Electron Tunneling through Ultrathin Boron Nitride Crystalline Barriers

TLDR

The study investigates the electronic properties of ultrathin hexagonal boron nitride layers sandwiched between graphite, graphene, or gold electrodes. The authors probe tunneling through these h‑BN barriers by measuring current across varying layer thicknesses and performing conductive AFM scans. They find that the tunnel current decays exponentially with each additional h‑BN layer down to a monolayer, the current is highly uniform across terraces, h‑BN behaves as a defect‑free dielectric with a high breakdown field, and it shows promise for tunnel devices and high‑carrier‑density field‑effect transistors.

Abstract

We investigate the electronic properties of ultrathin hexagonal boron nitride (h-BN) crystalline layers with different conducting materials (graphite, graphene, and gold) on either side of the barrier layer. The tunnel current depends exponentially on the number of h-BN atomic layers, down to a monolayer thickness. 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.