Semiconductor structures in the quantum size regime

Citation

Sercel, Peter C. (1992) Semiconductor structures in the quantum size regime. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/cmqv-p871. https://resolver.caltech.edu/CaltechETD:etd-08202007-132916

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. The physics of quantum wires and quantum dots is investigated theoretically. We develop an analytical formalism for determining the energy eigenstates and bandstructure of spherical quantum dots and cylindrical quantum wires. The technique is based upon a reformulation of second order [...] theory in a basis of eigenstates of total angular momentum. We are led by analysis of quantum wires and dots based upon the InAs-GaSb material system to propose a novel class of self-doping nanostructures for carrier transport experiments and possible future application. The polarization dependence of linear optical absorption and gain spectra in cylindrical quantum wires is calculated. Applicability of the results derived for cylindrical quantum wires to the case of wires with lower symmetry is addressed using symmetry group theory. Fabrication of quantum wires and dots is attempted by several techniques. A method for fabricating nanometer-scale GaAs wire structures from quantum well material by selective impurity induced disordering is demonstrated. The technique produces lateral bandgap modifications on a 100 nm scale, as verified by cathodoluminescence imaging and spectroscopy. We demonstrate vapor phase synthesis of nanometer-scale III-V semiconductor clusters in the 5 to 20 nm diameter regime. Clusters form by homogeneous nucleation from a non-equilibrium vapor created by the explosive vaporization of a bulk semiconductor filament in an inert atmosphere. The clusters produced have zincblende crystal structure and are faceted. The optical absorption spectra of the clusters are suggestive of quantum confinement effects. A second method of cluster formation utilizes homogeneous nucleation from volatile metal-organic and hydride precursors to produce nanometer-scale, zincblende GaAs clusters.

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