Defect-Mediated In-Plane Electrical Conduction in Few-Layer sp(2)-Hybridized Boron Nitrides

Abstract

In-plane electrical conduction in sp(2)-hybridized boron nitride (sp(2)-BN) is presented to explore a huge potential of sp(2)-BN as an active material for electronics and ultraviolet optoelectronics. Systematic investigation on temperature -dependent current-voltage (I-V) characteristics of a few-layer sp(2)-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 (V-N) are proposed as the origin of the shallow traps mediating the in-plane conduction in the sp(2)-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 V-N can be an alternative and better approach for the n-type doping of the sp(2)-BN film rather than ineffective conventional substitutional doping methods.