Recent Advances of High Voltage AlGaN/GaN Power HFETs

Yasuhiro Uemoto*, Tetsuzo Ueda, Tsuyoshi Tanaka, Daisuke Ueda

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

15 Scopus citations

Abstract

We review our recent advances of GaN-based high voltage power transistors. These are promising owing to low on-state resistance and high breakdown voltage taking advantages of superior material properties. However, there still remain a couple of technical issues to be solved for the GaN devices to replace the existing Si-based power devices. The most critical issue is to achieve normally-off operation which is strongly desired for the safety operation, however, it has been very difficult because of the built-in polarization electric field. Our new device called GIT (Gate Injection Transistor) utilizing conductivity modulation successfully achieves the normally-off operation keeping low on-state resistance. The fabricated GIT on a Si substrate exhibits threshold voltage of +1.0V. The obtained on-state resistance and off-state breakdown voltage were 2.6mΩcm2 and 800V, respectively. Remaining technical issue is to further increase the breakdown voltage. So far, the reported highest off-state breakdown voltage of AlGaN/GaN HFETs has been 1900V. Overcoming these issues by a novel device structure, we have demonstrated the world highest breakdown voltages of 10400V using thick poly-crystalline AlN as a passivation film and Via-holes through sapphire which enable very efficient layout of the lateral HFET array avoiding any undesired breakdown of passivation films. Since conventional wet or dry etching cannot be used for chemically stable sapphire, high power pulsed laser is used to form the via-holes. The presented GaN power devices demonstrate that GaN is advantageous for high voltage power switching applications replacing currently used Si-based power MOSFETs and IGBTs.

Original languageEnglish
Article number721606
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume7216
DOIs
StatePublished - 5 May 2009
EventGallium Nitride Materials and Devices IV - San Jose, CA, United States
Duration: 26 Jan 200929 Jan 2009

Keywords

  • GaN
  • High voltage
  • Hole injection
  • Laser drill
  • Low on-state resistance
  • Normally-off
  • Sapphire
  • Si
  • Via hole

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