Microwave planar capacitors employing low loss, high-K, and tunable BZN thin films

Planar capacitors having high Q factor and tunability were implemented with cubic pyrochlore Bi/sub 1.5/Zn/sub 1.0/Nb/sub 1.5/O/sub 7/ (BZN) thin films deposited by RF magnetron sputtering. Device Q factors (Q/sub DUT/) and capacitances (C/sub DUT/) were measured using reflection coefficients based on vector network analyzers on Vycor glass and sapphire substrates, respectively. Q factors (Q/sub int/) accounting for electrode and dielectric losses remained above 200 up to 20 GHz and around 1000 up to several GHz for the smaller devices on sapphire substrate and there was no sign of onset of dielectric relaxations. With the electric field dependent permittivity, the BZN thin films can be the alternative to conventional BST thin films.