Structural and electronic properties of 2D (graphene, hBN)/H-terminated diamond (100) heterostructures

Abstract

We report a first-principles study of the structural and electronic properties of two-dimensional (2D) layer/hydrogen-terminated diamond (100) heterostructures. Both the 2D layers exhibit weak van-der-Waals (vdW) interactions and develop rippled configurations with the H-diamond (100) substrate to compensate for the induced strain. The adhesion energy of the hexagonal boron nitride (hBN) layer is slightly higher, and it exhibits a higher degree of rippling compared to the graphene layer. A charge transfer analysis reveals a small amount of charge transfer from the H-diamond (100) surface to the 2D layers, and most of the transferred charge was found to be confined within the vdW gap. In the graphene/H-diamond (100) heterostructure, the semi-metallic characteristic of the graphene layer is preserved. On the other hand, the hBN/H-diamond (100) heterostructure shows semiconducting characteristics with an indirect bandgap of 3.55 eV, where the hBN layer forms a Type-II band alignment with the H-diamond (100) surface. The resultant conduction band offset and valence band offset are 0.10 eV and 1.38 eV, respectively. A thin layer of hBN offers a defect-free interface with the H-diamond (100) surface and provides a layer-dependent tunability of electronic properties and band alignment for surface-doped diamond field effect transistors.

Ab initio study of the effect of 2D layer rippling on the electronic properties of 2D/H-terminated diamond (100) heterostructures

“…Using the HSE functional, the energy gaps of the strained-planar and wavy layers increased to 5.34 eV and 5.52 eV, respectively. As compared to the PBE functional, the HSE calculations show a 20-35% increase in the magnitude of the gap, which is consistent with our previous study [10] and Refs. [39,40].…”

“…As the next step, we found the optimal vdW spacing between the constituent layer and the H-diamond surface. The procedure for finding the optimum vdW spacing is fully discussed in our earlier publication [10]. Accordingly, structures with a vdW spacing of 3.0 Å were found to yield convergence.…”

“…The slightly shorter bond length in the graphene means that it has a larger tensile strain but smaller compressive than the hBN, and as a result produces ripples with a smaller amplitude. Further details of the relaxation and structural transformation are provided in our earlier article [10].…”

“…Though rich in chemistry and compatible to the existing device fabrication technology, these oxide-based acceptor layers suffer from the higher degree of surface inhomogeneity and dangling bonds, leading to lower channel mobility and charge density. In an earlier work [10], we reported that a sheet of hBN or graphene interfaced with the H-diamond (100) surface-the technologically relevant surface for diamond-based electronic www.mrs.org/jmr © The Author(s) 2021 2 Invited Paper devices-could act as a protective layer that preserves the p-type bulk-like conductivity in the H-diamond (100) surface. During the analysis of the structural alignment of the 2D layers on the H-diamond (100) surface, we also noticed a strain-mediated 2D layer corrugation or rippling.…”

Graphene – Diamond Nanomaterials: A Status Quo Review

“…A first-principles study of the structural and electronic properties of two-dimensional 2D layer/hydrogen-terminated diamond (100) heterostructures was reported by Mirabedini et al [109]. Both the 2D layers exhibit weak van der Waals interactions and develop rippled configurations with the H-diamond (100) substrate to compensate for the induced strain.…”