Super-high-frequency SAW transducer utilizing AIN/ultrananocrystalline diamond architectures

SAW devices have been used in a variety of applications including high-volume telecommunications, electronic devices, and advanced sensors. Recently, high-bit-rate data processing in the gigahertz frequency range and ultrahigh-sensitivity sensors have called for the development of advanced SAW transducers. Because of its high acoustic velocity, ultrananocrystalline diamond (UNCD) with a crystal size of 3 to 5 nm, embedded in an amorphous carbon matrix with grain boundaries of 1 to 1.5 nm, is integrated with AlN to extend the operating frequency of SAW devices. We utilize this attractive property of UNCD through the facile synthesis of bilayer architectures consisting of sputtered AlN deposited on UNCD film. The UNCD films were synthesized using microwave plasma-enhanced chemical vapor deposition. The SAW devices were fabricated by electron beam lithography and lift off processes. The fabricated SAW nanodevices exhibit resonance frequencies up to 15.4 GHz. Multiple SAW transducers were fabricated with spatial periods ranging from 580 nm to 3.2 μm.