirm the presence of well-crystallized and continuous graphene, which exhibits a charge carrier mobility that reaches 2.0×10 4 cm 2 V −1 s −1 . Direct comparison of the mobility with graphene/h-BN devices obtained by wet transfer confirms an enhanced charge neutrality for the in situ grown structures.

Electron cooling with graphene-insulator-superconductor tunnel junctions and applications to fast bolometry

“…This condition in general holds experimentally, as indicated by the presence of a residual charge density n 0 [63]. The lowest values of residual charge density can be obtained in high quality hBN/G/hBN heterostructures and unlikely goes below n 0 ≈ 5 × 10 10 cm −2 [74]; this value corresponds to the lowest value of Fermi energy that is E F = v F √ πn 0 ≈ 26 meV, that is at least 100 times the value of ∆ 0 ≈ 0.2 meV, confirming the condition for graphene Fermi energy ∆ 0 E F . We remark that the BCS theory provides that ∆(T ) < ∆ 0 , implying that E F ∆ 0 > ∆(T ), i.e.…”

Linear scaling quantum transport methodologies

“…Grain boundaries are a natural result of chemical vapor deposition (CVD), which is the most useful approach for the large-scale production of graphene (Zhang et al, 2013b). During the CVD growth process, graphene grains nucleate and grow at random positions and orientations, resulting in a polycrystalline structure when growth is complete (Arjmandi-Tash et al, 2018). The grain boundaries that form at the interface of the graphene grains typically consist of disordered arrays of carbon pentagons, heptagons, and octagons.…”

In situ growth of graphene on hexagonal boron nitride for electronic transport applications

“…A new approach in the growth of graphene on non-catalyst materials such as h-BN was introduced recently. 28 Unlike previous approaches, the growth is performed on h-BN flakes which are pre-exfoliated on copper foil (Fig. 2d).…”