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Effects of oxygen plasma treatment on the formation of ohmic contacts to GaN and AlGaN
Author(s) -
Yan J.,
Kappers M. J.,
Crossley A.,
McAleese C.,
Phillips W. A.,
Humphreys C. J.
Publication year - 2004
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200405056
Subject(s) - ohmic contact , x ray photoelectron spectroscopy , plasma , materials science , argon , annealing (glass) , oxygen , analytical chemistry (journal) , electrical resistivity and conductivity , chemistry , nanotechnology , metallurgy , chemical engineering , layer (electronics) , physics , electrical engineering , organic chemistry , chromatography , engineering , quantum mechanics
The effects of oxygen plasma treatment prior to metal contact deposition have been studied for both n‐ and p‐GaN, as well as n‐AlGaN. In n‐GaN, the as‐deposited Ti/Al contacts change from rectifying to ohmic, and further improvements are observed after rapid thermal annealing (RTA). A specific contact resistivity better than 10 –7 Ω cm 2 was obtained using a plasma treatment of 20 s at 30 W and 0.2 mbar, followed by RTA at 500 °C in argon. The I–V characteristics of the Ti/Al contacts degraded when plasma treatments were performed for a longer time and/or at increased plasma pressure. However, in contrast to n‐GaN, the electrical properties of the Ni/Au contacts to p‐GaN and Ti/Al contacts to n‐Al 0.15 Ga 0.85 N deteriorated following oxygen plasma treatment. X‐ray photoelectron spectroscopy (XPS) was used in order to help elucidate the mechanisms behind these effects. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)