- 著者
- Sakurai Yoko Kakushima Kuniyuki Ohmori Kenji Yamada Keisaku Iwai Hiroshi Shiraishi Kenji Nomura Shintaro
- 出版者
- Optical Society of America
- 雑誌
- Optics Express (ISSN:10944087)
- 巻号頁・発行日
- vol.22, no.2, pp.1997-2006, 2014-01
- 被引用文献数
- 3
Low-temperature photoluminescence (PL) spectra of electron-hole systems in Si nanowires (NWs) prepared by thermal oxidization of Si fin structures were studied. Mapping of PL reveals that NWs with uniform width are formed over a large area. Annealing temperature dependence of PL peak intensities was maximized at 400 °C for each NW type, which are consistent with previous reports. Our results confirmed that the micro-PL demonstrated here is one of the important methods for characterizations of
- 著者
- Okada Susumu Shiraishi Kenji Oshiyama Atsushi
- 出版者
- American Physical Society
- 雑誌
- Physical review letters (ISSN:00319007)
- 巻号頁・発行日
- vol.90, no.2, pp.026803, 2003-01
- 被引用文献数
- 33 21
Based on total-energy electronic-structure calculations within the density-functional theory, we find that a high spin state is realized for an ultimate dangling bond unit on an otherwise hydrogen-covered Si(111) surface. We further propose a systematic method of constructing nanometer-scale dangling bond networks that exhibit the ferrimagnetic spin ordering. The interplay between the electron-electron interaction and the surface reconstruction is elucidated.
- 著者
- Umezawa Naoto Shiraishi Kenji
- 出版者
- American Institute of Physics
- 雑誌
- Applied physics letters (ISSN:00036951)
- 巻号頁・発行日
- vol.97, no.20, pp.202906, 2010-11
- 被引用文献数
- 11 12
The solubility of silicon in high-permittivity (high-κ) oxides significantly affects the performance of field-effect transistors. Our comparative study of silicon impurities in La2O3 and HfO2 reveals that the stability of silicon at substitutional sites strongly depends on its coordination number. When substituted for lanthanum, a silicon atom fits comfortably in La2O3, thanks to the formation of a SiO4 tetrahedral structure. In addition, the substitutional silicon acts as a donor impurity in La2O3, increasing oxygen content in the oxide. This contributes to absorbing silicon and oxygen from the interface region, leading to the formation of lanthanum silicate at the La2O3/silicon interface.
- 著者
- Kita Yuki Yoshida Shinichi Hosoi Takuji Shimura Takayoshi Shiraishi Kenji Nara Yasuo Yamada Keisaku Watanabe Heiji
- 出版者
- American Institute of Physics
- 雑誌
- Applied physics letters (ISSN:00036951)
- 巻号頁・発行日
- vol.94, no.12, pp.122905, 2009-03
- 被引用文献数
- 8 8
Change in the work function (WF) of the gate electrode material caused by the contact with Hf-based high-k gate dielectrics was investigated by means of the flat-band voltage (Vfb) shift in capacitance-voltage curves, and the interface dipole, which modifies the WF, was characterized by x-ray photoelectron spectroscopy. We observed a negative Vfb shift and corresponding interface dipole, which suggest the formation of oxygen vacancy (VO) in the Hf-based oxides. In contrast, we observed an opposite (positive) Vfb shift and interface dipole when Au electrodes were formed on cleaned Hf-based dielectrics. This indicates that Au–Hf bond hybridization at the Au/HfSiON interface also causes effective WF modulation, as theoretically predicted by Shiraishi et al. (Tech. - Dig. Int. Electron Devices Meet. 2005, 43).
- 著者
- Sasaoka Kenji Yamamoto Takahiro Watanabe Satoshi Shiraishi Kenji
- 出版者
- American Physical Society
- 雑誌
- Physical review B (ISSN:10980121)
- 巻号頁・発行日
- vol.84, no.12, pp.125403, 2011-09
- 被引用文献数
- 5
The alternating-current response of a quantum point contact (QPC) is numerically investigated using the nonequilibrium Green function method combined with an effective mass theory. We found that the susceptance of a QPC increases stepwise with increasing gate voltage, when the width of the quantization plateau in the gate voltage-conductance curve is narrower than the width of the region where the conductance changes gradually. We also show that the height of a susceptance step is proportional to the ac-bias frequency. These simulation results are in excellent qualitative agreement with recent experimental results. Moreover, we found that the transition from capacitive susceptance to inductive susceptance occurs with increasing gate voltage. The capacitive-inductive transition point is independent of the ac-bias frequency, but it does depend on the contact width.