著者

Takakura K. Ohyama H. Takarabe K. Suemasu T. Hasegawa F.

出版者

American Institute of Physics

雑誌

Journal of applied physics (ISSN:00218979)

巻号頁・発行日

vol.97, no.09, pp.093716, 2005-04

被引用文献数

24 13

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The hole mobility of intentionally undoped p-type beta-FeSi2 thin films grown by a multilayer method was investigated. With increasing annealing temperature and time, the hole mobility increased to approximately 450 cm2/V s at room temperature (RT). The observed hole mobility was analyzed by considering various carrier scatterings such as acoustic-phonon and polar-optical-phonon scatterings, intervalley scattering, ionized impurity scattering, and grain-boundary scattering. The nice fit of the mobility to the experimental results reveals that the polar-optical-phonon scattering determines the hole mobility at RT.

著者

Egorov A. Yu. Kalevich V. K. Afanasiev M. M. Shiryaev A. Yu. Ustinov V. M. Ikezawa M. Masumoto Y.

出版者

American Institute of Physics

雑誌

Journal of applied physics (ISSN:00218979)

巻号頁・発行日

vol.98, no.1, pp.013539, 2005-07

被引用文献数

24

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The paper studies the circularly polarized photoluminescence (PL) from dilute GaAsN alloys with nitrogen content of 1%–3.4%, grown on GaAs substrates. The room-temperature PL is found to consist of two bands whose splitting grows with increasing nitrogen content. The analysis of the PL circular polarization has shown that the PL bands originate from the splitting of light- and heavy-hole subbands, induced by an elastic strain in GaAsN layer. The dependence of the energy gap of unstrained GaAsN on the nitrogen content has been calculated using the measured light- and heavy-hole splittings.

著者

Fukata N. Oshima T. Okada N. Murakami K. Kizuka T. Tsurui T. Ito S.

出版者

American Institute of Physics

雑誌

Journal of applied physics (ISSN:00218979)

巻号頁・発行日

vol.100, no.2, pp.024311, 2006-07

被引用文献数

44 33

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The phonon confinement and self-limiting oxidation effects of silicon nanowires (SiNWs) synthesized by laser ablation were investigated. The size of SiNWs was controlled by the synthesis parameters during laser ablation and the subsequent thermal oxidation. Thermal oxidation increases the thickness of the SiNWs' surface oxide layer, resulting in a decrease in their crystalline Si core diameter. This effect causes a downshift and asymmetric broadening of the Si optical phonon peak due to phonon confinement, while excess oxidation causes an upshift due to compressive stress. The compressive stress retarded the oxidation of the SiNWs by self-limiting oxidation effect. This result shows that the Si core diameter can be controlled by compressive stress.

著者

Fukata N. Sato S. Morihiro H. Murakami K. Ishioka K. Kitajima M. Hishita S.

出版者

American Institute of Physics

雑誌

Journal of applied physics (ISSN:00218979)

巻号頁・発行日

vol.101, no.4, pp.046107, 2007-02

被引用文献数

12 3

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The formation of hydrogen (H)-related complexes and H effects on boron (B) and phosphorus (P) dopants was investigated in B- or P-doped silicon (Si) crystal treated with high concentration of H. The reactivation process of dopant carriers by annealing after hydrogenation was significantly different between the p-type and n-type specimens. The difference is likely to be attributable to the formation of H-related defects based on the stable sites of the H atoms, i.e., complicated H multiple trapping centers are formed by bond breaking due to H atoms in only p-type B-doped Si.

著者

Brian M Strem Kevin C Hicok Min Zhu Isabella Wulur Zeni Alfonso Ronda E Schreiber John K Fraser Marc H Hedrick

出版者

The Keio Journal of Medicine

雑誌

The Keio Journal of Medicine (ISSN:00229717)

巻号頁・発行日

vol.54, no.3, pp.132-141, 2005 (Released:2006-06-20)

参考文献数

108

被引用文献数

370 719 692

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Tissue engineering offers considerable promise in the repair or replacement of diseased and/or damaged tissues. The cellular component of this regenerative approach will play a key role in bringing these tissue engineered constructs from the laboratory bench to the clinical bedside. However, the ideal source of cells still remains unclear and may differ depending upon the application. Current research for many applications is focused on the use of adult stem cells. The properties of adult stem cells that make them well-suited for regenerative medicine are (1) ease of harvest for autologous transplantation, (2) high proliferation rates for ex vivo expansion and (3) multilineage differentiation capacity. This review will highligh the use of adipose tissue as a reservoir of adult stem cells and draw conclusions based upon comparisons with bone marrow stromal cells.

著者

Uedono A. Shaoqiang C. Jongwon S. Ito K. Nakamori H. Honda N. Tomita S. Akimoto K. Kudo H. Ishibashi S.

出版者

American Institute of Physics

雑誌

Journal of applied physics (ISSN:00218979)

巻号頁・発行日

vol.103, no.10, pp.104505, 2008-08

被引用文献数

22 27

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A relationship between intra-4f transitions of Er and vacancy-type defects in Er-doped GaN was studied by using a monoenergetic positron beam. Doppler broadening spectra of the annihilation radiation were measured for Er-doped GaN grown by molecular beam epitaxy. A clear correlation between the defect concentration and the photoluminescence (PL) intensity was observed. The major defect species detected by positrons was identified as a Ga vacancy VGa, and its concentration increased with increasing Er concentration [Er]. For the sample with [Er]=3.3 at. %, the maximum integrated intensity of PL was observed. The VGa concentration was above 1018 cm−3 and additional vacancies such as divacancies started to be introduced at this Er concentration. For the sample with higher [Er], the PL intensity decreased, and the mean size of vacancies decreased due to an introduction of precipitates and/or metastable phases.

著者

Aoki M. Toyoshima S. Kamada T. Sogo M. Masuda S. Sakurai T. Akimoto K.

出版者

American Institute of Physics

雑誌

Journal of applied physics (ISSN:00218979)

巻号頁・発行日

vol.106, no.4, pp.043715, 2009-08

被引用文献数

11 7

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Electron emission spectra resulting from thermal collision of He*(23S) atoms with 2,9-demethyl-4,7-diphenyl-1,10-phenanthroline (BCP) films deposited on metal substrates were measured to characterize gap states emerged at the organic-metal interface. For BCP on Au, the gap state is originated from weak chemisorption and serves as a mediator of metal wave functions to the first layer. For BCP on K, organic-metal complex is formed by spontaneous diffusion, yielding the gap states delocalized over the film. In the interfacial region, all the gap state reveals an incommensurate shift with the valence band top of the film, indicating the breakdown of the Schottky–Mott model as evaluating the transport characteristics in organic-metal system.

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

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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.

著者

Narahara A. Ito K. Suemasu T. Takahashi Y. K. Ranajikanth A. Hono K.

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.94, no.20, pp.202502, 2009-05

被引用文献数

62 29

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The spin polarization of (100)-oriented gamma[prime]-Fe4N layers grown on MgO(001) substrates by molecular beam epitaxy was deduced from point contact Andreev reflection measurements, and the value was compared with that of alpha-Fe. The spin polarization (P) for gamma[prime]-Fe4N is approximately 0.59 at 7.8 K. This value is distinctly larger than that for alpha-Fe (P=0.49 at 7.8 K) measured with an identical setting. The mechanism of enhanced spin polarization in gamma[prime]-Fe4N is discussed.

著者

Fukata N. Mitome M. Bando Y. Seoka M. Matsushita S. Murakami K. Chen J. Sekiguchi T.

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.93, no.20, pp.203106, 2008-11

被引用文献数

33 20

---

Codoping of boron (B) and phosphorus (P) atoms was performed during the synthesis of silicon nanowires (SiNWs) by laser ablation. The observation of a local vibrational mode of B clearly showed B doping in codoped SiNWs, while Fano broadening due to heavy B doping disappeared, indicating compensation by P donors. The electrospin resonance signal of conduction electrons also disappeared due to compensation by B acceptors. These results indicate that codoping of B and P atoms was achieved in SiNWs during laser ablation.

著者

Tanimoto H. Yamada K. Mizubayashi H. Matsumoto Y. Naramaoto H. Sakai S.

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.93, no.15, pp.151919, 2008-10

被引用文献数

7

---

C60 films with thicknesses of 100–480 nm were deposited on Si reed substrates under in situ photoirradiation. In anelasticity measurements, no internal friction peaks associated with rotational motions of the C60 molecules were observed, and Young's modulus was 1.5 times larger than that of a pristine C60 material. X-ray diffraction patterns suggested that the face-centered cubic lattice was contracted by about 3% and locally distorted from the pristine C60 material. Raman spectra very similar to those reported for dimerized C60 were also obtained. These characteristics recovered to those of the pristine C60 materials after annealing the C60 films at 523 K. These results indicate uniform dimerization in C60 films deposited under in situ photoirradiation.

著者

Chong S. V. Kadowaki K. Xia J. Idriss H.

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.92, no.23, pp.232502, 2008-06

被引用文献数

34

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The magnetic behavior of titanium dioxide nanobelts has been investigated with and without Codoping. Room temperature ferromagnetism was observed when the Co-doped anatase TiO2nanobelts were prepared via vacuum annealing of 2.5 at. % Co-doped titanate nanobelts, whileannealing them in air resulted in paramagnetic ordering. Interestingly, by vacuum annealing theundoped titanate nanobelts under the same conditions, superparamagnetic ordering was observed inthe resulting anatase TiO2 nanobelts. The electron paramagnetic resonance of this latter sampleshows a strong symmetrical signal at g=2.003 suggesting some sort of exchange interactions amongthe localized electrons’ spin moments from single electron trapped in oxygen vacancies.

著者

Fukata N. Chen J. Sekiguchi T. Matsushita S. Oshima T. Uchida N. Murakami K. Tsurui T. Ito S.

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.90, no.15, pp.153117, 2007-04

被引用文献数

40 32

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Phosphorus (P) doping was performed during the synthesis of silicon nanowires (SiNWs) by laser ablation. At least three types of signals were observed by electron spin resonance (ESR) at 4.2 K. Phosphorus doping into substitutional sites of crystalline Si in SiNWs was demonstrated by the detection of an ESR signal with a g value of 1.998, which corresponds to conduction electrons in crystalline Si, and by an energy-dispersive x-ray spectroscopy spectrum of the P Kalpha line. The ESR results also revealed the presence of defects. These defects were partially passivated by hydrogen and oxygen atoms.

著者

Kato K. Takata M. Moritomo Y. Nakamoto A. Kojima N.

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.90, no.20, pp.201902, 2007

被引用文献数

25

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A photoexcitation is one of the promising external fields to control the material phases. Here, the authors have demonstrated that the magnetic and structural properties of a spin-crossover complex, Fe(phen)2(NCS)2 (phen=1,10-phenanthroline), can be reversibly switched by the on-off action of the continuous photoexcitation at the same temperature. The structural data suggest that the density of the high-spin Fe2+ in the photoinduced phase is about 0.88. Suppressed atomic vibrations of the photoinduced phase exclude the conventional heating effect as the origin for the observed optical switching.

著者

Fukata N. Chen J. Sekiguchi T. Okada N. Murakami K. Tsurui T. Ito S.

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.89, no.20, pp.203109, 2006-11

被引用文献数

54 38

---

Local vibrational modes of boron (B) in silicon nanowires (SiNWs) synthesized by laser ablation were observed at about 618 and 640 cm−1 by Raman scattering measurements. Boron doping was performed during the growth of SiNWs. Fano [Phys. Rev. 124, 1866 (1961)] broadening was also observed in the Si optical phonon peak. These results prove that B atoms were doped in the SiNWs. Hydrogen (H) passivation of B acceptors in the SiNWs was also investigated. A broad peak was observed at around 650–680 cm−1 after hydrogenation, demonstrating that B dopants were passivated by the formation of the well-known H–B passivation centers.

著者

Umeda T. Okonogi K. Ohyu K. Tsukada S. Hamada K. Fujieda S. Mochizuki Y.

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.88, pp.253504, 2006-06

被引用文献数

25 18

---

The variable retention time phenomenon has recently been highlighted as an important issue in dynamic random access memory (DRAM) technology. Based on electrically detected magnetic resonance and simulation studies, we suggest that a single Si vacancy-oxygen complex defect is responsible for this phenomenon, when the defect is embedded in the near surface drain-gate boundary of a DRAM cell.

著者

Paul G. K. Nawa Y. Sato H. Sakurai T. Akimoto K.

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.88, no.14, pp.141901, 2006-04

被引用文献数

88 41

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Hole traps in p-type Cu2O were studied by means of deep level transient spectroscopy in the heterostructure of p-Cu2O/i-ZnO/n-ZnO. In addition to the trap level at about 0.45 eV from the valance band edge, which is already reported as being due to Cu vacancy, we found a new trap level at about 0.25 eV. The new trap is tentatively assigned as Cu-di-vacancy from the trap concentration dependence on oxygen flow rate and substrate temperature.

著者

Fukata N. Oshima T. Murakami K. Kizuka T. Tsurui T. Ito S.

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.86, no.21, pp.213112, 2005-05

被引用文献数

79 50

---

A gradual downshift and asymmetric broadening of the Si optical phonon peak were observed by Raman scattering measurements of continuously thermally oxidized silicon nanowires (SiNWs) synthesized by laser ablation. This downshift and broadening can be interpreted by the phonon confinement effect. Further thermal oxidation produced a reverse change; namely, an upshift of the optical phonon peak. This is considered to be due to compressive stress since this stress was relieved by removing the oxide layers formed around the SiNW cores, resulting in a downshift of the optical phonon peak.

著者

Yoshikawa M. Yasuhara R. Morimoto M. Shima Y. Kohagura J. Sakamoto M. Nakashima Y. Imai T. Yamada I. Kawahata K. Funaba H. Minami T.

出版者

American Institute of Physics

雑誌

Review of scientific instruments (ISSN:00346748)

巻号頁・発行日

vol.83, no.10, pp.10E333, 2012-10

被引用文献数

17 6

---

In the GAMMA 10 tandem mirror, the typical electron density is comparable to that of the peripheral plasma of torus-type fusion devices. Therefore, an effective method to increase Thomson scattering (TS) signals is required in order to improve signal quality. In GAMMA 10, the yttrium-aluminum-garnet (YAG)-TS system comprises a laser, incident optics, light collection optics, signal detection electronics, and a data recording system. We have been developing a multi-pass TS method for a polarization-based system based on the GAMMA 10 YAG TS. To evaluate the effectiveness of the polarization-based configuration, the multi-pass system was installed in the GAMMA 10 YAG-TS system, which is capable of double-pass scattering. We carried out a Rayleigh scattering experiment and applied this double-pass scattering system to the GAMMA 10 plasma. The integrated scattering signal was made about twice as large by the double-pass system.

著者

Nakajima K. Morita Y. Suzuki M. Narumi K. Saitoh Y. Ishikawa N. Hojou K. Tsujimoto M. Isoda S. Kimura K.

出版者

Elsevier B.V

雑誌

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms (ISSN:0168583X)

巻号頁・発行日

vol.291, pp.12-16, 2012-11

被引用文献数

16

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Thin films of amorphous Si3N4 (thickness 20 nm) were irradiated with 120–720 keV C60+, 2+ ions and observed using transmission electron microscopy (TEM). The ion track produced in an amorphous material was directly observed by TEM. For quantitative analysis, the ion tracks were also observed using high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM). The observed ion track consists of a low density core (radius ∼2.5 nm) and a high density shell (width ∼2.5 nm), which is very similar to the ion tracks in amorphous SiO2 irradiated with high energy heavy ions observed by small angle X-ray scattering (SAXS). Although the observed ion tracks may be affected by surface effects, the present result indicates that TEM and HAADF-STEM have potential to observe directly the fine structures of ion tracks in amorphous materials.