Schlögl, M., Schneider, M., & Schmid, U. (2021). Piezoelectricity in Y₀.₀₉Al₀.₉₁N thin films. Materials Science and Engineering: B, 276, Article 115543. https://doi.org/10.1016/j.mseb.2021.115543
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 (1 0 0) silicon substrates from an alloy target consisting of 15 at% yttrium and 85 at% 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.
