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Microstructure Of Au/Ti Ohmic Contacts On n-GaN

Published online by Cambridge University Press:  02 July 2020

R.-J. Liu ,
L. L. Smith ,
M. J. Kim ,
R. W. Carpenter  and
R. F. Davis
R.-J. Liu
Affiliation:
Science and Engineering of Materials Program and Center of Solid State Science, Arizona State University, Tempe, AZ85287-1704
L. L. Smith
Affiliation:
Department of Chemical Engineering, North Carolina State University, Raleig, NC27695-7905
M. J. Kim
Affiliation:
Science and Engineering of Materials Program and Center of Solid State Science, Arizona State University, Tempe, AZ85287-1704
R. W. Carpenter
Affiliation:
Science and Engineering of Materials Program and Center of Solid State Science, Arizona State University, Tempe, AZ85287-1704
R. F. Davis
Affiliation:
Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC27695-7907
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Extract

GaN is a semiconductor with a direct band-gap of 3.4 eV which has a potential application in optoelectronic devices such as UV-emitting lasers and blue light emitting diodes. Extensive efforts have been made to develop low-resistance, thermally stable and uniform ohmic contacts on GaN. In this study, n-GaN films (Si-doped) with an intermediate A1N buffer layer were grown on 6H-SiC substrates via MOVPE. The contacts were formed by depositing Ti and then Au films on GaN by e-beam evaporation at room temperature. Current-voltage measurements as a function of temperature showed that the ohmicity of the Au/Ti contact improved upon annealing, corresponding to changes in the microstructure of the contact interfaces involving a redistribution of nitrogen and gold.

Fig. 1 shows the microstructure of the as-deposited Au/Ti/GaN films. The nanocrystalline Ti film was about 50 nm thick. Au film was polycrystalline, containing many growth twins. The thickness of Au film varied from 260 to 350 nm.

Type
Microscopy of Semiconducting and Superconducting Materials
Information
Microscopy and Microanalysis , Volume 4 , Issue S2: Proceedings: Microscopy & Microanalysis '98, Microscopy Society of America 56th Annual Meeting, Microbeam Analysis Society 32nd Annual Meeting, Atlanta, Georgia July 12-16, 1998 , July 1998 , pp. 668 - 669
Copyright
Copyright © Microscopy Society of America

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References

References:

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2.Smith, L. L. et al., J. of Mater. Res. Vol. 12 (1997) 2249.CrossRefGoogle Scholar
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4. This research was supported by the Materials Sciences Division (Dr. Otto Buck) under grant DE-FG03-94ER45510 (ASU) and by the Office of Naval Research under grant NOOO 14-95-1-1080 (NCSU).Google Scholar