Near ideal, high barrier, Au-nGaN Schottky contacts

Gold Schottky contacts formed in situ on n-type GaN after a 600 degreesC an neal have been characterized by current-voltage (I-V) measurements and x-ra y photoelectron spectroscopy (XPS). The mean Schottky barrier height and lo west ideality factor were found to be 1.24 eV and 1.03, respectively, as me asured by I-V. The highest barrier measured was 1.35 eV with an ideality fa ctor of 1.12. XPS data showed that the 600 degreesC anneal produced an upwa rd band bending of 0.35 eV, the subsequent gold deposition caused a further band bending of 0.25 eV in the same direction. Our results can be interpre ted in terms of the Cowley-Sze model and suggest a high density of acceptor states at the bare GaN surface.