RESUMO
Six types of hexagonal boron nitride are investigated by terahertz time-domain spectroscopy. The loss coefficient is shown to be linear with porosity, while variations in refractive index indicate the distribution of porosity within the structure. Pyrolytic boron nitride is demonstrated to be suitable as a terahertz optical material.
RESUMO
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.