Change of characteristics of n-GaN MOS capacitors with Hf-rich HfSiOx gate dielectrics by post-deposition annealing

Erika Maeda, Toshihide Nabatame, Kazuya Yuge, Masafumi Hirose, Mari Inoue, Akihiko Ohi, Naoki Ikeda, Koji Shiozaki, Hajime Kiyono

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


We investigated the characteristics of n-GaN/Hf0.64Si0.36Ox/Pt MOS capacitors fabricated by post-deposition annealing (PDA) at 800 °C in O2 (PDO), N2 (PDN), and 3%H2 (PDH) ambients. After PDO, the Hf0.64Si0.36Ox film was partially crystallized and had a thick interfacial layer (6.3 nm) at the n-GaN/Hf0.64Si0.36Ox interface, while the Hf0.64Si0.36Ox films after PDN and PDH maintained an amorphous structure. Furthermore, the n-GaN/Hf0.64Si0.36Ox/Pt MOS capacitors produced by PDN and PDH exhibited superior characteristics, such as a small flat-band voltage (Vfb) hysteresis of +50 mV and + 25 mV, a small Vfb shift of 0.74 V and − 0.06 V, high dielectric constants of 15.1 and 16.0, and high breakdown electric fields of 8.7 and 9.1 MV/cm, respectively. However, the PDH capacitor exhibited an order of magnitude larger Dit than the PDN capacitor, suggesting that a Ga2O3 intermediate layer at n-GaN/Hf0.64Si0.36Ox interface may be decomposed after PDH and results in significant Ga diffusion into the Hf0.64Si0.36Ox films and electrical defects generation at n-GaN/Hf0.64Si0.36Ox interface. These strongly indicate that the PDN process can produce superior Hf0.64Si0.36Ox films for use as gate dielectrics in GaN power devices.

Original languageEnglish
Article number111036
JournalMicroelectronic Engineering
Publication statusPublished - 2019 Aug 15


  • GaN capacitor
  • HfO/SiO laminate
  • HfSiO dielectric
  • N annealing
  • Plasma-Enhanced ALD

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Electrical and Electronic Engineering


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