共查询到20条相似文献,搜索用时 0 毫秒
1.
Weber W 《Physical review letters》1987,58(13):1371-1374
2.
Swingle Nunes S. Sulaiman S.B. Sahoo N. Das T.P. Bharuth-Ram K. Frank M. Kreische W. Bonde Nielsen K. 《Hyperfine Interactions》1999,120(1-8):151-155
The Hartree-Fock cluster procedure was used to obtain the associated electronic distributions for 19F* (I = 5/2, E
x
= 197 KeV excited nuclear state of the 19F atom) at possible sites in crystalline Si, Ge and diamond and to calculate nuclear quadrupole coupling constants v
Q
and the asymmetry parameter η of the electric field gradient at the modelled sites. Lattice relaxation effects have been
incorporated by employing a geometry optimization method to obtain minimum energy configurations for the clusters modelling
each site. The intrabond (IB), antibonding (AB) and substitutional (S) sites in the bulk and the atop site on the surface
were studied. From a comparison with v
Q
and η values observed in time differential perturbed angular distribution (TDPAD) measurements we were able to identify the
high frequency component in Si and Ge with 19F* at the intrabond site. In diamond two high frequency components are observed. These are identified with 19F* at intrabond and substitutional sites. For the low frequency site in Si and Ge the assignment is made to 19F* implants at dangling bonds in the bulk resulting from implantation damage. In diamond none of the sites studied could provide
lower frequency nuclear quadrupole parameters close to the observed ones.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
3.
4.
De Padova P Olivieri B Mariot JM Favre L Berbezier I Quaresima C Paci B Generosi A Rossi Albertini V Cricenti A Ottaviani C Luce M Testa AM Peddis D Fiorani D Scarselli M De Crescenzi M Heckmann O Richter MC Hricovini K d'Acapito F 《J Phys Condens Matter》2012,24(14):142203
Densely packed epitaxial Mn-doped Si(0.3)Ge(0.7) nanodots self-assembled on Si(100) have been obtained. Their structural properties were studied using reflection high-energy electron diffraction, energy dispersive x-ray diffraction, atomic force microscopy, extended x-ray absorption fine structure measurements and high-resolution transmission electron microscopy. Mn(5)Ge(1)Si(2) crystallites embedded in Si(0.3)Ge(0.7) were found. They exhibit a ferromagnetic behaviour with a Curie temperature of about 225?K. 相似文献
5.
R. Abd-Shukor 《Solid State Communications》2007,142(10):587-590
The electron-phonon coupling constant in two-dimensional cuprate high temperature superconductors has been determined by the ultrasonic method. The electron-phonon coupling constant in the Van Hove scenario was found to increase with transition temperature Tc. is in the range of 0.025-0.060 which is 10-100 times smaller than the conventional three-dimensional Bardeen-Cooper-Schrieffer coupling constant. The characteristic Debye temperature θD does not correlate with Tc. These findings show that the interplay between the Debye frequency and electron-phonon coupling in the two-dimensional system and their variations have a combined effect in governing the transition temperature. 相似文献
6.
C.S. Guo 《Solid State Communications》2006,137(10):553-556
Influence of sublayer atoms on Si(100) surface reconstruction has been examined with density functional theory and molecular dynamic simulation. We found that the displacements of sublayer atoms under the buckled dimer affect the motions of their neighboring atoms and thus play an important role in determining the surface reconstructions. The present results reveal the relationship between the surface dimer reconstruction and the motion of the sublayer atoms and provide an account for experimental observations of Si(100) surface reconstructions at very low temperatures. 相似文献
7.
《Nuclear Physics B》2006,758(3):255-303
We study the localization properties of disordered d-wave superconductors by means of the fermionic replica trick method. We derive the effective non-linear σ-model describing the diffusive modes related to spin transport which we analyze by the Wilson–Polyakov renormalization group. A lot of different symmetry classes are considered within the same framework. According to the presence or the absence of certain symmetries, we provide a detailed classification for the behavior of some physical quantities, like the density of states, the spin and the quasiparticle charge conductivities. Following the original Finkel'stein approach, we finally extend the effective functional method to include residual quasiparticle interactions, at all orders in the scattering amplitudes. We consider both the superconducting and the normal phase, with and without chiral symmetry, which occurs in the so-called two-sublattice models. 相似文献
8.
Electron-phonon coupling in cuprate and iron-based superconductors revealed by Raman scattering
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Electron-phonon coupling (EPC) in cuprate and iron-based superconducting systems, as revealed by Raman scat- tering, is briefly reviewed. We introduce how to extract the coupling information through phonon lineshape. Then we discuss the strength of EPC in different high-temperature superconductor (HTSC) systems and possible factors affecting the strength. A comparative study between Raman phonon theories and experiments allows us to gain insight into some crucial electronic properties, especially superconductivity. Finally, we summarize and compare EPC in the two existing HTSC systems, and discuss what role it may play in the HTSC. 相似文献
9.
M. R. Bennett A. A. Cafolla J. W. Cairns C. J. Dunscombe R. H. Williams 《Surface science》1996,360(1-3):187-199
The interactions between CdTe, and in particular Te, and the (100) surface of Si have been probed using photoemission and low energy electron diffraction with a view to investigating the mechanisms responsible for (100) and (111) growth orientations for CdTe on Si(100). The interfacial reactions have been studied both on room temperature deposition followed by annealing and on depositions at typical epitaxial growth temperatures. In both cases the same precursor stage of an ordered submonolayer of Te on the Si(100) surface has been identified. Line shape analysis of the Si 2p core level has suggested a structural model in which Te adatoms make up an incomplete monolayer bound in bridge sites. This model is in excellent agreement both with the (1 × 1) LEED pattern and recent SEXAFS studies of this surface. The implications of the cubic symmetry of this surface in terms of the subsequent growth orientation of CdTe are discussed. Termination of the surface by Te was also seen to induce band bending suggestive of Fermi level pinning at around midgap, in contrast to the passivating behaviour of other group VI elements on this surface. The Si 2p core level line shape analysis on termination by Te has also provided evidence to support the “covalent dimer” interpretation of the clean dimerised Si(100) surface. 相似文献
10.
M. V. Gomoyunova I. I. Pronin D. E. Malygin S. M. Solov’ev D. V. Vyalykh S. L. Molodtsov 《Technical Physics》2005,50(9):1212-1216
Interaction of iron atoms with the Si(100)-2 × 1 surface at room temperature is studied by core-level photoelectron spectroscopy
using synchrotron radiation for Fe coverages ranging from a fraction of a monolayer to six monolayers. It is shown that the
Fe/Si(100)-2 × 1 interface is chemically active: the Fe-Si solid solution forms early in deposition of iron on silicon. When
the Fe coverage reaches four to five monolayers, the state of the system is changed and Fe3Si silicide arises. 相似文献
11.
12.
By bombardment of Ge targets with 7432Ge5+ of 81 MeV, a continuous X-ray intensity distribution has been obtained, which ranges up to the K X-ray energies of 64Gd. The shape of the spectra, corrected for the detector efficiency, confirms the assumption that this continuum is caused by K X-rays of Z = 64 quasimolecules, which are transiently formed during the adiabatic heavy-ion collision. The yield of quasimolecular radiation was determined to be about 4 x 10−5 X-rays per beam K-vacancy. 相似文献
13.
M. V. Gomoyunova I. I. Pronin D. E. Malygin N. R. Gall’ D. V. Vyalykh S. L. Molodtsov 《Physics of the Solid State》2005,47(10):1980-1985
The initial stages of oxidation of a Si(100)2 × 1 surface and the interaction of cobalt atoms with it were studied by core-level photoelectron spectroscopy. The study was carried out with cobalt coverages of up to 8 ML. Computer modeling of the spectra of photoexcited electrons revealed Co atom penetration under the silicon oxide layer, an effect observed even at room temperature. This process was shown to give rise to the disappearance of silicon interface phases at the oxide-layer-silicon boundary and to the formation of a more complex phase involving atoms of Co, O, and Si. After completion of the process, a Co-Si solid solution forms at the interface. 相似文献
14.
15.
16.
We have studied diffusion of Ge into subsurface layers of Si(100). Auger electron diffraction measurements show Ge in the fourth layer after submonolayer growth at temperatures as low as 500 degrees C. Density functional theory predictions of equilibrium Ge subsurface distributions are consistent with the measurements. We identify a surprisingly low energy pathway resulting from low interstitial formation energy in the third and fourth layers. Doping significantly affects the formation energy, suggesting that n-type doping may lead to sharper Si/Ge interfaces. 相似文献
17.
Using transmission ion channeling, we have made the first measurement of the Ge dimer geometry for the monohydride-covered Ge/Si(100)-2×1 surface. Comparison of calculated angular scans with experimental angular scans near the 100 and 110 directions has resulted in a measured Ge dimer bond length of 2.8 Å, which is 8% longer than the corresponding dimer bond length reported for Ge on Si(100) in the absence of H. This elongation is similar to that reported for Si dimers on the Si(100) surface. Also, relative to the (100) surface plane, the dimers change from tilted without H to untilted with H. 相似文献
18.
19.
20.
A. G. Milekhin A. I. Nikiforov O. P. Pchelyakov S. Schulze D. R. T. Zahn 《JETP Letters》2001,73(9):461-464
Ge/Si superlattices containing Ge quantum dots were prepared by molecular beam epitaxy and studied by resonant Raman scattering. It is shown that these structures possess vibrational properties of both two-and zero-dimensional objects. The folded acoustic phonons observed in the low-frequency region of the spectrum (up to 15th order) are typical for planar superlattices. The acoustic phonon lines overlap with a broad emission continuum that is due to the violation of the wave-vector conservation law by the quantum dots. An analysis of the Ge and Ge-Si optical phonons indicates that the Ge quantum dots are pseudoamorphous and that mixing of the Ge and Si atoms is insignificant. The longitudinal optical phonons undergo a low-frequency shift upon increasing laser excitation energy (2.54–2.71 eV) because of the confinement effect in small-sized quantum dots, which dominate resonant Raman scattering. 相似文献