Morphological and electrical comparison of Ti and Ta based ohmic contacts for AlGaN/GaN-on-SiC HFETs

Alexander Pooth, J. Bergsten, N. Rorsman, H. Hirshy, R. Perks, P. Tasker, Trevor Martin, R.F. Webster, D. Cherns, M.J. Uren, M. Kuball

Research output: Contribution to journalArticle (Academic Journal)peer-review

8 Citations (Scopus)
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The morphology and impact on leakage currents of two different ohmic metal stacks for GaN based transistor devices is investigated in this work. The results have implications for the performance and reliability of a GaN transistor device. A low temperature Ta based and a higher temperature anneal Ti based metallization are compared. The low temperature process shows a smoother metal semiconductor interface together with several orders of magnitude lower vertical and lateral leakage compared to the conventional higher temperature process. In addition to the leakage tests, back bias ramping experiments are performed unveiling potential advantages of the conventional approach in mitigating current collapse. However the low leakage will enable higher voltage operation making the low temperature process the preferable choice for high power RF applications, if simultaneously current collapse can be controlled.
Original languageEnglish
Pages (from-to)2-4
Number of pages3
JournalMicroelectronics Reliability
Early online date15 Nov 2016
Publication statusPublished - Jan 2017

Structured keywords

  • CDTR


  • GaN
  • Transistor
  • Ohmic contact
  • Morphology
  • Leakage current
  • Current collapse


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