2DEG electrodes for piezoelectric transduction of AlGaN/GaN MEMS resonators

A 2D electron gas (2DEG) interdigitated transducer (IDT) in Gallium Nitride (GaN) resonators is introduced and demonstrated. This metal-free transduction does not suffer from the loss mechanisms associated with more commonly used metal electrodes. As a result, this transducer can be used for both the direct interrogation of GaN electromechanical properties and the realization of high Q resonators. A 1.2 GHz bulk acoustic resonator with mechanical Q of 1885 is demonstrated, with frequency quality factor product (f·Q) of 2.3×10¹², the highest measured in GaN to date.