Effect of Ti thickness on contact resistance between GaN nanowiresand Ti∕Au electrodes

Abstract

We demonstrate the effect of Ti thickness on the contact resistance between GaN nanowires and Ti∕Au electrodes. We have carried out systematic characterization of many GaN nanowires contacted by various Ti∕Au electrodes. We conclude that the average resistance is reduced by almost six orders of magnitude as Ti thickness increases from 0 to 20nm, and the resistance value then saturates when the Ti thickness further increases. Our observation can be explained by the formation of TiOx through the reaction of surface oxide and the Ti layer. Scanning Auger microscopy of the Au∕Ti∕SiO2 interface also supports this explanation.