Aluminum Scandium Nitride as a Functional Material at 1000 °C

Abstract

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 Al_0.7Sc_0.3N thin films in extreme thermal environments, demonstrating functional stability up to 1000 °C, making it suitable for use in aerospace, hypersonics, deep-well, and nuclear reactor systems. Tantalum silicide (TaSi₂)/Al_0.7Sc_0.3N/TaSi₂ capacitors are fabricated and characterized across a wide temperature range, revealing robust ferroelectric and dielectric properties, along with significant enhancement in piezoelectric performance. At 1000 °C, the ferroelectric hysteresis loops showed a substantial reduction in coercive field from 4.3 to 1.2 MV cm⁻¹, while the longitudinal piezoelectric coefficient increased nearly tenfold, reaching 75.1 pm V⁻¹ at 800 °C. Structural analysis via scanning and transmission electron microscopy confirmed the integrity of the TaSi₂/Al_0.7Sc_0.3N interfaces, even after exposure to extreme temperatures. Furthermore, the electromechanical coupling coefficient is calculated to increase by over 500%, from 12.9% at room temperature to 82% at 700 °C. These findings establish AlScN as a versatile material for high-temperature ferroelectric, piezoelectric, and dielectric applications, offering unprecedented thermal stability and functional enhancement.