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Description
Thin film aluminum nitride (AlN) and its derivative alloys are widely utilized in lead-free piezoelectric microelectromechanical systems due to its high acoustic velocity, deposition process reproducibility and chemical compatibility with semiconductor technologies. While (Al, Sc)N is by far the most used alloy, there is significant push to find a replacement for Sc due to supply concerns.
In this work, we investigate a class of heterovalently alloyed AlN-based thin films synthesized by reactive magnetron sputtering, focusing on Al–Sc–O–N, Al–Hf–N, and Al–Si–C–N. By systematically varying growth conditions and alloy composition, we explore the impact of non-isovalent substitution on phase stability, texture evolution, and functional properties such as dielectric and piezoelectric responses.
We present a framework linking defect chemistry, microstructure, and electrical properties. These insights are further extended to other heterovalent alloys of interest such as Al–Zr–N, highlighting the broader potential of heterovalent alloying as a potential route to engineer high-performance piezoelectric nitride thin films for next-generation acoustic resonators, sensors, and energy harvesting devices.