Aluminum scandium nitride (AlScN) has emerged as a highly promising material for high-temperature applications due to its robust piezoelectric, ferroelectric, and dielectric properties. This study investigates the behavior of Al0.7Sc0.3N thin films in extreme thermal environments, demonstrating functional stability up to 1000{\deg}C, making it suitable for use in aerospace, hypersonics, deep-well, and nuclear reactor systems. Tantalum silicide (TaSi2)/Al0.7Sc0.3N/TaSi2 capacitors were fabricated and characterized across a wide temperature range, revealing robust ferroelectric and dielectric properties, along with significant enhancement in piezoelectric performance. At 1000{\deg}C, the ferroelectric hysteresis loops showed a substantial reduction in coercive field from 4.3 MV/cm to 1.2 MV/cm, while the longitudinal piezoelectric coefficient increased nearly tenfold, reaching 75.1 pm/V at 800{\deg}C. Structural analysis via scanning and transmission electron microscopy confirmed the integrity of the TaSi2/Al0.7Sc0.3N interfaces, even after exposure to extreme temperatures. Furthermore, the electromechanical coupling coefficient was calculated to increase by over 500%, from 12.9% at room temperature to 82% at 700{\deg}C. These findings establish AlScN as a versatile material for high-temperature ferroelectric, piezoelectric, and dielectric applications, offering unprecedented thermal stability and functional enhancement.
@article{arxiv.2410.17037,
title = {Aluminum Scandium Nitride as a Functional Material at 1000{\deg}C},
author = {Venkateswarlu Gaddam and Shaurya S. Dabas and Jinghan Gao and David J. Spry and Garrett Baucom and Nicholas G. Rudawski and Tete Yin and Ethan Angerhofer and Philip G. Neudeck and Honggyu Kim and Philip X. -L. Feng and Mark Sheplak and Roozbeh Tabrizian},
journal= {arXiv preprint arXiv:2410.17037},
year = {2025}
}