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M. Balkanski

Bio: M. Balkanski is an academic researcher from Centre national de la recherche scientifique. The author has contributed to research in topics: Raman spectroscopy & Electronic band structure. The author has an hindex of 17, co-authored 36 publications receiving 2116 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, light scattering of the linewidth and frequency shift of the optical phonon in silicon over the temperature range of 5-1400 K are presented. But they do not consider the four-phonon anharmonic processes.
Abstract: Systematic measurements by light scattering of the linewidth and frequency shift of the $\stackrel{\ensuremath{\rightarrow}}{\mathrm{q}}=0$ optical phonon in silicon over the temperature range of 5-1400 K are presented. Both the linewidth and frequency shift exhibit a quadratic dependence on temperature at high temperatures. This indicates the necessity of including terms in the phonon proper self-energy corresponding to four-phonon anharmonic processes.

1,208 citations

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TL;DR: In this article, the wave numbers of the transverse-optical phonon and longitudinal phonon were determined at temperatures between 8 and 300 degrees of freedom, and the total dielectric function including the interband contribution was analyzed.
Abstract: Reflectivity spectra of HgTe were measured in the spectral region from 80 to 600 ${\mathrm{cm}}^{\ensuremath{-}1}$ at temperatures between 8 and 300\ifmmode^\circ\else\textdegree\fi{}K. The wave numbers of the transverse-optical phonon ${\ensuremath{\omega}}_{\mathrm{TO}}=117$ ${\mathrm{cm}}^{\ensuremath{-}1}$ and longitudinal-optical phonon ${\ensuremath{\omega}}_{\mathrm{LO}}=132$ ${\mathrm{cm}}^{\ensuremath{-}1}$ at 8\ifmmode^\circ\else\textdegree\fi{}K were determined. The total dielectric function including the interband ${\ensuremath{\Gamma}}_{8}\ensuremath{-}{\ensuremath{\Gamma}}_{8}$ contribution was analyzed. Plasmon-phonon dispersion diagrams were obtained. The theoretical analysis is compared with experimental results at all temperatures. Possible consequences of the adiabatic approximation breaking down in zero-gap semiconductors is examined. A new low-frequency mode is reported, its temperature dependence is given, and its origin is discussed from physicochemical arguments.

128 citations

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TL;DR: In this article, the reflectivity spectra of ZnTe and ZnSe were studied experimentally and theoretically, and the theoretical calculations were done at an assumed temperature of 300\ifmmode^\circ\else\text degree\fi{}K.
Abstract: Reflectivity spectra of ZnTe and ZnSe are studied experimentally and theoretically. The measurements are made at 15 and 300\ifmmode^\circ\else\textdegree\fi{}K, and the theoretical calculations are done at an assumed temperature of 300\ifmmode^\circ\else\textdegree\fi{}K. Spin-orbit interactions are included in the empirical pseudopotential calculation of the electronic band structures for both ZnTe and ZnSe. The imaginary part of the frequency-dependent dielectric function, the reflectivity, and the derivative of the reflectivity are calculated. In addition, a direct comparison of the measured and calculated reflectivity is made. The calculated derivative of the reflectivity is compared with thermo-reflectance data. The electronic transitions causing the reflectivity peaks are identified.

120 citations

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TL;DR: Very accurate measurements of the photoemission yield were performed on the (111) face of Si as a function of photon energy in the threshold region down to the 10/sup -10/ range as mentioned in this paper.
Abstract: Very accurate measurements of the photoemission yield were performed on the (111) face of Si as a function of photon energy in the threshold region down to the 10/sup -10/ range. By using a set of differently doped samples cleaved in ultrahigh vacuum, one can distinguish between surface- and bulk-state photoelectrons. (WDM)

107 citations

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TL;DR: In this paper, the reflectivity spectra of CdTe and HgTe are compared and prominent features of the reflectivities are identified with critical point transitions in specific regions of the Brillouin zone.
Abstract: We have measured and calculated the reflectivity spectra of CdTe and HgTe. The measured and calculated reflectivities are compared and prominent features of the reflectivity spectra are identified with critical-point transitions in specific regions of the Brillouin zone. The symmetry and contribution to the reflectivity of important critical points are investigated. Empirical pseudopotential calculations of the band structure and the imaginary part of the frequency-dependent dielectric function, with spin-orbit effects included, are also presented.

85 citations


Cited by
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TL;DR: Weyl and Dirac semimetals as discussed by the authors are three-dimensional phases of matter with gapless electronic excitations that are protected by topology and symmetry, and they have generated much recent interest.
Abstract: Weyl and Dirac semimetals are three-dimensional phases of matter with gapless electronic excitations that are protected by topology and symmetry. As three-dimensional analogs of graphene, they have generated much recent interest. Deep connections exist with particle physics models of relativistic chiral fermions, and, despite their gaplessness, to solid-state topological and Chern insulators. Their characteristic electronic properties lead to protected surface states and novel responses to applied electric and magnetic fields. The theoretical foundations of these phases, their proposed realizations in solid-state systems, and recent experiments on candidate materials as well as their relation to other states of matter are reviewed.

3,407 citations

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TL;DR: A review of the methods for determining the behavior of solids whose properties vary randomly at the microscopic level, with principal attention to systems having composition variation on a well-defined structure (random "alloys") can be found in this paper.
Abstract: We review the methods which have been developed over the past several years to determine the behavior of solids whose properties vary randomly at the microscopic level, with principal attention to systems having composition variation on a well-defined structure (random "alloys"). We begin with a survey of the various elementary excitations and put the dynamics of electrons, phonons, magnons, and excitons into one common descriptive Hamiltonian; we then review the use of double-time thermodynamic Green's functions to determine the experimental properties of systems. Next we discuss these aspects of the problem which derive from the statistical specification of the microscopic parameters; we examine what information can and cannot be obtained from averaged Green's functions. The central portion of the review concerns methods for calculating the averaged Green's function to successively better approximation, including various self-consistent methods, and higher-order cluster effects. The last part of the review presents a comparison of theory with the experimental results of a variety of properties---optical, electronic, magnetic, and neutron scattering. An epilogue calls attention to the similarity between these problems and those of other fields where random material heterogeneity has played an essential role.

1,213 citations

Journal ArticleDOI
Leonard J. Brillson1
TL;DR: In this article, the contributions of surface science research to the understanding of metal-semiconductor interfaces are surveyed and a wide range of ultra-high vacuum techniques now available for probing metal-semiconductor interfaces on an atomic scale, and assess the current state of knowledge of the chemical, geometrical, and electronic structures of MSS interfaces.

667 citations

Journal ArticleDOI
TL;DR: In this paper, the temperature dependence of the first-order Raman scattering by phonons in Si, Ge, and $\ensuremath{\alpha}\ensureMath{-}\mathrm{S} n} was measured.
Abstract: We have measured the temperature dependence of the first-order Raman scattering by phonons in Si, Ge, and $\ensuremath{\alpha}\ensuremath{-}\mathrm{S}\mathrm{n}$. The full widths at half maximum of the Raman lines, extrapolated to zero temperature, are 1.24\ifmmode\pm\else\textpm\fi{}0.07, 0.75\ifmmode\pm\else\textpm\fi{}0.03, and 0.81\ifmmode\pm\else\textpm\fi{}0.15 ${\mathrm{cm}}^{\ensuremath{-}1}$ for Si, Ge, and $\ensuremath{\alpha}\ensuremath{-}\mathrm{S}\mathrm{n}$, respectively. The reliability of the data obtained allows a critical examination of the theoretical calculations published so far. We show that the model assuming the decay of the Raman phonon into two acoustical phonons belonging to the same branch, first proposed by Klemens, does not represent adequately the temperature dependence of the Raman linewidth. The most important decay channels are shown to be combinations of optical and acoustical phonons. However, the more complete calculation by Cowley, which involves all possible decay channels, gives very large zero-temperature linewidths. We show that this arises mainly from the poor description of the phonon dispersion curves by the shell model used by Cowley, and that a better agreement between theory and experiment is to be expected by repeating the calculation with Weber's adiabatic bond-charge model.

619 citations

Journal ArticleDOI
TL;DR: In this paper, the infrared reflectance spectra of lithium borate glasses (0.73 mol% Li 2 O) have been measured over a broad and continuous spectral range (30-4000 cm −1 ) in an attempt to study systematically their structure.
Abstract: The infrared reflectance spectra of lithium borate glasses (0–73 mol% Li 2 O) have been measured over a broad and continuous spectral range (30–4000 cm −1 ) in an attempt to study systematically their structure. The reflectance data have been analyzed by Kramers-Kronig inversion to obtain the optical and dielectric properties of the materials. The study of the deconvoluted mid-infrared spectra has revealed a glass network built up of various boron-oxygen groups, with structure and concentration strongly dependent on the Li 2 O content. Of particular interest was the far-infrared asymmetric absorption profile, which could be well simulated by two broad bands attributed to vibrations of lithium cations in two distinct network environments. The presence of these two Li + -host site distributions was found to be independent of the details of the borate network structure and has been taken to imply a more general characteristics of ionic conducting oxide glasses.

600 citations