High Efficiency Ultrasonic Transducer Using Polarity Inverted ZnO Film

The ultrasonic transducer is an important component to determine the performance of ultrasonic microscope. The ultrasonic emission area become smaller in the high frequency range when impedance matching between the transducer and 50 Ω measurement system is considered. Small emission area causes decrease in signal-to-noise ratio (S/N) due to the low sound pressure in the focus point. Polarity inverted n- layered transducer operates with high frequency in n-th mode. Therefore, the emission area and film thickness increase by n- times. Large emission area improves S/N. In this study, we report the fabrication of ZnO thin film polarity inverted structure on the Si02 glass buffer rod by RF magnetron sputtering. The piezoelectricity and performance of transducer in water medium were investigated.