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Thin-film zinc-oxide microwave acoustic transducers have been formed successfully by vacuum deposition techniques upon a cooled substrate (−50°C) by evaporation of zinc with an oxygen beam. The films are hexagonal preferentially oriented with c axis normal to the substrate. A device consisting of a ZnO film (1.9 μ) deposited on a metallic film on a sapphire delay line had a one-way conversion loss of 6 dB at 1.6 GHz with a large bandwidth indicating that zinc-oxide thin films deposited by this method make good ultrasonic transducers at frequencies above 1 GHz.
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Malbon et al. (1967) studied this question.
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