論文 - 鈴木 秀俊
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Sakai K., Takeshita H., Haraguchi T., Suzuki H., Ohashi F., Kume T., Fukuyama A., Nonomura S., Ikari T.
Thin Solid Films 621 32 - 35 2017年1月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Thin Solid Films
© 2016 Elsevier B.V. By means of high-resolution transmission electron microscopy (HR-TEM) observations, and energy dispersive X-ray analyses performed with a scanning TEM (STEM-EDX), we evaluated the residual Na contents and the induced crystal strains in type-II Si clathrate films grown on a Si substrate and treated with iodine for Na elimination. Cross-sectional TEM and STEM-EDX observations verified the formation of the type-II Si clathrate thin film on the Si substrate. The guest-free (without any Na inclusion) clathrate crystal was obtained by iodine (I 2 ) treatment for more than 3 cycles. The resulting films were polycrystalline. No buffer layer was observed at the boundary of the Si clathrate crystal film and the substrate, suggesting a chemical bonding between them. The crystalline strains defined here by the deviation of the d value were within 3.5%. These findings might allow us to fabricate epitaxial Si clathrate films on Si substrates.
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Fukuyama A., Matsuochi K., Nakamura T., Takeda H., Suzuki H., Toprasertpong K., Sugiyama M., Nakano Y., Ikari T.
Nanotechnology Materials and Devices Conference, NMDC 2016 - Conference Proceedings 2016年12月
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス） 出版者・発行元：Nanotechnology Materials and Devices Conference, NMDC 2016 - Conference Proceedings
© 2016 IEEE. To investigate the miniband and carrier transport properties in the superlattice structure embedded in the p-i-n GaAs solar cells, photoreflectance, photoluminescence, and photothermal spectroscopies were adopted. Two critical energies corresponding to the energy differences between mini-Brillouin zone edges were estimated for thinnest quantum barrier thickness sample by PR. From the PPT and PL, only broad peaks corresponding to the quantum levels were observed and we concluded that a built-in electric field inhibited the formation of miniband.
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Crystal growth of GaAs on high indexed Si substrates for multi-junction solar cells
Harada I., Suzuki H., Ikari T., Fukuyama A.
Conference Record of the IEEE Photovoltaic Specialists Conference 2016-November 1947 - 1949 2016年11月
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス） 出版者・発行元：Conference Record of the IEEE Photovoltaic Specialists Conference
© 2016 IEEE. The effects of surface orientation of Si surface on crystal quality and surface morphology of GaAs layer grown on the Si substrate was investigated. Si (001), (113) and (114) wafers were used as substrates, and GaAs crystal was deposited on the substrate using molecular beam epitaxy. Before growth, the substrates were thermally cleaned in an ultra high vacuum chamber using an infrared heating unit. Crystal quality and surface roughness of the GaAs/Si (113) was better than those of other samples. This suggested that crystal quality of GaAs/Si could be improved using the Si (113) substrate.
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Thin film of guest-free type-II silicon clathrate on Si(111) wafer 査読あり
Tetsuji Kume, Fumitaka Ohashi, Kentaro Sakai, Atsuhiko Fukuyama, Motoharu Imai, HaruhikoUdono, Takayuki Ban, Hitoe Habuchi, Hidetoshi Suzuki, Tetsuo Ikari, Shigeo Sasaki, Shuichi Nonomura
Thin Solid Films 609 30 - 34 2016年4月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Real-time observation of rotational twin formation during molecular-beam epitaxial growth of GaAs on Si (111) by x-ray diffraction 査読あり
Hidetoshi Suzuki, Yuka Nakata, Masamitu Takahasi, Kazuma Ikeda, Yoshio Ohshita, Osamu Morohara, Hirotaka Geka, Yoshitaka Moriyasu
AIP Advances 6 035303-1 - 035303-6 2016年3月
記述言語：英語 掲載種別：研究論文（学術雑誌）
DOI： 10.1063/1.4943511
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Nakamura T., Matsuochi K., Suzuki H., Ikari T., Toprasertpong K., Sugiyama M., Nakano Y., Fukuyama A.
Energy Procedia 102 121 - 125 2016年
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス） 出版者・発行元：Energy Procedia
© 2016 The Authors. We investigated the effect of built-in electric field on miniband formation and carrier nonradiative recombination in a superlattice structure by using photoreflectance (PR) and photoluminescence (PL) spectroscopy for a strain-balanced InGaAs/GaAsP superlattice inserted in p-i-n GaAs solar cell and n-n GaAs structures. Two critical energies were obtained in the PR spectra, which corresponded to the energy differences between the Γ and π points in the mini-Brillouin zone of the first electron level and the first heavy hole level. The obtained miniband widths of both samples were same, which were smaller than the calculated values by using a flat-band structure model without a built-in electric field. From these results, it was deduced that the built-in electric field does not affect the miniband width. The PL signal intensity of the p-i-n structure samples did not change, whereas that of the n-n structure samples decreased with decreasing barrier thickness. We concluded that the radiative recombination probability decreases and the non-radiative recombination probability increases due to miniband formation.
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新規Ge原料 t-C4H9GeH3のSiもしくはGaAs基板上における表面反応過程
河野 将大, 山内 俊浩, 石川 真人, 須藤 弘, 町田 英明, 大下 祥雄, 鈴木 秀俊
表面科学学術講演会要旨集 36 ( 0 ) 2016年
記述言語：日本語 掲載種別：研究論文（研究会，シンポジウム資料等） 出版者・発行元：公益社団法人 日本表面科学会
GaAs/Si構造は、多接合型太陽電池等への応用が期待されている。本構造の格子定数差等に起因する欠陥の低減手法として、Geバッファ層が提案されている。近年、安全で取扱いが容易な新しいGe原料としてt-C<sub>4</sub>H<sub>9</sub>GeH<sub>3</sub>（tBGe）が提案されているが、各種基板上での反応過程など不明な点が多い。本研究では、Si又はGaAs基板上におけるtBGeの表面反応と成長初期過程を明らかにすることを目的とした。
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Control of hydrogen and carbon impurity inclusion during the growth of GaAsN thin film by atomic layer epitaxy 査読あり
Yuki Yokoyama, Atsuhiko Fukuyama, Tomohiro Haraguchi, Toshihiro Yamauchi, Tetsuo Ikari, Hidetoshi Suzuki
Japanese Journal of Applied Physics 55 01AC06-1 - 01AC06-4 2015年12月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Shimomura K., Suzuki H., Sasaki T., Takahasi M., Ohshita Y., Kamiya I.
Journal of Applied Physics 118 ( 18 ) 2015年11月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Applied Physics
© 2015 AIP Publishing LLC. Direct measurements on the growth of InAs quantum dots (QDs) and various cap layers during molecular beam epitaxy are performed by in situ X-ray diffraction (XRD). The evolution of strain induced both in the QDs and cap layers during capping is discussed based on the XRD intensity transients obtained at various lattice constants. Transients with different features are observed from those obtained during InGaAs and GaAs capping. The difference observed is attributed to In-Ga intermixing between the QDs and the cap layer under limited supply of In. Photoluminescence (PL) wavelength can be tuned by controlling the intermixing, which affects both the strain induced in the QDs and the barrier heights. The PL wavelength also varies with the cap layer thickness. A large redshift occurs by reducing the cap thickness. The in situ XRD observation reveals that this is a result of reduced strain. We demonstrate how such information about strain can be applied for designing and preparing novel device structures.
DOI： 10.1063/1.4935456
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In situ three-dimensional X-ray reciprocal-space mapping of InGaAs multilayer structures grown on GaAs(001) by MBE 査読あり
Takuo Sasaki, Masamitu Takahasi, Hidetoshi Suzuki, Yoshio Ohshita, Masafumi Yamaguchi
Journal of Crystal Growth 425 13 - 15 2015年9月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Ikeda K., Ohshita Y., Tanaka T., Honda T., Inagaki M., Demizu K., Kojima N., Suzuki H., Machida H., Sudoh H., Yamaguchi M.
Japanese Journal of Applied Physics 54 ( 4 ) 2015年4月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Japanese Journal of Applied Physics
© 2015 The Japan Society of Applied Physics. The formation mechanism of N-H-related defects in GaAsN grown by chemical beam epitaxy (CBE) is studied on the basis of the isotope effects on the local vibration modes (LVMs) originating from N-H. When deuterated monomethylhydrazine (MMHy) is used as the N source, LVM signals from the nitrogen-deuterium bond (N- D) are obtained. However, there are still N-H peaks in the IR absorption spectra, which have intensities similar to those of N-D peaks. When the film is grown with deuterated triethylgallium (TEGa), there are no N-D peaks. The peak intensity at 2952 cm -1 increases with increasing tris(dimethylamino)arsenic (TDMAAs) flow rate, and that at 3098 cm -1 is almost constant regardless of the flow rate. These results indicate that H atoms in the N-H-related defects originate from H directly bonded to N in MMHy and CH 3 in MMHy and/or H in TDMAAs, not from TEGa.
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Effect of number of stack on the thermal escape and non-radiative and radiative recombinations of photoexcited carriers in strain-balanced InGaAs/GaAsP multiple quantum-well-inserted solar cells 査読あり
Taketo Aihara, Atsuhiko Fukuyama, Hidetoshi Suzuki, Hiromasa Fujii, Masakazu Sugiyama, Yoshiaki Nakano, Tetsuo Ikari
Journal of Applied Physics 117 084307 2015年2月
記述言語：英語 掲載種別：研究論文（学術雑誌）
DOI： 10.1063/1.4913593
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Zinc-blende and wurtzite phase separation in catalyst-free molecular beam epitaxy vapor–liquid–solid-grown Si-doped GaAs nanowires on a Si(111) substrate induced by Si doping 査読あり
Akio Suzuki, Atsuhiko Fukuyama, Hidetoshi Suzuki, Kentaro Sakai, Ji-Hyun Paek, Masahito Yamaguchi, Tetsuo Ikari
Japanese Journal of Applied Physics 54 ( 3 ) 035001 2015年2月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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大西 修, 境 健太郎, 鈴木 秀俊, 森田 翔
日本機械学会九州支部講演論文集 2015 ( 0 ) 327 - 328 2015年
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Fukuyama A., Ding W., Morioka G., Suzuki A., Suzuki H., Yamaguchi M., Ikari T.
2014 IEEE 40th Photovoltaic Specialist Conference, PVSC 2014 1148 - 1151 2014年10月
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス） 出版者・発行元：2014 IEEE 40th Photovoltaic Specialist Conference, PVSC 2014
© 2014 IEEE. To investigate the microstructure of nitrogen-induced localized state (E N ) that perturbs the conduction band of GaAs host material, we adopted the photoreflectance measurements to chemical-beam-epitaxy grown GaAsN thin films. We measured both two split subbands to estimate correct values of E N . It was clearly seen that estimated E N decreased with increasing nitrogen content and temperature. By considering a change of a mean distance between neighboring nitrogen atoms, we concluded that the microscopic structure of E N is not only an isolated nitrogen atom but also nitrogen-related complex, accompanied by low-order pairs of nitrogen atoms and/or nitrogen clusters.
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The effects of indium pre-evaporation on rotational twin formation in GaAs films on Si(111)
Suzuki H., Ito D., Haga A., Fukuyama A., Ikari T.
2014 IEEE 40th Photovoltaic Specialist Conference, PVSC 2014 1830 - 1833 2014年10月
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス） 出版者・発行元：2014 IEEE 40th Photovoltaic Specialist Conference, PVSC 2014
© 2014 IEEE. The effects of In pre-evaporation on the formation of rotational twin domains (TW) in GaAs layers on Si (111) substrates were systematically investigated. Atomic arrangements of In atoms on the Si substrate during pre-evaporation were studied and resulting formation of TW were discussed. The pre-evaporation of In resulted in the formation of InAs islands. The size of InAs islands was smaller than that of GaAs islands grown on Si substrate without In pre-evaporation. The amount of TW increased with increasing sizes of GaAs or InAs at initial phase. These results suggested that the size of island formed during the initial pre-evaporation phase could control the TW growth in the final GaAs film.
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Aihara T., Fukuyama A., Yokoyama Y., Kojima M., Suzuki H., Sugiyama M., Nakano Y., Ikari T.
Journal of Applied Physics 116 ( 4 ) 2014年7月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Applied Physics
To investigate the effect of the miniband formation on the optical absorption spectrum, we adopted two non-destructive methodologies of piezoelectric photothermal (PPT) and photoreflectance (PR) spectroscopies for strain-balanced InGaAs/GaAsP multiple quantum-well (MQW) and superlattice (SL) structures inserted GaAs p-i-n solar cells. Because the barrier widths of the SL sample were very thin, miniband formations caused by coupling the wave functions between adjacent wells were expected. From PR measurements, a critical energy corresponding to the inter-subband transition between first-order electron and hole subbands was estimated for MQW sample, whereas two critical energies corresponding to the mini-Brillouin-zone center (Ω) and edge (p) were obtained for SL sample. The miniband width was calculated to be 19 meV on the basis of the energy difference between Ω and p. This coincided with the value of 16 meV calculated using the simple Kronig-Penney potential models. The obtained PPT spectrum for the SL sample was decomposed into the excitonic absorption and inter-miniband transition components. The latter component was expressed using the arcsine-like signal rise corresponding to the Ω point in the mini-Brillouin zone that was enhanced by the Sommerfeld factor. The usefulness of the PPT methodology for investigating the inserted MQW and/or SL structure inserted solar cells is clearly demonstrated. © 2014 AIP Publishing LLC.
DOI： 10.1063/1.4887443
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Suzuki A., Fukuyama A., Suzuki H., Sakai K., Paek J., Yamaguchi M., Ikari T.
Japanese Journal of Applied Physics 53 ( 5 SPEC. ISSUE 1 ) 2014年5月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Japanese Journal of Applied Physics
The effect of Be doping on the crystal structure and the optical properties of catalyst-free Be-doped GaAs nanowires (NWs) grown on a (111)Si substrate were investigated by scanning transmission electron microscopy (STEM), X-ray diffraction (XRD) analysis, and photoreflectance (PR) and photoluminescence (PL) techniques. Be-doped NWs sample showed a striped pattern in STEM images. Owing to a high arsenic flux under the growth condition, the sample did not have a wurtzite but a zinc-blend (ZB) structure, and the observed striped pattern in STEM images suggests the presence of twin boundaries and stacking faults. The bandgap energy of the Be-doped NWs was lower than that of the nondoped NWs sample in the entire temperature range. In addition, the deviation from the conventional Varshni curve was found to be large in the low-temperature region. However, this is well explained by considering the strong electron-phonon interaction and high average phonon temperature. Therefore, we concluded that the induced strain increased the linear thermal expansion coefficient. This is because the Be atom has a smaller covalent radius than the Ga and As atoms. © 2014 The Japan Society of Applied Physics.
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N-H related defects in GaAsN grown through chemical beam epitaxy
Ohshita Y., Ikeda K., Suzuki H., Machida H., Sudoh H., Tanaka T., Honda T., Inagaki M., Yamaguchi M.
Japanese Journal of Applied Physics 53 ( 3 ) 2014年3月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Japanese Journal of Applied Physics
The local vibration modes of N-H related defects in GaAsN are studied using isotopes. When GaAsN is grown through chemical beam epitaxy (CBE) using triethylgallium/tris(dimethylamino)arsenic/monomethylhydrazine gas, there are several local vibration modes (LVMs) in Fourier transform infrared (FTIR) spectra. Signals with stretching mode peaks at 2952, 3098, and 3125 cm -1 are reported, along with new wagging and stretching mode peaks at 960 and 3011 cm -1 , which exist only in crystals grown through CBE. When the film is grown using deuterated MMHy as a nitrogen source, new peaks at 2206, 2302, 2318, 2245, and 714cm -1 appear. This suggests that D related defects are created because of the deuterated MMHy. The ratios of frequencies of these new peaks to those obtained from crystals grown using MMHy are nearly 1.34. This suggests that all defects in GaAsN grown through CBE, which appear as LVMs, are N-H related defects. Especially, those with LVMs at 960 and 3011 cm -1 are new N-H defects only found in GaAsN grown through CBE. © 2014 The Japan Society of Applied Physics.
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Optical properties of Be-doped GaAs nanowires on Si substrate grown by a catalyst-free molecular beam epitaxy vapor–liquid–solid method 査読あり
Akio Suzuki, Atsuhiko Fukuyama, Hidetoshi Suzuki, Kentaro Sakai, Ji-Hyun Paek, Masahito Yamaguchi, Tetsuo Ikari
Japanese Journal of Applied Physics 53 05FV03 2014年2月
記述言語：英語 掲載種別：研究論文（学術雑誌）