著者

高橋 健 佐藤 修 成瀬 昭二 牛嶋 陽 中村 敏行 山田 恵 古谷 誠一 建井 努 山下 正人 村上 晃一 飯沼 昌二 タカハシ タケシ サトウ オサム ナルセ ショウジ ウシジマ ヨウ ナカムラ トシユキ ヤマダ ケイ フルヤ セイイチ タテイ ツトム ヤマシタ マサト ムラカミ コウイチ イイヌマ ショウジ Takahashi Takeshi .Sato Osamu Naruse Shouji Ushijima you Nakamura Toshiyuki Yamada Kei Furuya Seiichi Tatei Ysutomu Yamashita Masato Murakami Kouichi Iinuma Shouji

出版者

日本医学放射線学会

雑誌

日本医学放射線学会雑誌 (ISSN:00480428)

巻号頁・発行日

vol.51, no.2, pp.185-187, 1991-02-25

著者

Murakami Kouichi Shirakawa Ryota Tsujimura Masatoshi Uchida Noriyuki Fukata Naoki Hishita Shun-ichi

出版者

American Institute of Physics

雑誌

Journal of applied physics (ISSN:00218979)

巻号頁・発行日

vol.105, no.5, pp.054307, 2009-03

被引用文献数

23 11

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We have investigated phosphorus ion (P+) implantation in Si nanocrystals (SiNCs) embedded in SiO2, in order to clarify the P donor doping effects for photoluminescence (PL) of SiNCs in wide P concentrations ranging in three orders. Some types of defects such as Pb centers were found to remain significantly at the interfaces between SiNCs and the surrounding SiO2 even by high-temperature (1000 °C) annealing of all the samples. Hydrogen atom treatment (HAT) method can efficiently passivate remaining interface defects, leading to significant increase in the intensity of PL arising from the recombination of electron-hole pairs confined in SiNCs, in addition to significant decrease in interface defects with dangling bonds detected by electron spin resonance. From both the results of the P dose dependence before and after HAT, it is found that the amount of remaining defects is higher for samples with SiNCs damaged by implantation with relatively lower P+ doses and then annealed, and that through HAT the observed PL intensity increases surely as the P concentration increases up to a critical concentration. Then it begins to decrease due to Auger nonradiative recombination above the critical concentration which depends on the size of SiNCs. These results suggest an effect of relatively low concentration of P atoms for the enhancement of PL intensity of SiNCs and we present an unconventional idea for explaining it.

著者

Uchida Noriyuki Mikami Youhei Kintoh Hiroshi Murakami Kouichi Fukata Naoki Mitome Masanori Hase Muneaki Kitajima Masahiro

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.92, no.15, pp.153112, 2008-04

被引用文献数

5

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We have developed a robust method for fabricating Si nanoregions in silica glass using femtosecond laser processing. We attained a vivid formation of silicon-rich nanoregions site-selectively generated in SiO2 by irradiation of femtosecond laser pulses to the interface of a SiO2 substrate and deposited aluminum (Al) thin film, where the Al element acts as a gettering site for O atoms. Growth of high-density Si nanocrystals and amorphous Si was observed by transmission electron microscopy in the region that was multiply irradiated with the femtosecond laser. Furthermore, local annealing with a cw laser enhances the Si nanocrystal growth, which was determined by micro-Raman measurements.

著者

Makimura Tetsuya Uchida Satoshi Murakami Kouichi Niino Hiroyuki

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.89, no.10, pp.101118, 2006-09

被引用文献数

21

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In order to demonstrate silica nanomachining, the authors fabricated line-and-space contact masks with spaces of 53 and 70 nm on silica glass plates, followed by irradiation with laser plasma softx rays (LPSXs) with wavelengths around 10 nm. Trenches with the narrowest width of 54 nm and an aspect ratio of ~1 were fabricated by the LPSX irradiation through the contact masks. It was also clarified that silica glass can be machined by irradiation with LPSXs in the wavelength range of 6–30 nm in Ar gas which was used as an x-ray bandpass filter.

著者

Boero Mauro Oshiyama Atsushi Silvestrelli Pier Luigi Murakami Kouichi

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.86, no.20, pp.201910, 2005-05

被引用文献数

17 18

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Recent experiments have shown that pure Si structures in a matrix of SiO2 can be formed by electron excitation techniques, with appealing applications in nanotechnology. Our ab initio simulations provide an insight into the underlying mechanism, showing that electron excitations weaken Si–O bonds in SiO2, dislodge O atoms and allow Si dangling bonds to reconstruct in stable Si–Si structures below the melting temperature. Differences in diffusivity of O (fast) and Si (slow) are shown to play a decisive role in the process.

著者

Boero Mauro Oshiyama Atsushi Silvestrelli Pier Luigi Murakami Kouichi

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.86, pp.201910, 2005-05

被引用文献数

17

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Recent experiments have shown that pure Si structures in a matrix of SiO2 can be formed by electron excitation techniques, with appealing applications in nanotechnology. Our ab initio simulations provide an insight into the underlying mechanism, showing that electron excitations weaken Si–O bonds in SiO2, dislodge O atoms and allow Si dangling bonds to reconstruct in stable Si–Si structures below the melting temperature. Differences in diffusivity of O (fast) and Si (slow) are shown to play a decisive role in the process.

著者

Makimura Tetsuya Miyamoto Hisao Kenmotsu Youichi Murakami Kouichi Niino Hiroyuki

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.86, no.10, pp.103111, 2005-03

被引用文献数

38 40

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We have investigated direct micromachining of quartz glass, using pulsed laser plasma soft x-rays (LPSXs) having a potential capability of nanomachining because the diffraction limit is ~10 nm. The LPSX's were generated by irradiation of a Ta target with 532 nm laser light from a conventional Q switched Nd:YAG laser at 700 mJ/pulse. In order to achieve a sufficient power density of LPSX's beyond the ablation threshold, we developed an ellipsoidal mirror to obtain efficient focusing of LPSXs at around 10 nm. It was found that quartz glass plates are smoothly ablated at 45 nm/shot using the focused and pulsed LPSX's.