The Experts below are selected from a list of 65634 Experts worldwide ranked by ideXlab platform
Kazuo Nakajima - One of the best experts on this subject based on the ideXlab platform.
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floating zone growth of si rich sige Bulk Crystal using pre synthesized sige feed rod with uniform composition
Journal of Crystal Growth, 2005Co-Authors: Noritaka Usami, Masayuki Kitamura, Kazuo Obara, Yoshitaro Nose, Toetsu Shishido, Kazuo NakajimaAbstract:Growth of SiGe Bulk Crystal was attempted by the floating zone (FZ) technique using high-power semiconductor lasers. SiGe feed rod with uniform composition was pre-synthesized from Si and Ge powders, and utilized as a source material for FZ growth. The Ge composition of the grown SiGe Crystal was found to be smaller than that of the feed rod owing to the segregation phenomena especially during the initial stage of the growth. This reduction of Ge was shown to be avoidable by applying an appropriate artificial design of the composition in the feed rod. Low-temperature photoluminescence measurement clarified that the grown SiGe Crystal exhibits well-resolved band-edge luminescence without any deep-level emissions.
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Successful growth of InxGa1-xAs (x > 0.18) single Bulk Crystal directly on GaAs seed Crystal with preferential orientation
Japanese Journal of Applied Physics, 2004Co-Authors: Yukinaga Azuma, Noritaka Usami, Nishijima Yoshito, Kazuo Nakajima, Kozo Fujiwara, Toru UjiharaAbstract:We attempted to utilize a GaAs single Crystal with preferential orientation as a seed to obtain an InGaAs single Bulk Crystal. The preferential orientation of the InGaAs Bulk Crystal was determined as [110] in a preliminary experiment to utilize multiple seed Crystals with random orientations. By subsequent zone growth of InGaAs on GaAs(110), an InxGa1-xAs (x>0.18) single Bulk Crystal with a diameter of 15 mm and a length of 13 mm was successfully obtained on the seed without a compositionally graded InGaAs layer. The large lattice mismatch between GaAs and InGaAs was likely to be accommodated by an array of thin columnar grains at the interface.
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Fabrication of SiGe Bulk Crystals with uniform composition as substrates for Si-based heterostructures
Materials Science and Engineering: B, 2002Co-Authors: Noritaka Usami, Yukinaga Azuma, Kozo Fujiwara, Toru Ujihara, Youichi Murakami, Sazaki, Kazuo NakajimaAbstract:Abstract SiGe Bulk Crystal was grown by the multicomponent zone-melting method equipped with an in situ monitoring system of the position and the temperature at the Crystal-solution interface. By utilizing the in situ monitoring system, an attempt was made to control the interface position at a fixed position during growth by balancing the growth rate and the pulling rate of the Crystal. This led to realization of SiGe Bulk Crystal with Ge composition of 0.86±0.004 over 22 mm in length. However, as growth proceeds, development of small angle boundaries was evidenced by X-ray characterizations. This polyCrystallization was found to be accompanied with appearance of deep-level emission in photoluminescence spectra. A preliminary result to grow SiGe with intermediate composition, which is important for Si-based heterostructures, was also performed.
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growth of sige Bulk Crystal with uniform composition by directly controlling the growth temperature at the Crystal melt interface using in situ monitoring system
Journal of Crystal Growth, 2001Co-Authors: Yukinaga Azuma, Noritaka Usami, Kozo Fujiwara, Toru Ujihara, Gen Sazaki, Youichi Murakami, Satoru Miyashita, Kazuo NakajimaAbstract:Abstract A SiGe Bulk Crystal with uniform composition was successfully fabricated by clarifying and controlling the growth parameters at the Crystal–melt interface. An apparatus was developed for the direct in situ observation and precise control of the interface parameters such as the temperature and the position. The dynamical change of the growth rate of a SiGe Bulk Crystal in a temperature gradient can be known by utilizing the apparatus. The growing Crystal was continuously pulled down at the pulling rate balanced to the growth rate to keep the interface temperature constant, which resulted in the excellent uniformity of the grown Crystal. Our technique opened the possibility to incorporate multicomponent semiconductor substrates to the semiconductor heterostructure technology.
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sige Bulk Crystal as a lattice matched substrate to gaas for solar cell applications
Applied Physics Letters, 2000Co-Authors: Noritaka Usami, Yukinaga Azuma, Kazuo Nakajima, Toru Ujihara, Gen Sazaki, Y Yakabe, T Kondo, Y Shiraki, Baoping Zhang, Y SegawaAbstract:SiGe Bulk Crystal fabricated by a multicomponent zone-melting method was used as a substrate for epitaxial growth of GaAs. Compared with conventional GaAs/Ge heterostructure, the lattice mismatch of GaAs/Si0.022Ge0.978 was confirmed to be reduced by a decrease of the peak separation of (400) x-ray diffraction from the epitaxial GaAs layer and the substrate. Furthermore, the linewidth of the rocking curve of GaAs on SiGe was found to be narrower than that of GaAs on Ge. These results show that SiGe is promising material as an alternative substrate to Ge for realization of exactly lattice-matched GaAs/SiGe solar cells.
Wudi Wang - One of the best experts on this subject based on the ideXlab platform.
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sn doped bi1 1sb0 9te2s Bulk Crystal topological insulator with excellent properties
Nature Communications, 2016Co-Authors: S K Kushwaha, Andras Gyenis, Tian Liang, I Pletikosic, S H Lapidus, Yao Tian, He Zhao, Kenneth S Burch, Jingjing Lin, Wudi WangAbstract:A long-standing issue in topological insulator research has been to find a Bulk single Crystal material that provides a high-quality platform for characterizing topological surface states without interference from Bulk electronic states. This material would ideally be a Bulk insulator, have a surface state Dirac point energy well isolated from the Bulk valence and conduction bands, display quantum oscillations from the surface state electrons and be growable as large, high-quality Bulk single Crystals. Here we show that this material obstacle is overcome by Bulk Crystals of lightly Sn-doped Bi1.1Sb0.9Te2S grown by the vertical Bridgman method. We characterize Sn-BSTS via angle-resolved photoemission spectroscopy, scanning tunnelling microscopy, transport studies, X-ray diffraction and Raman scattering. We present this material as a high-quality topological insulator that can be reliably grown as Bulk single Crystals and thus studied by many researchers interested in topological surface states.
Rupert Huber - One of the best experts on this subject based on the ideXlab platform.
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symmetry controlled temporal structure of high harmonic carrier fields from a Bulk Crystal
Nature Photonics, 2017Co-Authors: F Langer, Matthias Hohenleutner, U Huttner, Stephan W Koch, M Kira, Rupert HuberAbstract:The temporal structure of the polarization and carrier-envelope phase slip of high-harmonic waveforms generated in Bulk gallium selenide within the duration of a single multi-terahertz driving pulse can be controlled by the Crystal symmetry.
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symmetry controlled temporal structure of high harmonic carrier fields from a Bulk Crystal
Nature Photonics, 2017Co-Authors: F Langer, Matthias Hohenleutner, U Huttner, Stephan W Koch, M Kira, Rupert HuberAbstract:High-harmonic (HH) generation in Crystalline solids1-6 marks an exciting development, with potential applications in high-efficiency attosecond sources7, all-optical bandstructure reconstruction8,9, and quasiparticle collisions10,11. Although the spectral1-4 and temporal shape5 of the HH intensity has been described microscopically1-6,12, the properties of the underlying HH carrier wave have remained elusive. Here we analyse the train of HH waveforms generated in a Crystalline solid by consecutive half cycles of the same driving pulse. Extending the concept of frequency combs13-15 to optical clock rates, we show how the polarization and carrier-envelope phase (CEP) of HH pulses can be controlled by Crystal symmetry. For some Crystal directions, we can separate two orthogonally polarized HH combs mutually offset by the driving frequency to form a comb of even and odd harmonic orders. The corresponding CEP of successive pulses is constant or offset by π, depending on the polarization. In the context of a quantum description of solids, we identify novel capabilities for polarization- and phase-shaping of HH waveforms that cannot be accessed with gaseous sources.
Dongfeng Xue - One of the best experts on this subject based on the ideXlab platform.
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chemical bonding theory of single Crystal growth and its application to ϕ 3 yag Bulk Crystal
CrystEngComm, 2014Co-Authors: C Sun, Dongfeng XueAbstract:The growth of YAG Bulk Crystals was studied using both theoretical calculations based on the anisotropic chemical bonding conditions and practical growth via the Czochralski (Cz) method. The chemical bonding theory of single Crystal growth quantitatively describes the anisotropic bonding behaviors of constituent atoms during Crystallizing, which can be applied to the thermodynamic growth of YAG single Crystals. Both bonding conditions and Crystal symmetry determine the projection configuration along the pulling direction and Crystal ridges in the Crystal shoulder of YAG grown along [111] direction. During Cz growth process of YAG single Crystals, the relative low growth rate along directions results in the exposure of surfaces normal to directions. However, the chemical bonding energy density at the intersection of two adjacent growth directions is higher, leading to the exposure of surfaces normal to directions and the truncated-hexagon configuration of YAG along [111] direction. ϕ 3′′ YAG single Crystal was successfully grown. Our present work provides a promising approach to achieve controllable growth for functional Bulk Crystal via both thermodynamic and kinetic controls.
M Kira - One of the best experts on this subject based on the ideXlab platform.
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symmetry controlled temporal structure of high harmonic carrier fields from a Bulk Crystal
Nature Photonics, 2017Co-Authors: F Langer, Matthias Hohenleutner, U Huttner, Stephan W Koch, M Kira, Rupert HuberAbstract:The temporal structure of the polarization and carrier-envelope phase slip of high-harmonic waveforms generated in Bulk gallium selenide within the duration of a single multi-terahertz driving pulse can be controlled by the Crystal symmetry.
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symmetry controlled temporal structure of high harmonic carrier fields from a Bulk Crystal
Nature Photonics, 2017Co-Authors: F Langer, Matthias Hohenleutner, U Huttner, Stephan W Koch, M Kira, Rupert HuberAbstract:High-harmonic (HH) generation in Crystalline solids1-6 marks an exciting development, with potential applications in high-efficiency attosecond sources7, all-optical bandstructure reconstruction8,9, and quasiparticle collisions10,11. Although the spectral1-4 and temporal shape5 of the HH intensity has been described microscopically1-6,12, the properties of the underlying HH carrier wave have remained elusive. Here we analyse the train of HH waveforms generated in a Crystalline solid by consecutive half cycles of the same driving pulse. Extending the concept of frequency combs13-15 to optical clock rates, we show how the polarization and carrier-envelope phase (CEP) of HH pulses can be controlled by Crystal symmetry. For some Crystal directions, we can separate two orthogonally polarized HH combs mutually offset by the driving frequency to form a comb of even and odd harmonic orders. The corresponding CEP of successive pulses is constant or offset by π, depending on the polarization. In the context of a quantum description of solids, we identify novel capabilities for polarization- and phase-shaping of HH waveforms that cannot be accessed with gaseous sources.
