Speaker: Geoff Brennecka, Assistant Professor of Metallurgical and Materials Engineering at the Colorado School of Mines
Title: Coupled High Throughput Computation and Experimentation for Rapid Screening and Demonstration of New Piezoelectric Nitrides
Abstract: Aluminum nitride (AlN) thin films have come to dominate a significant subset of the piezoelectric microelectromechanical systems (piezoMEMS) device world despite exhibiting what can only be described as modest electromechanical properties. In recent years, the AlN-ScN system has received significant interest for its widely-reported increases in field-induced strain. Inspired by the massive property enhancements achievable near phase boundaries in oxide piezoelectrics and armed with high-throughput computational as well as experimental capabilities, we have embarked on a study to develop new piezoelectric nitride materials based on the concept of flattened free energy landscapes. Thermochemical calculations help to identify compounds and alloy compositions where one or more unstable forms exist in close energetic proximity to the stable form. Calculations based on density functional theory (DFT) provide a theoretical backdrop of the expected intrinsic properties of these various materials, which we are able to confirm via thin film sample libraries deposited using combinatorial multi-target reactive sputtering and parallelized measurement and characterization tools. Progress to-date includes an in-depth mechanistic study of the entire AlN-ScN phase diagram, screening studies of a number of AlN-based alloys, and discovery of previously unexplored binary and ternary nitride compounds.
Bio: Geoff Brennecka is an Associate Professor and Ben Fryrear Endowed Chair for Innovation and Excellence in the Metallurgical and Materials Engineering Department at the Colorado School of Mines. He received BS and MS degrees in Ceramic Engineering from the University of Missouri-Rolla (now Missouri S&T) in 2001 and 2002 and a PhD in Materials Science and Engineering from the University of Illinois in 2006. He spent 8 years as technical staff at Sandia National Laboratories before joining the Mines faculty in 2014. Geoff is a Fellow of the American Ceramic Society and the recipient of an NSF CAREER award, the Mines Dean’s Excellence Award, Young Alumnus awards from both Missouri S&T and the University of Illinois, the IEEE Ferroelectrics Young Investigator Award, Du-Co Ceramics Young Professional Award, and the Karl Schwartzwalder Professional Achievement in Ceramic Engineering award. Geoff has previously served on the Board of Directors for the American Ceramic Society and IEEE-UFFC, and is currently on the Board of Directors of the Ceramics and Glass Industry Foundation as well as Editor of the Journal of the American Ceramic Society.
MSE Seminar Host: Xiaoli Tan