Electric Conduction in a Single GaN Nanocolumn

Abstract

We study electric conduction of single GaN nanocolumns, which are synthesized by rf-plasma-assisted molecular beam epitaxy. We attach Ti/Al electrodes to a single GaN nanocolumn on SiO₂/Si substrate by using photolithography, and we succeed in creating the ohmic contacts. We observe the nonlinear conduction at large currents and low temperatures. The temperature dependence of resistivity represents the activation-type one with an activation energy of about 11 meV due to donor levels at high temperatures. At low temperatures, it shows the Mott variable-range hopping conduction. We find a strong positive magnetoresistance effect at low temperatures. [DOI: 10.1380/ejssnt.2012.355]