title: Sputter deposition of stress-controlled piezoelectric AlN and AlScN films for ultrasonic and energy harvesting applications.
abstract: This paper reports on the deposition and characterization of piezoelectric AlN and AlXSc1-XN layers. Characterization methods include XRD, SEM, active thermo probe, pulse echo, and piezometer measurements. A special focus is on the characterization of AlN regarding the mechanical stress in the films. The stress in the films changed between -2.2 GPa (compressive) and 0.2 GPa (tensile) and showed a significant dependence on film thickness. The cause of this behavior is presumed to be the different mean grain sizes at different film thicknesses, with bigger mean grain sizes at higher thicknesses. Other influences on film stress such as the sputter pressure or the pulse mode are presented. The deposition of gradient layers using those influences allowed the adjustment of film stress while retaining the piezoelectric properties.
authors: Stephan
authors: S
authors: Barth
authors: Hagen
authors: H
authors: Bartzsch
authors: Daniel
authors: D
authors: Gloess
authors: Peter
authors: P
authors: Frach
authors: Thomas
authors: T
authors: Herzog
authors: Susan
authors: S
authors: Walter
authors: Henning
authors: H
authors: Heuer