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Title: Influence of premetallization surface treatment on the formation of Schottky Au-nGaN contacts
Author: Maffeis, Thierry Gabriel Georges
Simmonds, Michael C.
Clark, S. A.
Peiró Martínez, Francisca
Haines, Paul
Parbrook, P. J.
Keywords: Propietats elèctriques
Ciència dels materials
Electric properties
Materials science
Issue Date: 15-Sep-2002
Publisher: American Institute of Physics
Abstract: The influence of premetallization surface preparation on the structural, chemical, and electrical properties of Au-nGaN interfaces has been investigated by x-ray photoemission spectroscopy (XPS), current-voltage measurement (I-V) and cross-section transmission electron microscopy (TEM). XPS analysis showed that the three GaN substrate treatments investigated i.e., ex situ hydrofluoric acid etch, in situ anneal in ultrahigh-vacuum (UHV), and in situ Ga reflux cleaning in UHV result in surfaces increasingly free of oxygen contamination. XPS and TEM characterization of Au-nGaN formed after the three premetallization surface treatments show that HF etching and UHV annealing produce abrupt, well-defined interfaces. Conversely, GaN substrate cleaning in a Ga flux results in Au/GaN intermixing. I-V characterization of Au¿nGaN contacts yields a Schottky barrier height of 1.25 eV with a very low-ideality factor and very good contact uniformity for the premetallization UHV anneal, while the Ga reflux cleaning results in a much lower barrier (0.85 eV), with poor ideality and uniformity. I-V and XPS results suggest a high density of acceptor states at the surface, which is further enhanced by UHV annealing. These results are discussed in the context of current models of Schottky barrier formation.
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It is part of: Journal of Applied Physics, 2002, vol. 92, núm. 6, p. 3179-3186
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ISSN: 0021-8979
Appears in Collections:Articles publicats en revistes (Enginyeria Electrònica i Biomèdica)

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