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Dow, J.D. Lee, Seongbok 2011-06-03T16:26:19Z 2011-06-03T16:26:19Z 10000-01-01 1986 In part I, we have calculated the structural properties of Si using an iterative method and the pressure dependences of energy gaps of Si, Ge, and GaAs at symmetry points in the Brillouin zone using a variational method within the local-density-functional formalism. The results are in good agreement with experimental values. The negative pressure derivatives of the gaps at the X point of the conduction band relative to the valence-band maxima are due to the d-states. In part II, the electronic structures of the pseudobinary alloy semiconductors Pb1_xSnxTe are analyzed using the tight-binding model with spin-orbit interaction. The density of states and the band gap at the L point are computed for both the effective medium using the virtual crystal approximation and the realistic medium employing the recursion method, and the results are compared. Both theories exhibit the band broadening and Dimmock's band crossing phenomena. However, the random alloys show disorder effects in the cation-derived s-like states which have the greatest alloying effect. In part III, the Green's function method, with an empirical tight- binding basis, is used to determine the deep levels of the singly ionized and neutral impurities S, Se, and Te in Si. The impurity potentials are determined self-consistently. The resulting theory accounts for the observed charge-state splittings of neutral and singly ionized Al deep levels, obtaining, for S, Se, and Te, 0.33, 0.27, and 0.32 eV (to be compared with experimental values of 0.30, 0.29, and 0.21 eV, and with a self-consistent local-density-theory value for S of 0.20). Submitted by Carolyn Mead (cmead2@illinois.edu) on 2011-06-03T16:26:19Z No. of bitstreams: 1 1986_lee.pdf: 6525262 bytes, checksum: ff692885e8bd08feb4cc321e1a532b2b (MD5) Made available in DSpace on 2011-06-03T16:26:19Z (GMT). No. of bitstreams: 1 1986_lee.pdf: 6525262 bytes, checksum: ff692885e8bd08feb4cc321e1a532b2b (MD5) Previous issue date: 1986 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Carolyn Mead (cmead2@illinois.edu) on 2011-06-03T16:26:19Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:12:42-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: Thesis Thesis U of I Only 999313 http://hdl.handle.net/2142/25255 en 1986 Seongbok Lee semiconductors Brillouin zone local density functional formalism d states Si Ge GaAs Topics in the theory of semiconductors Dissertation / Thesis text Physics Physics University of Illinois at Urbana-Champaign Dissertation Ph.D.