Effect of Substrate on PZT Films Properties

Two types of ferroelectric PZT films deposited at the same conditions on Silicon-on-Sapphire (SOS) and Si substrates are studied. The PZT on SOS shows a single (111) texture, symmetric hysteresis loops with high polarization values. The PZT film on Si is textured in the main (111) and weaker (100) directions, has lower polarization values and exhibits strongly asymmetrical hysteresis loops. Analysis of the substrate bending, mechanical stresses and deformations shows that the asymmetry of the hysteresis loops is due to the flexoelectric polarization caused by the compression strain gradient acting along (111) axis of the film. The flexoelectric coefficient for solgel PZT is measured to be 0.0154 μC/cm.