Atomically thin boron nitride: a tunnelling barrier for graphene devices

TL;DR

This study demonstrates that atomically thin hexagonal boron nitride acts as an effective, uniform, and defect-free tunneling barrier with exponential conductance dependence on layer number, suitable for advanced electronic devices.

Contribution

It provides experimental evidence that monolayer and few-layer h-BN serve as high-quality tunneling barriers with predictable exponential conductance behavior in graphene-based heterostructures.

Findings

Tunnel conductance decreases exponentially with h-BN layer number

h-BN exhibits high uniformity and defect-free dielectric properties

Potential for use in tunnel devices and high-density field-effect transistors

Abstract

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.