Mapping of microwave-induced phonons by μ-Brillouin spectroscopy: Hypersound in ZnO on Silicon
Résumé
High performance Brillouin microscopy has been used in order to characterize the spatial distribution of piezoelectrically induced acoustic fields excited at microwave frequencies in a ZnO film deposited on silicon directly within the area of the electrically excited inter-digital transducer (IDT). For a IDT of 300 micrometers length, the maximum of intensity is close to the edge of the transducer and the minimum lies between 200 and 250 micrometers from this maximum. Moreover, an acoustic second harmonic mode is observed for a fundamental excitation frequency of 1 GHz.