Gold Schottky contacts formed in situ on n-type GaN after a 600 °C anneal have been characterized by current-voltage (I-V) measurements and x-ray photoelectron spectroscopy (XPS). The mean Schottky barrier height and lowest ideality factor were found to be 1.24 eV and 1.03, respectively, as measured by I-V. The highest barrier measured was 1.35 eV with an ideality factor of 1.12. XPS data showed that the 600 °C anneal produced an upward 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 interpreted in terms of the Cowley-Sze model and suggest a high density of acceptor states at the bare GaN surface.
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Maffeïs et al. (2000) studied this question.