Thermally compensated aluminum nitride Lamb wave resonators for high temperature applications

In this letter, temperature compensation for aluminum nitride (AlN) Lamb wave resonators operating at high temperature is presented. By adding a compensating layer of silicon dioxide (SiO2), the turnover temperature can be designed for high temperature operation by varying the normalized AlN film thickness (h(AlN)/lambda) and the normalized SiO2 film thickness (h(SiO2)/lambda). With different designs of h(AlN)/lambda and h(SiO2)/lambda, the Lamb wave resonators were well temperature-compensated at 214 degrees C, 430 degrees C, and 542 degrees C, respectively. The experimental results demonstrate that the thermally compensated AlN Lamb wave resonators are promising for frequency control and sensing applications at high temperature. (C) 2010 American Institute of Physics. [doi:10.1063/1.3481361]