Current Injection into Single-Crystalline Carbon-Doped h‑BN toward Electronic and Optoelectronic Applications

The difficulty of current injection into single-crystalline hexagonal boron nitride (h-BN) has long hindered the realization of h-BN-based high-performance electronic and optoelectronic devices. Here, with the contact formed by Ar plasma treatment, Ni/Au metal deposition, and subsequent high-temperature annealing, we demonstrate current injection into single-crystalline h-BN with a C doping level of ∼1.5 × 10¹⁹ atoms/cm³. A comparison to the current flow during the dielectric breakdown of h-BN clearly verifies our current injection. The devices show non-Ohmic conduction for all measured temperatures (20–598 K). Analysis of activation energies for carrier transport suggests nearest-neighbor-hopping-assisted Poole–Frenkel (PF) conduction in the highly defective h-BN at the contact region. The estimated dominant defect level with the range of 240–720 meV is much smaller than the Schottky barrier height at the metal/h-BN interface, supporting the effective contact formation for current injection. Moreover, structural and chemical characterizations at the contact suggest that an interaction between Ni and defective h-BN introduces defect states in the gap, assisting the current injection. In contrast, the characterizations confirm the well-retained high crystallinity of h-BN in the channel, indicating the potential of the present contact formation method for the future development of high-performance h-BN-based devices.