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 × 10 19 atoms/cm 3 . 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.