Al2O3/Si3N4 insulated gate channel-doped AlGaN/GaN heterostructure field-effect transistors with regrown ohmic structure: Low gate leakage current with high transconductance

Narihiko Maeda, Takashi Makimura, Chengxin Wang, Masanobu Hiroki, Toshiki Makimoto, Takashi Kobayashi, Takatomo Enoki

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An advanced structure of AlGaN/GaN heterostructure field-effect transistors (HFETs) has been proposed and fabricated, which is characterized by the following structural features: (i) a metal-insulator-semiconductor (MIS) structure using an Al2O3/Si3N4 bilayer gate insulator to reduce the gate leakage current, (ii) a thin AlGaN barrier with a doped channel to simultaneously obtain the high transconductance and high drain current, and (iii) a regrown ohmic structure to reduce the contact resistance. The fabricated devices have been proved to exhibit attractive characteristics such as low gate leakage current, low contact resistance, high drain current, and high transconductance. An HFET with a gate length of 0.1 urn has exhibited a gate leakage current density of below 10 -4 A/mm even at a gate voltage of +3 V. It has also exhibited a low contact resistance of 0.3 Ωmm, a high maximum drain current density of 1.23 A/mm, and a high transconductance of 280 mS/ mm, which is the highest transconductance ever reported in the category of MIS-HFETs. The cutoff frequency and maximum oscillation frequency, measured with the pad capacitances included, were 52 and 75 GHz, respectively. The proposed structure has thus been proved to be effective in further improving the device performance in GaN-based HFETs.

Original languageEnglish
Pages (from-to)2747-2750
Number of pages4
JournalJapanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
Issue number4 B
Publication statusPublished - 2005 Apr 1



  • AlO/SiNgate insulator
  • Channel doped
  • GaN
  • Regrown ohmic

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy(all)

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