The microstructural properties of sputtered zinc oxide SAW transducers

Abstract

The microstructural properties of sputtered zinc oxide, ZnO, were investigated and related to their effective surface acoustic wave, SAW, transducer capabilities. SAW transducer films were fabricated on glass using different deposition parameters to produce different levels of transducer efficiency. The ZnO film microstructure was analysed using X-ray diffraction, surface profilometer and scanning electron microscope equipment. Etch techniques were used to further delineate the microstructural properties. The low coupling factor films had a low crystalline content, rougher surface topography and high etch rates. High coupling factor films were highly ordered, structurally dense, smooth surfaced films with etch properties characteristic of single crystal zinc oxide. The differences relate to growth conditions which produce a low defect density film structure of uniform polarity with a minimum of fibre grain inversions and weak intergrain boundaries Les proprietes microstructurales de l'oxyde de zinc pulverise sont etudiees et reliees a leur aptitude a la transduction piezoelectrique pour ondes de surface. Les films transducteurs a onde de surface sont deposes sur des supports en verre en faisant varier les conditions du depot de facon a atteindre differents degres d'efficacite de transduction. La microstructure du film de ZnO est analysee par diffraction X, profilometrie de surface et microscopie electronique a balayage. Des techniques de gravure sont egalement employees pour preciser les proprietes microstructurales