The Experts below are selected from a list of 612 Experts worldwide ranked by ideXlab platform
Heinz Schweizer - One of the best experts on this subject based on the ideXlab platform.
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Electronic Structure of Ordered Ga0.5In0.5P/GaAs Heterointerface Studied by Raman-Scattering and Photoluminescence-Excitation Measurements
Japanese Journal of Applied Physics, 2005Co-Authors: Kenichi Yamashita, Takashi Kita, Osamu Wada, Yong Wang, Christian Geng, Ferdinand Scholz, Heinz SchweizerAbstract:We have investigated the electronic band structure of a long-range-ordered Ga0.5In0.5P/GaAs heterointerface by optical measurements and a semi-empirical calculation. Raman-scattering spectra of the ordered Ga0.5In0.5P/GaAs Samples show plasmon–phonon coupled modes induced by dense electron accumulation at the heterointerface, in contrast to that of the Unordered Sample which shows the spectrum of bulk GaAs. Furthermore, the Franz–Keldysh oscillation observed in the photoluminescence-excitation spectrum indicates a strong interface electric field. According to the results of a comparison between the experiment and a semi-empirical calculation based on Poisson's law, it is found that the spatial distribution of the accumulated electron density is modified strongly by the conduction-band discontinuity and the interface field, depending on the order parameter.
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Magnetophotoluminescence study of the Ga0.5In0.5P/GaAs heterointerface with a ordering-induced two-dimensional electron gas
Physical Review B, 2002Co-Authors: Kenichi Yamashita, Takashi Kita, Osamu Wada, Christian Geng, Ferdinand Scholz, Y. Matsuura, Heinz SchweizerAbstract:We studied two-dimensional properties of electrons accumulated at the GaAs side of Ga 0 . 5 In 0 . 5 P/GaAs-single heterointerface. Long-range ordering in Ga 0 . 5 In 0 . 5 P causes the electron accumulation at the GaAs side of the heterointerface. Photoluminescence (PL) spectra of GaAs have been systematically measured for undoped Unordered and ordered Ga 0 . 5 In 0 . 5 P/GaAs Samples. A PL spectrum of the ordered Sample shows signals related to the quantized electron state in a triangular potential buried at the heterointerface and the Fermi-edge singularity, in contrast that the Unordered Sample shows a typical PL spectrum of a high-quality bulk GaAs. Magneto-PL spectra indicate that the reduced exciton masses between parallel and perpendicular to the heterointerface are anisotropic. We found clear optical Shubnikov-de Haas (SdH) oscillations in both the PL intensity and the transition energy under the perpendicular magnetic field. These PL features demonstrate that the electrons accumulated at the heterointerface act as two-dimensional electron gas (2DEG). The sheet-carrier density of the 2DEG is deduced from the period of the observed SdH oscillation and it found to be ∼ 1.20 × 10 1 2 cm - 2 .
Marco Piastra - One of the best experts on this subject based on the ideXlab platform.
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IJCNN - A growing self-organizing network for reconstructing curves and surfaces
2009 International Joint Conference on Neural Networks, 2009Co-Authors: Marco PiastraAbstract:Self-organizing networks such as Neural Gas, Growing Neural Gas and many others have been adopted in actual applications for both dimensionality reduction and manifold learning. Typically, the goal in these applications is obtaining a good estimate of the topology of a completely unknown subspace that can be explored only through an Unordered Sample of input data points. In the approach presented here, the dimension of the input manifold is assumed to be known in advance. This prior assumption can be harnessed in the design of a new, growing self-organizing network that can adapt itself in a way that, under specific conditions, will guarantee the effective and stable recovery of the exact topological structure of the input manifold.
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A growing self-organizing network for reconstructing curves and surfaces
2009Co-Authors: Marco PiastraAbstract:Self-organizing networks such as neural gas, growing neural gas and many others have been adopted in actual applications for both dimensionality reduction and manifold learning. Typically, the goal in these applications is obtaining a good estimate of the topology of a completely unknown subspace that can be explored only through an Unordered Sample of input data points. In the approach presented here, the dimension of the input manifold is assumed to be known in advance. This prior assumption can be harnessed in the design of a new, growing self-organizing network that can adapt itself in a way that, under specific conditions, will guarantee the effective and stable recovery of the exact topological structure of the input manifold
Kenichi Yamashita - One of the best experts on this subject based on the ideXlab platform.
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Electronic Structure of Ordered Ga0.5In0.5P/GaAs Heterointerface Studied by Raman-Scattering and Photoluminescence-Excitation Measurements
Japanese Journal of Applied Physics, 2005Co-Authors: Kenichi Yamashita, Takashi Kita, Osamu Wada, Yong Wang, Christian Geng, Ferdinand Scholz, Heinz SchweizerAbstract:We have investigated the electronic band structure of a long-range-ordered Ga0.5In0.5P/GaAs heterointerface by optical measurements and a semi-empirical calculation. Raman-scattering spectra of the ordered Ga0.5In0.5P/GaAs Samples show plasmon–phonon coupled modes induced by dense electron accumulation at the heterointerface, in contrast to that of the Unordered Sample which shows the spectrum of bulk GaAs. Furthermore, the Franz–Keldysh oscillation observed in the photoluminescence-excitation spectrum indicates a strong interface electric field. According to the results of a comparison between the experiment and a semi-empirical calculation based on Poisson's law, it is found that the spatial distribution of the accumulated electron density is modified strongly by the conduction-band discontinuity and the interface field, depending on the order parameter.
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Magnetophotoluminescence study of the Ga0.5In0.5P/GaAs heterointerface with a ordering-induced two-dimensional electron gas
Physical Review B, 2002Co-Authors: Kenichi Yamashita, Takashi Kita, Osamu Wada, Christian Geng, Ferdinand Scholz, Y. Matsuura, Heinz SchweizerAbstract:We studied two-dimensional properties of electrons accumulated at the GaAs side of Ga 0 . 5 In 0 . 5 P/GaAs-single heterointerface. Long-range ordering in Ga 0 . 5 In 0 . 5 P causes the electron accumulation at the GaAs side of the heterointerface. Photoluminescence (PL) spectra of GaAs have been systematically measured for undoped Unordered and ordered Ga 0 . 5 In 0 . 5 P/GaAs Samples. A PL spectrum of the ordered Sample shows signals related to the quantized electron state in a triangular potential buried at the heterointerface and the Fermi-edge singularity, in contrast that the Unordered Sample shows a typical PL spectrum of a high-quality bulk GaAs. Magneto-PL spectra indicate that the reduced exciton masses between parallel and perpendicular to the heterointerface are anisotropic. We found clear optical Shubnikov-de Haas (SdH) oscillations in both the PL intensity and the transition energy under the perpendicular magnetic field. These PL features demonstrate that the electrons accumulated at the heterointerface act as two-dimensional electron gas (2DEG). The sheet-carrier density of the 2DEG is deduced from the period of the observed SdH oscillation and it found to be ∼ 1.20 × 10 1 2 cm - 2 .
Takashi Kita - One of the best experts on this subject based on the ideXlab platform.
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Electronic Structure of Ordered Ga0.5In0.5P/GaAs Heterointerface Studied by Raman-Scattering and Photoluminescence-Excitation Measurements
Japanese Journal of Applied Physics, 2005Co-Authors: Kenichi Yamashita, Takashi Kita, Osamu Wada, Yong Wang, Christian Geng, Ferdinand Scholz, Heinz SchweizerAbstract:We have investigated the electronic band structure of a long-range-ordered Ga0.5In0.5P/GaAs heterointerface by optical measurements and a semi-empirical calculation. Raman-scattering spectra of the ordered Ga0.5In0.5P/GaAs Samples show plasmon–phonon coupled modes induced by dense electron accumulation at the heterointerface, in contrast to that of the Unordered Sample which shows the spectrum of bulk GaAs. Furthermore, the Franz–Keldysh oscillation observed in the photoluminescence-excitation spectrum indicates a strong interface electric field. According to the results of a comparison between the experiment and a semi-empirical calculation based on Poisson's law, it is found that the spatial distribution of the accumulated electron density is modified strongly by the conduction-band discontinuity and the interface field, depending on the order parameter.
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Magnetophotoluminescence study of the Ga0.5In0.5P/GaAs heterointerface with a ordering-induced two-dimensional electron gas
Physical Review B, 2002Co-Authors: Kenichi Yamashita, Takashi Kita, Osamu Wada, Christian Geng, Ferdinand Scholz, Y. Matsuura, Heinz SchweizerAbstract:We studied two-dimensional properties of electrons accumulated at the GaAs side of Ga 0 . 5 In 0 . 5 P/GaAs-single heterointerface. Long-range ordering in Ga 0 . 5 In 0 . 5 P causes the electron accumulation at the GaAs side of the heterointerface. Photoluminescence (PL) spectra of GaAs have been systematically measured for undoped Unordered and ordered Ga 0 . 5 In 0 . 5 P/GaAs Samples. A PL spectrum of the ordered Sample shows signals related to the quantized electron state in a triangular potential buried at the heterointerface and the Fermi-edge singularity, in contrast that the Unordered Sample shows a typical PL spectrum of a high-quality bulk GaAs. Magneto-PL spectra indicate that the reduced exciton masses between parallel and perpendicular to the heterointerface are anisotropic. We found clear optical Shubnikov-de Haas (SdH) oscillations in both the PL intensity and the transition energy under the perpendicular magnetic field. These PL features demonstrate that the electrons accumulated at the heterointerface act as two-dimensional electron gas (2DEG). The sheet-carrier density of the 2DEG is deduced from the period of the observed SdH oscillation and it found to be ∼ 1.20 × 10 1 2 cm - 2 .
Osamu Wada - One of the best experts on this subject based on the ideXlab platform.
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Electronic Structure of Ordered Ga0.5In0.5P/GaAs Heterointerface Studied by Raman-Scattering and Photoluminescence-Excitation Measurements
Japanese Journal of Applied Physics, 2005Co-Authors: Kenichi Yamashita, Takashi Kita, Osamu Wada, Yong Wang, Christian Geng, Ferdinand Scholz, Heinz SchweizerAbstract:We have investigated the electronic band structure of a long-range-ordered Ga0.5In0.5P/GaAs heterointerface by optical measurements and a semi-empirical calculation. Raman-scattering spectra of the ordered Ga0.5In0.5P/GaAs Samples show plasmon–phonon coupled modes induced by dense electron accumulation at the heterointerface, in contrast to that of the Unordered Sample which shows the spectrum of bulk GaAs. Furthermore, the Franz–Keldysh oscillation observed in the photoluminescence-excitation spectrum indicates a strong interface electric field. According to the results of a comparison between the experiment and a semi-empirical calculation based on Poisson's law, it is found that the spatial distribution of the accumulated electron density is modified strongly by the conduction-band discontinuity and the interface field, depending on the order parameter.
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Magnetophotoluminescence study of the Ga0.5In0.5P/GaAs heterointerface with a ordering-induced two-dimensional electron gas
Physical Review B, 2002Co-Authors: Kenichi Yamashita, Takashi Kita, Osamu Wada, Christian Geng, Ferdinand Scholz, Y. Matsuura, Heinz SchweizerAbstract:We studied two-dimensional properties of electrons accumulated at the GaAs side of Ga 0 . 5 In 0 . 5 P/GaAs-single heterointerface. Long-range ordering in Ga 0 . 5 In 0 . 5 P causes the electron accumulation at the GaAs side of the heterointerface. Photoluminescence (PL) spectra of GaAs have been systematically measured for undoped Unordered and ordered Ga 0 . 5 In 0 . 5 P/GaAs Samples. A PL spectrum of the ordered Sample shows signals related to the quantized electron state in a triangular potential buried at the heterointerface and the Fermi-edge singularity, in contrast that the Unordered Sample shows a typical PL spectrum of a high-quality bulk GaAs. Magneto-PL spectra indicate that the reduced exciton masses between parallel and perpendicular to the heterointerface are anisotropic. We found clear optical Shubnikov-de Haas (SdH) oscillations in both the PL intensity and the transition energy under the perpendicular magnetic field. These PL features demonstrate that the electrons accumulated at the heterointerface act as two-dimensional electron gas (2DEG). The sheet-carrier density of the 2DEG is deduced from the period of the observed SdH oscillation and it found to be ∼ 1.20 × 10 1 2 cm - 2 .
