Determination of piezoelectric coefficients and elastic constant of thin films by laser scanning vibrometry techniques

Knowledge of the electro-active properties of piezoelectric materials is essential for the modeling and design of novel MEMS devices employing the piezoelectric effect. Cantilevers of piezoelectric thin film on Si were fabricated by using sol-gel and photolithograph wafer processing techniques. A scanning laser vibrometer was used to measure the displacement at the contact pad, the first resonant frequency and the tip deflection of the cantilever. The longitudinal (d33,f), transverse (d31,f) piezoelectric coefficients, and the Young's modulus for the piezoelectric thin films were then determined from these results. Finite element analysis (FEA) modeling was carried out to understand the device behaviors and a good agreement has been found between the measurement and the FEA simulated results.