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

Hadi Arjmandi-Tash,Hadi Arjmandi-Tash,Hadi Arjmandi-Tash,Takashi Taniguchi,Cecile Berne,Dipankar Kalita,Dipankar Kalita,Dipankar Kalita,John Landers,John Landers,John Landers,Zheng Han,Zheng Han,Zheng Han,Goutham Nayak,Goutham Nayak,Goutham Nayak,Vincent Bouchiat,Vincent Bouchiat,Vincent Bouchiat,Nedjma Bendiab,Nedjma Bendiab,Nedjma Bendiab,Riadh Othmen,Riadh Othmen,Riadh Othmen,Johann Coraux,Johann Coraux,Johann Coraux,Laëtitia Marty,Laëtitia Marty,Laëtitia Marty,Kenji Watanabe

doi:10.1088/2515-7639/aac66e

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 × 104 cm2 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.

Highlights

Hexagonal boron nitride (h-BN) has been experimentally identified as an outstanding dielectric material for supporting graphene [1]. h-BN is a large bandgap semiconductor and its 2D lattice shares the same symmetry and almost identical lattice constant with graphene
A histogram of the height distribution measured inside this window (figure 1(h)) reveals an rms roughness of ∼4 Å, which is matching with the roughness of graphene on h-BN found in seminal works dealing with manual transferred stacks based on stamping technique [1]
We found that after a 20 min growth, graphene covers inner areas of h-BN flakes at least 100 μm from crystal edges (as shown in figures 2(d)–(g), in which a half-millimeter flake is fully covered with graphene); secondly, when performing interrupted growth of 180 s duration, the complementary scanning electron microscopy (SEM) and Raman analyses reveal that the edge of h-BN flakes are covered by graphene on a distance of ∼4 to ∼8 μm, which provides an estimation for the growth rate between 1.5 and 3 μm min−1, a speed significantly exceeding the values recently reported in the case of direct-growth onto h-BN placed on the surface of silicon carbide [27] or involving deposition using molecular beam epitaxy [19, 28]

Summary

Introduction

Hexagonal boron nitride (h-BN) has been experimentally identified as an outstanding dielectric material for supporting graphene [1]. h-BN is a large bandgap semiconductor and its 2D lattice shares the same symmetry and almost identical lattice constant with graphene. H-BN is a large bandgap semiconductor and its 2D lattice shares the same symmetry and almost identical lattice constant with graphene It possesses a smooth and charge-neutral surface [2]. In most studies involving graphene embedded within two h-BN layers, the heterostructures were prepared by direct transfer of flakes using processes relying on physical adhesion via van der Waals interaction. This implies that graphene (exfoliated or chemically grown) is firstly isolated and transferred onto h-BN host flakes. The concept has recently been extended to less stringent conditions [15], and in

Methods

Results

Conclusion