The piezoelectric film layer transducer represents the most efficient method for generating and detecting surface acoustic waves on nonpiezoelectric substrates. ZnO, which has a strong piezoelectric ef feet and can readily be sputtered as an oriented crystalline composite on a wide variety of substrates, is a natural choice as the piezoelectric
rdm layer. This paper summarizes a body of knowledge which has been developed on the characteristics of transducer quality ZnO film layers, and focuses attention on those sputtering parameters and microstructural properties which characterize a superior surface-wave transducer film. Requisite sputtering conditions are high substrate temperatures
(ISO-300·C), modest deposition rates (0.5-1.0 ",m/h), low background vapor pressures «S ",m Hg) and an ultraclean vacuum
system. Transducer quality surface-wave films are characterized by
their optical clarity, high density, smooth surface, small crystallite size,
and weD-oriented crystaUite axes. Such ZnO films wiD play an important
role in future surface acoustic wave device technology.