Defect-Mediated In-Plane Electrical Conduction in Few-Layer sp2-Hybridized Boron Nitrides

In-plane electrical conduction in sp2-hybridized boron nitride (sp2-BN) is presented to explore a huge potential of sp2-BN as an active material for electronics and ultraviolet optoelectronics. Systematic investigation on temperature-dependent current–voltage (I–V) characteristics of a few-layer sp2-BN grown by metal–organic vapor-phase epitaxy reveals two types of predominant conduction mechanisms that are Ohmic conduction at the low bias region and space-charge-limited conduction at the high bias region. From the temperature-dependent I–V characteristics, two shallow traps with activation energies of approximately 25 and 185 meV are observed. On the basis of the near-edge X-ray absorption fine-structure spectroscopy, boron–boron (B–B) homoelemental bonding which can be related to grain boundary and nitrogen vacancy (VN) are proposed as the origin of the shallow traps mediating the in-plane conduction in the sp2-BN layer. In addition, a drastic enhancement in the electrical conductivity is observed with the increasing amount of VN that acts as a donor, implying that controlled generation of VN can be an alternative and better approach for the n-type doping of the sp2-BN film rather than ineffective conventional substitutional doping methods