Recessed 70-nm gate-length AlGaN/GaN HEMTs fabricated using an Al2O3/SiNχ dielectric layer

Donghyun Kim, Vipan Kumar, Jaesun Lee, Minjun Yan, A. M. Dabiran, A. M. Wowchak, Peter P. Chow, Illesanmi Adesida

Research output: Contribution to journalArticlepeer-review


In this letter, a novel process for recessed-gate AlGaN/GaN high-electron-mobility transistors using an Al2O3/ SiNx dielectric has been developed. The Al2 O3/SiNx dielectric bilayer was used as a recess etch-mask for short-gate-footprint definition. Recessed-gate devices with a gate length of 70 nm have been fabricated on a molecular-beam-epitaxy-grown layer structure using this process. After the removal of the dielectric layers, excellent dc and small-signal results, a high drain-current density of 1.5 A/mm, a unity gain cutoff frequency of 160 GHz, and a maximum frequency of oscillation of 200 GHz were obtained.

Original languageEnglish (US)
Pages (from-to)913-915
Number of pages3
JournalIEEE Electron Device Letters
Issue number9
StatePublished - 2009
Externally publishedYes


  • AlGaN/GaN
  • AlO/SiN
  • GaN
  • High-electron-mobility transistors (HEMTs)
  • Recessed gate

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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