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Journal Articles

C-face interface defects in 4H-SiC MOSFETs studied by electrically detected magnetic resonance

Umeda, Takahide*; Okamoto, Mitsuo*; Arai, Ryo*; Sato, Yoshihiro*; Kosugi, Ryoji*; Harada, Shinsuke*; Okumura, Hajime*; Makino, Takahiro; Oshima, Takeshi

Materials Science Forum, 778-780, p.414 - 417, 2014/02

 Times Cited Count:2 Percentile:19.86

Interface defects of Metal-Oxide-Semiconductors (MOSFETs) fabricated on Carbone (C) face 4H-SiC were investigated by Electrically Detected Magnet Resistance (EDMR). Gate oxide of the MOSFETs was formed by either wet-oxidation and H$$_{2}$$ annealing or dry-oxidation. The values of channel mobility for MOSFETS with wet gate oxide and dry gate oxide are less than 1 and 90 cm$$^{2}$$/Vs, respectively. By EDMR measurement under low temperature (less than 20 K), EDMR signals related to C were detected. The peak height of the signals increased with increasing $$gamma$$-ray doses, and the channel mobility decreased. From this result, it is assumed that hydrogen atoms passivating C dangling bonds are released by $$gamma$$-rays and the channel mobility decreases with increasing the C related defects.

Journal Articles

A Silicon carbide room-temperature single-photon source

Castelletto, S.*; Johnson, B.*; Ivady, V.*; Stavrias, N.*; Umeda, Takahide*; Gali, A.*; Oshima, Takeshi

Nature Materials, 13(2), p.151 - 156, 2014/02

 Times Cited Count:287 Percentile:0.61(Chemistry, Physical)

The generation and detection of single photons play a central role in the experimental foundation of quantum mechanics and measurement theory. An effcient and high-quality single-photon source is thought to be necessary to realize quantum key distribution, quantum repeaters and photonic quantum information processing. We found the identication and formation of ultra-bright, room temperature, photo-stable single photon sources in silicon carbide (SiC). The single photon source consists of an intrinsic defect which is known as the carbon antisite vacancy pair, created by carefully optimized electron irradiation and annealing of ultra pure SiC. An extreme brightness (2$$times$$10$$^{6}$$ counts/s) resulting from polarization rules and a high quantum effciency is obtained in the bulk without resorting to the use of a cavity or plasmonic structure.

Journal Articles

Negative-U system of carbon vacancy in 4H-SiC

Son, N. T.*; Trinh, X. T.*; L${o}$vile, L. S.*; Svensson, B. G.*; Kawahara, Kotaro*; Suda, Jun*; Kimoto, Tsunenobu*; Umeda, Takahide*; Isoya, Junichi*; Makino, Takahiro; et al.

Physical Review Letters, 109(18), p.187603_1 - 187603_5, 2012/11

 Times Cited Count:152 Percentile:2.11(Physics, Multidisciplinary)

Journal Articles

Electrically Detected Magnetic Resonance (EDMR) studies of SiC-SiO$$_{2}$$ interfaces

Umeda, Takahide*; Kosugi, Ryoji*; Fukuda, Kenji*; Morishita, Norio*; Oshima, Takeshi; Ezaki, Kana*; Isoya, Junichi*

Materials Science Forum, 717-720, p.427 - 432, 2012/05

 Times Cited Count:6 Percentile:4.04

Metal-Oxide (SiO$$_{2}$$)-Semiconductor (MOS) structures fabricated on Silicon Carbide (SiC) were studied using Electrically Detected Magnetic Resonance technique (EDMR). The residual Carbons are expected to be near the interface between SiC and SiC-SiO$$_{2}$$SiO$$_{2}$$, which is different from Si-SiO$$_{2}$$ interface. By the EDMR measurements at 50K, a defect center related to C dangling bonds which is called P$$_{H1}$$ center and also a center related to C dangling bonds terminated by hydrogens or nitrogens (Ns) which is called P$$_{H1}$$ were observed. In addition, a center related to N donor which is called Nh exist near the interface from N-treatment samples. This suggests that carrier concentration increases near the interface due to the introduction of donors, and as a result, the channel conductance increases.

Journal Articles

Behavior of nitrogen atoms in SiC-SiO$$_{2}$$ interfaces studied by electrically detected magnetic resonance

Umeda, Takahide*; Ezaki, Kana*; Kosugi, Ryoji*; Fukuda, Kenji*; Oshima, Takeshi; Morishita, Norio*; Isoya, Junichi*

Applied Physics Letters, 99(14), p.142105_1 - 142105_3, 2011/10

 Times Cited Count:43 Percentile:13.62(Physics, Applied)

Journal Articles

Fluorine-vacancy defects in fluorine-implanted silicon studied by electron paramagnetic resonance

Umeda, Takahide*; Isoya, Junichi*; Oshima, Takeshi; Onoda, Shinobu; Morishita, Norio; Okonogi, Kensuke*; Shiratake, Shigeru*

Applied Physics Letters, 97(4), p.041911_1 - 041911_3, 2010/07

 Times Cited Count:5 Percentile:74.02(Physics, Applied)

Journal Articles

Photo-EPR study of vacancy-type defects in irradiated ${it n}$-type 4${it H}$-SiC

Umeda, Takahide*; Morishita, Norio; Oshima, Takeshi; Ito, Hisayoshi; Isoya, Junichi*

Materials Science Forum, 600-603, p.409 - 412, 2009/00

We have performed photo-electron paramagnetic resonance (photo-EPR) analyses on four types of fundamental vacancy-related defects in 3MeV electron-irradiated 4${it H}$-SiC, i.e., carbon vacancies $$V$$$$_{rm C}$$$$^{-}$$), silicon vacancies ($$T$$$$_{V2a}$$-type $$V$$$$_{rm Si}$$$$^{-}$$), divacancies $$V$$$$_{rm Si}$$$$V$$$$_{rm C}$$$$^{0/-}$$), and carbon antisite-vacancy pairs (C$$_{rm Si}$$$$V$$$$_{rm C}$$$$^{-}$$). The photo-induced transitions from their -2 to -1 charged states or from their -1 charged to neutral states were detected in the photon energy range between 0.80 and 1.20 eV. Based on these transitions, we have discussed positions of their defect levels with respect to the conduction band edge.

Journal Articles

Identification of the negative Di-carbon antisite defect in n-type 4H-SiC

Gali, A.*; Umeda, Takahide*; Janz$'e$n, E.*; Morishita, Norio; Oshima, Takeshi; Isoya, Junichi*

Materials Science Forum, 615-617, p.361 - 364, 2009/00

Carbon antisite defects in Silicon Carbide (SiC) were studied using Electron Spin Resonance (ESR) and first principle calculations. The samples used in this study were n-type 4H-SiC, and these samples were irradiated with MeV electrons at 10$$^{18}$$/cm$$^{2}$$ in temperature range between 300 and 800$$^{circ}$$C. As the results of ESR measurements, signals labeled HEI5 and HEI6, which have S=1/2 and C$$_{1h}$$ symmetry were observed. By the detailed measurements of $$^{29}$$Si and $$^{13}$$C hyperfine satellite, and first principle calculations, HEI5 and HEI6 were identified to be di-carbon antisite at cubic and hexagonal sites, respectively.

Journal Articles

Pulsed EPR studies of the T$$_{V2a}$$ center in 4$$H$$-SiC

Isoya, Junichi*; Umeda, Takahide*; Mizuochi, Norikazu*; Oshima, Takeshi

Materials Science Forum, 615-617, p.353 - 356, 2009/00

To indentify intrinsic defects in silicon carbide (SiC), a T$$_{V2a}$$ center in 4$$H$$-SiC was investigated using pulsed electron paramagnetic resonance (EPR). The T$$_{V2a}$$ is a center with S=3/2 and C$$_{3V}$$ symmetry, and in previous studies, the origin of the T$$_{V2a}$$ is thought to be a defects of negatively charged Si vacancy (V$$_{Si}$$$$^{-}$$). In this study, T$$_{V2a}$$ centers were introduced in n-type 4$$H$$-SiC samples by MeV range electron irradiation at 10$$^{18}$$ /cm$$^{2}$$. As a result of EPR, pulsed EPR and ENDOR measurements, the origin of the T$$_{V2a}$$center can be identified to be not a simple V$$_{Si}$$$$^{-}$$ defect but the complex between V$$_{Si}$$$$^{-}$$ with Next Nearest Neighbors.

Journal Articles

EPR identification of intrinsic defects in SiC

Isoya, Junichi*; Umeda, Takahide*; Mizuochi, Norikazu*; Son, N. T.*; Janz$'e$n, E.*; Oshima, Takeshi

Physica Status Solidi (B), 245(7), p.1298 - 1314, 2008/07

 Times Cited Count:59 Percentile:11.34(Physics, Condensed Matter)

Intrinsic defects in silicon carbide (SiC) were indentified using Electron Paramagnetic Resonance (EPR). The samples used in this study were cubic (3C) and hexagonal (4H, 6H) SiC. The angular dependence of hyperfine structure of $$^{29}$$Si, $$^{13}$$C was compared to the results from the first principle calculations As the results, positively charged carbon vacancies in $$h$$ and $$k$$ sites (V$$_{C}$$$$^{+}$$($$h$$), V$$_{C}$$$$^{+}$$($$k$$)), negatively charged carbon vacancy (V$$_{C}$$$$^{-}$$($$h$$)), and neutoral, positively and negatively charged di-vacancies of silicon vacancy and carbon vacancy ([V$$_{Si}$$V$$_{C}$$]$$^{0}$$, [V$$_{Si}$$V$$_{C}$$]$$^{+}$$, [V$$_{Si}$$V$$_{C}$$]$$^{-}$$) were identified.

Journal Articles

EPR study of electron-irradiated SiC; Structure determination of intrinsic defects in 4$$H$$-SiC

Isoya, Junichi*; Umeda, Takahide*; Mizuochi, Norikazu*; Katagiri, Masayuki*; Oshima, Takeshi; Morishita, Norio; Ito, Hisayoshi

JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 15, 2007/02

no abstracts in English

Journal Articles

Electron paramagnetic resonance study of carbon antisite-vacancy pair in $$p$$-type 4$$H$$-SiC

Umeda, Takahide*; Oshima, Takeshi; Morishita, Norio; Ito, Hisayoshi; Isoya, Junichi*

Materials Science Forum, 556-557, p.453 - 456, 2007/00

no abstracts in English

Journal Articles

Identification of divacancies in 4H-SiC

Son, N. T.*; Umeda, Takahide*; Isoya, Junichi*; Gali, A.*; Bockstedte, M.*; Magnusson, B.*; Ellison, A.*; Morishita, Norio; Oshima, Takeshi; Ito, Hisayoshi; et al.

Physica B; Condensed Matter, 376-377, p.334 - 337, 2006/04

 Times Cited Count:3 Percentile:80.94(Physics, Condensed Matter)

no abstracts in English

Journal Articles

Identification of the carbon antisite-vacancy pair in 4${it H}$-SiC

Umeda, Takahide*; Son, N. T.*; Isoya, Junichi*; Janz$'e$n, E.*; Oshima, Takeshi; Morishita, Norio; Ito, Hisayoshi; Gali, A.*; Bockstedte, M.*

Physical Review Letters, 96(14), p.145501_1 - 145501_4, 2006/04

 Times Cited Count:74 Percentile:9.01(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Divacancy in 4H-SiC

Son, N. T.*; Carlsson, P.*; Hassan, J. ul*; Janz$'e$n, E.*; Umeda, Takahide*; Isoya, Junichi*; Gali, A.*; Bockstedte, M.*; Morishita, Norio; Oshima, Takeshi; et al.

Physical Review Letters, 96(5), p.055501_1 - 055501_4, 2006/02

 Times Cited Count:156 Percentile:3.21(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Electron paramagnetic resonance study of the ${it HEI}$4/${it SI}$5 center in 4H-SiC

Umeda, Takahide*; Son, N. T.*; Isoya, Junichi*; Morishita, Norio; Oshima, Takeshi; Ito, Hisayoshi; Janz$'e$n, E.*

Materials Science Forum, 527-529, p.543 - 546, 2006/00

no abstracts in English

Journal Articles

Shallow P donors in 3${it C}$-, 4${it H}$-, and 6${it H}$-SiC

Isoya, Junichi*; Katagiri, Masayuki*; Umeda, Takahide*; Son, N. T.*; Henry, A.*; Gali, A.*; Morishita, Norio; Oshima, Takeshi; Ito, Hisayoshi; Janz$'e$n, E.*

Materials Science Forum, 527-529, p.593 - 596, 2006/00

no abstracts in English

Journal Articles

Divacancy model for P6/P7 centers in 4H- and 6H-SiC

Son, N. T.*; Umeda, Takahide*; Isoya, Junichi*; Gali, A.*; Bockstedte, M.*; Magnusson, B.*; Ellison, A.*; Morishita, Norio; Oshima, Takeshi; Ito, Hisayoshi; et al.

Materials Science Forum, 527-529, p.527 - 530, 2006/00

no abstracts in English

Journal Articles

Spin multiplicity and charge state of a silicon vacancy (${it T}$ $$_{V2a}$$) in 4${it H}$-SiC determined by pulsed ENDOR

Mizuochi, Norikazu*; Yamasaki, Satoshi*; Takizawa, Haruki; Morishita, Norio; Oshima, Takeshi; Ito, Hisayoshi; Umeda, Takahide*; Isoya, Junichi*

Physical Review B, 72(23), p.235208_1 - 235208_6, 2005/12

 Times Cited Count:46 Percentile:16.21(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

EPR and theoretical studies of positively charged carbon vacancy in 4$$H$$-SiC

Umeda, Takahide*; Isoya, Junichi*; Morishita, Norio; Oshima, Takeshi; Kamiya, Tomihiro; Gali, A.*; De$'a$k, P.*; Son, N. T.*; Janz$'e$n, E.*

Physical Review B, 70(23), p.235212_1 - 235212_6, 2004/12

 Times Cited Count:40 Percentile:16.59(Materials Science, Multidisciplinary)

no abstracts in English

44 (Records 1-20 displayed on this page)