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

Authors

  • D. Selvanathan
    • Department of Electrical and Computer Engineering and Micro and Nanotechnology LaboratoryUniversity of Illinois at Urbana Champaign
  • L. Zhou
    • Department of Electrical and Computer Engineering and Micro and Nanotechnology LaboratoryUniversity of Illinois at Urbana Champaign
  • V. Kumar
    • Department of Electrical and Computer Engineering and Micro and Nanotechnology LaboratoryUniversity of Illinois at Urbana Champaign
  • I. Adesida
    • Department of Electrical and Computer Engineering and Micro and Nanotechnology LaboratoryUniversity of Illinois at Urbana Champaign
  • N. Finnegan
    • Materials Research LaboratoryUniversity of Illinois at Urbana Champaign
Special Issue Paper

DOI: 10.1007/s11664-003-0154-7

Cite this article as:
Selvanathan, D., Zhou, L., Kumar, V. et al. Journal of Elec Materi (2003) 32: 335. doi:10.1007/s11664-003-0154-7

Abstract

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 stabilityohmic contactsTi/Al/Mo/AuGaN

Copyright information

© TMS-The Minerals, Metals and Materials Society 2003