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LOW-RESISTANCE OHMIC CONTACTS TO N-TYPE GaN USING Ti/Al/Re/Au MULTILAYER SCHEME

V. Rajagopal Reddy1,* , C. K. Ramesh1

Affiliation

  1. Department of Electronics, University of Mysore, Post-Graduate Centre, Hemagangotri, Hassan – 573 220, India

Abstract

A Ti/Al/Re/Au multilayer scheme has been developed for obtaining very low ohmic contact to moderately doped n-type GaN (4.07·1018 cm–3). It is shown that the I-V characteristics of the as-deposited contacts improved upon annealing temperatures in the range of 550–750 °C. Specific contact resistance as low as 1.3 · 10-6 Wcm2 is obtained from the Ti (150Å)/Al (600Å)/ Re (200Å)/ Au (500Å) contact annealed at 750 C for 1min in a N2 ambient. It is also shown that annealing results in a large reduction (by ~150 meV) in the Schottky barrier heights of contact, compared to the as-deposited one. Based on the XPS and AES results, possible explanations for the annealing temperature dependence of the specific contact resistance of the Ti/Al/Re/Au contacts are described and discussed..

Keywords

Ohmic Contacts, n-type GaN, Schottky barrier height, X-ray photoelectron spectroscopy, Auger electron microscopy.

Submitted at: Jan. 7, 2004
Accepted at: March 15, 2004

Citation

V. Rajagopal Reddy, C. K. Ramesh, LOW-RESISTANCE OHMIC CONTACTS TO N-TYPE GaN USING Ti/Al/Re/Au MULTILAYER SCHEME, Journal of Optoelectronics and Advanced Materials Vol. 6, Iss. 1, pp. 177-182 (2004)