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TEM Studies and Contact Resistance of Au/Ni/Ti/Ta/n-GaN Ohmic Contacts

Published online by Cambridge University Press:  01 February 2011

D.N. Zakharov
Affiliation:
Lawrence Berkeley National Laboratory, MS 62-203, Berkeley, CA 94720
Z. Liliental-Weber
Affiliation:
Lawrence Berkeley National Laboratory, MS 62-203, Berkeley, CA 94720
A. Motayed
Affiliation:
Howard University, Electrical Engineering Department 2300 Sixth St. NW, Washington, DC 20059
S.N. Mohammad
Affiliation:
Howard University, Electrical Engineering Department 2300 Sixth St. NW, Washington, DC 20059
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Abstract

Ohmic Ta/Ti/Ni/Au contacts to n-GaN have been studied using high resolution electron microscopy (HREM), energy dispersive X-ray spectrometry (EDX) and electron energy loss spectrometry (EELS). Two different samples were used: A - annealed at 7500C withcontact resistance 5×10-6 Ω cm2 and B-annealed at 7750C with contact resistance 6×10-5 Ω cm2. Both samples revealed extensive in- and out-diffusion between deposited layers with some consumption ofGaNlayerand formation of TixTa1-xN50 (0<x<25) at the GaN interface. Almost an order of magnitude difference in contact resistances can be attributed to structure and chemical bonding of Ti-O layers formed on the contact surfaces.

Type
Research Article
Copyright
Copyright © Materials Research Society 2003

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