Buffer design to minimize current collapse in GaN/AlGaN HFETs

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The bulk trap-induced component of current collapse (CC) in GaN/AlGaN heterojunction field-effect transistors is studied in drift diffusion simulations, distinguishing between acceptor traps situated in the top and the bottom half of the bandgap, with Fe and C used as specific examples. It is shown that Fe doping results in an inherent but relatively minor contribution to dispersion under pulse conditions. This simulation is in reasonable quantitative agreement with double pulse experiments. Simulations using deep-level intrinsic growth defects produced a similar result. By contrast, carbon can induce a strong CC which is dependent on doping density. The difference is attributed to whether the trap levels, whether intrinsic or extrinsic dopants, result in a resistive n-type buffer or a p-type floating buffer with bias-dependent depletion regions. This insight provides a key design concept for compensation schemes needed to ensure semi-insulating buffer doping for either RF or power applications.

Original languageEnglish
Pages (from-to)3327-3333
Number of pages7
JournalIEEE Transactions on Electron Devices
Issue number12
Early online date12 Oct 2012
Publication statusPublished - Dec 2012

Structured keywords

  • CDTR


  • dispersion
  • dynamic I–V analysis (DIVA)
  • HEMT
  • pulse IV


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