AC conductivity of hBN thin film on Si(111): A high temperature study

Abstract

Boron nitride (BN) is a layered two-dimensional insulator with excellent chemical, thermal, mechanical, and optical properties. We present a comprehensive characterization of hBN as a dielectric thin film using a high impedance measurement system (100 T Ω ) to reveal the AC conductivity and dielectric properties of reactively RF sputtered 200 nm thick films to 480 °C. The experimental results are analyzed with reference to various theoretical models proposed for electrical conduction in disordered or amorphous semiconductors. Electrical measurements indicate that the mechanism behind hBN AC conductivity is via correlated barrier hopping (CBH) and is assigned to localized states at the Fermi level, where N(EF) ∼ 1018 eV−1 cm−3. Our measurements also reveal a σdc component, with resistance reducing from ∼1010 Ω (50 °C) to 3 × 108 Ω (480 °C). Single RC parallel circuit fits to Cole–Cole plots are achieved signifying a sole conduction path with capacitance values of ∼8 × 10−11 F. These findings may be of interest to material and device scientists and could open new pathways for hBN both as a dielectric material encapsulant and for semiconductor device applications including high-temperature operation.