Quantum Dot Electronic Structure Of Molecules And Clusters Of Quantum Dots

In this dissertation, the electronic structures in semiconductor double-quantum-dot molecules and quantum-dot clusters are investigated in detail by using the effective mass approximation. The aim is to explore the physical mechanism of the new effects in quantum-dot molecules, and to provide physical models and theoretical validity in designing novel quantum devices with better properties.The electronic energy spectra and wave functions of various quantum-dot molecules are studied by means of the generalized LCAO approach and the finite element method, we have found the nature of the bonding can be covalent, ionic, or "intermediate" new mixed states, depending on the parameters such as the separation distance between the two dots, the height of the barrier potential, the matching of the energy levels and the parity of the orbits localized in each dot.The electronic structures of the quantum-dot molecules under electric field is investigated by the finite element method with the effective mass approximation. Numerical calculations show that the valence bond of the quantum-dot molecule alternates between the covalent bonds and ionic bonds as the electric field strength increases. The oscillator strength of intraband transition may reflect the valence-bond property. And the bound state with the highest energy level in the quantum-dot molecule changes gradually into a quasibound state when the electric field strength increases.The effects of magnetic field on the valence bond property of the double-quantum-dot molecule are numerically studied by the finite element method. The perturbation approach is adopted because of the absence of cylindrical...