| Description |
Oxide based materials have recently shifted from their traditional passive role as simple insulators, to technologically important active roles. They possess capabilities that semiconductors cannot approach, mainly the ability to couple properties and serve multiple purposes. Oxide based materials, namely the perovskite structure, have strong coupling between mechanical, electrical, optical, and magnetic properties. In most cases these functions can be switched or reversed easily to give the desired property. Piezoelectricity, thermoelectric power, and nonlinear optical affects are a few of the well known oxide roles. However there have been great strides made in oxide electronics, such as high temperature superconductors, colossal magnetoresistance, nonvolatile ferroelectric memory, and the recent advent of 2-dimensional electron gases (2DEG). The work presented herein focuses on the creation and in depth study of all-oxide 2DEGS. The possible mechanisms that enable two band insulators to conduct metallically at the interface are included in this study. The bulk of this thesis focuses on two innovative and never before studied uses with oxide 2DEGs. The first novel study is that of thermoelectric power utilizing LAO/STO 2DEGs. These experiments yielded exciting results with very high Seebeck values, the highest being 780 μV/K. This is the first report to indicate the great potential of these devices for thermoelectric power. The last section focused on theoretical work predicting that an oxide based 2DEG could be made switchable with the application of external electric field. The advent of an all oxide field effect transistor using a quantum confined 2DEG had never been accomplished above the milli-Kelvin range. With the KN/STO material system successful devices were made with the resistance of the film being greatly dependant on the applied field. Furthermore a very unusual low temperature metal-insulator-transition was observed. This report is the first to show these types of results with this material system, or with any all-oxide 2DEG at room temperature. |
