压电半导体薄膜换能器损耗小,能够在宽的频率范围内应用。正如以前所指出的那样,在换能器采用电容器型结构(薄膜夹在二个金属电极之间,图1a)时,薄膜换能器很有效。这时可以得到沿薄膜表面的均匀电位分布,与不带金属底层的压电换能器-薄膜相此,能降低损耗和加宽通带。但是换能器和 Piezoelectric semiconductor thin film transducers have low loss and can be used over a wide frequency range. As noted earlier, thin-film transducers are effective when the transducer uses a capacitor-type structure with the film sandwiched between two metal electrodes (Figure 1a). In this case, a uniform potential distribution along the surface of the film can be obtained, reducing the loss and widening the pass band as compared with the piezoelectric transducer-film without metal substrate. But the transducer and