Characteristics of Surface Acoustic Wave on AlN Thin Films

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Abstract
A surface acoustic wave (SAW) on a (00·1) plane of hexagonal aluminum nitride (AlN) deposited on R-plane sapphire ( (1\bar1·2)Al2O3) with an inclination of about 26 degrees to the substrate was analyzed. A Rayleigh wave and shear-horizontal-type (SH-type) wave were found. The phase velocity of these was 5400-5800 m/s and 6100-6600 m/s, respectively. To confirm this results, the propagating characteristics of both SAW modes were measured by input admittance of single interdigital transducers (IDT) and by transmission characteristics between two IDTs. The phase velocity of the Rayleigh wave and the SH-type wave was 5600 m/s and 6500 m/s, respectively, and the propagation loss was 0 dB/λ and 0.04 dB/λ, respectively. These measured characteristics approximately agree with the results of the simulation.