To investigate the influence of ionic/covalent interface of Al2O3/SiO2 gate insulator on the electrical properties of thin-film transistors (TFTs) with ionic Ga-In-Zn-O (GIZO) semiconducting channel layers, Al2O3 layers of different thickness were introduced between SiO2 and GIZO using plasma-enhanced atomic layer deposition. The GIZO layers were obtained by DC magnetron sputtering using a GIZO target (Ga:In:Zn = 1:1:1 mol. %). The GIZO TFTs with an Al2O3/SiO2 gate insulator exhibited positive threshold voltage (Vth) shift (about 1.1 V), Vth hysteresis suppression (0.23 V), and electron mobility degradation (about 13%) compared with those of a GIZO TFT with SiO2 gate insulator by the influence of ionic/ionic and ionic/covalent interface at Al2O3/GIZO and Al2O3/SiO2, respectively. To clarify the origin of the positive Vth shift, the authors estimated the shifts of flatband voltage (0.4 V) due to the dipole and the fixed charge (−1.1 × 1011/cm2) at Al2O3/SiO2 interface, from capacitance–voltage data for Pt/Al2O3/SiO2/p-Si capacitors. Based on these experimental data, the authors found that the positive Vth shift (1.1 V) could be divided into three components: the dipole (−0.4 V) and fixed charge (0.15 V) at the SiO2/Al2O3 interface, and the fixed charge (1.35 V) at the Al2O3/GIZO interface. Finally, it is noted that heterointerface of SiO2/Al2O3/GIZO stacks is important not only to recognize mechanism of Vth shift but also to design future TFTs with high-k dielectrics and low operating voltage.
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November 2015
Research Article|
August 20 2015
Influence of Al2O3 layer insertion on the electrical properties of Ga-In-Zn-O thin-film transistors
Kazunori Kurishima;
Kazunori Kurishima
a)
Department of Electronics and Bioinformatics, School of Science and Technology,
Meiji University
, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan and Nano-Electronics Materials Unit, International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS)
, 1-1 Namiki, Tsukuba 305-0044, Japan
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Toshihide Nabatame;
Toshihide Nabatame
b)
MANA Foundry and Nano-Electronics Materials Unit, International Center for Materials Nanoarchitectonics (WPI-MANA),
National Institute for Materials Science (NIMS)
, 1-1 Namiki, Tsukuba 305-0044, Japan
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Maki Shimizu;
Maki Shimizu
International Center for Materials Nanoarchitectonics (WPA-MANA),
National Institute for Materials Science (NIMS)
, 1-1 Namiki, Tsukuba 305-0044, Japan
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Nobuhiko Mitoma;
Nobuhiko Mitoma
International Center for Materials Nanoarchitectonics (WPA-MANA),
National Institute for Materials Science (NIMS)
, 1-1 Namiki, Tsukuba 305-0044, Japan
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Takio Kizu;
Takio Kizu
International Center for Materials Nanoarchitectonics (WPA-MANA),
National Institute for Materials Science (NIMS)
, 1-1 Namiki, Tsukuba 305-0044, Japan
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Shinya Aikawa;
Shinya Aikawa
International Center for Materials Nanoarchitectonics (WPA-MANA),
National Institute for Materials Science (NIMS)
, 1-1 Namiki, Tsukuba 305-0044, Japan
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Kazuhito Tsukagoshi;
Kazuhito Tsukagoshi
International Center for Materials Nanoarchitectonics (WPA-MANA),
National Institute for Materials Science (NIMS)
, 1-1 Namiki, Tsukuba 305-0044, Japan
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Akihiko Ohi;
Akihiko Ohi
MANA Foundry, International Center for Materials Nanoarchitectonics,
National Institute for Materials Science (NIMS)
, 1-1 Namiki, Tsukuba 305-0044, Japan
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Toyohiro Chikyow;
Toyohiro Chikyow
Nano-Electronics Materials Unit, International Center for Materials Nanoarchitectonics (WPA-MANA),
National Institute for Materials Science (NIMS)
, 1-1 Namiki, Tsukuba 305-0044, Japan
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Atsushi Ogura
Atsushi Ogura
Department of Electronics and Bioinformatics, School of Science and Technology,
Meiji University
, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
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a)
Electronic mail: [email protected]
b)
Electronic mail: [email protected]
J. Vac. Sci. Technol. A 33, 061506 (2015)
Article history
Received:
May 21 2015
Accepted:
August 07 2015
Citation
Kazunori Kurishima, Toshihide Nabatame, Maki Shimizu, Nobuhiko Mitoma, Takio Kizu, Shinya Aikawa, Kazuhito Tsukagoshi, Akihiko Ohi, Toyohiro Chikyow, Atsushi Ogura; Influence of Al2O3 layer insertion on the electrical properties of Ga-In-Zn-O thin-film transistors. J. Vac. Sci. Technol. A 1 November 2015; 33 (6): 061506. https://doi.org/10.1116/1.4928763
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