MATERIALS SEMINAR
Department of Materials Science & Engineering
Tuesday November 5, 2019
2:15 – 3:15 PM~ SERF 307
Please join us for refreshments at 2:10

"Kinetic approaches for characterizing the structure of sol-gel derived metal-oxide semiconductors using nanocalorimetry"

Speaker: 
Dr. Andre Zeumault, Assistant Professor
Department of Electrical Engineering & Computer Science
University of Tennessee, Knoxville TN

Abstract:
Conventional physical vapor deposition processes predominantly used to deposit oxide semiconductors allow for film stoichiometry and crystallinity to be separately controlled due to the physical distinction between target and substrate. In contrast, solution processing involves thermally-coupled chemical and structural transformations in which the stoichiometry and crystallinity vary simultaneously throughout the annealing process and are not easily controlled. Although correlations exist relating electrostatics and electronic transport to stoichiometry and crystallinity, current processing methods do not allow independent control of the latter, thereby limiting the degree to which film properties can be tailored to meet application-specific needs. To expand the versatility of these materials, this talk outlines the use of flash DSC, a chip-based nanocalorimetry technique, to observe in-situ enthalpic changes in sol-gel derived metal-oxide semiconductors. I will discuss the exploitation of high heating/cooling rates as a means to decouple decomposition from crystallization, effectively as a kinetic separations technique. Preliminary insights gained from this approach include — an in-situ study of crystallization kinetics in sol-gel derived ZnO as well as the observation of an unprecedented glass transition in flash dried ZnO as evidenced by changes in specific heat, electronic and thermal conductivity.

Biography:
Dr. Zeumault is an Assistant Professor at the University of Tennessee – Knoxville in the Department of Electrical Engineering and Computer Science. He received his Ph.D. and B.S. in Electrical Engineering from the University of California – Berkeley in 2017 and 2011 respectively. Following his Ph.D., he was a postdoctoral fellow at the Georgia Institute of Technology in the Departments of Materials Science and Engineering, Chemistry and Physics. His research focuses on preparation and characterization methods of solution-processed metal oxide semiconductors for electronics applications. His specific interests include: refining electrical characterization methods for accurate benchmarking of device performance, modeling the role of disorder in electronic and thermal transport and defining processing protocols for controlling the structural and chemical evolution of films. Recently, he has focused on methods of decoupling crystallinity from chemical composition during film evolution to facilitate greater electrostatic control for device applications.

Faculty Host: Dr. Peter Liaw