Researchers in the Nanofabrication and Devices group at the Argonne
National Laboratory, in collaboration with the University of Pennsylvania,
Advanced Diamond Technologies Inc., and Innovative Micro Technology, have discovered
that defects at the grain boundary in ultrananocrystalline diamond (UNCD) hold
primary responsibility for the fundamental mechanism of energy dissipation.
SEM micrograph of fabricated UNCD microresonator
Because of a high Young's modulus and high sound propagation velocity, UNCD
materials hold potential for fabricating high-frequency microelectromechanical
(MEMS) resonators.
However, their mechanical dissipation at high frequency, which is important
for developing high-frequency resonator applications, is not well understood.
Dissipation in UNCD cantilevers was determined by using ring-down measurement
under ultrahigh-vacuum conditions, and the quality factor measured in the range
of 5000-16000 at kHz resonance frequencies.
These studies reveal that dissipation in UNCD films is mainly due to the presence
of defects such as nondiamond-carbon bonding at grain boundaries.
More information: V. P. Adiga, A. V. Sumant, S. Suresh, C, Gudeman, O. Auciello,
J. A. Carlisle, R. W. Carpick, "Mechanical stiffness and dissipation in
ultrananocrystalline diamond microresonators," Phys. Rev. B, 79, 245403
(2009)