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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
Abstract 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)