Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Christle, D.*; Falk, A.*; Andrich, A.*; Klimov, P.*; Hassan, J.*; Son, N. T.*; Janz
n, E.*; Oshima, Takeshi; Awschalom, D.*
Nature Materials, 14(2), p.160 - 163, 2015/02
Times Cited Count：330 Percentile：99.21(Chemistry, Physical)Widmann, M.*; Lee, S.-Y.*; Rendler, T.*; Son, N. T.*; Fedder, H.*; Paik, S.*; Yang, L.-P.*; Zhao, N.*; Yang, S.*; Booker, I.*; et al.
Nature Materials, 14(2), p.164 - 168, 2015/02
Times Cited Count：435 Percentile：99.55(Chemistry, Physical)Son, N. T.*; Isoya, Junichi*; Ivanov, I. G.*; Oshima, Takeshi; Janzn, E.*
AIP Conference Proceedings 1583, p.341 - 344, 2014/02
-Irradiated n-type 4H-SiCBeyer, F. C.*; Hemmingsson, C. G.*; Pedersen, H.*; Henry, A.*; Isoya, Junichi*; Morishita, Norio*; Oshima, Takeshi; Janzn, E.*
Journal of Physics D; Applied Physics, 45(45), p.455301_1 - 455301_7, 2012/11
Times Cited Count：18 Percentile：57.55(Physics, Applied)Son, N. T.*; Trinh, X. T.*; L
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：199 Percentile：97.98(Physics, Multidisciplinary)Son, N. T.*; Gali, A.*; Szab
, 
.*; Bikermann, M.*; Oshima, Takeshi; Isoya, Junichi*; Janzn, E.*
Applied Physics Letters, 98(24), p.242116_1 - 242116_3, 2011/06
Times Cited Count：9 Percentile：38.03(Physics, Applied)AlN samples were irradiated with 2 MeV electrons, and defects in the AlN were measured using an electron paramagnetic resonance (EPR). As a result, a defect center, labeled EI-1, with an electron spin S=1/2 and a clear hyperfine hf structure was observed. The hf structure was shown to be the interaction between the electron spin and the nuclear spins of four 
A nuclei with the hf splitting varying between 
6.0 and 7.2 mT. By the Comparison between the hf data obtained from EPR and 
supercell calculations, we concluded that the EI-1 defect is the best candidate for the neutral nitrogen vacancy in AlN.
-type 4H-SiCBeyer, F. C.*; Hemmingsson, C.*; Pedersen, H.*; Henry, A.*; Janzn, E.*; Isoya, Junichi*; Morishita, Norio*; Oshima, Takeshi
Journal of Applied Physics, 109(10), p.103703_1 - 103703_6, 2011/05
Times Cited Count：17 Percentile：57.65(Physics, Applied)By low-energy electron (200 keV) irradiation into epitaxial n-type 4H-SiC with a dose of 5
10
/cm
, the bistable M-center is detected in the deep level transient spectroscopy (DLTS) spectrum. The annealing behavior of the M-center is investigated. During the annihilation process of M-center, the bistable EB-centers are detected in the low temperature range of the DLTS spectrum. The value of annealing energy of the M-center is similar to the generation energy of the EB-centers. This suggests that the M-center partially transforms to the EB-centers by annealing. The EB-centers completely disappeared after annealing temperatures higher than 700 
C. Since the threshold energy for moving Si atom in SiC is higher than the applied irradiation energy of electrons, and the annihilation temperatures are relatively low, the M-center and the EB-centers are attributed to defects related to the C atom in SiC.
calculation study on the EI4 center in 4
- and 6-SiCCarlsson, P.*; Son, N. T.*; Gali, A.*; Isoya, Junichi*; Morishita, Norio; Oshima, Takeshi; Magnusson, B.*; Janzn, E.*
Physical Review B, 82(23), p.235203_1 - 235203_11, 2010/12
Times Cited Count：11 Percentile：46.11(Materials Science, Multidisciplinary)Electron Paramagnetic Resonance (EPR) studies of the EI4 center in 4- and 6-Silicon Carbide (SiC) were carried out. The EI4 center was drastically enhanced in electron-irradiated high-purity semi-insulating materials by annealing at 700-750 C. An additional large-splitting 
Si hf structure and 
C hf lines of the EI4 defect were observed. Comparing the data obtained from the hf interactions and the annealing behavior, and also from supercell calculations of different carbon-vacancy-related complexes, we propose a complex between a carbon vacancy-carbon antisite and a carbon vacancy at the third-neighbor site of the antisite in the neutral charge state, (V
-C
V)
, as a new defect model for the EI4 center.
Son, N. T.*; Carlsson, P.*; Isoya, Junichi*; Morishita, Norio; Oshima, Takeshi; Magnusson, B.*; Janzn, E.*
Materials Science Forum, 645-648, p.399 - 402, 2010/00
Defects in high-purity semi-insulating 4H SiC irradiated with 2 MeV electrons at room temperature were studied using Electron paramagnetic resonance (EPR). The EPR signal named EI4 defect increased with annealing temperature up to 750 C. Additional large-splitting Si hyperfine (hf) structures and C hf lines by the interaction with one C nucleus were investigated. Based on the observed hf structures, the C
symmetry as well as the annealing behaviour, the EI4 defects is determined to be the complex between two carbon vacancies and a carbon antisite in the neutral charge state, VVC. The formation of the complex is interpreted in terms of the migration of the silicon vacancy and the formation of the carbon vacancy-carbon antisite pair next to a carbon vacancy.
Beyer, F. C.*; Hemmingsson, C.*; Pedersen, H.*; Henry, A.*; Isoya, Junichi*; Morishita, Norio; Oshima, Takeshi; Janzn, E.*
Materials Science Forum, 645-648, p.435 - 438, 2010/00
By low-energy electron irradiation of epitaxial n-type 4H-SiC, the Deep Level Transient Spectroscopy (DLTS) peaks called the defects Z1/2 and EH6/7 were observed, which were also observed in as-grown layer and the commonly found peaks EH1 and EH3 (M-center) also appeared. New defect named the EB-centers increased after annealing out of EH1 and EH3. Since low energy electron irradiation (less than 220 keV) affects mainly the carbon atom in SiC, both the M- and EB-centers might be carbon related defects.
Son, N. T.*; Hemmingsson, C. G.*; Paskova, T.*; Evans, K. R.*; Usui, Akira*; Morishita, Norio; Oshima, Takeshi; Isoya, Junichi*; Monemar, B.*; Janzn, E.*
Physical Review B, 80(15), p.153202_1 - 153202_4, 2009/10
Times Cited Count：40 Percentile：79.94(Materials Science, Multidisciplinary)GaN samples were irradiated with electrons of 2 MeV at 110
/cm, and electron spin resonance (ESR) was measured at 77 K. As a result, four defect signals which are labeled D1 to D4 were observed. The D2 signal was identified to be negatively charged gallium vacancy - oxygen pair from the details studies of 
N hf structure.
SiCSon, N. T.*; Janzn, E.*; Isoya, Junichi*; Morishita, Norio; Hanaya, Hiroaki; Takizawa, Haruki; Oshima, Takeshi; Gali, A.*
Physical Review B, 80(12), p.125201_1 - 125201_8, 2009/09
Times Cited Count：10 Percentile：42.43(Materials Science, Multidisciplinary)Defects in electron irradiated 3-SiC were studied by electron paramagnetic resonance EPR. The spectrum labeled LE1 was observed in -type 3 SiC after electron irradiation at low temperatures (80-100 K). Supercell calculations of different configurations of silicon vacancy-interstitial Frenkel-pairs, V
-Si
, were carried out. Comparing the data obtained from experiments using EPR and supercell calculations, the LE1 center is assigned to the Frenkel-pair between V and a second neighbor Si interstitial along the [100] direction in the 3+ charge state. In addition, a path for the migration of Si
was found in 3 SiC. In samples electron-irradiated at low temperatures, the LE1 Frenkel-pair was found to be the dominating defect whereas EPR signals of single vacancies were not detected. The center disappears after warming up the samples to room temperature.
Son, N. T.*; Isoya, Junichi*; Morishita, Norio; Oshima, Takeshi; Ito, Hisayoshi; Gali, A.*; Janzn, E.*
Materials Science Forum, 615-617, p.377 - 380, 2009/00
Defects introduced by electron irradiation at 80-100 K in 3C-, 4H- and 6H-Silicon Carbide (SiC) were investigated by Electron Paramagnetic Resonance (EPR). A number of EPR spectra, labelled LE1-10, were detected. Combining EPR and theoretical calculations (supercell calculation), the LE1 center in 3C-SiC with C
symmetry and an electron spin S=3/2 could be determined to be the (V-Si
)
Frenkel pair between the silicon vacancy and a second neighbor Si interstitial along the 
100 
direction.
Gali, A.*; Umeda, Takahide*; Janzn, 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
/cm in temperature range between 300 and 800C. As the results of ESR measurements, signals labeled HEI5 and HEI6, which have S=1/2 and C symmetry were observed. By the detailed measurements of Si and C hyperfine satellite, and first principle calculations, HEI5 and HEI6 were identified to be di-carbon antisite at cubic and hexagonal sites, respectively.
Isoya, Junichi*; Umeda, Takahide*; Mizuochi, Norikazu*; Son, N. T.*; Janzn, E.*; Oshima, Takeshi
Physica Status Solidi (B), 245(7), p.1298 - 1314, 2008/07
Times Cited Count：65 Percentile：88.1(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 Si, C was compared to the results from the first principle calculations As the results, positively charged carbon vacancies in 
and 
sites (V
(), V()), negatively charged carbon vacancy (V()), and neutoral, positively and negatively charged di-vacancies of silicon vacancy and carbon vacancy ([VV], [VV], [VV]) were identified.
Son, N. T.*; Ivanov, I. G.*; Kuznetsov, A. Yu.*; Svensson, B. G.*; Zhao, Q. X.*; Willander, M.*; Morishita, Norio; Oshima, Takeshi; Ito, Hisayoshi; Isoya, Junichi*; et al.
Physica B; Condensed Matter, 401-402, p.507 - 510, 2007/12
Times Cited Count：3 Percentile：17.87(Physics, Condensed Matter)Defects in electron-irradiated (3, 6 MeV) ZnO substrates were investigated using optical detection of magnetic response (ODMR). The shallow donor and the Zn vacancy were detected. In addition, several ODMR centers with S=
were also observed. Among these, LU3 and LU4 shows a behavior as recombination centers. After annealing at 400C, both LU3 and LU4 still remain in ZnO substrates.
Son, N. T.*; Ivanov, G.*; Kuznetsov, A.*; Svensson, B. G.*; Zhao, Q. X.*; Willander, M.*; Morishita, Norio; Oshima, Takeshi; Ito, Hisayoshi; Isoya, Junichi*; et al.
Journal of Applied Physics, 102(9), p.093504_1 - 093504_5, 2007/11
Times Cited Count：18 Percentile：56.71(Physics, Applied)Optical detection of magnetic resonance (ODMR) was performed to investigate defects in ZnO irradiated with 3 MeV electrons at room temperature. As a result, the Zn vacancy and some other centers were detected by ODMR. The Zn vacancy and two other centers whish are labeled as LU3 and LU4, were also commonly observed in different types of as-grown ZnO. Therefore, it can be concluded that the both LU3 and LU4 might be related to intrinsic defects, and they act as dominating recombination centers in irradiated and as-grown ZnO.
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：17.99(Physics, Condensed Matter)no abstracts in English
-SiCUmeda, Takahide*; Son, N. T.*; Isoya, Junichi*; Janzn, 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：80 Percentile：90.67(Physics, Multidisciplinary)no abstracts in English
Son, N. T.*; Carlsson, P.*; Hassan, J. ul*; Janzn, 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：186 Percentile：96.99(Physics, Multidisciplinary)no abstracts in English
