From <i>h</i>‐BN to Graphene: Characterizations of Hybrid Carbon‐Doped <i>h</i>‐BN for Applications in Electronic and Optoelectronic Devices
Supawan Ngamprapawat, Jimpei Kawase, Tomonori Nishimura, Kenji Watanabe, Takashi Taniguchi, Kosuke Nagashio
Abstract
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.