Epitaxial ZnO gate dielectrics deposited by RF sputter for AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors

Seonno Yoon, Seungmin Lee, Hyun Seop Kim, Ho Young Cha, Hi Deok Lee, Jungwoo Oh

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2 Citations (Scopus)


Radio frequency (RF)-sputtered ZnO gate dielectrics for AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs) were investigated with varying O2/Ar ratios. The ZnO deposited with a low oxygen content of 4.5% showed a high dielectric constant and low interface trap density due to the compensation of oxygen vacancies during the sputtering process. The good capacitance-voltage characteristics of ZnO-on-AlGaN/GaN capacitors resulted from the high crystallinity of oxide at the interface, as investigated by x-ray diffraction and high-resolution transmission electron microscopy. The MOS-HEMTs demonstrated comparable output electrical characteristics with conventional Ni/Au HEMTs but a lower gate leakage current. At a gate voltage of -20 V, the typical gate leakage current for a MOS-HEMT with a gate length of 6 μm and width of 100 μm was found to be as low as 8.2 ×10-7 mA mm-1, which was three orders lower than that of the Ni/Au Schottky gate HEMT. The reduction of the gate leakage current improved the on/off current ratio by three orders of magnitude. These results indicate that RF-sputtered ZnO with a low O2/Ar ratio is a good gate dielectric for high-performance AlGaN/GaN MOS-HEMTs.

Original languageEnglish
Article number015007
JournalSemiconductor Science and Technology
Issue number1
Publication statusPublished - 2018 Jan

Bibliographical note

Funding Information:
This research was supported by the MSIT, Korea, under the ICT Consilience Creative program (IITP-2017-2017-0-01015) supervised by the IITP; the Future Semiconductor Device Technology Development Program (10048536) funded by MOTIE and KSRC; and the Basic Science Research Program (2015R1A6A1A03031833) through NRF of Korea.

Publisher Copyright:
© 2017 IOP Publishing Ltd.

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering
  • Materials Chemistry


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