skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Infrared absorption and Raman scattering on coupled plasmon-phonon modes in superlattices

Abstract

We theoretically consider a superlattice formed by thin conducting layers spatially separated between insulating layers. The dispersion of two coupled phonon-plasmon modes of the system is analyzed by using the Maxwell equations, with the retardation effect included. Both transmission for the finite plate and the absorption for the semi-infinite superlattice in the infrared are calculated. Reflectance minima are determined by the longitudinal and transverse phonon frequencies in the insulating layers and by the density-state singularities of the coupled modes. We also evaluate the Raman cross section from the semi-infinite superlattice.

Authors:
;  [1]
  1. Landau Institute for Theoretical Physics (Russian Federation)
Publication Date:
OSTI Identifier:
21067701
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Experimental and Theoretical Physics; Journal Volume: 102; Journal Issue: 4; Other Information: DOI: 10.1134/S1063776106040169; Copyright (c) 2006 Nauka/Interperiodica; Article Copyright (c) 2006 Pleiades Publishing, Inc; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ABSORPTION; CROSS SECTIONS; LAYERS; MAXWELL EQUATIONS; PHONONS; RAMAN EFFECT; SINGULARITY; SUPERLATTICES

Citation Formats

Falkovsky, L. A., E-mail: falk@itp.ac.ru, and Mishchenko, E. G. Infrared absorption and Raman scattering on coupled plasmon-phonon modes in superlattices. United States: N. p., 2006. Web. doi:10.1134/S1063776106040169.
Falkovsky, L. A., E-mail: falk@itp.ac.ru, & Mishchenko, E. G. Infrared absorption and Raman scattering on coupled plasmon-phonon modes in superlattices. United States. doi:10.1134/S1063776106040169.
Falkovsky, L. A., E-mail: falk@itp.ac.ru, and Mishchenko, E. G. Sat . "Infrared absorption and Raman scattering on coupled plasmon-phonon modes in superlattices". United States. doi:10.1134/S1063776106040169.
@article{osti_21067701,
title = {Infrared absorption and Raman scattering on coupled plasmon-phonon modes in superlattices},
author = {Falkovsky, L. A., E-mail: falk@itp.ac.ru and Mishchenko, E. G.},
abstractNote = {We theoretically consider a superlattice formed by thin conducting layers spatially separated between insulating layers. The dispersion of two coupled phonon-plasmon modes of the system is analyzed by using the Maxwell equations, with the retardation effect included. Both transmission for the finite plate and the absorption for the semi-infinite superlattice in the infrared are calculated. Reflectance minima are determined by the longitudinal and transverse phonon frequencies in the insulating layers and by the density-state singularities of the coupled modes. We also evaluate the Raman cross section from the semi-infinite superlattice.},
doi = {10.1134/S1063776106040169},
journal = {Journal of Experimental and Theoretical Physics},
number = 4,
volume = 102,
place = {United States},
year = {Sat Apr 15 00:00:00 EDT 2006},
month = {Sat Apr 15 00:00:00 EDT 2006}
}
  • The technique of Raman spectroscopy has been used to investigate doped (n-type) and undoped GaAs/AlAs superlattices with AlAs barrier thicknesses from 17 to 1 monolayers. The peak corresponding to the scattering by a two-dimensional plasmon was found in the Raman spectrum of a doped superlattice with relatively thick barriers. The position of the experimental peak corresponded to the value calculated in the model of plasma oscillations in periodic planes of a two-dimensional electron gas. The electron tunneling effects played an increasingly prominent role as the AlAs barrier thickness decreased. The peaks corresponding to the scattering by coupled phonons with three-dimensionalmore » plasmons were found in the Raman spectra for a superlattice with an AlAs thickness of 2 monolayers; i.e., the delocalization of coupled modes was observed. In this case, the folding of acoustic phonons was observed in the superlattice under consideration, indicative of its good periodicity, while the localization of optical phonons in GaAs layers was observed in undoped superlattices with an AlAs thickness of 2 monolayers.« less
  • Low energy optical modes of molecular beam epitaxy-grown In{sub 1-x}Ga{sub x}N thin films with 0<=x<=0.6 are investigated using infrared reflectance measurements. We found that the reflectance of the films for wave vectors in the range from 600 to 800 cm{sup -1} is determined by the high energy E{sub 1}(LO)-plasmon coupled modes. In the higher energy regime of the UV-visible reflectance spectrum of InN, critical points with energies 4.75, 5.36, and 6.12 eV belonging to A and B structures are observed. The energies of these critical points increase with increasing values of x, similar to the band gap energy of thesemore » films.« less
  • In this study we use Raman scattering from Ga{sub 1{minus}{ital x}}In{sub {ital x}}Sb/InAs grown by molecular-beam epitaxy superlattices to identify and study interface modes. Those modes are localized around the interfaces of the superlattices. We identify three types of longitudinal interface modes; two GaAs-like and one InSb-like. The frequency and the Raman activity of those modes are in good agreement with theoretical calculations. In addition, it is shown that the interface modes can be used to identify the interface composition (InSb or GaAs) for a variety of samples grown under controlled shutter sequences.
  • We have performed micro-Raman-scattering experiments on ordered GaInP{sub 2} alloy samples in three different geometries where the phonon wave vector is either parallel or perpendicular to the ordering axis of the crystal. By comparing results from the ({bar 1}11) backscattering and right-angle scattering measurements with the C{sub 3v} symmetry of the crystal, we found that the recently discovered peaks at 205 and 354 cm{sup {minus}1} in the Raman spectra of ordered alloys are due to longitudinal-phonon modes with A{sub 1} symmetry in these geometries. In the (110) backscattering geometry, selection-rule forbidden longitudinal-phonon modes appear in the Raman spectra measured inmore » parallel polarizations. Possible mechanisms for this selection-rule violation are discussed. {copyright} {ital 1997} {ital The American Physical Society}« less