共查询到20条相似文献,搜索用时 31 毫秒
1.
The Hall effect in heterostructures with a two-dimensional array of tunneling-coupled Ge quantum dots grown by molecular-beam epitaxy on Si is investigated. The conductivity of these structures in zero magnetic field at 4.2 K varies in the range of 10?12?10?4 Ω?1, which includes both the diffusive transport under weak localization conditions and hopping conduction. It is shown that the Hall effect can be discerned against the magnetoresistance-related background in both high- and low-conductivity structures. The Hall coefficient in the hopping regime exhibits a nonmonotonic dependence on the occupancy of quantum dots by holes. This behavior correlates with that of the localization length of the hole wavefunctions. 相似文献
2.
A. A. Dmitrievskiy N. Yu. Efremova E. M. Vihlyaeva V. V. Korenkov A. V. Shuklinov M. V. Badylevich Yu. G. Fedorenko 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(2):209-212
The mechanical properties of AIN/Si structures under conditions of beta irradiation with fluence F = 3.6 × 1010 cm−2 were investigated by the dynamic micro- and nanoindentation methods. A beta-induced increase in radial cracks in the area
of indentor imprints was discovered. 相似文献
3.
In present work the formation of dusty plasma structures in cryogenic glow dc discharge was investigated. The ordered structures from large number (~104) of charged diamagnetic dust particles in a cusp magnetic trap have been also studied in microgravity conditions. The super high charging (up to 5·107e) of dust macroparticles under direct stimulation by an electron beam is experimentally performed and investigated. The results of the investigation of Brownian motion for strongly coupled dust particles in plasma are presented. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
4.
We have grown silver dendrites by electrolysis of silver-to-sodium ion-exchanged silicate glass slides. The DC voltage of 150 and 300 V was applied to thin film coplanar electrodes deposited on the slide surface. Exposing the silver structures with weak etchant resulted in some increase in optical absorption and in the essential enhancement of Raman scattering, by the factor of ~106-107. The solid state nature of the glass-dendrite system provided stability of the formed structures, and the prepared SERS substrates did not require special conditions for storage, but a short etching before use. 相似文献
5.
S. V. Stovbun O. N. Krutius A. M. Zanin D. S. Skorobogat’ko R. G. Kostyanovskii 《Russian Journal of Physical Chemistry B, Focus on Physics》2011,5(5):846-849
Gelators with a molecular mass of 200 Da are synthesized, and the mechanisms of the formation of anisotropic supramolecular
structures during the gelation of N-trifluoroacetyl derivatives of amino alcohols are discussed. The conditions of their stability
are identified and the thresholds of gelation of the alcohols in various solvents are determined. It is shown that the gels
are formed at concentrations of 10−2–10−3 M, values substantially lower the percolation threshold for isotropic molecules. An analysis of possible topological structures
formed in the gel phase is performed. 相似文献
6.
O. A. Klimenko N. V. D’yakonova V. Knap Yu. A. Mityagin V. N. Murzin S. A. Savinov V. S. Syzranov V. A. Chuenkov 《Bulletin of the Lebedev Physics Institute》2009,36(1):21-28
The conditions of the implementation of the quantum mode of microwave generation in semiconductor resonant-tunneling diode (RTD) structures were theoretically analyzed. The high-frequency response in structures with symmetric and asymmetric barriers was analyzed by numerical simulation methods. The effect of the Fermi distribution of carriers in the near-contact region was studied. It was shown that asymmetric structures with decreased impurity concentrations (1017 cm?3) in the emitter region are optimum from the viewpoint of experimental observation of the quantum amplification mode. 相似文献
7.
本文用分子动力学模拟研究了Ni熔体以不同冷速凝固后微观结构的演变规律, 并通过理论计算确定出了Ni熔体凝固后获得理想非晶的临界条件. 模拟结果发现冷速小于1011 K/s时, Ni 熔体凝固后形成晶态组织; 冷速在1011 K/s到1014.5 K/s之间时, Ni熔体凝固后形成由晶态结构与非晶态结构组成的混合组织. 冷速小于1010 K/s, Ni 熔体凝固后形成的晶态组织具有fcc结构; 冷速在1010 K/s到1014.5 K/s之间时, Ni熔体凝固后组织中的晶态由fcc和hcp结构层状镶嵌排列构成. 通过分析模拟结果和计算结果, 确定出了Ni熔体凝固后形成理想非晶的临界冷速为1014.5 K/s. 并发现Ni熔体中临界晶核(冷速等于1014.5 K/s)和亚临界晶核(冷速大于1014.5 K/s) 均由fcc和hcp组成层状偏聚结构, 这表明Ni熔体中生长的晶体、临界晶核和晶胚的结构是相同的.
关键词:
分子动力学模拟
晶体团簇
临界冷速
结构 相似文献
8.
S. I. Zaitsev V. N. Pavlov V. Ya. Panchenko M. A. Polikarpov A. A. Svintsov E. B. Yakimov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2014,8(5):843-845
The current induced by the radiation from a 63Ni film of variable thickness is simulated taking into account the real spectrum of emitted electrons and their angular distribution for GaN. The efficiency of β-radiation detectors made from Si and SiC is estimated based on the results obtained in this paper and previously. Using a scanning electron microscope the efficiency of β-radiation detectors made from Si and SiC under conditions corresponding to β radiation from a Ni film with a thickness of 3 μm and activity of 10 mCi/cm2 is analyzed. It is shown that the efficiency of real Si-based structures is virtually as good as the efficiency of SiC-based structures. 相似文献
9.
A. S. Komolov E. F. Lazneva N. S. Chepilko N. B. Gerasimova 《Physics of the Solid State》2013,55(7):1373-1376
The photovoltaic effect has been detected and studied in thin-film structures based on thermally deposited 200-nm-thick copper phthalocyanine (CuPc) films on the surface of polycrystalline CdS. The structures under study demonstrate the linear current-voltage characteristics at external electric fields to 3.5 × 104 V/cm. Two components of the photovoltage of different signs have been revealed when the sample is illuminated in the wavelength range from 350 to 700 nm. The first component has the positive sign on the CuPc film side and is observed when using the radiation with a wavelength lesser than 500 nm, i.e., in conditions of predominant absorption of the radiation in the CdS layer. The second component has the negative sign on the CuPc film side and is observed when using the radiation with a wavelength in the range from 500 to 570 nm, corresponding to the spectral region of the absorption edge of the CuPc films. The dependences of the photovoltage on the radiation intensity studied in the range from 5 × 1012 to 1014 photons cm?2 s?1 are different in the cases of the two detected components. Mechanisms of generation of the photovoltage components associated with a change in the band bending during photogeneration of charge carriers in the region of space charge in CdS and a change in conditions of the charge transfer in the interfacial CuPc/CdS region during the radiation absorption in the CuPc film have been proposed. 相似文献
10.
L. N. Zaitsev S. L. Zaitsev A. D. Kovalenko V. P. Sidorin E. P. Cherevatenko 《Physics of Particles and Nuclei Letters》2007,4(1):96-98
Maximum permissible absorbed doses of 60Co ionizing radiation were first measured in thin (1 mm) polystyrene scintillator samples at simultaneous irradiation by 0.01–1 Gy s?1 gamma radiation and ~1016 cm2 s?1 light in vacuum. It was shown that photoradiation resistance (unlike radiation resistance) is not increased if samples are placed into vacuum and all other conditions are preserved the same. The process of formation in the polymer of unsaturated conjugated structures, whose fraction is independent of oxygen content and supply, is probably responsible for the loss of light yield. 相似文献
11.
B S Prabhananda 《Pramana》1990,34(6):491-506
The “minimum linewidths” seen in the ESR linewidths against temperature plots, the dependence of line widths on the63Cu nuclear magnetic quantum numbers and the Hubbard relation provide sufficient number of equations to determine the anisotropic
ESR parameters in the case of axially symmetric Cu(II) complexes even when unresolved hyperfine structures make contributions
to linewidths. After testing the method by reanalysing the literature data on Cu(II) bis-acetylacetonate, it has been used
to obtain the anisotropic ESR parameters in the case of bis-salicylaldehydate of Cu(II). Linewidth contributions from unresolved
hyperfine structures associated with the1H of coordinating CHCl3 inferred in these studies, were confirmed by comparing the widths in CHCl3 and CDCl3 under ideal conditions. The temperature dependence of this contribution and the estimate of rate constant at room temperature
(∼ 1010 s−1) suggest that the coordinating solvent exchange is diffusion controlled. 相似文献
12.
M. Petitjean N. Proust J. -F. Chapeaublanc J. Perrin 《Applied Physics A: Materials Science & Processing》1992,54(1):95-99
High quality silicon nitride films are deposited at low temperature on InP substrates by direct photolysis at 185 nm of a NH3-SiH4 gas mixture. The composition of the films is measured by nuclear analysis. The thickness and refractive index are obtained by ellipsometry at 632.8 nm. As-deposited and post annealed samples are electrically characterized: quasi-static I(V) at 5×10–4 Hz and C(V) characteristics at 1 MHz are performed on InP MIS diodes structures in order to optimize bulk and interface properties. At 250° C and 4 Torr, it is found that the highest critical field (measured for a leakage current density of 10–9 A/cm2) is obtained for the injected ratio [SiH4]/[NH3]=2%. For these conditions, the film is stoichiometric, the critical field is 4 MV/cm and the resistivity is 6×1015 cm. The interface state density (N
ss) on InP is deduced from Terman analysis. The annealing conditions and the surface cleaning of InP have been optimized in order to reduce the N
ss which is, for our best conditions, as low as 2×1011 eV–1 cm–2. 相似文献
13.
D. Yu. Remizov V. B. Shmagin A. V. Antonov V. P. Kuznetsov Z. F. Krasil’nik 《Physics of the Solid State》2005,47(1):98-101
A series of Si: Er electroluminescent diode structures is fabricated by sublimation molecular-beam epitaxy. The diode structures efficiently emit at a wavelength of 1.5 μm under conditions of p-n junction breakdown at room temperature. The effective cross section of excitation of Er3+ ions with hot carriers heated by the electric field of a reverse-biased p-n junction and the lifetime of Er3+ ions in the first excited state 4I13/2 are determined for structures that emit in a mixed breakdown mode and are characterized by the maximum intensity and excitation efficiency of the Er3+ electroluminescence. 相似文献
14.
V. I. Molotkov A. P. Nefedov M. Yu. Pustyl'nik V. M. Torchinsky V. E. Fortov A. G. Khrapak K. Yoshino 《JETP Letters》2000,71(3):102-105
Ordered structures formed of 300-μm-long cylindrical nylon grains with diameters of 15 and 7.5 μm are obtained. In contrast to conventional spherical monodisperse grains, which, under certain conditions, form the plasma-dust Coulomb crystal, the cylindrical grains in the plasma acquire a charge of ~7×105 electrons and form a structure similar to a liquid crystal. The parameter characterizing the nonideality of the dusty component of the plasma attains 106. Grains are suspended in the striation in the horizontal plane and line up in parallel with each other. 相似文献
15.
Pt/W/Cr/SiC Schottky-barrier diodes that retain good electrophysical parameters up to 450°C are studied. With the Auger electron spectroscopy (AES) method, it is shown that the thermal stability is provided by using a multilayer metal composition that ensures the metal/SiC interface stability. The surface-barrier structures obtained are tested for radiation hardness. They are irradiated by fast neutrons with a fluence of 4.42×1015 n/cm2 and attendant γ radiation with a dose of 8.67×105 R in the concentration range of N d-N a=1016−5×1017 cm−3. Irreversible modifications of the structures at N d-N a≤8×1016 cm−3 are found. The degradation of the parameters is inversely proportional to the doping level. 相似文献
16.
《Physica E: Low-dimensional Systems and Nanostructures》2011,43(10):2739-2741
A fabrication technique and optimal growth conditions are reported to develop a Sb-based quantum dot (QD) structure as a nanostructured III–V semiconductor on a silicon substrate. By using solid-source molecular beam epitaxy, high-density (>1010 cm−2) InGaSb QD structures can be obtained under a low growth temperature, which is compatible for use with Si-CMOS processes. We also proposed the construction of a metal/quantum dot/semiconductor (MDS) structure by using the InGaSb QD on a Si substrate. An infrared light emission with a photon energy of 0.95 eV is successfully observed from the fabricated MDS structure under the current injection conditions. It is expected that a MDS structure using a Sb-based QD will be used as a small-sized infrared light source for silicon photonic technology. 相似文献
17.
Electrically charged (up to 107 e) macroscopic superconducting particles with sizes in the micrometer range confined in a static magnetic trap in liquid nitrogen and in nitrogen vapor at temperatures of 77–91 K are observed experimentally. The macroparticles with sizes up to 60 μm levitate in a nonuniform static magnetic field B ~ 2500 G. The formation of strongly correlated structures comprising as many as ~103 particles is reported. The average particle distance in these structures amounts to 475 μm. The coupling parameter and the Lindemann parameter of these structures are estimated to be ~107 and ~0.03, respectively, which is characteristic of strongly correlated crystalline or glasslike structures. 相似文献
18.
开展了超短超强激光与稀薄等离子体相互作用实验,在实验中采用等离子体单色成像法观测等离子体发光图像,捕捉到了近乎对称的环形等离子体发光结构. 在对实验结果进行分析并与理论预言进行比较后确认这是由激光-等离子体相互作用形成的后孤立子云外围的高密度等离子体壳层发光所致. 同时通过对等离子体通道的观测还发现,孤立子的形成对超短超强激光在稀薄等离子体中的传输产生了非常大的影响.
关键词:
超短超强激光
稀薄等离子体
单色成像
后孤立子 相似文献
19.
Electroluminescence and high-frequency voltage-capacitance methods are used to study Si/SiO2 structures obtained by thermal oxidation of KéF-5 (100)Si wafers at 950°C in wet oxygen (oxide thickness 250 nm). The structures are irradiated by 130-keV argon ions with doses in the range of 1013−3.2×1017 cm−2. A correlation between the origin, properties, and formation mechanism of implantation-induced defects in the oxide layer is established, and a model of defect formation is proposed. 相似文献
20.
The influence of MeV electron irradiation on the interface states of argon implanted thin oxide MOS samples has been studied
by the thermally stimulated current (TSC) method. The oxide thickness of the structures is 18 nm. Two groups of n-type MOS structures non-implanted and implanted with 20 keV Ar+ ions and a dose of 5×1012 cm−2 are examined. Both groups are simultaneously irradiated by 23 MeV electrons with doses of 1.2×1016, 2.4×1016 or 6.0×1016 el/cm2. The energy position and density of the interface states (generated by electron irradiation, ion implantation or both treatments
of the samples) are determined. It is shown that MeV electron irradiation decreases the concentration of interface states
(like an oxygen-vacancy and di-vacancy) slightly and creates additional interface states (like an impurity-vacancy) at the
Si–SiO2 interface of argon implanted MOS structures. 相似文献