Enhanced piezoelectric properties of c-axis textured aluminium scandium nitride thin films with high scandium content: Influence of intrinsic stress and sputtering parameters

Aluminium scandium nitride (ASN) exhibits a largely enhanced piezoelectric response as compared to aluminium nitride (AlN), which makes it an upcoming piezoelectric material for use in next generation RF filters, sensors, actuators and energy harvesting devices. In this work, process-microstructure-property relationships of such sputtered ASN films containing up to 42 at% Sc were investigated. Hereby, the influence of the process parameters on the film structure, the intrinsic stress and the piezoelectric response were carefully investigated. A high piezoelectric response (e 31, f = −2.67 C/m 2 and d 33, f = 10.3 pm/V) was measured for films with 42 at% and 34 at% Sc, respectively. The results are very promising towards industrial applications.