DC bias-dependent shift of the resonance frequencies in BST thin film membranes.
Direct current (DC) bias-dependent acoustic resonance phenomena have been observed in micromachined tunable thin film capacitors based on Ba(0.3)Sr(0.7)TiO3 (BST) thin films. The antiresonance frequency is only weakly DC bias dependent, and the resonance frequency exhibits a much stronger dependence on the applied DC bias. The resonance frequency shifted by 1.2% for a frequency of about 6.7 GHz and an applied field of 667 KV/cm. At the same time the effective electromechanical coupling constant k(2)(t,eff) increased to 2.0%. The tuning of the resonance frequency depends on the tunability of the film permittivity and on the mechanical load on the piezoactive layer. The experimental observations correlate well with the theoretical predictions derived from the free energy P expansion using Landau theory.
Noeth
Andreas
A
Ceramics Laboratory, Swiss Federal Institute of Technology EPFL, Lausanne, Switzerland. andreas.noeth@epfl.ch
Yamada
Tomoaki
T
Sherman
Vladimir O
VO
Muralt
Paul
P
Tagantsev
Alexander K
AK
Setter
Nava
N
D000162:Acoustics / Q000295:instrumentation*; D002516:Ceramics / Q000737:chemistry*; D017097:Electric Impedance; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods; D004574:Electromagnetic Fields; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008422:Materials Testing; D008567:Membranes, Artificial; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014159:Transducers
D008567:Membranes, Artificial