Hyper frequency modeling of resonated systems based on piezoelectric LiTaO3 thin layers

In this work, we discuss the piezoelectric activity of lithium tantalite (LiTaO3) thin layers and to more understand this phenomenon we have developed a model for our LiTaO3 resonators based on mason model and simulated the hyper frequency behavior. Our LiTaO3 resonators are made from three layers staked on silicon substrates. The aluminum thin film constitutes the external electrode, the platinum forms the internal electrode and the lithium tantalite constitutes the piezoelectric layer. Each element of these layers is represented by an arrangement of impedances. The simulation shows the reflection coefficient, ρ, as a function of the frequency. We observe a resonant frequency that decreases with the increase of the thickness of the piezoelectric LiTaO3 layers. A slight variation of this resonant frequency is obtained when comparing it with that of the uncharged piezoelectric device, which is due to the different layers loading the system. Over oscillations superposing to the envelope are observed and found to be related to the propagation of the acoustic wave in the silicon substrate. From these over oscillations one can see that this system can be used as an efficient method to calculate the thickness of any substrate.

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