Bimodal Dielectric Breakdown in Electronic Devices Using Chemical Vapor Deposited Hexagonal Boron Nitride as Dielectric. (15th January 2018) - Palumbo, Felix
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. Abstract : The dielectric breakdown (BD) in multilayer h‐BN happens layer‐by‐layer, implying thickness modifications of 0.33 nm. During the BD measurements show large jumps that can be fitted by reducing the h‐BN thickness more than 0.33 nm, meaning that one/few h‐BN layers broke. However, other jumps are smaller than the current increase generated by breaking one layer, implying lateral BD propagation.