Low-voltage and high-tunability inter-digital capacitors using lead zinc niobate (PbO-ZnO-Nb2O5) thin films

In this work, we present tunable inter-digital capacitors (IDCs) employing high tunable PbO-ZnO-Nb₂O₅ (PZN) cubic pyrochlore thin film dielectrics for low-voltage and high-tunability microwave applications. In order to reduce the bias voltage of the IDC and increase its tunability, its electrodes were fully embedded into the thin film dielectrics to confine fringing electric fields within them. In 4 V, the tunability of the IDCs was analyzed in terms of the electrode width and spacing by measuring reflection coefficients at 1 GHz. The fabricated IDC with width and spacing of 1.5 and 1.8 mum, respectively, achieved tunability of 26 % and Q-factor of 10 at the applied DC voltage of 5.5 V.