Bimodal Dielectric Breakdown in Electronic Devices Using Chemical Vapor Deposited Hexagonal Boron Nitride as Dielectric

Abstract

Multilayer hexagonal boron nitride (h-BN) is an insulating 2D material that shows good interaction with graphene and MoS2, and it is considered a very promising dielectric for future 2D-materials-based electronic devices. Previous studies analyzed the dielectric properties of thick (>10 nm) mechanically exfoliated h-BN nanoflakes (diameter < 20 μm) via conductive atomic force microscopy and applying very high voltages (>10 V); however, these methods are not scalable. In this work, the first device-level reliability study of large area h-BN dielectric stacks (grown via chemical vapor deposition) is presented, and the complete dielectric breakdown (BD) process is described. The experiments and calculations indicate that the BD process in metal/h-BN/metal devices starts with a progressive current increase across the h-BN stack until current densities up to 0.1 A cm−2 are reached. After that, the currents increase by sudden steps, which can be large (>1 order of magnitude, related to the BD of one/few h-BN layers) or small (<1 order of magnitude, related to the lateral propagation of the BD). The bimodal BD process of h-BN here presented (which cannot be detected via conductive atomic force microscopy) is essential to understand the reliability of 2D-material-based electronic devices using h-BN as dielectric.