Buffer Induced Current-Collapse in GaN HEMTs on Highly Resistive Si Substrates

Hareesh Chandrasekar, Michael J. Uren, Abdalla Eblabla, Hassan Hirshy, Michael A. Casbon, Paul J. Tasker, Khaled Elgaid, Martin Kuball

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

15 Citations (Scopus)
246 Downloads (Pure)


We demonstrate that the highly-resistive Si substrate in GaN-on-Si RF HEMTs does not act as an insulator, but instead behaves as a conductive ground plane for static operation and can cause significant back-gate induced current collapse. Substrate ramp characterization of the buffer shows good agreement with device simulations and indicates that the current collapse is caused by charge-redistribution within the GaN layer. Potential solutions which alter charge storage and leakage in the epitaxy to counter this effect are then presented.

Original languageEnglish
Pages (from-to)1556-1559
Number of pages4
JournalIEEE Electron Device Letters
Issue number10
Early online date10 Aug 2018
Publication statusPublished - Oct 2018

Structured keywords

  • CDTR


  • Buffer storage
  • current collapse
  • Epitaxial growth
  • Gallium nitride
  • GaN buffers
  • HEMTs
  • high resistivity silicon
  • Radio frequency
  • RF transistors
  • Silicon
  • substrate ramps
  • Substrates

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