Superior suppression of gate current leakage in Al 2O 3/Si 3N 4 bilayer-based AlGaN/GaN insulated gate heterostructure field-effect transistors

C. X. Wang, N. Maeda, M. Hiroki, T. Tawara, Toshiki Makimoto, T. Kobayahsi, T. Enoki

Research output: Contribution to journalArticle

11 Citations (Scopus)


AlGaN/GaN-based metal-insulator-semiconductor heterostructure field-effect transistors (MIS-HFETs) with Al 2O 3/Si 3N 4 bilayer as insulator have been investigated in detail, and compared with the conventional HFET and Si 3N 4-based MIS-HFET devices. Al 2O 3/Si 3N 4 bilayer-based MIS-HFETs exhibited much lower gate current leakage than conventional HFET and Si 3N 4-based MIS devices under reverse gate bias, and leakage as low as 1 × 10 -11 A/mm at -15 V has been achieved in Al 2O 3/Si 3N 4-based MIS devices. By using ultrathin Al 2O 3/Si 3N 4 bilayer, very high maximum transconductance of more than 180 mS/mm with ultra-low gate leakage has been obtained in the MIS-HFET device with gate length of 1.5 μm, a reduction less than 5% in maximum transconductance compared with the conventional HFET device. This value was much smaller than the more than 30% reduction in the Si 3N 4-based MIS device, due to the employment of ultra-thin bilayer with large dielectric constant and the, large conduction band offset between Al 2O 3 and nitrides. This work demonstrates that Al 2O 3/Si 3N 4 bilayer insulator is a superior candidate for nitrides-based MIS-HFET devices.

Original languageEnglish
Pages (from-to)361-364
Number of pages4
JournalJournal of Electronic Materials
Issue number4
Publication statusPublished - 2005 Apr
Externally publishedYes



  • Al o /si n dielectric layer
  • Heterostructure field-effect transistor (HFET)
  • Metal-insulator-semiconductor (MIS)

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Electronic, Optical and Magnetic Materials
  • Materials Science(all)
  • Physics and Astronomy (miscellaneous)

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