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.
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 piezoelectricrdm 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 vacuumsystem. Transducer quality surface-wave films are characterized bytheir optical clarity, high density, smooth surface, small crystallite size,and weD-oriented crystaUite axes. Such ZnO films wiD play an importantrole in future surface acoustic wave device technology.
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