Characteristics of Al 2 O 3 /native oxide/n-GaN capacitors by post-metallization annealing

Kazuya Yuge, Toshihide Nabatame, Yoshihiro Irokawa, Akihiko Ohi, Naoki Ikeda, Liwen Sang, Yasuo Koide, Tomoji Ohishi

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

This work investigated characteristics of Al 2 O 3 /native oxide/n-GaN MOS capacitors by post-metallization annealing (PMA). A native oxide interlayer which composed of ϵ- and γ-Ga 2 O 3 phases (Native oxide) and the reduced amount of one (Reduced) on n-GaN were prepared by cleaning only a sulfuric acid peroxide mixture (SPM) and both SPM and buffered hydrofluoric acid, respectively. The effect of trimethylaluminum precursor on removal of a native oxide layer was not observed during Al 2 O 3 deposition using atomic layer deposition. An as-grown capacitor (Native oxide) exhibited a small flatband voltage (V fb ) hysteresis of ∼30 mV and a large frequency dispersion, suggesting that the initial growth of the Al 2 O 3 resulted in the formation of electrical defects on the GaN surface. Both the V fb hysteresis and frequency dispersion were drastically improved by PMA of the device at 300 °C. The positive fixed charge values (Q IL ) estimated from the relationships between capacitance equivalent thickness and V fb were +6.1 -10 12 and +0.4-1.0 -10 12 cm -2 for as-grown and PMA-processed capacitors in the PMA temperature range of 300 °C-600 °C, respectively. The interface state density (D it ) determined using a conductance method was also significantly reduced (by an order of magnitude) after PMA processing at 300 °C. These trends in the Q IL and D it data were observed in both the Native oxide and Reduced capacitors, indicating that this interlayer does not greatly affect fixed charge generation at the Al 2 O 3 /native oxide and Al 2 O 3 /modified native oxide interfaces. As a result, two types of treatments result in insignificant difference in the electrical properties of the capacitors.

Original languageEnglish
Article number034001
JournalSemiconductor Science and Technology
Volume34
Issue number3
DOIs
Publication statusPublished - 2019 Jan 31

Fingerprint

Metallizing
Oxides
capacitors
Capacitors
Annealing
annealing
oxides
Peroxides
peroxides
sulfuric acid
Sulfuric acid
Hysteresis
interlayers
hysteresis
Hydrofluoric Acid
MOS capacitors
Hydrofluoric acid
Atomic layer deposition
Interface states
hydrofluoric acid

Keywords

  • Al O dielectric
  • ALD
  • fixed charge
  • flatband voltage
  • GaN
  • native oxide interlayer

ASJC Scopus subject areas

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

Cite this

Characteristics of Al 2 O 3 /native oxide/n-GaN capacitors by post-metallization annealing . / Yuge, Kazuya; Nabatame, Toshihide; Irokawa, Yoshihiro; Ohi, Akihiko; Ikeda, Naoki; Sang, Liwen; Koide, Yasuo; Ohishi, Tomoji.

In: Semiconductor Science and Technology, Vol. 34, No. 3, 034001, 31.01.2019.

Research output: Contribution to journalArticle

Yuge, Kazuya ; Nabatame, Toshihide ; Irokawa, Yoshihiro ; Ohi, Akihiko ; Ikeda, Naoki ; Sang, Liwen ; Koide, Yasuo ; Ohishi, Tomoji. / Characteristics of Al 2 O 3 /native oxide/n-GaN capacitors by post-metallization annealing In: Semiconductor Science and Technology. 2019 ; Vol. 34, No. 3.
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T1 - Characteristics of Al 2 O 3 /native oxide/n-GaN capacitors by post-metallization annealing

AU - Yuge, Kazuya

AU - Nabatame, Toshihide

AU - Irokawa, Yoshihiro

AU - Ohi, Akihiko

AU - Ikeda, Naoki

AU - Sang, Liwen

AU - Koide, Yasuo

AU - Ohishi, Tomoji

PY - 2019/1/31

Y1 - 2019/1/31

N2 - This work investigated characteristics of Al 2 O 3 /native oxide/n-GaN MOS capacitors by post-metallization annealing (PMA). A native oxide interlayer which composed of ϵ- and γ-Ga 2 O 3 phases (Native oxide) and the reduced amount of one (Reduced) on n-GaN were prepared by cleaning only a sulfuric acid peroxide mixture (SPM) and both SPM and buffered hydrofluoric acid, respectively. The effect of trimethylaluminum precursor on removal of a native oxide layer was not observed during Al 2 O 3 deposition using atomic layer deposition. An as-grown capacitor (Native oxide) exhibited a small flatband voltage (V fb ) hysteresis of ∼30 mV and a large frequency dispersion, suggesting that the initial growth of the Al 2 O 3 resulted in the formation of electrical defects on the GaN surface. Both the V fb hysteresis and frequency dispersion were drastically improved by PMA of the device at 300 °C. The positive fixed charge values (Q IL ) estimated from the relationships between capacitance equivalent thickness and V fb were +6.1 -10 12 and +0.4-1.0 -10 12 cm -2 for as-grown and PMA-processed capacitors in the PMA temperature range of 300 °C-600 °C, respectively. The interface state density (D it ) determined using a conductance method was also significantly reduced (by an order of magnitude) after PMA processing at 300 °C. These trends in the Q IL and D it data were observed in both the Native oxide and Reduced capacitors, indicating that this interlayer does not greatly affect fixed charge generation at the Al 2 O 3 /native oxide and Al 2 O 3 /modified native oxide interfaces. As a result, two types of treatments result in insignificant difference in the electrical properties of the capacitors.

AB - This work investigated characteristics of Al 2 O 3 /native oxide/n-GaN MOS capacitors by post-metallization annealing (PMA). A native oxide interlayer which composed of ϵ- and γ-Ga 2 O 3 phases (Native oxide) and the reduced amount of one (Reduced) on n-GaN were prepared by cleaning only a sulfuric acid peroxide mixture (SPM) and both SPM and buffered hydrofluoric acid, respectively. The effect of trimethylaluminum precursor on removal of a native oxide layer was not observed during Al 2 O 3 deposition using atomic layer deposition. An as-grown capacitor (Native oxide) exhibited a small flatband voltage (V fb ) hysteresis of ∼30 mV and a large frequency dispersion, suggesting that the initial growth of the Al 2 O 3 resulted in the formation of electrical defects on the GaN surface. Both the V fb hysteresis and frequency dispersion were drastically improved by PMA of the device at 300 °C. The positive fixed charge values (Q IL ) estimated from the relationships between capacitance equivalent thickness and V fb were +6.1 -10 12 and +0.4-1.0 -10 12 cm -2 for as-grown and PMA-processed capacitors in the PMA temperature range of 300 °C-600 °C, respectively. The interface state density (D it ) determined using a conductance method was also significantly reduced (by an order of magnitude) after PMA processing at 300 °C. These trends in the Q IL and D it data were observed in both the Native oxide and Reduced capacitors, indicating that this interlayer does not greatly affect fixed charge generation at the Al 2 O 3 /native oxide and Al 2 O 3 /modified native oxide interfaces. As a result, two types of treatments result in insignificant difference in the electrical properties of the capacitors.

KW - Al O dielectric

KW - ALD

KW - fixed charge

KW - flatband voltage

KW - GaN

KW - native oxide interlayer

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DO - 10.1088/1361-6641/aafdbd

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