All-GaN Integrated Cascode Heterojunction Field Effect Transistors

Research output: Contribution to journalArticle

  • External authors:
  • Sheng Jiang
  • Kean Boon Lee
  • Ivor Guiney
  • Pablo Miaja
  • Zaffar Zaidi
  • Hongtu Qian
  • David Wallis
  • Colin Humphreys
  • Peter Houston

Abstract

All-GaN integrated cascode heterojunction field effect transistors were designed and fabricated for power switching applications. A threshold voltage of +2 V was achieved using a fluorine treatment and a metal-insulator-semiconductor gate structure on the enhancement mode part. The cascode device exhibited an output current of 300 mA/mm by matching the current drivability of both enhancement and depletion mode parts. The optimisation was achieved by shifting the threshold voltage of the depletion mode section to a more negative value with the addition of a dielectric layer under the gate. The switching performance of the cascode was compared to the equivalent GaN enhancement-mode-only device by measuring the hard switching speed at 200 V under an inductive load in a double pulse tester. For the first time, we demonstrate the switching speed advantage of the cascode over equivalent GaN enhancement-mode-only devices, due to the reduced Miller-effect and the unique switching mechanisms. These observations suggest that practical power switches at high power and high switching frequency will benefit as part of an integrated cascode configuration.

Bibliographical metadata

Original languageEnglish
JournalIEEE Transactions on Power Electronics
Early online date17 Feb 2017
DOIs
StateE-pub ahead of print - 17 Feb 2017