A new group of lead free piezoelectric perovskite solid solutions, (1-x)Bi(B'B")O₃-xABO₃, were obtained via solid-state processing techniques. The solubility of unstable perovskite Bi(B'B")O₃ compounds into stable perovskite compounds was found to be related to the tolerance factor of the ABO₃ perovskite endmembers. The morphotropic phase boundary (MBP) in perovskite solid...
Since its discovery, the anomalous dielectric behavior of CaCu₃Ti₄O₁₂ (CCTO)
has drawn a great deal of attention for many possible applications in electronic
devices. The origin of the giant dielectric constant in CCTO was explained via an
internal barrier layer capacitor model, and it has been reported that the dielectric...
Periodic metal and metal-dielectric composite nanostructures have been of interest from the field of plasmonics and metamaterial fabrication. In order to exploit the behavior of these unique materials in the visible region of the optical spectrum, these structures need to be significantly shorter than the wavelength of response, and hence...
Crystals of an incongruent-melting compound, Ba₃MgSi₂O₈, were grown by the flux method and its structure was determined by single crystal X-ray diffraction methods. Ba₃MgSi₂O₈ crystallizes in trigonal space group P-3[bar]m1 with a = 5.6123(3) Å, c = 7.2667(9) Å and Z = 1. Eu²⁺ ions prefer one crystallographic Ba site...
Amorphous oxide semiconductor (AOS) thin-film transistors (TFTs) constitute the central theme of this thesis. Within this theme, three primary areas of focus are pursued.
The first focus is the realization of a transparent three-stage ring oscillator with buffered output and an output frequency in the megahertz range. This leads to...
Nanolaminate dielectrics combine two or more insulating materials in a many-layered film. These structures can be made to significantly outperform films composed of a single one of their constituent materials by adjusting the composition ratio, arrangement, and size of the component layers. In this work, atomic layer deposition (ALD) is...
We developed a model to investigate the dielectric properties of the
BaTiO₃ − Bi(Zn₁/₂Ti₁/₂)O₃ (BT-BZT) solid solution, which is a relaxor ferroelectric and exhibits long range disorder. The model uses ab initio methods
to determine all polarization states for every atomic configuration of 2 x 2 x 2
supercells of...
Accurate modeling and simulation of wave propagation in dispersive dielectrics such as water, human tissue and sand, among others, has a variety of applications. For example in medical imaging, electromagnetic waves are used to interrogate human tissue in a non-invasive manner to detect anomalies that could be cancerous. In non-destructive...
In this thesis the concept of inhomogeneous
dielectrics is demonstrated for various optical coating
applications. Compositionally-varying silicon oxynitride
(SiON) dielectric layers, with the refractive index
varying as a function of position, are grown by computer-controlled
plasma-enhanced chemical vapor deposition
(PECVD) using silane, nitrogen, and nitrous oxide reactant
gases. Compositionally graded...