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Publication - Professor Martin Kuball

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

    Citation

    Chandrasekar, H, Uren, MJ, Eblabla, A, Hirshy, H, Casbon, MA, Tasker, PJ, Elgaid, K & Kuball, M, 2018, ‘Buffer Induced Current-Collapse in GaN HEMTs on Highly Resistive Si Substrates’. IEEE Electron Device Letters, vol 39., pp. 1556-1559

    Abstract

    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.

    Full details in the University publications repository