Geometrical parameter fluctuations and localized electronic states in quantum-scale structures

Abstract

Electronic states of natural quantum dots formed by fluctuations of quantum wells and barrier widths in quantum-scale structures have been studied both experimentally and theoretically. An approximate method based on the reduction of the 3D problem to a 1D one has been developed to calculate the electronic spectrum of quantum dots of arbitrary shape. It was shown using this method that narrow equidistant peaks in spatially resolved photoluminescence spectra of superlattices with thin barriers could be a consequence of the formation of a new type of electronic states resulting from the overlap of thickness fluctuations of neighbouring quantum wells. The equidistant spectrum of new states is explained by a nearly parabolic dependence of the overlap region width on coordinate in the layer plane. Quantitative calculations of electronic states of quantum dots and quantum wires of some specific shapes were also performed. The inverse problem of finding the profile of a cylindrical quantum dot possessing an equidistant energy spectrum was solved.