We investigate the electronic properties of heterostructures based on ultrathin hexagonal boron nitride (h-BN) crystalline layers sandwiched between two layers of graphene as well as other conducting materials (graphite, gold). The tunnel conductance depends exponentially on the number of h-BN atomic layers, down to a monolayer thickness. Exponential behaviour of I-V characteristics for graphene/BN/graphene and graphite/BN/graphite devices is determined mainly by the changes in the density of states with bias voltage in the electrodes. Conductive atomic force microscopy scans across h-BN terraces of different thickness reveal a high level of uniformity in the tunnel current. Our results demonstrate that atomically thin h-BN acts as a defect-free dielectric with a high breakdown field; it offers great potential for applications in tunnel devices and in field-effect transistors with a high carrier density in the conducting channel.
@article{arxiv.1202.0735,
title = {Atomically thin boron nitride: a tunnelling barrier for graphene devices},
author = {Liam Britnell and Roman V. Gorbachev and Rashid Jalil and Branson D. Belle and Fred Schedin and Mikhail I. Katsnelson and Laurence Eaves and Sergey V. Morozov and Alexander S. Mayorov and Nuno M. R. Peres and Antonio H. Castro Neto and Jon Leist and Andre K. Geim and Leonid A. Ponomarenko and Kostya S. Novoselov},
journal= {arXiv preprint arXiv:1202.0735},
year = {2012}
}