MIJ-NSR Vol. 2, Art. 2, Holger Cordes and Y. A. Chang

Interfacial Reactions and Electrical Properties of Ti/n-GaN Contacts

Holger Cordes , Y. A. Chang
Department of Materials Science and Engineering, University of Wisconsin, Madison

This article was received on December 17, 1996 and accepted on January 22, 1997.

Abstract

The phase equilibria in the ternary Ti-Ga-N have been investigated. Interfacial reactions in Ti/GaN contacts have been studied by diffusion couple experiments. The ternary phase Ti₂GaN was confirmed by x-ray diffraction in bulk samples as well as in massive Ti/GaN diffusion couples and annealed Ti thin films on GaN. The diffusion path in samples, annealed at 850°C in Ar gas, is GaN/TiN/Ti₂GaN/Ti₃Ga/Ti. A planar TiN layer forms in direct contact to GaN and governs the electrical properties of annealed Ti/GaN contacts. Thin film contacts were fabricated by sputtering Ti on MOVPE grown n-GaN (5x10¹⁷cm^-3) and subsequent rapid thermal annealing in an Argon atmosphere. Initially non-linear current-voltage characteristics become ohmic after annealing and a specific contact resistance of approximately 10^-2