Charge transport in quantum confined structures: Sub-60 nm wires and nanoparticle solar cells

This dissertation investigates charge transport in quantum confined structures. "Quantum confined" means that an electron in a conductive structure is confined in a space that has dimensions less than its mean free path.;Part I examines narrow wires, where the charges are confined in such a small space that the resistance of the metal wire increases dramatically. Narrow wires have geometry such that the electrons are quantum confined in two dimensions. Understanding more about this problem is crucial to the future of the microchip industry.;After narrow wires, Part II discusses nanoparticles, which have geometry such that the electrons are quantum confined in three dimensions. Several charge transport mechanisms are discussed, with special emphasis on how these mechanisms are affected by the quantum confinement. Semi-conducting nanoparticles, known as quantum dots, are introduced and are the basis for the solar cells discussed in the remainder of the dissertation.;Part III transitions to the solar cell, which is a direct application of the charge transport mechanisms previously presented. Several materials are discussed which are very important to present photovoltaic research. The efficiency of solar cell performance can be determined by several electrical characterization methods. The reliability of a cell depends on its degradation mechanisms and can be illuminated by failure analysis techniques. Reconnecting with the concept of quantum confinement, two interesting phenomena are discussed which can be achieved if the quantum confinement of electrons in solar cells can be utilized.;In Part IV, the theory discussed in Parts I and II and the measurement techniques discussed in Part III are applied to electrical characterization and analysis of quantum dot-based solar cells. Genuine quantum dot TiO 2/PbS solar cells are analyzed over a range of temperatures. Thin film CdTe solar cells undergo failure analysis as they degrade in air. Transient behavior is analyzed with both current and capacitance measurements, and correlations between the two techniques are discussed.;Herein, all occurrences of the word "current" refer to a measured flow of charge and should not be confused with the same word meaning "present" or "contemporary." A useful index can be found in the appendix, which, hopefully, defines all of the variables, constants, abbreviations, and acronyms used in this dissertation.