AgTaO3 and AgNbO3 thin films by pulsed laser deposition

Silver tantalate AgTaO3 (ATO) and silver niobate AgNbO3 (ANO) films have been grown on to the LaAlO3 (001) and sapphire Al2O3 (0112, r-cut) single crystals by pulsed laser deposition technique from stoichiometric ATO and ANO targets. X-ray diffraction study revealed epitaxial quality of ATO and ANO films on the LaAlO3 (001) whereas on the sapphire r-cut substrate they are preferential (110) and (001) oriented. To characterize microwave films properties in the range from 1 to 40 GHz, coplanar line interdigital capacitors were fabricated by photolithography and lift-off technique. ANO film capacitors show superior properties: frequency dispersion was as low as 13%, voltage tunability (40 V, 200 kV/cm) was about 4.6% at 20 GHz, loss tangent ∼0.106 at 20 GHz, K-factor = tunability / tanδ from 49% @ 10 GHz to 33% at 40 GHz.