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Klein, Miles V. Delaney, Malcolm Emil 2011-05-07T12:24:50Z 2011-05-07T12:24:50Z 10000-01-01 1991 Raman spectroscopy, an inelastic light scattering technique, explores III-V semiconductors by conveying crystal lattice structural information and by probing carrier dynamics both directly and via the electron-phonon interaction. We have examined three physical systems accentuating three aspects of Raman utility. Al$\sb{\rm x}$Ga$\sb{\rm 1-x}$As alloy work emphasizes electronic behavior, migration enhanced epitaxy (MEE) studies highlight structural results, and a phonon-assisted lasing project underscores electron-phonon interaction. The disorder-induced frequency difference between the dipole-forbidden and dipole-allowed longitudinal optic (LO) modes in Al$\sb{\rm x}$Ga$\sb{\rm 1-x}$As alloys has been investigated as a function of laser photon energy, aluminum mole fraction x, and the indirect versus direct nature of the electronic band gap. For the indirect gap alloy, the intermediate resonant state is an X-valley electron effectively localized because of its short inelastic lifetime. Raman scattering via this state is described by a calculation of the Raman susceptibility that considers the random alloy potential generated by local concentration fluctuations. MEE is a new growth technology that can order these materials in two spatial directions. In a GaSb/AlSb system we show Raman evidence of this ordering via observation of zone folded acoustic modes and compare to AlAs/GaAs results. In other work resonant Raman documents the effects on the dipole-forbidden interface mode of a periodic corrugation introduced in AlAs barrier GaAs single quantum wells. "Finally, we investigate ""phonon-assisted"" lasing in photopumped quantum well heterostructure lasers. Resonant Raman is the natural choice to probe this system purported to have an enhanced electron-phonon interaction. For both the AlGaAs/GaAs and AlGaAs/GaAs/InGaAs structures examined, we provide evidence that indicates first order ""phonon-assisted"" lasing is actually renormalized band gap luminescence filtered by absorption from the unpumped sample volume. Although unable to examine second order ""phonon-assisted"" lasing, we suggest that it is a stimulated Raman process." Made available in DSpace on 2011-05-07T12:24:50Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9136583.pdf: 3990273 bytes, checksum: bcc2b4b672821553054c8718e68e1a4e (MD5) Previous issue date: 1991 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:40:42Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:17:29-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission ETDs are only available to UIUC Users without author permission U of I Only AAI9136583 (UMI)AAI9136583 http://hdl.handle.net/2142/19977 eng Copyright 1991 Delaney, Malcolm Emil Physics, Condensed Matter Physics, Optics Resonant Raman scattering studies of III-V semiconductor microstructures text Physics Physics University of Illinois at Urbana-Champaign Dissertation Ph.D.