Numerical analysis of anchor loss and thermoelastic damping in piezoelectric AlN-on-Si Lamb wave resonators

Even though many thin-film piezoelectric aluminum nitride (AlN) on silicon (Si) Lamb wave resonators have been proposed in the literature, little focus has been set on the modeling of the quality factors Q. Their Qs are associated with numerous dissipation sources, which are often difficult to separate from each other in experiments. Besides, the values of Q measured in experiments can largely deviate from sample-to-sample of the same design. In order to gain better insight into these issues, we have applied numerical models to estimate anchor losses and thermoelastic damping to a large set of AlN-on-Si resonators specifically designed to have significantly different Qs. The data set includes biconvex resonators of different curvatures (designed to reduce anchor losses), regular flat-edge resonators, and different electrode patterns. For the broad range of devices tested, we show that the computed values of Q agree well with the experimental data. In particular, the experimentally measured values of Q in regular flat-edge Lamb wave resonators are due to comparable contributions of the two types of losses.