Roshaun C. Titus
Advisor: Prof. Rosario A. Gerhardt

will defend a doctoral thesis entitled,

Processing and Microstructural Effects on the Electrical Response and Quality Assessment of Beta SiC Composites for Electronic Devices

On

Thursday, May 14 at 11:00 a.m.
LOVE Manufacturing Room 184
771 Ferst Dr NW, Atlanta, GA 30332

and/or

 Virtually via MS Teams

Roshaun Titus Dissertation Defense | Teams Link

Committee

            Prof. Rosario A. Gerhardt – School of Materials Science and Engineering (advisor)

            Prof. Chaitanya Deo – School of Mechanical Engineering
            Prof. Robert Speyer – School of Materials Science and Engineering
            Prof. Preet Singh – School of Materials Science and Engineering
                       Dr. J. Elliot Fowler – Principal Investigator, Sandia National Laboratory

Abstract
This dissertation investigates the electromagnetic properties of cubic 3C (beta) silicon carbide (SiC) composites. SiC is a crucial ceramic of interest in the semiconductor, energy, and aerospace industries for its ability to perform in extreme conditions such as high temperatures and space travel. While the hexagonal 4H polytype is commonly used due to its wider band gap, beta SiC offers lower fabrication costs along with enhanced electron mobility and dielectric constant used for creating products such as sensors or transistors. By incorporating three distinct SiC morphologies—micron-sized spheres, whisker-like rods, and nano-sized spheres—into a polymer or ceramic matrix (PMMA or alpha alumina), this work examines how variations in geometric configurations (size, shape, dispersion, volume fraction) can affect the electrical and dielectric responses of the different matrix materials. Fabrication is carried out using pressure-only hydraulic pressing of the individual powders, compression molding of the PMMA matrix composites, and spark plasma sintering of the alumina matrix composites. Impedance & dielectric spectroscopy provides in-situ and post-fabrication electromagnetic characterization, which substantially broadens the understanding of observed trends in inductive and capacitive behavior that affect device performance. Confirmed during this study is the mechanism behind SiC microwave absorption, a useful property for electromagnetic interference (EMI) shielding that can be used to protect electronics such as that of satellites systems. This was tested using a vector network analyzer via a designed and assembled waveguide setup for measuring 2-port scattering parameters of samples. Statistical methodologies for broadband frequency measurements are demonstrated, useful for determining repeatability and reproducibility in quality analysis.  Quality assessment was validated by working with interdigitated electrodes (IDEs) printed on composite FR4 substrates that serve as sensors for environmental conditions. The application of finite element analysis with COMSOL Multiphysics facilitated a more generalizable assessment approach, allowing for optimization of composite designs before large-scale production. This research thus provides a comprehensive framework linking processing methods and microstructure to electronic performance and quality assurance in SiC-based devices.