- 著者
- Umeda T. Isoya J. Morishita N. Ohshima T. Kamiya T. Gali A. Deák P. Son N. T. Janzén E.
- 出版者
- American Physical Society
- 雑誌
- Physical review B (ISSN:10980121)
- 巻号頁・発行日
- vol.70, pp.235212, 2004-12
- 被引用文献数
- 49
The carbon vacancy is a dominant defect in 4H-SiC, and the "EI5" electron-paramagnetic-resonance (EPR) spectrum originates from positively charged carbon vacancies (VC+) at quasicubic sites. The observed state for EI5, however, has been attributed to a motional-averaged state with the C3v symmetry, and its true atomic structure has not been revealed so far. We here report low temperature (<40 K) EPR measurements on EI5 and show that this center has a C1h-symmetric structure due to Jahn-Teller distortion. We also performed ab inito calculations of the hyperfine tensors for EI5, and obtained a good agreement between experiment and theory in not only their principal values but also their principal axis directions. A good agreement was also demonstrated for the EI6 center (hexagonal-site VC+) in this paper. The transition from EI5(C1h) to EI5(C3v) was found to be thermally activated and its activation energy was measured as 0.014 eV.
- 著者
- Umeda T. Ishitsuka Y. Isoya J. Son N. T. Janzén E. Morishita N. Ohshima T. Itoh H. Gali A.
- 出版者
- American Physical Society
- 雑誌
- Physical review B (ISSN:10980121)
- 巻号頁・発行日
- vol.71, pp.193202, 2005-05
- 被引用文献数
- 55
Carbon vacancies (VC) are typical intrinsic defects in silicon carbides (SiC) and so far have been observed only in the form of positively charged states in p-type or semi-insulating SiC. Here, we present electron-paramagnetic-resonance (EPR) and photoinduced EPR (photo-EPR) observations of their negatively charged state (V<sub>C</sub><sup>-</sup>) in n-type 4H-SiC. This EPR center (called HEI1) is characterized by an electron spin of 1/2 in a Si-Si antibonding state of VC. First-principles calculations confirm that the HEI1 center arises from V<sub>C</sub><sup>-</sup> at hexagonal sites. The HEI1 spectrum shows a transition between C1h and C3v symmetries due to a fast reorientation effect reflected in the nature of this defect. The photo-EPR data suggest that V<sub>C</sub><sup>2-</sup> is the dominant form of VC when the Fermi level lies 1.1 eV below the conduction band.
- 著者
- Seuster R. Abe K. Aihara H. Asano Y. Aushev T. Bakich A. M. Barbero M. Bedny I. Bitenc U. Bizjak I. Bozek A. Dragic J. Drutskoy A. Eidelman S. Fang F. Gershon T. Go A. Gokhroo G. Golob B. Gorišek A. Hayasaka K. Kim H. J. Hazumi M. Hoshi Y. Hou S. Hou W. -S. Iijima T. Ikado K. Itoh R. Iwasaki Y. Kang J. H. Kang J. S. Kim S. M. Kapusta P. Katayama N. Kawai H. Kawasaki T. Khan H. R. Kichimi H. Križan P. Krokovny P. Kulasiri R. Kuo C. C. Kuzmin A. Kwon Y. -J. Lange J. S. Lesiak T. Okuno S. Li J. Lin S. -W. Mandl F. Mitaroff W. Miyake H. Miyazaki Y. Mizuk R. Nagamine T. Nagasaka Y. Nakano E. Olsen S. L. Nakao M. Nishida S. Nitoh O. Ogawa S. Ohshima T. Okabe T. Onuki Y. Ozaki H. Pakhlov P. Palka H. Park C. W. Park H. Park K. S. Pestotnik R. Takasaki F. Piilonen L. E. Sakai Y. Sato N. Schietinger T. Schneider O. Schümann J. Schwanda C. Sevior M. E. Shibuya H. Sidorov V. Tamai K. Somov A. Soni N. Stamen R. Stanič S. Starič M. Suzuki S. Y. Tamura N. Tanaka M. Taylor G. N. Teramoto Y. Tian X. C. Uehara S. Uglov T. Ueno K. Bračko M. Uno S. Urquijo P. Varner G. Wang C. C. Wang C. H. Wang M. -Z. Xie Q. L. Yabsley B. D. Yamaguchi A. Yamashita Y. Brodzicka J. Yamauchi M. Ying J. Yusa Y. Zhang L. M. Zhang Z. P. Zhilich V. Chen A. Cheon B. G. Choi Y. Chuvikov A. Cole S. Dalseno J. Danilov M. Dash M. Dong L. Y.
- 出版者
- The American Physical Society
- 雑誌
- PHYSICAL REVIEW D (ISSN:15507998)
- 巻号頁・発行日
- vol.73, no.32002, pp.1-22, 2006
- 被引用文献数
- 70
- 著者
- Umeda T. Isoya J. Morishita N. Ohshima T. Kamiya T.
- 出版者
- American Physical Society
- 雑誌
- Physical review B (ISSN:10980121)
- 巻号頁・発行日
- vol.69, pp.121201, 2004-03
- 被引用文献数
- 42
The EI5 and EI6 centers are typical intrinsic defects in radiation-damaged and semi-insulating 4H-SiC. So far, their origins have been assigned to positively charged carbon vacancies (VC+) and silicon antisites (SiC+), respectively. However, our complete set of 29Si hyperfine (HF) data clearly reveals that both the centers should originate from VC+ but their locations are different, i.e., quasicubic sites for EI5 and hexagonal sites for EI6, as recently predicted by the first-principle calculation [M. Bockstedte et al., Phys. Rev. B 67, 193102 (2003)]. The two types of VC+ centers showed remarkable differences in their atomic structures as well as in the temperature dependence of HF interactions, which are closely related to the nature of the two sites.
- 著者
- Umeda T. Son N. T. Isoya J. Janzén E. Ohshima T. Morishita N. Itoh H. Gali A. Bockstedte M.
- 出版者
- American Physical Society
- 雑誌
- Physical review letters (ISSN:00319007)
- 巻号頁・発行日
- vol.96, pp.145501, 2006-04
- 被引用文献数
- 70
The metastability of vacancies was theoretically predicted for several compound semiconductors alongside their transformation into the antisite-vacancy pair counterpart; however, no experiment to date has unambiguously confirmed the existence of antisite-vacancy pairs. Using electron paramagnetic resonance and first principles calculations we identify the SI5 center as the carbon antisite-vacancy pair in the negative charge state (CSiV<sub>C</sub><sup>-</sup>) in 4H-SiC. We suggest that this defect is a strong carrier-compensating center in n-type or high-purity semi-insulating SiC.
1 0 0 0 OA Fluorine-vacancy defects in fluorine-implanted silicon studied by electron paramagnetic resonance
- 著者
- Umeda T. Isoya J. Ohshima T. Onoda S. Morishita N. Okonogi K. Shiratake S.
- 出版者
- American Institute of Physics
- 雑誌
- Applied physics letters (ISSN:00036951)
- 巻号頁・発行日
- vol.97, no.4, pp.041911, 2010-07
- 被引用文献数
- 5
An electron paramagnetic resonance (EPR) study on fluorine-vacancy defects (FnVm) in fluorine-implanted silicon is demonstrated. Fluorine implantation is an important technology for Si microdevices and EPR measurements showed that this process created a variety of FnVm defects of different sizes (V2, V4, and V5). In FnVm, a Si–F bond exhibited a different chemical nature compared to a Si–H bond in hydrogen-vacancy complexes. The most primitive defect was FV2 (F0 center) and the final types were FnV5 (F1 center) and FnV2 (F2 center) which increased in annealing processes as low temperature as 200 °C.