Short-time piezoelectric measurements in ferroelectric thin films using a double-beam laser interferometer

An evolution of the double-beam laser interferometer used for piezoelectric measurements in ferroelectric thin films is reported. Measuring the d(33) hysteresis of a ferroelectric material using lock-in technique with large time constants requires a varying bias field to be applied to the sample over a long period of time. This long-term application leads to electrical stress during the measurement. We present a measurement technique using a different source for the applied field and a varied method for averaging the interferometric response. The measurement time for a complete d(33) hysteresis will be shortened down to several seconds. Also, the cycle frequency becomes comparable to electrical hysteresis measurements. Experimental results on quartz and Pb(Zr-(X),Ti(1-X))O-3 are given to demonstrate the capabilities of the interferometer and the new measurement method. (C) 2003 American Institute of Physics.