Foto-ışıma ile uyarılmış bireyakın boyutlu elektron deşik sistemlerinde çok parçacık etkileşmeleri

Abstract MANY-BODY INTERACTION EFFECTS IN QUASI-ONE-DIMENSIONAL PHOTO-EXCITED ELECTRON-HOLE SYSTEMS Kaan Güven Doctor of Philosophy in Physics Supervisor: Assoc. Prof. Bilal Tanatar September 1999 The work in this thesis concerns many-body interaction effects in a quasi-one- dimensional electron-hole plasma, which may be generated under intense photo- excitation in a semiconductor quantum-well wire. In particular, we investigate how these interactions affect the optical properties of the semiconductor quantum wire. We address this question in two parts: First, the band-gap renormalization (BGR) induced by self-energy corrections of electrons and holes is studied. A two subband model arising from the confinement of the quantum wire is developed to include the multisubband effects. The many-body theoretical formalism of electron (hole) self-energy is given within the GW approximation. We use the dielectric function both in full dynamical random-phase approximation, and in quasi-static approximation, in order to emphasize the dynamical properties of screening. The dependence of BGR on the e - h plasma density, temperature and wire width is studied. In the second part, the exciton renormalization induced by e - h plasma screening, and Coulomb correlation effects on the optical spectra of a quantumwire are considered. The optical properties are directly associated with the e - h two particle propogator, which obeys the Bethe-Salpeter equation. Based on recent studies, we review the solution of this equation with screened Coulomb interaction. In particular it is shown* that the dynamical treatment of screening produces an optical absorption/luminescence spectra which is consistent with experimental results. We present a discussion on the interplay of excitons and unbound carriers and on the reflection of this interplay to the optical spectra. Keywords: Quasi-one-dimensional dimensional electron-hole plasma, self- energy, band-gap renormalization, T-matrix formulation, random-phase approximation. *S. Das Sarma and D. W. Wang, "Many-body renormalization of semiconductor quantum wire excitons: absorption, gain, binding, unbinding, and Mott transition", cond-matt/9905038 11