INTERVALLEY ELECTRON-PHONON AND HOLE-PHONON INTERACTIONS IN SILICON, GERMANIUM AND GALLIUM PHOSPHIDE: EXPERIMENT AND THEORY.
Item
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Title
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INTERVALLEY ELECTRON-PHONON AND HOLE-PHONON INTERACTIONS IN SILICON, GERMANIUM AND GALLIUM PHOSPHIDE: EXPERIMENT AND THEORY.
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Identifier
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AAI8302509
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identifier
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8302509
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Creator
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GLEMBOCKI, OREST JAROSLAW.
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Contributor
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Fred H. Pollak
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Date
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1982
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Language
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English
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Publisher
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City University of New York.
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Subject
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Physics, Condensed Matter
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Abstract
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Intervalley electron-phonon (e-ph) and hole-phonon (h-ph) interactions play an important role in many properties of semiconductors. Understanding indirect phonon assisted transitions requires a precise knowledge of the e-ph and h-ph matrix elements. In these types of materials the fundamental absorption of light proceeds via two scattering mechanisms involving both e-ph and h-ph interactions and in such a way that they can interfere either constructively or destructively. The absorption coefficient in some indirect gap semiconductors is sensitive to the magnitudes and phases of the e-ph and h-ph matrix elements. Consequently, this area is ideal for studying the intervalley e-ph and h-ph interactions.;In this thesis, we present a study of the e-ph and h-ph interactions in GaP, Si and Ge. A piezospectroscopic experiment is performed in GaP for the (GAMMA)-X phonon assisted transitions (LA,TA,LO,TO) and the ratio of the e-ph and h-ph scattering matrix elements is obtained for the LA and TA phonons. The e-ph and h-ph matrix elements are evaluated individually by comparing the above results together with experimental values for the absorption coefficient to theoretical expressions for the absorption coefficient. A similar analysis is performed for the TO phonon assisted transition in Si and its e-ph and h-ph matrix elements are also obtained.;A theoretical calculation of the (GAMMA)-(DELTA) and (GAMMA)-L matrix elements of Si and Ge is performed. This work uses the "rigid-pseudoion" model, which represents the lattice displacements through a rigid-ion model and the potential and electronic states by local pseudopotential theory. The theoretical and experimental values of the matrix elements for the TO phonon of Si are in good agreement. Consequently, we can now account for the absolute as well as relative intensities of the indirect transitions in both Si ((GAMMA)-(DELTA)) and Ge ((GAMMA)-L). The determination of the e-ph and h-ph matrix elements in GaP, Si and Ge permits us to gain insights into the mechanisms responsible for the indirect transitions in these materials.;The calculation is also performed for points midway into the Brillouin zone along (DELTA) for Si and Ge and along (LAMDA) in Ge. These results, in conjunction with the (GAMMA)-(DELTA) and (GAMMA)-L numbers and the values in GaP allow us to prove the nature of the scattering in these materials.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Physics
