“…Aluminum nitride (AlN), as one of the III-nitrides, has a wide bandgap, high acoustic velocity, high electrical resistivity, excellent piezoelectricity, good thermal and chemical stability as well as friendly compatibility with traditional IC fabrication process [1,2]. Due to these outstanding properties, AlN has been widely employed to manufacture electrodevices, such as energy harvesting devices [3,4], surface acoustic wave (SAW) devices [5][6][7], thin film bulk acoustic resonators (FBAR) [8,9], and Lamb wave devices [10], all of which have found their applications in power generation, signal processing and sensing.…”