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81.
Mathematical Notes - 相似文献
82.
Shklover V. Ya. Kazanskii P. R. Artemov N. A. Maryasev I. G. 《Crystallography Reports》2021,66(4):663-672
Crystallography Reports - The development of fundamental and applied geology requires an ever-increasing amount of data on the structures and properties of rocks at different scales. Of particular... 相似文献
83.
Acoustical Physics - An adaptive version of the multirank Capon algorithm is constructed for acoustic-source localization by a vertical array in the case of incomplete information on the random... 相似文献
84.
Algebras and Representation Theory - We introduce and study the category of twisted modules over a triangular differential graded bocs. We show that in this category idempotents split, that it... 相似文献
85.
Annals of Operations Research - The vehicle routing problem is a traditional combinatorial problem with practical relevance for a wide range of industries. In the literature, several specificities... 相似文献
86.
Crystallography Reports - Nd1 – yEuyF3 – y crystals (y is the molar fraction of EuF2; 0 ≤ y ≤ 0.15) with a tysonite (LaF3) structure have... 相似文献
87.
Russian Journal of General Chemistry - New manganese(II) and iron(III) complexes with hydrazones derived from malonic acid dihydrazide and 3,5-di-tert-butylsalicylaldehyde have been synthesized.... 相似文献
88.
S.V. Ivanov M.Yu. Chernov V.A. Solovev P.N. Brunkov D.D. Firsov O.S. Komkov 《Progress in Crystal Growth and Characterization of Materials》2019,65(1):20-35
High-efficiency semiconductor lasers and light-emitting diodes operating in the 3–5?μm mid-infrared (mid-IR) spectral range are currently of great demand for a wide variety of applications, in particular, gas sensing, noninvasive medical tests, IR spectroscopy etc. III-V compounds with a lattice constant of about 6.1?Å are traditionally used for this spectral range. The attractive idea to fabricate such emitters on GaAs substrates by using In(Ga,Al)As compounds is restricted by either the minimum operating wavelength of ~8?μm in case of pseudomorphic AlGaAs-based quantum cascade lasers or requires utilization of thick metamorphic InxAl1-xAs buffer layers (MBLs) playing a key role in reducing the density of threading dislocations (TDs) in an active region, which otherwise result in a strong decay of the quantum efficiency of such mid-IR emitters. In this review we present the results of careful investigations of employing the convex-graded InxAl1-xAs MBLs for fabrication by molecular beam epitaxy on GaAs (001) substrates of In(Ga,Al)As heterostructures with a combined type-II/type-I InSb/InAs/InGaAs quantum well (QW) for efficient mid-IR emitters (3–3.6?μm). The issues of strain relaxation, elastic stress balance, efficiency of radiative and non-radiative recombination at T?=?10–300?K are discussed in relation to molecular beam epitaxy (MBE) growth conditions and designs of the structures. A wide complex of techniques including in-situ reflection high-energy electron diffraction, atomic force microscopy (AFM), scanning and transmission electron microscopies, X-ray diffractometry, reciprocal space mapping, selective area electron diffraction, as well as photoluminescence (PL) and Fourier-transformed infrared spectroscopy was used to study in detail structural and optical properties of the metamorphic QW structures. Optimization of the growth conditions (the substrate temperature, the As4/III ratio) and elastic strain profiles governed by variation of an inverse step in the In content profile between the MBL and the InAlAs virtual substrate results in decrease in the TD density (down to 3?×?107 cm?2), increase of the thickness of the low-TD-density near-surface MBL region to 250–300?nm, the extremely low surface roughness with the RMS value of 1.6–2.4?nm, measured by AFM, as well as rather high 3.5?μm-PL intensity at temperatures up to 300?K in such structures. The obtained results indicate that the metamorphic InSb/In(Ga,Al)As QW heterostructures of proper design, grown under the optimum MBE conditions, are very promising for fabricating the efficient mid-IR emitters on a GaAs platform. 相似文献
89.
Ganina O. G. Bondarenko G. N. Isaeva V. I. Kustov L. M. Beletskaya I. P. 《Russian Journal of Organic Chemistry》2019,55(12):1813-1820
The catalytic activity of copper-containing heterogeneous catalysts, in particular metal-organic frameworks, zeolites, and alumina-supported nanoparticles, in the carboxylation of terminal alkynes and oxiranes has been evaluated. Temperature dependences of these reactions have been studied.
相似文献90.
Ghochikyan T. V. Vardanyan A. S. Samvelyan M. A. Galstyan A. S. Langer P. 《Russian Journal of Organic Chemistry》2019,55(2):279-281
Russian Journal of Organic Chemistry - The reactions of 2-(2-chloroprop-2-en-1-yl)-5,5-dimethyloxolan-2-one with arylboronic acids in the presence of Pd(PPh3)4 and K2CO3 was used to synthesize... 相似文献