Chapter 4 - Piezoelectric thin films: Processing and properties

Abstract

This chapter reviews the available experimental and theoretical studies of piezoelectric thin films. The most important techniques of deposition are presented, with emphasis on the particular growth conditions for obtaining piezoelectric thin films of high technological interest. Piezoelectric materials can be classified according to different criteria. Usually they are divided into 70 polar piezoelectric materials and nonpolar piezoelectric materials. Polar materials are also called “pyroelectric” because they show production of electric charge as a consequence of uniform heating. Among the 20 non-centrosymmetric piezoelectric classes, 10 have a spontaneous polarization. Polar materials can be classified as ferroelectrics and nonferroelectrics. From the applications point of view the most important piezoelectrics belong to the ferroelectric class. In ferroelectrics the piezoelectric effect is produced by a variation of the intrinsic net dipole moment as a consequence of an applied stress. The large piezoelectric response in these materials is mainly because of the large relative displacement of cationic and anionic sublattices induced by the macroscopic strain.