Preferential excitation of 2nd-mode piezoelectric surface waves in zinc-oxide-layered substrates

Calculations of ¿v/v for 2nd-mode Rayleigh waves in zinc-oxide-layered substrates show levels of coupling coefficients considerably greater than those of the fundamental mode, for a suitable choice of substrate. Such coupling coefficients offer attractive possibilities for devices using the second Rayleigh mode, and further suggest that, for devices using the fundamental mode, it is necessary to be certain that second modes cannot be excited, to avoid anomalous results due to mode interference.