Dielectric relaxation behavior of Ag(Ta,Nb)O-3 interdigital capacitors on oxide substrates

The time-dependent dielectric relaxation behavior of Ag(Ta,Nb)O-3 interdigital capacitors was investigated for tunable device applications. Ag(Ta,Nb)03 thin films, which have high k-factor (tunability/ loss tangent), were deposited on the oxide substrates by pulsed laser deposition technique. Ag(Ta,Nb)03 thin film on the LaAlO3 substrate has an epitaxial relationship with the substrate. The observed tunabilities and K-factors of Ag(Ta,Nb)O-3/LaAlO3 and Ag(Ta,Nb)O-3/AI(2)O(3) interdigital capacitors were 5.9% and 17.8 and 3.8% and 9.9, respectively, at 40 V (maximum electric field of 100 kV/cm), 300 K, and 1 MHz. Capacitance relaxation follows the power law C(t) = C-infinity + C-0(t/ls)-(beta) with a very small exponent negligibly fitted in the time domain. Due to this small exponent, the capacitance was changed by less than 0.05% in 2V in 71 s. Time-dependent leakage current was measured by employing the Ag(Ta,Nb)O-3(0.4mum)/Al2O3 interdigital capacitor. The time-dependent relaxation current follows the power law j(t) = j(leak) +j(0)(t/ls)-(alpha) with an exponent alpha = 0-98, j(leak) = 1.14 x 10(-14), and j(0) = 11.42s.
QC 20100525 QC 20111028