Piezoelectricity in thin film materials

Abstract

The need for efficient ultrasonic transducers in the 100 MHz to several GHz frequency range has stimulated the development of a number of transducer structures using piezoelectric thin films. Starting in the early 1960’s with primarily longitudinal bulk mode transduction in CdS films, the piezoelectric thin film transducer technology has progressed over the years to the controlled generation and detection of both longitudinal and shear waves in films of CdS, ZnO, and other materials. While most of the early work was directed towards bulk waves, the more recent strong interest in SAW devices has encouraged the use of piezoelectric thin films, primarily ZnO, in this arena also. A combination of experimental work and theoretical studies has generated a rather comprehensive understanding of the structure and behavior of piezoelectric thin films for both bulk and surface wave applications.