Resonant transformation of acoustic waves observed for the diamond based HBAR

The resonant transformation of acoustic waves in “Al/AlN/Mo/(100) diamond” piezoelectric structure has been studied by means of 2D FEM simulation. The nature of arising acoustical modes has been defined by the detail investigation of fields of elastic displacements. It was shown that the appearance of strongest spurious resonant peaks at frequencies above the bulk acoustic overtones is concerned with Lamb-like modes within diamond substrate, excited on the critical frequencies. In these points Lamb mode transforms into standing plate wave. Experimental and calculated data are in good accordance.