Effect of ozone cleaning and annealing on Ti/Al/Pt/Au ohmic contacts on GaN nanowires

Abstract

We report studies on the effect of UV/ozone cleaning on n-type GaN nanowires prior to Ti/Al/Pt/Au ohmic contact deposition and the effect of annealing temperature on the total resistance of the contacted nanowires. The UV/ozone cleaning for periods of 1-5 min reduced surface carbon and oxygen contamination, as determined by Auger electron spectroscopy measurements and led to a specific contact resistivity of 1.8 × 10-2 Ω cm2 after annealing in the range 700-800°C. After subtraction of this contact resistivity from the total resistance of the nanowires, it was found that the ozone treatment reduced the apparent resistivity from 71 to ∼ 0.7 Ω cm. These results show the importance of surface cleaning in extracting the transport properties of GaN nanowires. © 2006 The Electrochemical Society. All rights reserved.