Gigahertz surface acoustic wave generation on ZnO thin films depositedby radio frequency magnetron sputtering on III-V semiconductor substrates

The authors demonstrate 1.6 GHz surface acoustic wave (SAW) generation using interdigital transducers patterned by e-beam lithography on a thin ZnO piezoelectric film deposited on an InP substrate. The highly oriented, dense, and fine-grain ZnO film with high resistivity was deposited by radio frequency magnetron sputtering and was characterized by x-ray diffraction, scanning electron microscopy, atomic force microscopy, and a four-point probe station. The acoustic wavelength of the 1.6 GHz SAW generated by exciting the interdigital transducer on Zn O ∕ In P with a microwave signal is 1.6 μ m . This SAW filter device could be monolithically integrated with optoelectronic devices, opening new opportunities to use SAWs for applications such as gigahertz-frequency filters on optoelectronic devices and novel widely tunable quantum cascade lasers.