Barium Strontium Titanate (BST) based ferroelectric thin film devices have been popular over the last decade due to their versatile applications in tunable microwave devices such as delay lines, resonators, phase shifters, and varactors. BST thin films are promising candidates due to their high dielectric constant, tunability and low dielectric loss. Dielectric-tunable properties of BST films deposited by different deposition techniques have been reported which study the effects of factors, such as oxygen vacancies, film thickness, grain size, Ba/Sr ratio, etc. Researchers have also studied doping concentrations, high temperature annealing and multilayer structures to attain higher tunability and lower loss. The aim of this investigation was to study material properties of Barium Strontium Titanate from a comprehensive point of view to establish relations between various growth techniques and the film physical and electrical properties. The primary goal of this investigation was to synthesize and characterize RF magnetron sputtered Barium Strontium Titanate (Ba1-xSrxTiO3), thin film structures and compare their properties with BST thin films deposited by sol-gel method with the aim of determining relationships between the oxide deposition parameters, the film structure, and the electric field dependence. In order to achieve higher thickness and ease of fabrication, and faster turn around time, a `stacked' deposition process was adopted, wherein a thin film (around 200nm) of BST was first deposited by RF magnetron sputtering process followed by a sol-gel deposition process to achieve higher thickness. The investigation intends to bridge the knowledge gap associated with the dependence of thickness variation with respect to the tunability of the films. The film structures obtained using the three different deposition methods were also compared with respect to their analytical and electrical properties. The interfacial effect on these `stacked' films that enhance the properties, before and after annealing these structures was also studied. There has been significant attention given to Graphene-based supercapacitors in the last few years. Even though, supercapacitors are known to have excellent energy storage capability, they suffer from limitations pertaining to both cost and performance. Carbon (CNTs), graphene (G) and carbon-based nanocomposites, conducting polymers (polyaniline (PANI), polypyrrole (PPy), etc.) have been the fore-runners for the manufacture of supercapacitor electrodes. In an attempt to better understand the leakage behavior of Graphene Polyaniline (GPANI) electrodes, BST and BST thin films were incorporated as constituents in the process of making supercapacitor electrodes resulting in improved leakage behavior of the electrochemical cells. A detailed physical, chemical and electrochemical study of these electrochemical cells was performed. The BST thin films deposited were structurally characterized using Veeco Dektek thickness profilometer, X-ray diffraction (XRD), Scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. The interfacial structural characterization was carried out using high-resolution transmission electron microscopy (HRTEM). This investigation, also presents noncontact electrical characterization of BST films using Corona Kelvin metrology (C-KM). The `stacked' BST thin films and devices, which were electrically tested using Corona Kelvin metrology, showed marked improvement in their leakage characteristics over both, the sputtered and the sol-gel deposited counterparts. The `stacked' BST thin film samples were able to withstand voltages up to 30V positive and negative whereas, the sol-gel and sputtered samples could hold only up to a few volts without charge leaking to reduce the overall potential. High frequency, 1GHz, studies carried out on BST thin film interdigitated capacitors yielded tunability near 43%. Leakage barrier studies demonstrated improvement in the charging discharging response of the GPANI electrochemical electrodes by 40% due to the addition of BST layer.

Consistent charge or defect control in oxide grown on silicon carbide (SiC) continues to be difficult to achieve and directly impacts the electrical performance of SiC-based metal oxide semiconductor (MOS) devices. This research applied non-contact Corona-Kelvin metrology to investigate the charge transport in oxides grown on n-type 4H-SiC epitaxial substrates. The cost and engineering science impact of this metrology are significant as device fabrication is avoided leading to quick determination of electrical characteristics from as-grown oxide films. Non-contact current-voltage (I-V) measurements of oxide on SiC were first demonstrated within this work and revealed that Fowler-Nordheim (F-N) current emission was the dominant conduction mechanism at high electric fields. Oxides on SiC were grown at atmospheric pressure (thermal oxides) or at a reduced pressure (afterglow oxides) ambient and examined using non-contact charge-voltage (Q-V), capacitance-voltage (C-V), equivalent oxide thickness (EOT), and I-V methods. The F-N conduction model was modified to address charge trapping and effective barrier effects obtained from experimental oxide films. Trap densities determined with this metrology were used to show that the F-N model including their density and position was adequate for thermal oxides on SiC but not for afterglow films. Data from the latter films required further modification of the theory to include a chemical effect of the oxide growth process on the effective conduction band offset or barrier. This work showed that afterglow chemistry was able to vary the effective conduction band offset from 2.9 eV, typical of thermal oxidation of SiC, up to 3.2 eV. Stress induced leakage current (SILC), an excess above the F-N base current resulting from prolonged current through the dielectric films, was also investigated. Multiple point SILC testing was used to identify statistical effects of process variations and defects in as-grown oxide films on SiC. These results open the possibility to improve oxide manufacture on SiC using methods common in the silicon IC industry. This work demonstrated the first non-contact F-N current determination in oxides on SiC and showed both charge trapping and chemical dependencies of as-grown films. Future studies may extend the findings of this work to further improve this important dielectric-semiconductor system.