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Author Fu, H. ♦ Ozolins, V. ♦ Zunger, A.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword MATERIALS SCIENCE ♦ GALLIUM COMPOUNDS ♦ BRILLOUIN ZONES ♦ GALLIUM PHOSPHIDES ♦ PHONONS ♦ POTENTIALS ♦ EIGENFUNCTIONS ♦ QUANTIZATION ♦ SIZE
Abstract The phonon structure of GaP quantum dots is studied using an atomistic potential model. The dot eigenmodes are obtained from a direct diagonalization of the dynamical matrix and classified using an efficient dual-space analysis method. Our calculations provide a theoretical explanantion for several experimental observations. (1) Depending on the spatial localization, the phonon modes of dots are either dot-interior (bulklike) or surfacelike. (2) The frequencies of the dot-interior modes can be qualitatively described by the {open_quotes}truncated crystal method{close_quotes} using a single branch and a single wave vector of the bulk-phonon dispersion. In contrast, the surface modes cannot be described by this model. (3) The dot-interior modes have a dominant bulk parentage from a specific part of the Brillouin zone, while the surface modes do not. (4) The frequencies of the bulklike {Gamma}-derived longitudinal optical (LO) and transverse optical (TO) phonon modes are found to decrease with decreasing dot size. This decrease reflects the downward dispersion of the bulk optical-phonon branches away from the {Gamma} point. (5) The surface modes located between the bulk TO- and LO-phonon bands have a significant bulk {Gamma} character, and are thus Raman detectable. (6) The dot-interior modes exhibit only a slight LO/TO mode mixing, while the surfacelike modes show a strong mode mixing. {copyright} {ital 1999} {ital The American Physical Society}
ISSN 01631829
Educational Use Research
Learning Resource Type Article
Publisher Date 1999-01-01
Publisher Place United States
Journal Physical Review, B: Condensed Matter
Volume Number 59
Issue Number 4


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