Abstract
We report on design, fabrication, and comparative test of three different types of voltage-variable interdigital capacitors made on ferroelectric Ag(Ta,Nb)O3 films deposited on MgO and A12O3 substrates. X-ray diffraction patterns show that ATN films pulsed laser deposited on MgO(001) and Al2O3(0112) single crystals have preferential (00/) and (0kk) orientation. Capacitance and loss tangent in interdigital capacitors were measured as the functions of frequency and applied dc voltage bias. Loss tangent was as low as 0.0025 and 0.0034 and AT-factor (tunability/tanδ) was around 26.2 and 20.0 for MgO and A12O3, respectively, @ ± 40 V (maximum electric field 200 kV/cm), 300 K, and 1 MHz. Both of polarization and steady leakage currents were observed in the current-time domain measurements. 0.1 pF interdigital capacitors have pA leakage current level @ ± 40 V.