Development of a Novel Method for Measuring the Transverse Piezoelectric Coefficients of Thin Piezoelectric Films

By Timothy Michael Sullivan, M.S. Washington State University August 2004 Chair: David F. Bahr The transverse piezoelectric properties of thin piezoelectric films were measured using the rectangular membrane method (RMM) developed at Washington State University. This method was compared with other methods from literature performed at WSU. The measured properties were used to evaluate piezoelectric chemistry, processing, poling and substrate conditions. In addition, a alternate generator structure was developed and tested. Using the RMM it was found that typical values for solution-deposited PZT thin films synthesized at WSU and annealed in a conventional furnace with a titanium to zirconium ratio of 40:60 are an e31 of –6.56 C/m and a d31 of –76.0 pC/N. These values are for 1 μm thick films poled at 120 kV/cm and aged for 24 hours. The d31 value is for a measured PZT Young’s modulus of 80 GPa. This is compared with PZT films of 40:60 composition annealed in the RTA. The e31 value measured for this film is –4.63 C/m. In addition films with he morphotropic phase boundary composition, 52:48, were tested and values of –9.4 C/m and –108.5 pC/N, using the measured 80 GPa Young’s modulus, were typical.