Nanocrystalline Diamond Surface
Acoustic Wave Devices

Baokang Bi, Jes Asmussen, and Brage Golding
Center for Sensor Materials
Michigan State University

In the first studies of the mechanical properties of nanocrystalline diamond, the surface acoustic wave (SAW) velocity was discovered to be the same as for single crystal diamond. Surface wave devices on diamond, such as microwave filters, are particularly attractive since their large wavelength allows photolithography for fabricating GHz transducers. The smoothness of nanocrystalline diamond, with its grain size below 30 nm, also eliminates the time-consuming and costly polishing steps presently required for polycrystalline diamond devices. Sound velocities in excess of 104 m/s have been realized for specific SAW configurations.

Top view of the metallic interdigital fingers that form part of a SAW transducer. The high-speed GHz acoustic waves propagate perpendicular to the photolithographically-produced arrays.

References:
Method and Apparatus for Synthesizing Uniform Nanocrystalline Diamond Films," J. Asmussen and W.S. Huang, 2001 U.S. Patent application by Michigan State University.

"Surface Acoustic Wave Devices Based on Nanocrystalline Diamond", B. Bi, B. Golding, W.S. Huang, and J. Asmussen, 2001 U.S. Patent application by Michigan State University.

"Surface Acoustic Waves on Nanocrystalline Diamond," B. Bi , W.-S. Huang, J. Asmussen, and B. Golding, Diamond and Related Materials, in press, 2002.