A comparative study of structural, mechanical and electrical properties of ZnO and AlN thin films for MEMS based piezoelectric sensors

In this work, a comparative study has been carried out to compare the relative performance of ZnO (Zinc Oxide) and AlN (Aluminum Nitride) thin films for their application in piezoelectric sensors. The thin films material properties are being characterized using various material characterization techniques such as SEM, XRD, and Nanoindentation. Further the MIM (Metal-Insulator-Metal) based devices have been fabricated with piezoelectric films sandwiched between Al electrodes. The devices have been evaluated for mechanical and electrical performances. The natural frequency of the devices recorded as 46.8 kHz (ZnO) and 40.8 kHz (AlN). The average nominal capacitance of the MIM structure is measured as ~98pF and ~120pF where as corresponding dissipation factor obtained as ~0.03 and ~0.0005 respectively for ZnO and AlN devices. The repeatability investigation carried out on the sample devices for up to 90 days and the output has been monitored. The result showed that the AlN devices exhibit better output stability compared to ZnO devices.