Experimental and theoretical examination of orientation effect on piezoelectric charge at gate periphery in AlGaN/GaN HFETs

Hidetoshi Ishida*, Tomohiro Murata, Motonori Ishii, Yutaka Hirose, Yasuhiro Uemoto, Tsuyoshi Tanaka, Daisuke Ueda

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Orientation effect on AlGaN/GaN heterojunction field-effect transistors (HFETs) has been experimentally and theoretically examined in detail. The drain-currents of the fabricated AlGaN/GaN HFETs with various gate directions do not depend on the gate orientation, whereas those of GaAs-based HFETs strongly depend on the gate direction due to the piezoelectric charges induced around the gate electrode. The piezoelectric charges induced in the vicinity of the gate electrode are simulated by using a finite-element method. This simulation solves the piezoelectric equations with piezoelectric and elastic stiffness constants, assuming that stress is applied to the gate edges in the HFET. The detailed simulation reveals that the piezoelectric charge distribution does not depend on the gate direction, although a large amount of piezoelectric charges is induced in the vicinity of the gate edges, which is consistent with the experimental result. Moreover, it is mathematically clarified that these experimental and simulated results are due to the symmetry characteristic of the piezoelectric and elastic stiffness constants for nitride semiconductor materials.

Original languageEnglish
Pages (from-to)1524-1529
Number of pages6
JournalIEEE Transactions on Electron Devices
Volume53
Issue number7
DOIs
StatePublished - 1 Jul 2006

Keywords

  • Direction
  • Field-effect transistor (FET)
  • Finite-element method
  • GaN
  • Orientation
  • Piezoelectric
  • Stress

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