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Diamond-SAW devices: a reverse fabrication method

Mukherjee, D.M. ; Oliveira, F. ; Silva, R. ; Rino, L. ; Correia, R. ; Rotter, S. ; Alves, L. ; Mendes, J. C.

Physica Status Solidi Vol. 13, Nº 1, pp. 53 - 58, January, 2016.

ISSN (print): 1862-6351
ISSN (online): 1610-1642

Journal Impact Factor: 1,648 (in 2015)

Digital Object Identifier: 10.1002/pssc.201510313

Surface acoustic wave (SAW) devices are key components
in modern wireless communication systems. Besides
being used as reflective delay lines, filters or resonators,
SAW devices can be used as sensors and fixedcode
identification tags. Due to their high-acoustic velocity,
diamond films can be combined with piezoelectric
materials to fabricate diamond-based SAW devices with
potential for high frequency applications. This paper presents
results of coating commercial SAW delay lines
with diamond films. The films were deposited on lithium
niobate under different conditions in a hot filament
chemical vapour deposition system. Seeding was performed
using 6-12 mm diamond grit and 20-30 nm nanodiamond
particles based suspensions. After tuning the
deposition conditions, dies of 74 MHz delay lines were
coated with diamond. The quality, morphology and conformability
of the coatings were evaluated by scanning
electron microscopy (SEM) and Raman spectroscopy.
The integrity of the interdigitated transducers (IDTs) after
deposition was evaluated by SEM. S-parameters of
as-bought and diamond-coated dies were measured using
a network analyser. Although the frequency response is
attenuated after diamond deposition, integrity of the IDTs
and the operating principle of the devices are kept intact.
These preliminary results open the door to a simplified
fabrication procedure of diamond-based SAW devices.