Electrical, structural and microstructural characteristics of as-deposited and annealed Pt and Au contacts on chemical-vapor-cleaned GaN thin films

E. A. Preble, K. M. Tracy, S. Kiesel, H. Mclean, P. Q. Miraglia, Robert Nemanich, R. F. Davis, M. Albrecht, David Smith

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10 Scopus citations

Abstract

Schottky contacts of Pt(111) and Au(111) were deposited on chemical-vapor-cleaned, n-type GaN(0001) thin films. The growth mode of the deposition, as determined by x-ray photoelectron spectroscopy analysis, followed the two-dimensional Frank-van der Merwe growth model. The resulting as-deposited metal films were monocrystalline and epitaxial with a (111)//(0002) relationship with the GaN. Selected samples were annealed for three minutes at 400°C, 600°C or 800°C. The rectifying behavior of both contacts degraded at 400°C; they became ohmic after annealing at 600°C (Au) or 800°C (Pt). High-resolution transmission electron micrographs revealed reactions at the metal/GaN interfaces for the higher temperature samples. X-ray diffraction results revealed an unidentified phase in the Pt sample annealed at 800°C. A decrease in the room temperature in-plane (111) lattice constant for both metals, ranging from -0.1% to -0.5%, was observed as the annealing temperature was increased from 400 to 800°C. This plastic deformation was caused by tensile stresses along the [111] direction that exceeded the yield strength as a result of the large differences in the coefficients of thermal expansion between the metal contacts and the GaN film.

Original languageEnglish (US)
Pages (from-to)2133-2137
Number of pages5
JournalJournal of Applied Physics
Volume91
Issue number3
DOIs
StatePublished - Feb 1 2002

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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