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 as well as screening studies of AlN modified with other trivalent cations. Exploratory work on perovskite nitrides and pseudo-2D piezoelectrics will also be discussed.