Chemical, electrical, and structural properties of Au/Pd contacts on chemical vapor cleaned p-type GaN surfaces

P. J. Hartlieb, A. Roskowski, B. J. Rodriguez, Robert Nemanich, R. F. Davis

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The chemical, electrical, and microstructural properties of Au/Pd contacts on p-type GaN(0001) surfaces previously cleaned either ex situ or ex situ and in situ have been investigated. The in situ process involved a high temperature, NH 3-based chemical vapor clean (CVC); it produced ordered, stoichiometric, p-type GaN surfaces with no detectable C and an O constituent which was subsequently reduced from 15 at% on the ex situ treated surface to 2 ± 1 at% following the CVC process. The Pd contacting layer grew epitaxially in a layer-by-layer mode on the CVC surface and formed an abrupt, unreacted metal-semiconductor interface. The Au capping layer also grew epitaxially on the Pd. Au/Pd contacts on both HCl and CVC treated surfaces exhibited identical surface roughness values (RMS) in the as-deposited state and following a 500°C anneal. Contact structures on CVC treated surfaces demonstrated excellent high-temperature microstructural stability as evidenced by the absence of significant change in the surface roughness (RMS) with successive annealing at 600 and 700°C. Identical contact structures on ex situ cleaned surfaces exhibited poor high temperature microstructural stability, as indicated by a significant increase in the surface roughness (RMS) following successive anneals at 600 and 700°C. There was a significant degradation in the morphology of both surfaces following the 800°C anneal as evidenced by the formation of large voids in the contact metallization and the exposure of the underlying p-type GaN substrate. The lowest resistance contact structures with uniform metal coverage were obtained for Au/Pd contacts on a CVC treated surface annealed at 700°C.

Original languageEnglish (US)
Title of host publicationMaterials Research Society Symposium - Proceedings
EditorsJ.E. Northrup, J. Neugebauer, D.C. Look, S.F. Chichibu, H. Riechert
Number of pages6
StatePublished - 2002
Externally publishedYes
EventGaN and Related Alloys-2001 - Boston, MA, United States
Duration: Nov 26 2001Nov 30 2001


OtherGaN and Related Alloys-2001
Country/TerritoryUnited States
CityBoston, MA

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials


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