Faculty Profiles - OHNO, Yutaka

Papers - OHNO, Yutaka

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Characterization of Electrical Properties of Micro-Schottky Contacts on Epitaxial Lateral Overgrowth GaN

Kumada Keiichiro, Murata Tomohiro, Ohno Yutaka, Kishimoto Shigeru, Maezawa Koichi, Mizutani Takashi, Sawaki Nobuhiko

Japanese Journal of Applied Physics Vol. 42 ( 4B ) page： 2250 - 2253 2003.4

Language：Japanese Publisher：The Japan Society of Applied Physics

Current-voltage characteristics of micro-Schottky contacts fabricated on Epitaxial lateral overgrowth (ELO) GaN have been measured. The obtained characteristics are classified into two groups; good contacts with small ideality factor (n-value) and poor contacts with large n-value. By comparing the distribution of I-V characteristics of the micro-Schottky contact array with the distribution of dislocations revealed by molten KOH etching, it was concluded that the dislocations are not responsible for the poor I-V characteristics of the Schottky contacts. Regarding the origin of the poor I-V characteristics, the high doping density area formed at the top surface of the as-grown wafer was suggested.

DOI： 10.1143/JJAP.42.2250

Web of Science

CiNii Research

Fluidic Assembly of Thin GaAs Blocks on Si Substrates

Soga Ikuo, Ohno Yutaka, Kishimoto Shigeru, Maezawa Koichi, Mizutani Takashi

Japanese Journal of Applied Physics Vol. 42 ( 4B ) page： 2226 - 2229 2003.4

Language：Japanese Publisher：The Japan Society of Applied Physics

We have studied the fluidic assembly technique for heterogeneous integration. In this technique, small device blocks, the size of which ranges from a few tens of microns to a few hundreds of microns, can be assembled into the recesses formed on the Si substrate. First, we used thin disk-shaped GaAs blocks to study the fundamental process of the fluidic assembly. A 100% yield was achieved with an appropriate strength of sonic vibration. The assembled blocks were confirmed to have no strain by using Raman scattering spectroscopy even if they were annealed at 320°C for 30 min. In addition, the effects of the shape of blocks are discussed based on the experimental results for disk- and square-shaped blocks.

DOI： 10.1143/JJAP.42.2226

Web of Science

CiNii Research

Comparison of Electrical Characteristics of Metamorphic HEMTs with InP HEMTs and PHEMTs

Kawada Kenji, Ohno Yutaka, Kishimoto Shigeru, Maezawa Koichi, Mizutani Takashi, Takakusaki Misao, Nakata Hirofumi

Japanese Journal of Applied Physics Vol. 42 ( 4B ) page： 2219 - 2222 2003.4

Language：Japanese Publisher：The Japan Society of Applied Physics

Metamorphic In0.52Al0.48As/In0.53Ga0.47As high electron mobility transistors (MHEMTs) were fabricated on GaAs substrates. A step-graded InAlAs buffer layer was used to relax the lattice mismatch between the active layers and the substrates. The electrical characteristics of the MHEMTs were compared with those of HEMTs on InP substrates (InP HEMTs) and pseudomorphic HEMTs (PHEMTs). Present MHEMTs have exhibited superior characteristics in the low-frequency (LF) noise and side-gate effect to InP HEMTs and PHEMTs. A sufficiently high current-gain cutoff frequency of 210 GHz was obtained for the MHEMTs with gate length of 0.1 μm.

DOI： 10.1143/JJAP.42.2219

Web of Science

CiNii Research

Electronic properties of Gd@C-82 metallofullerene peapods: (Gd @ C-82)(n)@SWNTs

Okazaki T, Shimada T, Suenaga K, Ohno Y, Mizutani T, Lee J, Kuk Y, Shinohara H

APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING Vol. 76 ( 4 ) page： 475 - 478 2003.3

Measurement of Frequency Dispersion of AlGaN/GaN High Electron Mobility Transistors.

Mizutani Takashi, Makihara Hiroshi, Akita Mitsutoshi, Ohno Yutaka, Kishimoto Shigeru, Maezawa Koichi

Japanese Journal of Applied Physics Vol. 42 ( 2A ) page： 424 - 425 2003.2

Language：Japanese Publisher：The Japan Society of Applied Physics

Frequency dispersion of the drain conductance was observed in AlGaN/GaN high electron mobility transistors (HEMTs). The transition frequency shifted to higher frequencies with increasing temperature. The activation energy for the change of the transition frequency was 0.47 eV, which was almost the same as that obtained by the measurement of the temperature dependence of the low-frequency noise.

DOI： 10.1143/JJAP.42.424

Web of Science

CiNii Research

Carrier transport properties of carbonnanotubes and nanopeapods

Shimada Takashi, Ohno Yutaka, Okazaki Toshiya, Sugai Toshiki, Kishimoto Shigeru, Mizutani Takashi, Shinohara Hisanori

Meeting Abstracts of the Physical Society of Japan Vol. 58.2.4 ( 0 ) page： 760 2003

Experimental demonstration of a resonant tunneling delta-sigma modulator for high-speed, high-resolution analog-to-digital converter

Yokoyama Y, Ohno Y, Kishimoto S, Maezawa K, Mizutani T

COMPOUND SEMICONDUCTORS 2002 Vol. 174 page： 243 - 246 2003

Study on off-state breakdown in AlGaN/GaN HEMTs

Nakao T, Ohno Y, Kishimoto S, Maezawa K, Mizutani T

5TH INTERNATIONAL CONFERENCE ON NITRIDE SEMICONDUCTORS (ICNS-5), PROCEEDINGS Vol. 0 ( 7 ) page： 2335 - 2338 2003

The round table talk of the successive presidents of JSSST

OHNO Yutaka, KATAYAMA Takuya, YONEZAWA Akinori, TAKEICHI Masato, AGUSA Kiyoshi

Computer Software Vol. 20 ( 6 ) page： 537 - 548 2003

Current collapse in AlGaN/GaN HEMTs investigated by electrical and optical characterizations

Mizutani T, Ohno Y, Akita M, Kishimoto S, Maezawa K

PHYSICA STATUS SOLIDI A-APPLIED RESEARCH Vol. 194 ( 2 ) page： 447 - 451 2002.12

Ambipolar field-effect transistor behavior of Gd@C-82 metallofullerene peapods

Shimada T, Okazaki T, Taniguchi R, Sugai T, Shinohara H, Suenaga K, Ohno Y, Mizuno S, Kishimoto S, Mizutani T

APPLIED PHYSICS LETTERS Vol. 81 ( 21 ) page： 4067 - 4069 2002.11

Effects of the HEMT parameters on the operation frequency of resonant tunneling logic gate MOBILE

Aoyama T, Ohno Y, Kishimoto S, Maezawa K, Mizutani T

ELECTRONICS AND COMMUNICATIONS IN JAPAN PART II-ELECTRONICS Vol. 85 ( 10 ) page： 1 - 6 2002.10

Large Gate Leakage Current in AlGaN/GaN High Electron Mobility Transistors.

Mizuno Shinya, Ohno Yutaka, Kishimoto Shigeru, Maezawa Koichi, Mizutani Takashi

Japanese Journal of Applied Physics Vol. 41 ( 8 ) page： 5125 - 5126 2002.8

Language：Japanese Publisher：The Japan Society of Applied Physics

A large gate leakage current in AlGaN/GaN high electron mobility transistors (HEMTs) was observed. Temperature dependence of Ig-Vg characteristics revealed that tunneling current is dominant in the leakage current. By introducing ECR plasma treatment before the gate metal deposition, the gate leakage current was reduced by two to three orders of magnitude.

DOI： 10.1143/JJAP.41.5125

Web of Science

CiNii Research

Temperature distribution measurement in AlGaN/GaN high-electron-mobility transistors by micro-Raman scattering spectroscopy

Ohno Y, Akita M, Kishimoto S, Maezawa K, Mizutani T

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS Vol. 41 ( 4B ) page： L452 - L454 2002.4

Electroluminescence in AlGaN/GaN High Electron Mobility Transistors under High Bias Voltage.

Nakao Takeshi, Ohno Yutaka, Akita Mitsutoshi, Kishimoto Shigeru, Maezawa Koichi, Mizutani Takashi

Japanese Journal of Applied Physics Vol. 41 ( 4A ) page： 1990 - 1991 2002.4

Language：Japanese Publisher：The Japan Society of Applied Physics

Electroluminescence (EL) in GaN high electron mobility transistors (HEMTs) biased at high drain-source voltages was investigated. The electroluminescence was observed at the drain edge where the high-field region is formed. This is quite different from the case of GaAs HEMTs where luminescence was observed at the gate edge. EL spectroscopy was also performed. The luminescence with the wavelength of visible to near-infrared light, the energy of which was less than the band gap energy, was observed with polarization in the direction parallel to the drain current.

DOI： 10.1143/JJAP.41.1990

Web of Science

CiNii Research

50 GHz frequency divider using resonant tunnelling chaos circuit

Kawano Y, Ohno Y, Kishimoto S, Maezawa K, Mizutani T

ELECTRONICS LETTERS Vol. 38 ( 7 ) page： 305 - 306 2002.3

Indium Phosphide & Related Materials. High-Speed Operation of a Novel Frequency Divider Using Resonant Thnneling Chaos Circuit.

Kawano Yoichi, Ohno Yutaka, Kishimoto Shigeru, Maezawa Koichi, Mizutani Takashi

Japanese Journal of Applied Physics Vol. 41 ( 2B ) page： 1150 - 1153 2002.2

Language：Japanese Publisher：The Japan Society of Applied Physics

This paper demonstrates high-frequency operations of the frequency divider IC composed of a resonant tunneling diode and a high electron mobility transistor. The maximum frequency dividing operation of 6.3 GHz was confirmed. This circuit is based on the long-period behavior of the nonlinear circuits generating chaos. We investigate the effects of the input frequency, the bias voltage, and the input amplitude on the operation to discuss the operating margins. It is also shown that the dividing ratio can be selected by changing the input amplitude.

DOI： 10.1143/JJAP.41.1150

Web of Science

CiNii Research

Electroluminescence in AlGaN/GaN HEMTS

Ohno Y, Nakao T, Akita M, Kishimoto S, Maezawa K, Mizutani T

COMPOUND SEMICONDUCTORS 2001 ( 170 ) page： 119 - 124 2002

Low-frequency noise characteristics of AlGaN/GaN HEMT

Makihara H, Akita M, Ohno Y, Kishimoto S, Maezawa K, Mizutani T

COMPOUND SEMICONDUCTORS 2001 ( 170 ) page： 113 - 117 2002

Temperature distributions in AlGaN/GaN HEMTs measured by micro-Raman scattering spectroscopy

Ohno Y, Akita M, Kishimoto S, Maezawa K, Mizutani T

INTERNATIONAL WORKSHOP ON NITRIDE SEMICONDUCTORS, PROCEEDINGS page： 57 - 60 2002

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Papers - OHNO, Yutaka