Low loss surface acoustic wave SAW devices based on Al1-xMxN (M=Cr, Y, Sc) thin films

摘要

In this work, the coupling-of-modes (COM) approach and P-matrix model are used to investigate the frequency response of a two-port surface & nbsp;acoustic wave & nbsp;SAW delay line based on & nbsp;piezoelectric & nbsp;AlN & nbsp;doped with & nbsp;transition metals. The elastic and & nbsp;piezoelectric properties & nbsp;of Al1-xMxN (M & nbsp;=& nbsp;Cr, Y, Sc)& nbsp;thin films & nbsp;are theoretically investigated using the & nbsp;density functional theory & nbsp;(DFT). The results revealed that doping with Cr at x & nbsp;=& nbsp;25% increases the piezoelectric response up to 288% compared to pure AlN, which is better than results obtained by others transition metal (Sc, Y)& nbsp;dopants. The frequency response of a two-port SAW delay line IDT/Al1-xMxN (M & nbsp;=& nbsp;Cr, Y, Sc)/Si shows that increasing dopants (Cr, Y and Sc) concentration considerably enhances the insertion loss and causes a significant shift down in the operating frequency. The obtained results are helpful in the design and fabrication of acoustic sensors and resonators with improved performances.