Exploring capacitance-voltage measurements to find the piezoelectric coefficient of aluminum nitride

In this work we explore an uncommon method to extract the piezoelectric coefficient of the piezoelectric material aluminum nitride. The method exploits the bias dependence of CV (capacitance voltage) measurements on MπM (metal-piezoelectric-metal) capacitors. We propose a bias dependent capacitance model for piezoelectric capacitors such as BAW (Bulk Acoustic Wave) resonators. With this model we extract both the piezoelectric coefficient and dielectric constant from the CV recording. In contrast to earlier reports we verified that our results do not depend on layer thickness, biasing and sweep direction of the CV recording. In addition, we discuss the accuracy of our measurements in depth.