Abstract
The resonance frequency,fs, and the effective electromechanical coupling factor,keff2, of thin film bulk acoustic resonators (FBARs) are derived by transfer matrix method. The effects of thickness and density of electrode onfsandkeff2with different piezoelectric layers are investigated by numerical calculation method. The results show that thickness and density of electrode affectfsobviously, especially in large thickness and density area. Moreover, the effects of thickness, density, and acoustic velocity of electrode onkeff2of FBAR were also studied. The results show that there is a maximumkeff2corresponding to the composition of thickness and density of electrode which is about 20% over the original electromechanical factor of piezoelectric film.keff2is in the direct proportion to the densityρeandveof electrode, respectively. The electrode thickness affectskeff2small with highve; moreover, whenveis high enough, thenkeff2has almost nothing to do withde.keff2always rises with electrode thickness first and then descends with its rising, and the thickness corresponding to the maximumkeff2is different with different electrode, but it always locates in the special area. All above results indicate that the thickness, density, and acoustic velocity of electrode are so important that these results can be applied to design FBAR.
Highlights
The thin film bulk acoustic resonators (FBARs) are extensively applied for filters, resonators, and sensors, since they were first realized with the resonance frequency of 1.9 GHz in 1999, such as MEMS, biosensors, and gas sensors [1,2,3,4,5,6,7,8]
All of above researches aim at the excellent FBAR performance because the resonance frequency, the effective coupling coefficient, and the accurate optimization for the design of FBAR are the key points for FBAR performance
As a kind of bulk acoustic resonator (BAR), the figure of merit of an FBAR can be defined by M = ke2ff ⋅ QS/(1 − ke2ff ), and QS is the resonance quality factor which is obviously controlled by the piezoelectric layer and electrode effect, and the special research has been done by our research group [14], and so we deeply discuss the material parameter Journal of Nanomaterials
Summary
The thin film bulk acoustic resonators (FBARs) are extensively applied for filters, resonators, and sensors, since they were first realized with the resonance frequency of 1.9 GHz in 1999, such as MEMS, biosensors, and gas sensors [1,2,3,4,5,6,7,8]. As a kind of bulk acoustic resonator (BAR), the figure of merit of an FBAR can be defined by M = ke2ff ⋅ QS/(1 − ke2ff ), and QS is the resonance quality factor which is obviously controlled by the piezoelectric layer and electrode effect, and the special research has been done by our research group [14], and so we deeply discuss the material parameter. The transmission matrix method was used in this research, and the following research points and corresponding simulation results are presented: (1) the transfer matrix method being used to derive the input impedance equation, (2) effects of ρe and de on fs, (3) effects of ρe and de on ke2ff , (4) effects of Ve and de on ke2ff , and (5) the two cases with the piezoelectric films of ZnO and AlN, respectively, being compared for discussion
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
