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Papers by Author: Hiroyuki Kinoshita

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Characterization of Schottky Diodes on 4H-SiC with Various Off-Axis Angles Grown by Sublimation Epitaxy

Authors: Mitsutaka Nakamura, Yoshikazu Hashino, Tomoaki Furusho, Hiroyuki Kinoshita, Hiromu Shiomi, Masahiro Yoshimoto

Abstract: The effects of basal-plane defects on the performance of 4H-SiC Schottky diodes using a Ni electrode are demonstrated. Systematic characterization was performed using 4H-SiC epitaxial layers grown by sublimation epitaxy on substrates with various off-axis angles. As the off-axis angle increases, the ideality factor of the current-voltage characteristics increases, and the Schottky barrier height decreases, corresponding to an increase in the number of basal-plane defects. The reverse-bias current degrades for high off-axis samples. These results indicate that basal-plane defects degrade the device performance. Schottky diodes that possesses good characteristics were obtained for samples with low off-axis angles (2o- and 4o-off samples).

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TEM Observation of the Polytype Transformation of Bulk SiC Ingot

Authors: Masahiko Aoki, Megumi Miyazaki, Taro Nishiguchi, Hiroyuki Kinoshita, Masahiro Yoshimoto

Abstract: This article describes the analysis of the polytype transformation of SiC ingot. We analyzed the sample by Raman spectroscopy and TEM observation. The result of the analysis shows the polytype is transformed from 4H-SiC to 6H-SiC, and then returned to 4H-SiC. We found that the direction of the c-axis is not the same as the growth direction of the ingot. And also we found the existence of 8H-SiC at the interface between 6H-SiC and 4H-SiC region by the selected area diffraction pattern and confirmed it by HR-TEM observation.

365

Dependence of DAP Emission Properties on Impurity Concentrations in N-/B-co-doped 6H-SiC

Authors: Satoshi Murata, Yoshihiro Nakamura, Tomohiko Maeda, Yoko Shibata, Mina Ikuta, Masaaki Sugiura, Shugo Nitta, Motoaki Iwaya, Satoshi Kamiyama, Hiroshi Amano, Isamu Akasaki, Masahiro Yoshimoto, Tomoaki Furusho, Hiroyuki Kinoshita

Abstract: The dependence of donor-acceptor pair (DAP) emission properties on impurity concentrations of N and B in 6H-SiC epilayers was investigated. Doped samples were grown by closed sublimation technique, and impurity concentrations were confirmed by secondary ion mass spectrometry (SIMS). Photoluminescence (PL) measurement results indicate that p-type 6H-SiC with NA>ND had extremely low DAP emission efficiency, whereas n-type 6H-SiC with NA

335

Nondestructive Analysis of Stacking Faults in 4H-SiC Bulk Wafers by Room-Temperature Photoluminescence Mapping under Deep UV Excitation

Authors: Norihiro Hoshino, Michio Tajima, Toshihiko Hayashi, Taro Nishiguchi, Hiroyuki Kinoshita, Hiromu Shiomi

Abstract: The advantage of room-temperature photoluminescence (PL) mapping was demonstrated for nondestructive detection of stacking faults (SFs) in off-oriented 4H-SiC epitaxial and bulk wafers. In mapping of the SF-related emission at 2.9 eV on the wafers, the SFs in the surface region appeared as a bar-shaped pattern with the long side perpendicular to the off-cut direction. The use of 266 nm light excitation is essential to detect the SF pattern in the bulk wafers because of its shallow penetration depth. The dark lines crossing the bar-shaped patterns in the epitaxial wafers are ascribable to the basal plane dislocation located close to the SF-planes.

275

Characterization of SiC Wafers by Photoluminescence Mapping

Authors: Michio Tajima, E. Higashi, Toshihiko Hayashi, Hiroyuki Kinoshita, Hiromu Shiomi

Abstract: The effectiveness of room-temperature photoluminescence (PL) mapping was demonstrated for nondestructive detection of structural defects, such as dislocations, micropipes and stacking faults, in SiC wafers. PL spectra of bulk wafers were dominated by deep-level emissions due to Si vacancies, vanadium and undefined centers like UD-1 at room temperature, while those from epitaxial wafers involved near band-edge emission. We developed a whole-wafer PL intensity mapping system with a capability of zooming in on the area of interest with a spatial resolution as high as 1 μm, and showed that the mapping patterns agree well with the etch-pit patterns originating from the structural defects both on a wafer scale and on a microscopic scale. The intensity contrast around the defects varied depending on the emission band, suggesting differences in their interactions with impurities and point defects.

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6H-SiC Homoepitaxial Growth and Optical Property of Boron- and Nitrogen-Doped Donor-Acceptor Pair (DAP) Emission of 1º-Off Substrate by Closed-Space Sublimation Method

Authors: Y. Kawai, Tomohiko Maeda, Yoshihiro Nakamura, Yoji Sakurai, Motoaki Iwaya, Satoshi Kamiyama, Hiroshi Amano, Isamu Akasaki, Masahiro Yoshimoto, Tomoaki Furusho, Hiroyuki Kinoshita, Hiromu Shiomi

Abstract: We demonstrate high-speed and high-quality 6H-SiC homoepitaxial growth on a 1°-off c-plane SiC substrate by a closed-space sublimation method. By optimizing the size of single-crystal source materials in the growth system, a high-quality 6H-SiC epilayer with an X-ray diffraction rocking curve (0006) full-width at the half maximum (FWHM) of 38 arcsec was obtained. We also carried out doping of nitrogen and boron during the growth of the SiC epilayer. A strong donor-acceptor pair (DAP) emission at a peak wavelength of 570 nm under excitation by a 395 nm nitride-based light-emitting diode (LED) was observed. The 6H-SiC with DAP emission is promising for use as a phosphor in a nitride-based LED, because high-quality nitride layers can be grown on the SiC substrates with small off-oriented angles.

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Growth of Micropipe Free Crystals on 4H-SiC {03-38} Seeds

Authors: Tomoaki Furusho, Ryota Kobayashi, Taro Nishiguchi, M. Sasaki, K. Hirai, Toshihiko Hayashi, Hiroyuki Kinoshita, Hiromu Shiomi

Abstract: Growth of 4H-SiC bulk crystals on 4H-SiC {03-38} seeds was done. 4H-SiC {03-38} is obtained by inclining the c-plane toward <01-10> at a 54.7 degrees angle. Growth on the 4H-SiC {03-38} seed has the potential to achieve high quality crystals without micropipes and stacking faults. Micropipe-free c-plane 4H-SiC wafers were achieved by growth on the 4H-SiC {03-38} seed. A transmission X-ray topograph image of the micropipe free c-plane wafer revealed that there are no macroscopic defects with displacements.