AlN and GaN layers deposited on sapphire or silicon substrates: theory and experiment

As the operating frequencies of telecommunication systems increase, surface acoustic wave (SAW) devices would benefit from the propagation on "high velocity" substrates such as sapphire or [100] silicon. However, the excitation of SAW on such materials requires additional piezoelectric layers, such as AlN or GaN, deposited atop their surface. This paper reports on first theoretical and experimental results with such material combinations.