Figure 3.
The simplified schematics of configurations of the applied voltage when the second layer is electrode, null, and SiO2. (a) The second layer is electrode, the top and bottom electrode are connected with the voltage and ground; (b) the second layer is null, that is there are only three layers: top electrode, piezoelectric layer, and substrate. The top electrode and the substrate are connected with voltage and ground; (c) the second layer is SiO2, the top electrode and the substrate are connected with voltage and ground.