Effect of diamond nucleation process on propagation losses of AlN/diamond SAW filter.
In this work, the effect of a diamond nucleation process on freestanding aluminium nitride (AlN)/diamond surface acoustic wave (SAW) device performances was studied. Before diamond deposition, silicon (Si) substrates have been mechanically nucleated, using an ultrasonic vibration table with submicron diamond slurry, and bias-enhanced nucleated (BEN). Freestanding diamond layers obtained on mechanically scratched Si substrates exhibit a surface roughness of R(MS) = 13 nm, whereas very low surface roughness (as low as R(MS) < or = 1 nm) can be achieved on a freestanding BEN diamond layer. Propagation losses have been measured as a function of the operating frequency for the two nucleation techniques. Dispersion curves of phase velocities and electromechanical coupling coefficient (K2) were determined experimentally and by calculation as a function of normalized thickness AlN film (kh(AlN) = 2pi h(AlN)/lambda). Experimental results show that the propagation losses strongly depend on the nucleation technique, and that these losses are weakly increased with frequency when the BEN technique is used.
Elmazria
Omar
O
LPMIA UMR 7040, Université H. Poincaré-Nancy I, F-54506 Vandoeuvre-les-Nancy, France. omar.elmazria@lpmi.uhp-nancy.fr
El Hakiki
Mohamed
M
Mortet
Vincent
V
Assouar
Badreddine M
BM
Nesládek
Milos
M
Vanecek
Milan
M
Bergonzo
Philippe
P
Alnot
Patrick
P