Piezoelectric and structural properties of textured aluminum scandium nitride thin films on SiC substrate

Abstract

In this study, the structural and electrical properties of Al0.8Sc0.2N thin films deposited on single-crystal SiC were systematically investigated. The film, with a thickness of 877.6 nm, exhibited a dense and well-defined morphology with excellent crystallinity in the wurtzite phase, as indicated by a full width at half maximum of 0.3° in the x-ray diffraction pattern. Despite the wurtzite phase formation, the film grew on a zinc blende phase substrate, resulting in a relatively low piezoelectric coefficient of 2.39 pm/V. The electrical resistivity of the film (22.2 MΩ) was found to be comparable to those grown on silicon substrates. At the frequency of 1 MHz, the dielectric permittivity was 23.6, with an exceptionally low dielectric loss of 0.018. The low loss tangent reduces energy dissipation, enhancing sensor efficiency, especially in high-temperature environments. Although measured remnant polarization was found to be 127 μC/cm2, the leakage current reached as low as 5.15 × 10−3 A/cm2. These characteristics ensure stable sensor output and minimize power consumption, making the material suitable for low-power applications. Additionally, the superior thermal conductivity of SiC facilitates effective heat management, enabling stable performance of the Al0.8Sc0.2N thin films under elevated temperatures. These combined properties position Al0.8Sc0.2N on SiC as a promising candidate for high-temperature piezoelectric sensors.