The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Yoshikazu Takeda - One of the best experts on this subject based on the ideXlab platform.
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Elimination of Local Thickness modulation in GaAs/GaAsP strained superlattices for high spin-polarization photocathodes
Journal of Physics: Conference Series, 2011Co-Authors: Yuya Maeda, Toshio Sasaki, Shigeo Arai, Shingo Fuchi, T Ujihar, Yoshikazu TakedaAbstract:We successfully developed a transmission-type photocathode, and a high spin-polarization (90%) with a super-high brightness (1.3×107 Acm−2sr−1) of electron beam was achieved. In this research, the elimination of Thickness modulation of GaAs/GaAsP superlattice by introduction of a GaAs inter-layer on a GaP substrate is the key point to realize the high spin-polarization. The Thickness modulation of the superlattice is related with the surface roughness of the buffer layer. The compressive strain introduced in the GaAsP buffer layer on the GaP substrate causes hillock formation, where several degree off-angle surfaces are formed. The GaAs inter-layer deposited on the GaP substrate introduced a tensile strain in the GaAsP buffer layer instead of the compressive strain and relatively smooth GaAsP buffer layer was achieved. The smooth GaAsP buffer layer was attributed to the periodic GaAs/GaAsP superlattice layer growth.
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Effects of defects and Local Thickness modulation on spin-polarization in photocathodes based on GaAs/GaAsP strained superlattices
Journal of Applied Physics, 2010Co-Authors: Yuya Maeda, Toshio Sasaki, Shigeo Arai, Shingo Fuchi, Toru Ujihara, Yoichi Ishida, Masataka Kanda, Takashi Saka, Yoshikazu TakedaAbstract:The spin-polarization of electrons from the GaAs/GaAsP superlattice on a GaAs substrate (∼90%) is higher than that from the same superlattice on a GaP substrate (∼60%). Transmission electron microscopy and atomic force microscopy observations revealed that stacking faults were the main defects in the superlattice on the GaAs substrate, while Local Thickness modulation of the superlattice layers was prominent in the superlattice on the GaP substrate. According to the density of stacking faults and the areal ratio of the Thickness modulation, it was concluded that the Thickness modulation in the superlattice was the main reason for the spin-polarization reduction in the photocathode on the GaP substrate. Growth of a thin GaAs layer on a GaP substrate prior to superlattice growth eliminated the Thickness modulation and the spin-polarization was recovered to 90%.
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effects of defects and Local Thickness modulation on spin polarization in photocathodes based on gaas gaasp strained superlattices
Journal of Applied Physics, 2010Co-Authors: Yuya Maeda, Toshio Sasaki, Shigeo Arai, Shingo Fuchi, Toru Ujihara, Yoichi Ishida, Masataka Kanda, Takashi Saka, Yoshikazu TakedaAbstract:The spin-polarization of electrons from the GaAs/GaAsP superlattice on a GaAs substrate (∼90%) is higher than that from the same superlattice on a GaP substrate (∼60%). Transmission electron microscopy and atomic force microscopy observations revealed that stacking faults were the main defects in the superlattice on the GaAs substrate, while Local Thickness modulation of the superlattice layers was prominent in the superlattice on the GaP substrate. According to the density of stacking faults and the areal ratio of the Thickness modulation, it was concluded that the Thickness modulation in the superlattice was the main reason for the spin-polarization reduction in the photocathode on the GaP substrate. Growth of a thin GaAs layer on a GaP substrate prior to superlattice growth eliminated the Thickness modulation and the spin-polarization was recovered to 90%.
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8.5: Effects of defects and Local Thickness modulation on spin-polarization in photocathodes based on GaAs/GaAsP strained superlattices
International Vacuum Nanoelectronics Conference, 2010Co-Authors: Yuya Maeda, Toshio Sasaki, Shigeo Arai, Shingo Fuchi, Toru Ujihara, Yoshikazu TakedaAbstract:The spin-polarization of electrons from the GaAs/GaAsP superlattice on GaAs is higher than that from the same superlattice on GaP. TEM observation revealed that in the superlattice on GaAs stacking faults were the main defects but in the superlattice on GaP Local Thickness modulation of superlattice layers was prominent. Stacking faults and Thickness modulation have different effects on the spin-polarization.
Yuya Maeda - One of the best experts on this subject based on the ideXlab platform.
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Elimination of Local Thickness modulation in GaAs/GaAsP strained superlattices for high spin-polarization photocathodes
Journal of Physics: Conference Series, 2011Co-Authors: Yuya Maeda, Toshio Sasaki, Shigeo Arai, Shingo Fuchi, T Ujihar, Yoshikazu TakedaAbstract:We successfully developed a transmission-type photocathode, and a high spin-polarization (90%) with a super-high brightness (1.3×107 Acm−2sr−1) of electron beam was achieved. In this research, the elimination of Thickness modulation of GaAs/GaAsP superlattice by introduction of a GaAs inter-layer on a GaP substrate is the key point to realize the high spin-polarization. The Thickness modulation of the superlattice is related with the surface roughness of the buffer layer. The compressive strain introduced in the GaAsP buffer layer on the GaP substrate causes hillock formation, where several degree off-angle surfaces are formed. The GaAs inter-layer deposited on the GaP substrate introduced a tensile strain in the GaAsP buffer layer instead of the compressive strain and relatively smooth GaAsP buffer layer was achieved. The smooth GaAsP buffer layer was attributed to the periodic GaAs/GaAsP superlattice layer growth.
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Effects of defects and Local Thickness modulation on spin-polarization in photocathodes based on GaAs/GaAsP strained superlattices
Journal of Applied Physics, 2010Co-Authors: Yuya Maeda, Toshio Sasaki, Shigeo Arai, Shingo Fuchi, Toru Ujihara, Yoichi Ishida, Masataka Kanda, Takashi Saka, Yoshikazu TakedaAbstract:The spin-polarization of electrons from the GaAs/GaAsP superlattice on a GaAs substrate (∼90%) is higher than that from the same superlattice on a GaP substrate (∼60%). Transmission electron microscopy and atomic force microscopy observations revealed that stacking faults were the main defects in the superlattice on the GaAs substrate, while Local Thickness modulation of the superlattice layers was prominent in the superlattice on the GaP substrate. According to the density of stacking faults and the areal ratio of the Thickness modulation, it was concluded that the Thickness modulation in the superlattice was the main reason for the spin-polarization reduction in the photocathode on the GaP substrate. Growth of a thin GaAs layer on a GaP substrate prior to superlattice growth eliminated the Thickness modulation and the spin-polarization was recovered to 90%.
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effects of defects and Local Thickness modulation on spin polarization in photocathodes based on gaas gaasp strained superlattices
Journal of Applied Physics, 2010Co-Authors: Yuya Maeda, Toshio Sasaki, Shigeo Arai, Shingo Fuchi, Toru Ujihara, Yoichi Ishida, Masataka Kanda, Takashi Saka, Yoshikazu TakedaAbstract:The spin-polarization of electrons from the GaAs/GaAsP superlattice on a GaAs substrate (∼90%) is higher than that from the same superlattice on a GaP substrate (∼60%). Transmission electron microscopy and atomic force microscopy observations revealed that stacking faults were the main defects in the superlattice on the GaAs substrate, while Local Thickness modulation of the superlattice layers was prominent in the superlattice on the GaP substrate. According to the density of stacking faults and the areal ratio of the Thickness modulation, it was concluded that the Thickness modulation in the superlattice was the main reason for the spin-polarization reduction in the photocathode on the GaP substrate. Growth of a thin GaAs layer on a GaP substrate prior to superlattice growth eliminated the Thickness modulation and the spin-polarization was recovered to 90%.
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8.5: Effects of defects and Local Thickness modulation on spin-polarization in photocathodes based on GaAs/GaAsP strained superlattices
International Vacuum Nanoelectronics Conference, 2010Co-Authors: Yuya Maeda, Toshio Sasaki, Shigeo Arai, Shingo Fuchi, Toru Ujihara, Yoshikazu TakedaAbstract:The spin-polarization of electrons from the GaAs/GaAsP superlattice on GaAs is higher than that from the same superlattice on GaP. TEM observation revealed that in the superlattice on GaAs stacking faults were the main defects but in the superlattice on GaP Local Thickness modulation of superlattice layers was prominent. Stacking faults and Thickness modulation have different effects on the spin-polarization.
Marek Malac - One of the best experts on this subject based on the ideXlab platform.
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Local Thickness measurement through scattering contrast and electron energy loss spectroscopy
Micron, 2012Co-Authors: Huairuo Zhang, R F Egerton, Marek MalacAbstract:Abstract Scattering contrast measurements were performed on thin films of amorphous carbon and polycrystalline Au, as well as single-crystal MgO nanocubes. Based on the exponential absorption law, mass-Thickness can be obtained within 10% accuracy by measuring the incident and transmitted intensities in the same image. For mass-Thickness measurement of a thin amorphous specimen, a small collection semiangle improves the measurement sensitivity, whereas for the measurement of polycrystalline or single-crystal specimens, a large collection semiangle should be used to reduce diffraction-contrast effects. EELS Thickness measurements on MgO nanocubes suggest that the Kramers–Kronig sum-rule method (with correction for plural and surface scattering) gives 10% accuracy at medium collection semiangles but overestimates the Thickness at small collection semiangles, due to underestimation of the surface-mode scattering. The log-ratio method, with a formula for inelastic mean free path proposed by Malis et al. (1988) , provides 10% accuracy at small collection semiangle, while that proposed by Iakoubovskii et al. (2008a) is preferable for medium and large collection semiangles. As a result of this work, we provide recommendations of preferred methods and conditions for Local-Thickness measurement in the TEM.
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Local Thickness Measurement in TEM
Microscopy and Microanalysis, 2010Co-Authors: Huairuo Zhang, Ray F. Egerton, Marek MalacAbstract:Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.
Toshio Sasaki - One of the best experts on this subject based on the ideXlab platform.
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Elimination of Local Thickness modulation in GaAs/GaAsP strained superlattices for high spin-polarization photocathodes
Journal of Physics: Conference Series, 2011Co-Authors: Yuya Maeda, Toshio Sasaki, Shigeo Arai, Shingo Fuchi, T Ujihar, Yoshikazu TakedaAbstract:We successfully developed a transmission-type photocathode, and a high spin-polarization (90%) with a super-high brightness (1.3×107 Acm−2sr−1) of electron beam was achieved. In this research, the elimination of Thickness modulation of GaAs/GaAsP superlattice by introduction of a GaAs inter-layer on a GaP substrate is the key point to realize the high spin-polarization. The Thickness modulation of the superlattice is related with the surface roughness of the buffer layer. The compressive strain introduced in the GaAsP buffer layer on the GaP substrate causes hillock formation, where several degree off-angle surfaces are formed. The GaAs inter-layer deposited on the GaP substrate introduced a tensile strain in the GaAsP buffer layer instead of the compressive strain and relatively smooth GaAsP buffer layer was achieved. The smooth GaAsP buffer layer was attributed to the periodic GaAs/GaAsP superlattice layer growth.
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Effects of defects and Local Thickness modulation on spin-polarization in photocathodes based on GaAs/GaAsP strained superlattices
Journal of Applied Physics, 2010Co-Authors: Yuya Maeda, Toshio Sasaki, Shigeo Arai, Shingo Fuchi, Toru Ujihara, Yoichi Ishida, Masataka Kanda, Takashi Saka, Yoshikazu TakedaAbstract:The spin-polarization of electrons from the GaAs/GaAsP superlattice on a GaAs substrate (∼90%) is higher than that from the same superlattice on a GaP substrate (∼60%). Transmission electron microscopy and atomic force microscopy observations revealed that stacking faults were the main defects in the superlattice on the GaAs substrate, while Local Thickness modulation of the superlattice layers was prominent in the superlattice on the GaP substrate. According to the density of stacking faults and the areal ratio of the Thickness modulation, it was concluded that the Thickness modulation in the superlattice was the main reason for the spin-polarization reduction in the photocathode on the GaP substrate. Growth of a thin GaAs layer on a GaP substrate prior to superlattice growth eliminated the Thickness modulation and the spin-polarization was recovered to 90%.
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effects of defects and Local Thickness modulation on spin polarization in photocathodes based on gaas gaasp strained superlattices
Journal of Applied Physics, 2010Co-Authors: Yuya Maeda, Toshio Sasaki, Shigeo Arai, Shingo Fuchi, Toru Ujihara, Yoichi Ishida, Masataka Kanda, Takashi Saka, Yoshikazu TakedaAbstract:The spin-polarization of electrons from the GaAs/GaAsP superlattice on a GaAs substrate (∼90%) is higher than that from the same superlattice on a GaP substrate (∼60%). Transmission electron microscopy and atomic force microscopy observations revealed that stacking faults were the main defects in the superlattice on the GaAs substrate, while Local Thickness modulation of the superlattice layers was prominent in the superlattice on the GaP substrate. According to the density of stacking faults and the areal ratio of the Thickness modulation, it was concluded that the Thickness modulation in the superlattice was the main reason for the spin-polarization reduction in the photocathode on the GaP substrate. Growth of a thin GaAs layer on a GaP substrate prior to superlattice growth eliminated the Thickness modulation and the spin-polarization was recovered to 90%.
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8.5: Effects of defects and Local Thickness modulation on spin-polarization in photocathodes based on GaAs/GaAsP strained superlattices
International Vacuum Nanoelectronics Conference, 2010Co-Authors: Yuya Maeda, Toshio Sasaki, Shigeo Arai, Shingo Fuchi, Toru Ujihara, Yoshikazu TakedaAbstract:The spin-polarization of electrons from the GaAs/GaAsP superlattice on GaAs is higher than that from the same superlattice on GaP. TEM observation revealed that in the superlattice on GaAs stacking faults were the main defects but in the superlattice on GaP Local Thickness modulation of superlattice layers was prominent. Stacking faults and Thickness modulation have different effects on the spin-polarization.
Shigeo Arai - One of the best experts on this subject based on the ideXlab platform.
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Elimination of Local Thickness modulation in GaAs/GaAsP strained superlattices for high spin-polarization photocathodes
Journal of Physics: Conference Series, 2011Co-Authors: Yuya Maeda, Toshio Sasaki, Shigeo Arai, Shingo Fuchi, T Ujihar, Yoshikazu TakedaAbstract:We successfully developed a transmission-type photocathode, and a high spin-polarization (90%) with a super-high brightness (1.3×107 Acm−2sr−1) of electron beam was achieved. In this research, the elimination of Thickness modulation of GaAs/GaAsP superlattice by introduction of a GaAs inter-layer on a GaP substrate is the key point to realize the high spin-polarization. The Thickness modulation of the superlattice is related with the surface roughness of the buffer layer. The compressive strain introduced in the GaAsP buffer layer on the GaP substrate causes hillock formation, where several degree off-angle surfaces are formed. The GaAs inter-layer deposited on the GaP substrate introduced a tensile strain in the GaAsP buffer layer instead of the compressive strain and relatively smooth GaAsP buffer layer was achieved. The smooth GaAsP buffer layer was attributed to the periodic GaAs/GaAsP superlattice layer growth.
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Effects of defects and Local Thickness modulation on spin-polarization in photocathodes based on GaAs/GaAsP strained superlattices
Journal of Applied Physics, 2010Co-Authors: Yuya Maeda, Toshio Sasaki, Shigeo Arai, Shingo Fuchi, Toru Ujihara, Yoichi Ishida, Masataka Kanda, Takashi Saka, Yoshikazu TakedaAbstract:The spin-polarization of electrons from the GaAs/GaAsP superlattice on a GaAs substrate (∼90%) is higher than that from the same superlattice on a GaP substrate (∼60%). Transmission electron microscopy and atomic force microscopy observations revealed that stacking faults were the main defects in the superlattice on the GaAs substrate, while Local Thickness modulation of the superlattice layers was prominent in the superlattice on the GaP substrate. According to the density of stacking faults and the areal ratio of the Thickness modulation, it was concluded that the Thickness modulation in the superlattice was the main reason for the spin-polarization reduction in the photocathode on the GaP substrate. Growth of a thin GaAs layer on a GaP substrate prior to superlattice growth eliminated the Thickness modulation and the spin-polarization was recovered to 90%.
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effects of defects and Local Thickness modulation on spin polarization in photocathodes based on gaas gaasp strained superlattices
Journal of Applied Physics, 2010Co-Authors: Yuya Maeda, Toshio Sasaki, Shigeo Arai, Shingo Fuchi, Toru Ujihara, Yoichi Ishida, Masataka Kanda, Takashi Saka, Yoshikazu TakedaAbstract:The spin-polarization of electrons from the GaAs/GaAsP superlattice on a GaAs substrate (∼90%) is higher than that from the same superlattice on a GaP substrate (∼60%). Transmission electron microscopy and atomic force microscopy observations revealed that stacking faults were the main defects in the superlattice on the GaAs substrate, while Local Thickness modulation of the superlattice layers was prominent in the superlattice on the GaP substrate. According to the density of stacking faults and the areal ratio of the Thickness modulation, it was concluded that the Thickness modulation in the superlattice was the main reason for the spin-polarization reduction in the photocathode on the GaP substrate. Growth of a thin GaAs layer on a GaP substrate prior to superlattice growth eliminated the Thickness modulation and the spin-polarization was recovered to 90%.
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8.5: Effects of defects and Local Thickness modulation on spin-polarization in photocathodes based on GaAs/GaAsP strained superlattices
International Vacuum Nanoelectronics Conference, 2010Co-Authors: Yuya Maeda, Toshio Sasaki, Shigeo Arai, Shingo Fuchi, Toru Ujihara, Yoshikazu TakedaAbstract:The spin-polarization of electrons from the GaAs/GaAsP superlattice on GaAs is higher than that from the same superlattice on GaP. TEM observation revealed that in the superlattice on GaAs stacking faults were the main defects but in the superlattice on GaP Local Thickness modulation of superlattice layers was prominent. Stacking faults and Thickness modulation have different effects on the spin-polarization.
