Tapered Phononic Crystal sawresonator in GaN

This paper presents a new Phononic Crystal (PnC) resonator design in which a tapered PnC is used to confine a 970 MHz SAW resonance in a GaN-on-Si platform. Like other SAW resonator designs, the proposed resonator eliminates the release step common to most MEMS devices, leading to higher yield and simpler design and packaging. However, the use of a tapered PnC reflector in this work (Fig. 1) reduces the footprint of SAW resonators by > 100× relative to conventional metal grating reflectors while maintaining high Q. A 3.5× improvement in Q is experimentally demonstrated relative to resonators with uniform PnC reflectors of comparable dimensions. These devices can be integrated seamlessly with GaN MMIC technology.