Surface acoustic wave devices based on thin film piezoelectric interdigital transducers

In this work, we investigate the case for using an AFM to directly define a piezoelectric transducer in a ferroelectric thin film in order to excite and detect high frequency SAW signals. The wavelength of the SAW signal is given by twice the domain size of the periodically polarized ferroelectric thin film. This technique has recently been demonstrated at the University of Geneva. The proposal combines the theoretical and experimental know-how of classical SAW technology accumulated at NTNU with the know -how at AFM manipulation of ferroelectric domain geometry at the University of Geneva. The objective is to study the acoustic propagation properties of this novel device, using both electrical and optical techniques. The SAW laser probe technique, in combination with AFM tailoring of ferroelectric domains, constitute a unique experimental s et-up for the study of acoustic properties of ferroelectric this films. In particular, we shall investigate the reflection and transmission coefficients of a single ferroelectric domain wall, important to explain the attenuation of SAW signals in ferroelectric materials. We shall also use theoretical modelling to study the re sponse and simulate/optimize the device characteristics. The AFM writing is foreseen to be carried out in Geneva, whereas the subsequent characterization and analysis will take place at the Department of Physical Electronics, NTNU.