Piezoelectricity in Y0.09Al0.91N thin films

• Published in: Materials science & engineering. B, Solid-state materials for advanced technology Solid-state materials for advanced technology, 2022-02, Vol.276, p.1, Article 115543
• Main Authors: Schlögl, M., Schneider, M., Schmid, U.
• Format: Article
• Language: English
• Subjects: Actuators; AlN; Aluminum; Aluminum nitride; Crystal structure; Crystallinity; Degree of crystallinity; Density functional theory; EDX; Gas composition; HRTEM; Mathematical analysis; Piezoelectricity; Reactive Sputtering; SAED; Scandium; SEM; Silicon substrates; Thin films; XRD; YAlN; Yttrium
• ISSN: 0921-5107; 1873-4944
• DOI: 10.1016/j.mseb.2021.115543

[Display omitted] •Sputter deposited piezoelectric Y0.09Al0.91N compound thin films with improved d33.•Investigation of the sputter parameters power, pressure and gas composition.•Detailed investigation of the microstructure using SEM, XRD, HRTEM, SAED and EDX. Alloying aluminum nitride thin films with elements, such as scandium, is an established approach to increase piezoelectric coefficients, what is a strong request for future micro- and nano-machined, piezoelectric sensor and actuator applications. As an alternative to scandium, Y0.09Al0.91N thin films were reactively synthesized on (100) silicon substrates from an alloy target consisting of 15at% yttrium and 85at% aluminum to demonstrate the increase in piezoelectric coefficient d33 . For this purpose, sputter parameters such as plasma power, gas composition and sputter pressure, have been varied to achieve a highly c-axis oriented crystalline microstructure. X-ray diffraction, transmission electron microscopy and energy dispersive X-ray analyses were performed to determine the degree of crystallinity and to analyze the elemental composition. Under optimized sputter conditions, a d33 value of 7.79 pm/V is measured at Y0.09Al0.91N being in excellent agreement with density functional theory calculations predicting at this composition a value of 6.9 pm/V.