Extraction of electromechanical coupling coefficient of piezoelectric thin films deposited on substrates

✍ Scribed by Qing-Biao Zhou; Yue-kai Lu; Shu-Yi Zhang

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 144 KB
• Volume: 39
• Category: Article
• ISSN: 0041-624X
• DOI: 10.1016/s0041-624x(01)00062-2

✦ Synopsis

A method to extract the electromechanical couplig coecient k 2 t of the thickness extensional mode of a piezoelectric thin ®lm deposited on a substrate is presented, in which a two-layer structure is as a composite resonator. Based on the method proposed by Wang et al. (IEEE Trans. UFFC 46 (1999) 1327), we present two alternative approximate equations of k 2 t , then k 2 t can be calculated directly from the eective electromechanical coupling factor k 2 eff of two special modes of the composite resonator. The new method is unnecessary to know the thickness of the piezoelectric ®lm, which is very dicult to accuracy measure for a high frequency composite resonator or transducer. The accuracy and validity of this method are checked by numerical simulation on two typical samples. The results of numerical simulation show that the proposed approximate method is available for a real piezoelectric thin ®lm, if the mechanical loss in the ®lm is less than 5% and the mechanical loss in the substrate is less than 0.8%.