The future for some high tech electronic communications systems lies in extremely small mechanical beams that vibrate at tremendously high frequencies.

Researchers at The California Institute of Technology (CIT) and Case Western Reserve University Case School of Engineering, report in the January 30 issue of Nature the successful fabrication of a nanoscale mechanical oscillator with an operating frequency of over 1 gigahertz.

The new nanoscale device, a long, narrow bridge-like beam roughly 700 times thinner than a human hair, is made of a silicon carbide thin film grown on silicon chips by the CWRU research team. It is the first of its kind to operate at a frequency above one gigahertz, or one billion cycles per second.

"Our job was to provide ultra-thin silicon carbide films suitable for the new device. Our research partners at CIT, in turn, used their expertise in nanofabrication and testing to create the device and evaluate its performance," said Christian Zorman, principal investigator of the CWRU team and associate professor of electrical engineering and computer science at CWRU. "Structures such as these have previously been made from silicon and gallium arsenide, but the higher stiffness of silicon carbide enables devices to have resonant frequencies above 1 gigahertz."

The CIT/CWRU research effort was funded by a grant from the United States Navy.

"As an added benefit, the chemical inertness of silicon carbide actually enhances the fabrication yield, since silicon carbide is not at all attacked by the silicon etchants used to selectively remove sections of the underlying chip," said Mehran Mehregany, the other principal investigator on the CWRU team and B.F Goodrich Professor of Engineering Innovation.

Mehregany and Zorman are well-known for producing microelectromechanical devices on the micron scale, but these new nanoscale silicon carbide devices have critical dimensions up to 10 times smaller.

"This development gives our effort at CWRU an important foothold in the rapidly expanding field of nanoelectromechanical systems (NEMS) because it relies on silicon carbide, a material that we have been developing for microelectromechanical systems (MEMS) over the last 10 years," Zorman said.

CWRU is considered a leader in silicon carbide MEMS, having developed several novel thin film deposition systems and associated processes to fabricate silicon carbide devices for harsh environment applications.

"Current interest for developing nanoscale devices with gigahertz resonant frequencies comes from the military for use in communications systems, but we see the potential for this technology in a wide variety of sensor, detector and biological imaging applications," said Zorman. "The partnership with CIT is ideal as it combines our expertise in materials with theirs in nanofabrication. It's really what made this development possible."