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Yusaburo Segawa - One of the best experts on this subject based on the ideXlab platform.
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Optical properties of ZnO:Al Epilayers and of undoped Epilayers capped by wider-gap MgZnO grown by laser MBE
Physica Status Solidi (B) Basic Research, 2002Co-Authors: T. Makino, Chee H. Chia, A. Ohtomo, Yusaburo Segawa, K. Tamura, M. Kawasaki, Hideomi KoinumaAbstract:Interaction between photocreated carriers and background excess-electrons in single-crystalline Al-doped ZnO Epilayers (1.9 × 1019 ≤ n ≤ 6.7 × 1020 cm-3) are studied by using optical absorption spectroscopy. The Burstein Moss shift of the absorption edge energy over the carrier concentration range of n ≥ 5.9 × 1020 cm-3 was confirmed. We propose that the Fermi-edge singularity as a result of many-body Coulomb effect could be observed in the samples of 1.9 × 1019 ≤ n ≤ 4.8 × 1019 cm-3 even at room temperature. In the second part, we report the optical properties of a ZnO epilayer capped with a MgZnO layer. The luminescence spectrum taken at 5 K encompassed free exciton emissions from the ZnO layer. These free excitons have been hardly recognized in the uncapped Epilayers grown under the identical condition. This may indicate the suppression of the exciton-trapping center formation attained by the capping.
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Plasma-assisted molecular-beam epitaxy of ZnO Epilayers on atomically flat MgAl2O4(111) substrates
Applied Physics Letters, 2000Co-Authors: Yelan Chen, Soon-Ku Hong, Masa Nakajima, Takafumi Yao, Hang Ju Ko, Yusaburo SegawaAbstract:Plasma-assisted molecular-beam epitaxy of ZnO Epilayers on MgAl2O4(111) substrates is described. Acid mixed by H2SO4 and H3PO4 was used for the substrate etching, which provides atomically flat surfaces with a regular terrace array. The influence of the substrate on lateral growth and coalescence of ZnO islands during epitaxy is discussed with corresponding morphological and structural properties. The epitaxial relationship between the ZnO epilayer and MgAl2O4 substrate is determined as: ZnO[01(1) over bar 0]parallel to MgAl2O4[2] and ZnO[0]parallel to MgAl2O4[(1) over bar 10]. X-ray diffraction, photoluminescence, and Hall-effect measurements are reported, which indicate that high-quality ZnO Epilayers are obtained by using atomically flat MgAl2O4(111) substrates to suppress columnar growth. (C) 2000 American Institute of Physics. [S0003-6951(00)01902-1].
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plasma assisted molecular beam epitaxy of zno Epilayers on atomically flat mgal2o4 111 substrates
Applied Physics Letters, 2000Co-Authors: Yefan Chen, Soon-Ku Hong, Masa Nakajima, Hang Ju Ko, Yusaburo SegawaAbstract:Plasma-assisted molecular-beam epitaxy of ZnO Epilayers on MgAl2O4(111) substrates is described. Acid mixed by H2SO4 and H3PO4 was used for the substrate etching, which provides atomically flat surfaces with a regular terrace array. The influence of the substrate on lateral growth and coalescence of ZnO islands during epitaxy is discussed with corresponding morphological and structural properties. The epitaxial relationship between the ZnO epilayer and MgAl2O4 substrate is determined as: ZnO[0110]∥MgAl2O4[112] and ZnO[2110]∥MgAl2O4[110]. X-ray diffraction, photoluminescence, and Hall-effect measurements are reported, which indicate that high-quality ZnO Epilayers are obtained by using atomically flat MgAl2O4(111) substrates to suppress columnar growth.
Hang Ju Ko - One of the best experts on this subject based on the ideXlab platform.
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Plasma-assisted molecular-beam epitaxy of ZnO Epilayers on atomically flat MgAl2O4(111) substrates
Applied Physics Letters, 2000Co-Authors: Yelan Chen, Soon-Ku Hong, Masa Nakajima, Takafumi Yao, Hang Ju Ko, Yusaburo SegawaAbstract:Plasma-assisted molecular-beam epitaxy of ZnO Epilayers on MgAl2O4(111) substrates is described. Acid mixed by H2SO4 and H3PO4 was used for the substrate etching, which provides atomically flat surfaces with a regular terrace array. The influence of the substrate on lateral growth and coalescence of ZnO islands during epitaxy is discussed with corresponding morphological and structural properties. The epitaxial relationship between the ZnO epilayer and MgAl2O4 substrate is determined as: ZnO[01(1) over bar 0]parallel to MgAl2O4[2] and ZnO[0]parallel to MgAl2O4[(1) over bar 10]. X-ray diffraction, photoluminescence, and Hall-effect measurements are reported, which indicate that high-quality ZnO Epilayers are obtained by using atomically flat MgAl2O4(111) substrates to suppress columnar growth. (C) 2000 American Institute of Physics. [S0003-6951(00)01902-1].
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plasma assisted molecular beam epitaxy of zno Epilayers on atomically flat mgal2o4 111 substrates
Applied Physics Letters, 2000Co-Authors: Yefan Chen, Soon-Ku Hong, Masa Nakajima, Hang Ju Ko, Yusaburo SegawaAbstract:Plasma-assisted molecular-beam epitaxy of ZnO Epilayers on MgAl2O4(111) substrates is described. Acid mixed by H2SO4 and H3PO4 was used for the substrate etching, which provides atomically flat surfaces with a regular terrace array. The influence of the substrate on lateral growth and coalescence of ZnO islands during epitaxy is discussed with corresponding morphological and structural properties. The epitaxial relationship between the ZnO epilayer and MgAl2O4 substrate is determined as: ZnO[0110]∥MgAl2O4[112] and ZnO[2110]∥MgAl2O4[110]. X-ray diffraction, photoluminescence, and Hall-effect measurements are reported, which indicate that high-quality ZnO Epilayers are obtained by using atomically flat MgAl2O4(111) substrates to suppress columnar growth.
Masa Nakajima - One of the best experts on this subject based on the ideXlab platform.
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Plasma-assisted molecular-beam epitaxy of ZnO Epilayers on atomically flat MgAl2O4(111) substrates
Applied Physics Letters, 2000Co-Authors: Yelan Chen, Soon-Ku Hong, Masa Nakajima, Takafumi Yao, Hang Ju Ko, Yusaburo SegawaAbstract:Plasma-assisted molecular-beam epitaxy of ZnO Epilayers on MgAl2O4(111) substrates is described. Acid mixed by H2SO4 and H3PO4 was used for the substrate etching, which provides atomically flat surfaces with a regular terrace array. The influence of the substrate on lateral growth and coalescence of ZnO islands during epitaxy is discussed with corresponding morphological and structural properties. The epitaxial relationship between the ZnO epilayer and MgAl2O4 substrate is determined as: ZnO[01(1) over bar 0]parallel to MgAl2O4[2] and ZnO[0]parallel to MgAl2O4[(1) over bar 10]. X-ray diffraction, photoluminescence, and Hall-effect measurements are reported, which indicate that high-quality ZnO Epilayers are obtained by using atomically flat MgAl2O4(111) substrates to suppress columnar growth. (C) 2000 American Institute of Physics. [S0003-6951(00)01902-1].
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plasma assisted molecular beam epitaxy of zno Epilayers on atomically flat mgal2o4 111 substrates
Applied Physics Letters, 2000Co-Authors: Yefan Chen, Soon-Ku Hong, Masa Nakajima, Hang Ju Ko, Yusaburo SegawaAbstract:Plasma-assisted molecular-beam epitaxy of ZnO Epilayers on MgAl2O4(111) substrates is described. Acid mixed by H2SO4 and H3PO4 was used for the substrate etching, which provides atomically flat surfaces with a regular terrace array. The influence of the substrate on lateral growth and coalescence of ZnO islands during epitaxy is discussed with corresponding morphological and structural properties. The epitaxial relationship between the ZnO epilayer and MgAl2O4 substrate is determined as: ZnO[0110]∥MgAl2O4[112] and ZnO[2110]∥MgAl2O4[110]. X-ray diffraction, photoluminescence, and Hall-effect measurements are reported, which indicate that high-quality ZnO Epilayers are obtained by using atomically flat MgAl2O4(111) substrates to suppress columnar growth.
Soon-Ku Hong - One of the best experts on this subject based on the ideXlab platform.
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Plasma-assisted molecular-beam epitaxy of ZnO Epilayers on atomically flat MgAl2O4(111) substrates
Applied Physics Letters, 2000Co-Authors: Yelan Chen, Soon-Ku Hong, Masa Nakajima, Takafumi Yao, Hang Ju Ko, Yusaburo SegawaAbstract:Plasma-assisted molecular-beam epitaxy of ZnO Epilayers on MgAl2O4(111) substrates is described. Acid mixed by H2SO4 and H3PO4 was used for the substrate etching, which provides atomically flat surfaces with a regular terrace array. The influence of the substrate on lateral growth and coalescence of ZnO islands during epitaxy is discussed with corresponding morphological and structural properties. The epitaxial relationship between the ZnO epilayer and MgAl2O4 substrate is determined as: ZnO[01(1) over bar 0]parallel to MgAl2O4[2] and ZnO[0]parallel to MgAl2O4[(1) over bar 10]. X-ray diffraction, photoluminescence, and Hall-effect measurements are reported, which indicate that high-quality ZnO Epilayers are obtained by using atomically flat MgAl2O4(111) substrates to suppress columnar growth. (C) 2000 American Institute of Physics. [S0003-6951(00)01902-1].
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plasma assisted molecular beam epitaxy of zno Epilayers on atomically flat mgal2o4 111 substrates
Applied Physics Letters, 2000Co-Authors: Yefan Chen, Soon-Ku Hong, Masa Nakajima, Hang Ju Ko, Yusaburo SegawaAbstract:Plasma-assisted molecular-beam epitaxy of ZnO Epilayers on MgAl2O4(111) substrates is described. Acid mixed by H2SO4 and H3PO4 was used for the substrate etching, which provides atomically flat surfaces with a regular terrace array. The influence of the substrate on lateral growth and coalescence of ZnO islands during epitaxy is discussed with corresponding morphological and structural properties. The epitaxial relationship between the ZnO epilayer and MgAl2O4 substrate is determined as: ZnO[0110]∥MgAl2O4[112] and ZnO[2110]∥MgAl2O4[110]. X-ray diffraction, photoluminescence, and Hall-effect measurements are reported, which indicate that high-quality ZnO Epilayers are obtained by using atomically flat MgAl2O4(111) substrates to suppress columnar growth.
Hideomi Koinuma - One of the best experts on this subject based on the ideXlab platform.
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Reduced defect densities in the ZnO epilayer grown on Si substrates by laser-assisted molecular-beam epitaxy using a ZnS epitaxial buffer layer
Applied Physics Letters, 2004Co-Authors: Tomoyuki Onuma, Y. Z. Yoo, Takayuki Sota, Shigefusa F Chichibu, Akira Uedono, Toyohiro Chikyow, M. Kawasaki, Hideomi KoinumaAbstract:Nonradiative photoluminescence (PL) lifetime (τnr) and point defect density in the (0001) ZnO epilayer grown on (111) Si substrates by laser-assisted molecular-beam epitaxy (L-MBE) using a (0001) ZnS epitaxial buffer layer were compared with those in the ZnO films on (111) and (001) Si substrates prepared by direct transformation of ZnS Epilayers on Si by thermal oxidation [Yoo et al., Appl. Phys. Lett. 78, 616 (2001)]. Both the ZnO films exhibited excitonic reflectance anomalies and corresponding PL peaks at low temperature, and the density or size of vacancy-type point defects (Zn vacancies), which were measured by the monoenergetic positron annihilation measurement, in the L-MBE epilayer was lower than that in the films prepared by the oxidation transformation. The ZnO epilayer grown on a (0001) ZnS epitaxial buffer on (111) Si exhibited longer τnr of 105 ps at room temperature.
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Optical Properties of ZnO:Al Epilayers and of Undoped Epilayers Capped by Wider‐Gap MgZnO Grown by Laser MBE
Physica Status Solidi B-basic Solid State Physics, 2002Co-Authors: T. Makino, Chee H. Chia, A. Ohtomo, K. Tamura, Y. Segawa, Masashi Kawasaki, Hideomi KoinumaAbstract:Interaction between photocreated carriers and background excess-electrons in single-crystalline Al-doped ZnO Epilayers (1.9 × 10 19 ≤ n ≤ 6.7 × 10 20 cm -3 ) are studied by using optical absorption spectroscopy. The Burstein Moss shift of the absorption edge energy over the carrier concentration range of n > 5.9 × 10 20 cm -3 was confirmed. We propose that the Fermi-edge singularity as a result of many-body Coulomb effect could be observed in the samples of 1.9 x 10 19 < n < 4.8 x 10 19 cm -3 even at room temperature. In the second part, we report the optical properties of a ZnO epilayer capped with a MgZnO layer. The luminescence spectrum taken at 5 K encompassed free exciton emissions from the ZnO layer. These free excitons have been hardly recognized in the uncapped Epilayers grown under the identical condition. This may indicate the suppression of the exciton-trapping center formation attained by the capping.
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Optical properties of ZnO:Al Epilayers and of undoped Epilayers capped by wider-gap MgZnO grown by laser MBE
Physica Status Solidi (B) Basic Research, 2002Co-Authors: T. Makino, Chee H. Chia, A. Ohtomo, Yusaburo Segawa, K. Tamura, M. Kawasaki, Hideomi KoinumaAbstract:Interaction between photocreated carriers and background excess-electrons in single-crystalline Al-doped ZnO Epilayers (1.9 × 1019 ≤ n ≤ 6.7 × 1020 cm-3) are studied by using optical absorption spectroscopy. The Burstein Moss shift of the absorption edge energy over the carrier concentration range of n ≥ 5.9 × 1020 cm-3 was confirmed. We propose that the Fermi-edge singularity as a result of many-body Coulomb effect could be observed in the samples of 1.9 × 1019 ≤ n ≤ 4.8 × 1019 cm-3 even at room temperature. In the second part, we report the optical properties of a ZnO epilayer capped with a MgZnO layer. The luminescence spectrum taken at 5 K encompassed free exciton emissions from the ZnO layer. These free excitons have been hardly recognized in the uncapped Epilayers grown under the identical condition. This may indicate the suppression of the exciton-trapping center formation attained by the capping.