High Overtone Mode Solid Mounted Resonators with Polarity Inverted Multilayered SiAlN/AlN Films

High-order mode solid mounted resonators with polarity inverted multilayered GeAlN/AlN films

“…Recently, we demonstrated that electromechanical coupling k t 2 of c-axis oriented GeAlN films are almost the same as those of c-axis oriented SiAlN films. 17,18) Also, we achieved the fabrication of the polarity inverted multilayered films by alternately growing AlN layers and SiAlN layers. 17) The high overtone bulk acoustic wave resonators (HBAR) consisting of the polarity inverted SiAlN/AlN films/ silica glass substrates operated at high-order mode resonances.…”

“…Metal (Ge) grains on the target sometimes have a negative effect on the crystalline orientation of the films in a metal grain sputtering deposition, as their position and shape may not be strictly the same in each layer deposition. 18) This led to the low crystallinity of the second layer GeAlN film. Unknown peaks where the material and crystal plane could not be identified were also observed around 2θ = 69°, and the intensity of the unknown peak increased with increasing number of layers in the multilayered film.…”