Measurement methods for the d33 coefficient of PZT thin films on silicon substrates:: A comparison of double-beam laser interferometer (DBI) and single-beam laser vibrometer (LDV) techniques

To date there is no well accepted method for the measurement of piezoelectric thin films displacements. The measurement is difficult since the displacement is very small. As the thin films are 'clamped' to a silicon substrate, the contribution of the substrate bending can completely mask the 'true' value of d(33) piezoelectric coefficient. Whilst double beam interferometers (DBI) have been specifically developed to circumvent this effect, results are presented in this paper to demonstrate that specific sample preparation can yield equivalent results using a single beam laser Doppler vibrometer (LDV).