Long-term thermal stability of Ti/Ai/Mo/Au ohmic contacts on n-GaN

D. Selvanathan, L. Zhou, V. Kumar, I. Adesida, N. Finnegan

Research output: Contribution to journalArticlepeer-review


Improved performance of the ohmic contacts on n-GaN has been demonstrated with the use of MoAu as the capping layer on TiAl metallization. Contact resistance as low as 0.13 Ω-mm was achieved in these ohmic contacts when annealed at 850°C for 30 sec. We have studied the long-term thermal stability of these contacts at 500°C, 600°C, 750°C, and 850°C, respectively. The Ti/Al/Mo/Au metallization forms low contact-resistance ohmic contacts on n-GaN that are stable at 500°C and 600°C after 25 h of thermal treatment. The ohmic-contact performance degrades after 10 h of thermal treatment at 750°C, while the contacts exhibit nonlinear current-voltage (I-V) characteristics after 1 h of thermal treatment at 850°C with the formation of oxide on the surface of the contacts accompanied by surface discoloration. The intermetallic reactions taking place in the contacts during the long-term thermal treatments were studied using Auger electron spectroscopy (AES), and the surface morphology was characterized using atomic force microscopy (AFM).

Original languageEnglish (US)
Pages (from-to)335-340
Number of pages6
JournalJournal of Electronic Materials
Issue number5
StatePublished - May 2003


  • GaN
  • Ohmic contacts
  • Thermal stability
  • Ti/Al/Mo/Au

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering
  • Materials Chemistry


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