Junji Kataoka

Tokyo Institute of Technology

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Nobuyoshi Saito

Toshiba (Japan)

Tomomasa Ueda

Toshiba (Japan)

Tsutomu Tezuka

Toshiba (Japan)

Keiji Ikeda

Toshiba (Japan)

Tomoaki Sawabe

Toshiba (Japan)

Takuya Hoshii

Tokyo Institute of Technology

Sung‐Lin Tsai

National Formosa University

Kazuo Tsutsui

Tokyo Institute of Technology

Reiko Saito

Kogakuin University

Kuniyuki Kakushima

Tokyo Institute of Technology

Cooperative Institutions

Toshiba (Japan)

The University of Tokyo

National Institute of Advanced Industrial Science and Technology

Tokyo Institute of Technology

Toshiba (South Korea)

Yokohama National University

Nagoya University

Tokyo University of Science

BioElectronics (United States)

Association of Super-Advanced Electronics

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Optical Waveguide Sensor System Using Fluorescent Dye Film/K+-doped Glass Composite Structure

Electrochemistry (2008)

Kenichi Uchiyama Junji Kataoka Chengshu LIAN Takashi Amemiya Kiminori Itoh

Planar optical waveguides (OWGs) formed by ion-exchange in glass are useful to fabricate optical sensors for biochemical and environmental use. Conventional OWGs need delicate equipment to adjust incident light position and angle. In order to overcome this difficulty, a fluorescent dye (Alq3) film was deposited onto an ion-exchanged waveguide layer and used as a broad-band light source. The properties of the OWG system were analyzed; e.g., the highest light transfer efficiency was obtained at the Alq3 film thickness close to the cutoff thickness of TE0 mode.

Waveguide

10.5796/electrochemistry.76.656

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High thermal stability of doped oxide semiconductor for monolithic 3D integration

MRS Bulletin (2021)

Hiroki Kawai Junji Kataoka Nobuyoshi Saito Tomomasa Ueda Takamitsu Ishihara

10.1557/s43577-021-00230-0

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A possible origin of the large leakage current in ferroelectric Al_1−xSc_xN films

Japanese Journal of Applied Physics (2021)

Junji Kataoka Sung‐Lin Tsai Takuya Hoshii Hitoshi Wakabayashi Kazuo Tsutsui

Abstract Leakage current analysis on 50 nm thick ferroelectric Al 0.78 Sc 0.22 N films with TiN electrodes has been performed. The electron conduction followed Schottky emission with an initial Schottky barrier height ( ϕ B ) of 0.46 eV. During the initial switching, a gradual shift in the leakage current was observed, changing the ϕ B to 0.36 eV, and stayed constant for further switching cycles. From the extracted Richardson constant, the change in the ϕ B can be interpreted as the formation of a tunneling barrier due to the formation of nitrogen vacancies at the metal interface.

Leakage (economics)

Schottky effect

10.35848/1347-4065/abe644

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Citations (41)

High mobility (>30 cm² V⁻¹ s⁻¹) and low source/drain parasitic resistance In–Zn–O BEOL transistor with ultralow <10−20 A μm⁻¹ off-state leakage current

Japanese Journal of Applied Physics (2019)

Nobuyoshi Saito Tomoaki Sawabe Junji Kataoka Tomomasa Ueda Tsutomu Tezuka

We have demonstrated and experimentally verified the advantages of the In–Zn–O (InZnO) channel compared with the In–Ga–Zn–O (InGaZnO) channel for a high-performance oxide semiconductor channel field-effect transistor (FET) with both ultralow off-state leakage current and high on-current. Compared with the InGaZnO FET, high mobility (>30 cm2 V−1 s−1) and a reduction of source/drain (S/D) parasitic resistance by 75% were achieved by the InZnO FET. Analysis of the Schottky barrier height at the S/D contact and the band offset between the oxide semiconductor channel and gate insulator SiO2 revealed that the reduction of S/D parasitic resistance originates from the lowering of the conduction band minimum by the InZnO channel. Moreover, ultralow (<10−20 A μm−1) off-state leakage current characteristics including not only S/D leakage current but also gate leakage current were confirmed to be maintained even with a thin gate insulator with an equivalent oxide thickness of 6.2 nm.

Leakage (economics)

Parasitic element

Equivalent series resistance

Electron Mobility

10.7567/1347-4065/ab01d7

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Citations (11)

Demonstration of Ultralow ( -20 A/um) Off Leakage Current In-Zn-O Channel Transistor with EOT of 6.2nm

The Japan Society of Applied Physics (2018)

Nobuyoshi Saito Tomoaki Sawabe Junji Kataoka Tomomasa Ueda Tsutomu Tezuka

Leakage (economics)

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Reduction of plasma-induced damage on AlGaN/GaN HEMT by atomic layer etching

Koji Kanomaru Ayaka Suko Junji Kataoka Takuo Kikuchi Reiko Saito

Wide-bandgap semiconductor

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N-type conduction of sputter-deposited polycrystalline Al_0.78Sc_0.22N films by Si ion implantation

Applied Physics Express (2020)

Junji Kataoka Sung‐Lin Tsai Takuya Hoshii Hitoshi Wakabayashi Kazuo Tsutsui

Abstract N-type conduction of sputter-deposited polycrystalline Al 0.78 Sc 0.22 N films was verified by Si ion implantation followed by activation annealing. The activation of dopants was found above an annealing temperature of 800 °C. Under a dose of 2 × 10 15 cm −2 with an activation annealing at 900 °C, n-type conduction was obtained with Hall mobility and a carrier concentration of 8.6 cm 2 V −1 s −1 and 8.9 × 10 18 cm −3 , respectively. The surface of n-type Al 0.78 Sc 0.22 N films was sensitive to humidity, and two orders of magnitude increase in the sheet resistance were measured. The phenomena can be understood by the formation of depletion from the backside of the film, caused by the balance between the spontaneous polarization and the surface charges.

10.35848/1882-0786/abd6a0

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Suppression of channel shortening effect for InGaZnO Thin-Film-Transistor by In-Sn-O source/drain electrodes

The Japan Society of Applied Physics (2018)

Junji Kataoka Nobuyoshi Saito Tomomasa Ueda Tsutomu Tezuka Tomoaki Sawabe

Suppressing the channel shortening effect is a key to realize a short channel InGaZnO Thin-Film-Transistor (TFT). We investigated the lateral diffusion length L_{ext}} of low-resistivity region formed in InGaZnO quantitatively. The TFTs with In-Sn-O (ITO) electrode showed no change of L_{ext}}, even though the TFTs with Ti electrode showed the extension of L_{ext}} after high temperature annealing. We revealed that the suppression effect of channel shortening effect of ITO electrode, by using both of electrical characterization and scanning spreading resistance microscopy (SSRM) observation.

Lateral diffusion

Spreading resistance profiling

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High Performance In-Zn-O FET with High On-current and Ultralow (<10⁻²⁰ A/μm) Off-state Leakage Current for Si CMOS BEOL Application

Nobuyoshi Saito Tomoaki Sawabe Junji Kataoka Tomomasa Ueda Tsutomu Tezuka

We have demonstrated and experimentally verified the advantages of In-Zn-O (InZnO) channel compared with In-Ga-Zn-O (InGaZnO) channel for high performance oxide semiconductor channel field effect transistor (FET) with both ultralow off-state leakage current and high on-current. Compared with InGaZnO FET, high mobility (>30 cm ² /Vs) and reduction of source/drain (S/D) parasitic resistance by 75% were achieved by InZnO FET. Analysis of a Schottky barrier height at S/D contact and a band offset between oxide semiconductor channel and gate insulator SiO2 revealed that the reduction of S/D parasitic resistance originated from a lowering of conduction band minimum by InZnO channel. Moreover, ultralow (<;10 ^-20 A/μm) off-state leakage current characteristics including not only S/D leakage current but also gate leakage current were confirmed to maintain even at thin gate insulator with an equivalent oxide thickness of 6.2 nm.

Leakage (economics)

10.23919/am-fpd.2019.8830602

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Tungsten/In–Sn–O stacked source/drain electrode structure of In–Ga–Zn–O thin-film transistor for low-contact resistance and suppressing channel shortening effect

Japanese Journal of Applied Physics (2019)

Junji Kataoka Nobuyoshi Saito Tomomasa Ueda Tsutomu Tezuka Tomoaki Sawabe

The reduction of source/drain (S/D) contact resistance by suppressing effective channel length (Leff) shortening after the high-temperature process is key to realizing integration of high-performance short-channel In–Ga–Zn–O (IGZO) thin-film transistors to 3D large-scale integration. In order to achieve this requirement, we propose a stacked S/D electrode structure of a metal thin film and In–Sn–O (ITO). By inserting around 2 nm tungsten thin film at the interface between the IGZO channel and ITO electrode, about 11 times improvement of on-current (drain current @ Vg = 20 V, Vd = 0.05 V, Lg/W = 0.8/2.4 μm) was achieved. Moreover, Leff shortening was also suppressed to less than 80 nm even after 360 °C annealing.

Contact resistance

10.7567/1347-4065/aafd97

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Citations (4)