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P. V. Seredin P. Domashevskaya I. N. Arsentyev D. A. Vinokurov A. L. Stankevich T. Prutskij 《Semiconductors》2013,47(1):1-6
Epitaxial heterostructures produced on the basis of Al x Ga1 ? x As and Ga x In1 ? x P ternary alloys by metal-organic chemical vapor deposition are studied. The composition parameter x of the alloys was ~0.50. By X-ray diffraction studies, scanning electron microscopy, atomic force microscopy, and photoluminescence spectroscopy, it is shown that superstructured ordered phases with the stoichiometry composition III1 ? ηIII1 + ηV2 can be formed. As a consequence of this effect, not only does the cubic crystal symmetry change to the tetragonal type in the new compound, but also the optical properties become different from those of disordered alloy with the same composition. 相似文献
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Light-element-containing CaAl2Si2-type Zintl phases CaZn2?x Cu x P2 and CaMnZn1?x Cu x P2 (x = 0.0–0.2) have been synthesized by solid-state reaction. Electrical resistivity (ρ), Seebeck coefficient (α), and thermal conductivity (κ) were measured over a wide temperature (T) range (80–1000 K) to evaluate the thermoelectric potential of these materials. Below 300 K, the power factor (PF; α 2/ρ) is very small. Above 600 K, however, PF increases rapidly for all compositions because of a rapid increase of α and a simultaneous decrease of ρ. The measured large α is consistent with the wider band gap expected for these compositions. Compared with the pure compounds, larger PF values are observed for the Cu-substituted compounds; the largest observed PF is ~0.5 mW/m K2. The thermal conductivity is found to be rather low, despite the presence of light elements, and is in the range 1.0–1.5 W/m K at 1000 K. Because of the combination of low κ and moderate PF values, the dimensionless figure of merit ZT = α 2 T/ρκ reaches a maximum of 0.4 for CaZn1.9Cu0.1P2. 相似文献
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Hung Chi Chou Anas Mazady John Zeller Tariq Manzur Mehdi Anwar 《Journal of Electronic Materials》2013,42(5):882-888
A ZnO/Zn1?x Mg x O-based quantum cascade laser (QCL) is proposed as a candidate for generation of THz radiation at room temperature. The structural and material properties, field dependence of the THz lasing frequency, and generated power are reported for a resonant phonon ZnO/Zn0.95Mg0.05O QCL emitting at 5.27 THz. The theoretical results are compared with those from GaN/Al x Ga1?x N QCLs of similar geometry. Higher calculated optical output powers [ $ {P}_{\rm{ZnMgO}} $ = 2.89 mW (nonpolar) at 5.27 THz and 2.75 mW (polar) at 4.93 THz] are obtained with the ZnO/Zn0.95Mg0.05O structure as compared with GaN/Al0.05Ga0.95N QCLs [ $ {P}_{\rm{AlGaN}} $ = 2.37 mW (nonpolar) at 4.67 THz and 2.29 mW (polar) at 4.52 THz]. Furthermore, a higher wall-plug efficiency (WPE) is obtained for ZnO/ZnMgO QCLs [24.61% (nonpolar) and 23.12% (polar)] when compared with GaN/AlGaN structures [14.11% (nonpolar) and 13.87% (polar)]. These results show that ZnO/ZnMgO material is optimally suited for THz QCLs. 相似文献
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采用托盘式光盘进退方式,其IDE接口能支持Ultra ATA/33传输模式,提供支持读取8cm光盘及直立工作能力,附赠“PowerDVD”及“PowerPlayer”应用软件 相似文献
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E. I. Rogacheva A. N. Doroshenko O. N. Nashchekina Yu. V. Men′shov 《Journal of Electronic Materials》2013,42(7):2098-2102
Bi1?x Sb x solid solutions have attracted much attention as promising low-temperature thermoelectric materials. Previously, we observed distinct extrema in the isotherms of the transport and mechanical properties of polycrystalline Bi1?x Sb x and attributed their presence to the transition from diluted to concentrated solid solutions and to the reconstruction of the energy band structure under increasing Sb concentration. The goal of the present work is a detailed study of the concentration dependences of the thermal conductivity λ for Bi1?x Sb x polycrystalline solid solutions (x = 0 to 0.09) in the temperature range of 170 K to 300 K. It is established that the λ(x) dependences exhibit a nonmonotonic behavior: in certain concentration ranges an anomalous increase in λ with increasing x is observed. It is shown that the concentration dependences of the thermoelectric figure of merit calculated on the basis of the measured λ values are also nonmonotonic. The obtained data represent additional evidence in favor of our assumptions stated earlier about a significant effect of electronic phase transitions observed in Bi1?x Sb x solid solutions on the concentration dependences of their thermoelectric properties. These results should be taken into account when developing new Bi1?x Sb x -based materials. 相似文献
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以往,在对专用系统实现浮点处理时,需预留电路板空间以容纳多处理器和片外处理器,为了让工程师更轻松,更经济的实现设计目标,ADI推出全新高性能SHARC 2148x及低功耗SHARC 2147x系列处理器。 相似文献