Large-area epitaxial growth of curvature-stabilized ABC trilayer graphene

Zhaoli Gao,Qicheng Zhang,Jose Avila,Julian Gebhardt,Andrew M Rappe,Chaoyu Chen,A T Charlie Johnson,William M Parkin,Feng Wang,Sheng Wang,Maria C Asensio,Marija Drndić,David J Srolovitz,Hemian Yi,Joel Berry,Zhengtang Luo,James M Kikkawa,Sebastian Hurtado-Parra

doi:10.1038/s41467-019-14022-3

Abstract

The properties of van der Waals (vdW) materials often vary dramatically with the atomic stacking order between layers, but this order can be difficult to control. Trilayer graphene (TLG) stacks in either a semimetallic ABA or a semiconducting ABC configuration with a gate-tunable band gap, but the latter has only been produced by exfoliation. Here we present a chemical vapor deposition approach to TLG growth that yields greatly enhanced fraction and size of ABC domains. The key insight is that substrate curvature can stabilize ABC domains. Controllable ABC yields ~59% were achieved by tailoring substrate curvature levels. ABC fractions remained high after transfer to device substrates, as confirmed by transport measurements revealing the expected tunable ABC band gap. Substrate topography engineering provides a path to large-scale synthesis of epitaxial ABC-TLG and other vdW materials.

Highlights

The properties of van der Waals materials often vary dramatically with the atomic stacking order between layers, but this order can be difficult to control
Van der Waals materials composed of individual atomic layers held together by van der Waals (vdW) interactions have attracted considerable attention due to their unique physical properties that can be tuned by manipulating interlayer twisting angles[1,2,3], creating heterostructures[4,5], and controlling stacking configurations[6,7]
We develop a model for how substrate topography and, the curvature of surface corrugations, plays a principal role in stabilizing ABC-Trilayer graphene (TLG) during growth

Summary

Introduction

The properties of van der Waals (vdW) materials often vary dramatically with the atomic stacking order between layers, but this order can be difficult to control. A critical experimental challenge is to develop large-area synthesis of highquality ABC-TLG20–22, which would catalyze a wide range of studies of the unexplored physics and applications of this unique material system To answer this need, we develop a high-yield chemical vapor deposition (CVD) process to grow epitaxial TLG on Ni–Cu gradient alloy substrates. Transmission electron microscopy is used to assess the atomic structure of the material, and it reveals the existence of quasi-lamellar patterns of ABA-TLG and ABC-TLG Based on these observations, we develop a model for how substrate topography and, the curvature of surface corrugations, plays a principal role in stabilizing ABC-TLG during growth. Our finding that substrate topography can be used to stabilize the ABC stacking structure may enable development of related CBSS synthesis strategies for other vdW epitaxies with specific interlayer stacking configurations and study concerning their physical properties and applications

Methods

Results

Conclusion