Jonathan Taub

Date of Graduation

2015

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Industrial and Managements Systems Engineering

Committee Chair

Edward M Sabolsky

Committee Co-Chair

Thomas A Evans

Committee Member

Mark A Jerabek

Committee Member

Konstantinos Sierros

Abstract

The main objective of this work was to research and develop a sensor device to monitor gas leakage in cryogenic temperatures and high vacuum. In addition, the sensor device should be small in size, function with low power, and display a short recovery time. The end application for this technology would be to monitor fuel leaks of hydrazine when refueling space satellites. To meet the specified requirements, an acoustic wave device was studied in this work. A micro-surface acoustic wave (muSAW) device was fabricated through a multi-layer thin film technique, where the active sensing material is based on a 300 nm thick PbZr0.52Tii0.48O3 (PZT) piezoelectric film grown via a sol-gel process. The electrodes were based on Si/SiO2/TiOx/Pt and Si/SiO 2/TiOx multi-layered structures and were fabricated by thermal oxidation and sputtering techniques. Improved deposition and crystallization methods for the PZT film were developed in this work which resulted in crack- and porous-free texturized and randomly-oriented PZT films. The phase, chemistry and microstructure of the PZT films were determined by X-ray diffraction (XRD), Energy Dispersive X-Ray Analysis (EDX), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) techniques. The surface energy of the films was measured by means of a static sessile drop method. The ferroelectric and electrical characterization of the film was completed longitudinally by measuring the polarization-voltage (P-V), capacitance-voltage (C-V) and current-voltage (I-V) curves. The propagation wave velocity for the multi-layered structure was approximated using an electromechanical equivalent model and the results were used to design the interdigitated transducers (IDTs) for the SAW devices. IDTs were later deposited over the PZT via photolithography process. Finally, the electro-acoustic frequency response in |S21| mode was measured using a vector network analyzer (VNA) and Rayleigh mode SAW and non-Rayleigh mode SAW responses were observed.

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