Journal of Electronic Materials

, Volume 32, Issue 5, pp 335–340

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

  • D. Selvanathan
  • L. Zhou
  • V. Kumar
  • I. Adesida
  • N. Finnegan
Special Issue Paper


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 Θ-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).

Key words

Thermal stability ohmic contacts Ti/Al/Mo/Au GaN 


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Copyright information

© TMS-The Minerals, Metals and Materials Society 2003

Authors and Affiliations

  • D. Selvanathan
    • 1
  • L. Zhou
    • 1
  • V. Kumar
    • 1
  • I. Adesida
    • 1
  • N. Finnegan
    • 2
  1. 1.Department of Electrical and Computer Engineering and Micro and Nanotechnology LaboratoryUniversity of Illinois at Urbana ChampaignUrbana
  2. 2.Materials Research LaboratoryUniversity of Illinois at Urbana ChampaignUSA

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