GEOMETRICAL PARAMETER FLUCTUATIONS AND LOCALIZED ELECTRONIC STATES INQUANTUM-SCALE STRUCTURES

Electronic states of natural quantum dots formed by fluctuations of qu antum wells and barrier widths in quantum-scale structures have been s tudied both experimentally and theoretically. An approximate method ba sed on the reduction of the 3D problem to a 1D one has been developed to calculate the electronic spectrum of quantum dots of arbitrary shap e. It was shown using this method that narrow equidistant peaks in spa tially resolved photoluminescence spectra of GaAs/AlxGa1-xAs superlatt ices with thin barriers could be a consequence of the formation of a n ew type of electronic states resulting from the overlap of thickness f luctuations of neighbouring quantum wells. The equidistant spectrum of new states is explained by a nearly parabolic dependence of the overl ap region width on coordinate in the layer plane. Quantitative calcula tions of electronic states of quantum dots and quantum wires of some s pecific shapes were also performed. The inverse problem of finding the profile of a cylindrical quantum dot possessing an equidistant energy spectrum was solved.