Switchable piezoelectric transduction in AlGaN/GaN MEMS resonators

This work presents a new switching mechanism in piezoelectric transduction of AlGaN/GaN bulk acoustic resonators. A piezoelectric transducer is formed in the AlGaN, between a top Schottky electrode and a 2D electron gas (2DEG) as a second electrode. In the off state, this 2DEG can be depleted by applying a negative bias to the top electrode, suppressing transduction and reducing capacitive loading. Switchable AlGaN/GaN resonators are demonstrated from 240MHz to 3.5GHz with frequency-quality factor products up to 1.7×10¹² in air. Switching is shown in both devices with passive piezoelectric and HEMT sensing, with >19dB suppression in the off state.