The observation of the low-frequency acoustic phonon torsional modes in nanocrystalline silicon
نویسندگان
چکیده
Low-frequency Raman spectra of the porous structure formed on C-implanted silicon were examined using the 514.5 and 488 nm lines of Ar laser. The sharp low-frequency Raman peaks were observed with narrow linewidth and large intensity. According to usual vibration theory of the elastic body and related symmetry analysis, they are identified as the localized acoustic phonon torsional modes resulting from the surface vibrations of quasifree Si nanocrystals with nonspherical shapes. © 1998 American Institute of Physics. @S0003-6951~98!03837-6#
منابع مشابه
Observation of folded acoustic phonons in nanocrystalline silicon/ amorphous silicon multilayers
We report in this letter the observation of folded acoustic phonons in hydrogenated nanocrystalline silicon/amorphous silicon multilayers with visible emission, which are prepared in a plasma enhanced chemical vapor deposition system. In the low-frequency range of 10–100 cm, the obtained Raman spectra clearly show some folded doublets from longitudinal acoustic phonons. Using the elastic contin...
متن کاملLow frequency phonons in nanoparticles
The consequence of the phonon confinement on the phonon spectra particularly the low frequency spectra in nanocrystal quantum dots has been investigated. Due to the phonon confinement effect, there appears spheroidal and quadrupolar modes of nanoparticles in the low frequency spectra. The frequency of these modes increases with the decrease of the size of the nanocrystal quantum dot (nanopartic...
متن کاملInvestigation of phononic, dynamic and thermal properties of indium nitride in different phases
In this paper, the phonon, dynamic and thermal properties of indium nitride in two phases are investigated. The calculations are performed using the pseudopotantial method in the framework of density functional theory and by using the quantum-espresso Package. In the calculations, the exchange-correlation terms of LDA, GGA and PBE0 approximation are used. Investigation of phononic properties s...
متن کاملTheory of Nonlinear s-Polarized Phonon-Polaritons in Multilayered Structures
A theory is presented for the dispersion relations of the nonlinear phonon-polaritons arising when phonons are coupled to the electromagnetic waves in multilayered structures of nonlinear materials. The calculations are applied to a multilayered structure consisting of a thin film surrounded by semi-infinite bounding media where each layer may have a frequency dependent dielectric function and ...
متن کاملImportance of frequency-dependent grain boundary scattering in nanocrystalline silicon and silicon-germanium thermoelectrics
Nanocrystalline silicon and silicon-germanium alloys are promising thermoelectric materials that have achieved substantially improved figure of merits compared to their bulk counterparts. This enhancement is typically attributed to a reduction in lattice thermal conductivity by phonon scattering at grain boundaries. However, further improvements are difficult to achieve because grain boundary s...
متن کامل