Preparation of ZnO Thin-Film Transducers by Vapor Transport

Thin films of ZnO were prepared for transducers and microwave acoustic delay lines. Preliminary results are reported for the latter devices. Vapor transport of ZnO in a sealed system was achieved at a source temperature of 700°C, a source-substrate distance of 10 cm, a substrate temperature of 570°C, and 2 mm O2. On (0001) sapphire substrates, x-ray diffraction proved ZnO (0002) planes were oriented parallel to the substrate. Methods were developed for the construction of predominantly longitudinal mode transducers. A one-way conversion loss of 20 dB at 1.2 GHz was measured.