共查询到20条相似文献,搜索用时 13 毫秒
1.
A. I. Sharkov T. I. Galkina V. S. Krivobok A. Yu. Klokov P. V. Shapkin V. S. Bagaev 《Physics of the Solid State》2006,48(9):1764-1768
The photoluminescence and nonequilibrium heat transfer observed in ZnSe single crystals grown by the free growth method on an oriented single-crystal ZnSe substrate in a hydrogen atmosphere were investigated. The nonequilibrium heat transfer (or propagation of nonequilibrium phonons) was studied by the heat pulse method. A region of local thermal equilibrium or “a hot phonon spot” was found to form in the material, and the threshold of its formation was determined. The constant of spontaneous anharmonic phonon decay in ZnSe was estimated from an analysis of the propagation of nonequilibrium phonons via comparison of the experimental responses with those calculated by the Monte Carlo method. 相似文献
2.
O. V. Karban’ E. I. Salamatov A. V. Taranov E. N. Khazanov O. L. Khasanov 《Journal of Experimental and Theoretical Physics》2009,108(4):661-667
The kinetics of weakly nonequilibrium subterahertz thermal phonons is studied in nanodispersed iron-containing corundum-based cermets at liquid-helium temperatures. For the chosen method of fabricating cermets (which restricts grain growth), iron inclusions are shown to be described as point trapping centers of phonons. The transport of nonequilibrium phonons is analyzed in a ceramic matrix containing metallic trapping centers. 相似文献
3.
Ion-implanted buried layer in diamond as a source of ballistic phonons at liquid-helium temperatures
T. I. Galkina A. I. Sharkov A. Yu. Klokov M. M. Bonch-Osmolovskii R. A. Khmel’nitskii V. A. Dravin A. A. Gippius 《JETP Letters》1996,64(4):298-300
It is shown that an approximately 150 nm thick ion-implanted buried layer in diamond and excited by a pulsed laser at wavelength
λ=337 nm is a source of nonequilibrium acoustic phonons propagating ballistically through the diamond sample at temperatures
∼2 K.
Pis’ma Zh. éksp. Teor. Fiz. 64, No. 4, 270–272 (25 August 1996) 相似文献
4.
Parfen’eva L. S. Orlova T. S. Smirnov B. I. Smirnov I. A. Misiorek H. Wlosewicz D. Jezowski A. 《Physics of the Solid State》2011,53(8):1747-1751
Physics of the Solid State - The heat capacity at constant pressure C p of the biocarbon matrix prepared at a beech wood carbonization temperature of 1000°C has been measured in the... 相似文献
5.
The role of the peripheral and non-peripheral phonons in the estimation of the lattice thermal conductivity of a metal has been studied at low temperatures by calculating their separate contributions towards the total lattice thermal conductivity. The study is made in the temperature range 0.4–2.5 K with the help of the Ziman expression for the scattering of phonons by the charge carriers and the Callaway expression of the phonon conductivity, and Sb is taken as an example. The separate percentage contributions due to peripheral and non-peripheral phonons have also been studied and it is found that the percentage contribution due to peripheral phonons increases with increasing temperature while the percentage contribution due to non-peripheral phonons decreases with increasing temperature. The percentage contributions of the lattice thermal resistivities due to electrons and holes towards the total lattice thermal resistivity of Sb have also been reported in the present note. 相似文献
6.
CanKun Zhang QiongYu Li Bo Tian ZhiYi Huang WeiYi Lin HongYang Li DaHai He YingHui Zhou WeiWei Cai 《中国科学:物理学 力学 天文学(英文版)》2014,57(10):1817-1821
The isotope labeled graphene was synthesized in the concentration of 13C carbon atom in 1%, 25%, 50%, 75% and 99%. The isotope effect on the phonon behavior in graphene was investigated based on the micro-Raman analysis of 13C isotope labeled graphene samples. We found that the phonon scattering is affected by the isotopic carbon atom as a point defect. Based on the experiment results, the Klemens-Callaway model and uncertainty principle were used to obtain the mean free path of the G and D phonons. The results agree with the thermal conductivity measurement by non-contact optical method and with other theoretical calculations. 相似文献
7.
V. V. Brazhkin S. G. Lyapin I. A. Trojan R. N. Voloshin A. G. Lyapin N. N. Mel’nik 《JETP Letters》2000,72(4):195-198
Second-order Raman spectra corresponding to transverse acoustic phonons are studied in detail for crystalline Si over the temperature range 20–620°C. The largest relative softening and anharmonicity at the boundaries of the Brillouin zone were observed for the TA(X) mode. Extrapolation of the TA(X) frequency to high temperatures suggests that the Si lattice should be dynamically unstable at temperatures on the order of a doubled melting temperature. It is found that the main contribution to the softening of the transverse acoustic phonons in silicon comes from the anharmonicity and not from the volume expansion. 相似文献
8.
Lherbier A Dubois SM Declerck X Roche S Niquet YM Charlier JC 《Physical review letters》2011,106(4):046803
Quantum transport properties of disordered graphene with structural defects (Stone-Wales and divacancies) are investigated using a realistic π-π* tight-binding model elaborated from ab initio calculations. Mean free paths and semiclassical conductivities are then computed as a function of the nature and density of defects (using an order-N real-space Kubo-Greenwood method). By increasing the defect density, the decay of the semiclassical conductivities is predicted to saturate to a minimum value of 4e2/πh over a large range (plateau) of carrier density (>0.5×10(14) cm(-20). Additionally, strong contributions of quantum interferences suggest that the Anderson localization regime could be experimentally measurable for a defect density as low as 1%. 相似文献
9.
10.
《Comptes Rendus Physique》2016,17(10):1154-1160
It has been proposed for a long time now that the reduction of the thermal conductivity by reducing the phonon mean free path is one of the best way to improve the current performance of thermoelectrics. By measuring the thermal conductance and thermal conductivity of nanowires and thin films, we show different ways of increasing the phonon scattering from low-temperature up to room-temperature experiments. It is shown that playing with the geometry (constriction, periodic structures, nano-inclusions), from the ballistic to the diffusive limit, the phonon thermal transport can be severely altered in single crystalline semiconducting structures; the phonon mean free path is in consequence reduced. The diverse implications on thermoelectric properties will be eventually discussed. 相似文献
11.
I. I. Kuleev 《Physics of the Solid State》2017,59(4):682-693
The physical aspects of the influence of the elastic energy anisotropy of crystals on the anisotropy of the mean free paths of phonons in single-crystal films of germanium, silicon, and diamond in the diffuse scattering of phonons at the boundaries of the samples have been considered. It has been shown that, for sufficiently wide films of germanium, silicon, and diamond with the {100} and {111} orientations and the lengths of less than or equal to their width, the phonon mean free paths are isotropic (independent of the direction of the temperature gradient in the plane of the film). The anisotropy of the phonon mean free paths depends primarily on the orientation of the film plane and is determined by the focusing and defocusing of phonon modes. For single-crystal films of germanium, silicon, and diamond with the {100} and {111} orientations and lengths much larger than their width, the phonon mean free paths are anisotropic. 相似文献
12.
Summary An original Monte Carlo study of the equilibrium microscopic and macroscopic recombination cross-sections at shallow impurity
centres is presented. Both cross-sections are investigated in lightly dopedp-Si as functions of the temperature and ionized acceptor concentration. In order to treat generation-recombination processes
we extend the semi-classical Boltzmann equation through a simulation of the carrier motion in the energy-configuration space
of an impurity centre. The analysis of the scattering rates as a function of the total carrier energy enables a microscopic
interpretation of the capture process to be carried out. The role of excited levels is naturally included and found to be
of main importance at increasing lattice temperatures. Numerical results are then compared with available experiments and
existing analytical calculations. 相似文献
13.
We have observed dispersive two-phonon Raman scattering of polaritons by LO and acoustic phonons near the lowest exciton state of ZnTe. From the Stokes shifts of these Raman lines, it has been found that the scattering process switches from an acoustic phonon followed by one LO phonon to the reversed one: a LO phonon followed by an acoustic one. 相似文献
14.
A magnon–phonon interaction model is developed on the basis of two-dimensional square Heisenberg ferromagnetic system. By using Matsubara Green function theory transverse acoustic phonon excitation is studied and transverse acoustic phonon excitation dispersion curves is calculated on the main symmetric point and line in the first Brillouin zone. On line Σ it is found that there is hardening for transverse acoustic phonon on small wave vector zone (nearby point Γ), there is softening for transverse acoustic phonon on the softening zone and there is hardening for transverse acoustic phonon near point M. On line Δ it is found there is no softening and hardening for transverse acoustic phonon. On line Z it is found that there is softening for transverse acoustic phonon on small wave vector zone (nearby point X) and there is hardening for transverse acoustic phonon nearby point M. The influences of various parameters on transverse acoustic phonon excitation are also explored and it is found that the coupling of the magnon–phonon and the spin wave stiffness constant play an important role for the softening of transverse acoustic phonon. 相似文献
15.
The velocity of longitudinal long-wave phonons in crystals with a small number of randomly distributed static edge dislocations was shown to be the same as in ideal crystals. The correction to the velocity of phonons is determined by their interaction with the field of lattice deformations caused by the presence of dislocations. The field of deformations of dislocation displacements is long-range. In addition, these deformations experience sign reversal when the sign of the coordinate perpendicular to the dislocation line and Burgers vector changes. It follows that a crystal contracts or expands in this direction because of the interaction of phonons with dislocations as the defect deformation sign alters. Such an anisotropic volume (and density) change over the whole crystal should however be balanced somehow. For this reason, the density of samples with edge dislocations should remain constant, and the correction δc to the velocity of phonons should be zero. The procedure for averaging that gives δc = 0 is based on the independence of this macro value from the orientation of phonon momemtum incident on randomly distributed dislocations, the unaveraged correction being a diverging value because of the long-range character of the field of defect deformations. For comparison, the correction to the velocity of phonons in crystals with point impurities was calculated. Lattice deformation caused by such defects is isotropic. For this reason, the mean density of crystals with point impurities and the velocity of phonons in them are different from those in ideal crystals. All calculations were performed using the Dyson equation derived on the basis of the Keldysh diagram technique. 相似文献
16.
V. G. Lyubivyi 《Russian Physics Journal》1988,31(1):14-18
This report examines one of the reasons for the scatter in the dielectric permeability values of semiinsulating gallium arsenide (GaAs): the presence in the material of impurities or defects which lead to the formation of impurity defect microinclusions. Some of these microinclusions enhance the polarizability of the material and hence increase. A quantitative evaluation of these effects is included.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 17–22, January, 1988. 相似文献
17.
A theory of the dephasing rate of quasi-2D free excitons due to acoustic phonon interaction at low exciton densities is presented. Both deformation potential and piezoelectric couplings are considered for the exciton–phonon interaction in quantum wells. Using the derived interaction Hamiltonian obtained recently by us, exciton linewidth and dephasing rate are calculated as a function of the exciton density, exciton temperature, exciton momentum and lattice temperature. 相似文献
18.
Electron scattering from boundaries and impurities destroys the single-particle picture of the electron–phonon interaction. We show that quantum interference between ‘pure‘ electron–phonon and electron–boundary/impurity scattering may result in the reduction as well as to the significant enlargement of the electron dephasing rate. This effect crucially depends on the extent, to which electron scatterers, such as boundaries and impurities, are dragged by phonons. Static and vibrating scatterers are described by two dimensionless parametersqTl and qTL, where q is the wavevector of the thermal phonon, l is the total electron mean-free path, L is the mean-free path due to scattering from static scatterers. According to the Pippard ineffectiveness condition , without static scatterers the dephasing rate at low temperatures is slower by the factor 1 / ql than the rate in a pure bulk material. However, in the presence of static potential the dephasing rate turns out to be 1 / qL times faster. Thus, at low temperatures electron dephasing and energy relaxation may be controlled by electron boundary/impurity scattering in a wide range. 相似文献
19.
The current induced step-like structure in the V-I characteristics of tin whiskers with indium impurities up to 4 at.% shows a zero voltage intercept I0 of approximatively 0.5Ic. This current can be explained by the existence of phase slip centers above the critical current which carry a time averaged supercurrent of ≈0.5Ic. From the differential resistance associated with the first step a “healing length” Ln proportional to l (l = mean free path) was obtained which can be related to the quasi-particle diffusion length Λ introduced by Tinkham et al. in the explanation of temperature independent nonequilibrium processes between pairs and quasiparticles at a phase slip center. 相似文献
20.
V.I. Arakin N.N. Zinovev U. Parmanbekov I.D. Yaroshetskii 《Solid State Communications》1985,55(8):733-735
We report the first direct observation of radiative no-phonon and acoustic phonon-assisted transitions, determination of relative rates of radiative and non-radiative phonon-assisted decay for centres of various types in semiconductors. We also have suggested improvement of experimental approach to get a form of the distribution function for non-equilibrium acoustic phonons in crystals. 相似文献