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Kakuda, Naoki*; Kaizu, Toshiyuki*; Takahashi, Masamitsu; Fujikawa, Seiji; Yamaguchi, Koichi*
Japanese Journal of Applied Physics, 49(9), p.095602_1 - 095602_4, 2010/09
Times Cited Count：4 Percentile：18.76(Physics, Applied)Takahashi, Masamitsu; Kaizu, Toshiyuki*
Journal of Crystal Growth, 311(7), p.1761 - 1763, 2009/03
Times Cited Count：10 Percentile：70.00(Crystallography)The molecular beam epitaxial (MBE) growth of InAs/GaAs(001) quantum dots was investigated by grazing-incidence X-ray diffraction using a diffractometer integrated with an MBE apparatus. Use of synchrotron radiation and a two-dimensional X-ray detector enabled three-dimensional mapping of X-ray diffraction intensity at a rate of 10 s per frame. A series of X-ray diffraction images have revealed the evolution of the shape and internal strains of InAs quantum dots in the whole growth processes including the island formation and encapsulation with GaAs. The optical quality of InAs quantum dots was evaluated by photoluminescence spectra. It shows a clear correlation with structural properties measured by in situ X-ray diffraction.
Tinkham, B. P.*; Romanyuk, O.*; Braun, W.*; Ploog, K. H.*; Grosse, F.*; Takahashi, Masamitsu; Kaizu, Toshiyuki*; Mizuki, Junichiro
Journal of Electronic Materials, 37(12), p.1793 - 1798, 2008/12
Times Cited Count：4 Percentile：30.56(Engineering, Electrical & Electronic)Kaizu, Toshiyuki*; Takahashi, Masamitsu; Yamaguchi, Koichi*; Mizuki, Junichiro
Journal of Crystal Growth, 310(15), p.3436 - 3439, 2008/07
Times Cited Count：11 Percentile：68.31(Crystallography)An Sb-adsorbed GaAs(001) substrate that serves as a template for high-density InAs quantum dot (QD)growth was investigated using in situ X-ray diffraction. The Sb distribution in the top eight layers from the surface was determined by crystal truncation rod scattering analysis. It was found that Sb atoms penetrated to the eighth layer when GaAs(001) came in contact with an Sb environment. The amounts of Sb in the first and second layers were, however, saturated at 1/3 atomic layer (AL) and 2/3 AL, respectively. A comparison between the X-ray results and atomic force microscopy observations of the QD density showed that the formation of high-density QDs is correlated with the total amount of Sb in the surface and subsurface layers.
Kaizu, Toshiyuki; Takahashi, Masamitsu; Yamaguchi, Koichi*; Mizuki, Junichiro
Journal of Crystal Growth, 301-302, p.248 - 251, 2007/04
Times Cited Count：13 Percentile：76.94(Crystallography)no abstracts in English
Takahashi, Masamitsu; Kaizu, Toshiyuki; Mizuki, Junichiro
AIP Conference Proceedings 893, p.75 - 76, 2007/03
Stranski-Krastanov islands are far from equilibrium and coarsening occurs when they are annealed. This coarsening is driven by chemical potential differences between islands. In lattice-mismatched systems, the chemical potential difference is governed by strain as well as surface and interface energies. In the present work, we discuss ripening kinetics of InAs/GaAs(001) on the basis of in situ X-ray diffraction, which is sensitive to strain distribution within islands. Experiments were performed at a synchrotron beamline 11XU at SPring-8 using an X-ray diffractometer integrated with an MBE chamber. From X-ray diffraction data, the lattice constant distribution and the height of the InAs quantum dots were evaluated during growth and annealing at substrate temperatures ranging from 430
C to 480C. X-ray results suggest that strain relief via thermally enhanced alloying plays a major role in the coarsening process as it does in continuous growth of InAs.
Takahashi, Masamitsu; Kaizu, Toshiyuki; Mizuki, Junichiro
Transactions of the Materials Research Society of Japan, 32(1), p.209 - 214, 2007/03
Molecular beam epitaxial (MBE) growth of InAs/GaAs(001) quantum dots was investigated by grazing-incidence X-ray diffraction using a diffractometer integrated with an MBE apparatus, which was installed on beamline 11XU at SPring-8. Use of synchrotron radiation and a two-dimensional X-ray detector enabled X-ray diffraction intensity mapping in the reciprocal lattice space at a rate of less than 10 s per frame. A series of X-ray diffraction images revealed the evolution of the strain, composition and height of InAs quantum dots during the growth process including InAs nanoisland formation, growth interruption and encapsulation with GaAs. Because the propagation of X-rays is not hindered even in gaseous atmosphere, this technique can be applied to vapor-phase epitaxy as well and thus is suitable for industrial applications.
Takahashi, Masamitsu; Kaizu, Toshiyuki; Mizuki, Junichiro
e-Journal of Surface Science and Nanotechnology (Internet), 4, p.426 - 430, 2006/04
A monitoring technique for molecular beam epitaxial growth of InAs/GaAs(001) nanoislands is presented. With the help of a combination of synchrotron radiation and a two-dimensional X-ray detector, X-ray diffraction intensity mappings in the reciprocal space have been measured during growth at a rate of 9.6 s per frame. This method provides information on strain distribution and height of Stranski-Krastanov islands under the in situ condition. Because the use of X-rays is not hindered by ambient pressure, this technique is suitable for industry-oriented applications such as organometallic vapor-phase epitaxy as well.
monitoring of internal strain and height of InAs nanoislands grown on GaAs(001)Takahashi, Masamitsu; Kaizu, Toshiyuki; Mizuki, Junichiro
Applied Physics Letters, 88(10), p.101917_1 - 101917_3, 2006/03
Times Cited Count：17 Percentile：52.43(Physics, Applied)A monitoring technique for molecular beam epitaxial growth of InAs/GaAs(001) nanoislands is presented. With the help of synchrotron radiation, X-ray diffraction intensity mapping in reciprocal space has been measured during growth. The internal strain distribution and height of the Stranski-Krastanov islands were monitored at a temporal resolution of 9.6 s. The relaxation process of internal strain inside the Stranski-Krastanov islands displayed significant dependence on the growth temperature.
Takahashi, Masamitsu; Kaizu, Toshiyuki; Mizuki, Junichiro
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no abstracts in English
Takahashi, Masamitsu; Kaizu, Toshiyuki; Mizuki, Junichiro
no journal, ,
no abstracts in English
Takahashi, Masamitsu; Kaizu, Toshiyuki
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no abstracts in English
