| The inverted RPA dielectric functions for quantum well and quantum wire tunneling superlattices are derived and examined within the framework of a tight binding approximation. For quantum wires, the intrasubband and intersubband tunneling superlattice plasmon spectra are analyzed, with intrasubband modes exhibiting a crossover between 1D and 3D behavior in the long wavelength limit, which depends upon miniband width. Such 1D behavior is manifested in an acoustic dispersion law, as opposed to 3D behavior evidenced by a finite gap in the local superlattice plasmon spectrum. Intersubband modes also exhibit characteristics associated with finite miniband width.; Application of dielectric response properties to dynamic transport is made for planar tunneling quantum well superlattices. A.C. conductivity for the superlattice is determined using a memory function technique, and the absorption involving the excitation of tunneling superlattice plasmons is determined explicitly along the planar direction. Furthermore, the dynamic conductivity in the growth direction normal to the quantum well planes is treated with the development of a superlattice variant of the Kubo formula, and the relaxation time is shown to be generally anisotropic for random scattering by finite-size impurities. Furthermore, special attention was given to weak localization phenomena, and it is seen that the scaling behavior can be of either 2D or 3D character, depending upon miniband width.; Tunneling transport through a resonant double-barrier structure is also treated in this thesis. Attention is focused here on the suppression of transmission current due to Pauli exclusion arising from population growth of the resonant state. A quasi-analytic theory is developed to self-consistently determine the population of the resonant state and its exclusion suppression of tunneling. Furthermore, the role of resonant state population in inducing an electrostatic increase of the resonant level energy, which tends to enhance tunneling, is considered. Taking all these features in joint consideration, a quasi-analytic description of intrinsic bistability in the regime of negative differential conductance is achieved, exhibiting hysteresis in the I-V characteristic. |
