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A. Alamin Dow, H. Lin, M. Schneider, Ch. Petkov, A. Bittner, A. Ahmed, C. Popov, U. Schmid, N. Kherani:
"Ultrananocrystalline Diamond-Based High-Velocity SAW Device Fabricated by Electron Beam Lithography";
IEEE Transactions on Nanotechnology, 11 (2012), 5; S. 979 - 984.

Surface acoustic wave (SAW) devices have been used
extensively for a variety of applications such as telecommunications,
electronic devices, and sensors. The emerging need for highbit
data processing at gigahertz frequencies and the requirement of
high-sensitivity sensors demand the development of high-efficiency
SAW devices. With the objective of exploiting the high acoustic
velocity of diamond, we report on an optimally developed nanodiamond
thin film with crystal size of 3-5 nm, embedded in an
amorphous carbon matrix with grain boundaries of 1-1.5 nm, that
is integrated with aluminum nitride (AlN) to extend the operating
frequency of SAW transducers. We utilize this attractive property
of diamond through facile synthesis of a bilayer structure consisting
of sputtered AlN deposited on an ultrananocrystalline diamond
(UNCD) film. We report the realization of a high-frequency SAW
resonator, using a device architecture based on anUNCDlayer. The
UNCD films were synthesized using amicrowave plasma-enhanced
chemical vapor deposition (MWPECVD) technique and were used
to enhance the SAW velocity in the AlN thin film, thus opening
the way for the application of CMOS compatible high-frequency
SAW devices. The deposition and characterization of UNCD thin
films are presented and highlighted for the realization of the SAW
resonators. The high velocity associated with the UNCD/AlN bilayered
approach together with the high lateral resolution of the
interdigital transducers obtained with electron beam lithography
is essential for the realization of high-frequency SAWdevices. The
fabricated devices demonstrate resonance frequencies of 11.3 and
6.2 GHz corresponding to spatial periods of 800 and 1600 nm,
respectively, yielding a SAW velocity of 9040 and 10 064 m/s,
respectively.

http://dx.doi.org/10.1109/TNANO.2012.2210731