Unrestricted.2016-11-142011-02-182016-11-141993-12http://hdl.handle.net/2346/8428As device sizes have decreased, the effect of localized defects on semiconductor performance has increased. Many point defects are electrically active and can therefore directly affect the charge carrier concentrations and lifetimes of devices. This makes understanding the behavior of these defects important. This dissertation involves theoretical work on localized defects (impurities and intrinsic defects) in the elemental and compound semiconductors C, 5f, -BP, AlP., SiC, and BN. The theoretical level is approximate HF, ab-initio Hartree-Fock (HF), and post-HF treatments in electron correlation. The host crystals are modeled with molecular clusters.application/pdfengSiliconSemiconductorsDissertation