From h-BN to Graphene: Characterizations of Hybrid Carbon-Doped h-BN for Applications in Electronic and Optoelectronic Devices

Abstract

Hybrid two-dimensional materials consisting of graphene and hexagonal boron nitride (h-BN) have drawn significant interest due to their tunable bandgap and electrical properties. Considering their composition-dependent properties, ohmic current injection and the development of h-BN-based optoelectronic and high-power electronic devices should be achievable by controlling the C concentration. In this study, electrical and optical characterizations of single-crystal h-BN synthesized under high-pressure and high-temperature (HPHT) are conducted by varying C concentrations via post-growth diffusion. Low C-doped h-BN (h-BN:C) with ≈0.1 at% C exhibits nonohmic conduction within a voltage range of ±100 V at all temperatures. In contrast, high h-BN:C (≈10 at% C) containing C domains and graphite/graphene layers shows additional luminescence peaks and initially exhibits nonohmic conduction at 298 K, which then transforms to ohmic conduction after breakdown-like behavior at 598 K. This phenomenon, observed only in the high h-BN:C devices, is attributed to the C-containing conductive path formed on the channel surface through C drift and local dielectric breakdown of h-BN mother phase, indicating that ohmic conduction itself does not guarantee the current flow in the conduction/valence bands in h-BN:C. With these findings, the present thorough and fruitful characterizations are beneficial for the development of h-BN:C-based devices.