Realization of Tunable Varactors Using Bi1.5Zn1.0Nb1.5O7 Thin Films

Cubic pyrochlore bismuth zinc niobate thin films are known to exhibit voltage dependent dielectric properties. In this paper, we are demonstrating the fabrication and characterization of interdigital (IDC) and circular patch (CPC) capacitors using the pulsed laser deposited Bi1.5Zn1.0Nb1.5O7 (BZN) thin films on sapphire and platinised silicon substrates respectively. The IDCs fabricated are having 12 fingers of width 12 m each and separated by a gap of 8 m. The CPC are having circular patches with inner radius of 100 m and concentric ground plane with a radius of 300m. The electrical properties of these capacitors were characterized both at low frequencies and at microwave frequencies. The CPC varactors were having a tunability of 25% at 15 Volts. The calculated capacitance of the IDC varactor at 5.3 GHz with 0 V dc bias was 1.1 pF, which has got changed to 0.99 pF by the application of 30 Volts exhibiting a tunability of 10%.