Mg/sub x/Zn/sub 1-x/O: a new piezoelectric material

Piezoelectric ZnO thin films have been successfully used for multi-layer surface acoustic wave (SAW) and bulk acoustic wave (BAW) devices. Piezoelectric magnesium zinc oxide (Mg/sub x/Zn/sub 1-x/O) films, which are formed by alloying ZnO and MgO, allow for flexibility in thin film SAW and BAW device design. The piezoelectric properties can be tailored by controlling the Mg content, as well as by using Mg/sub x/Zn/sub 1-x/O/ZnO multilayer structures. In this study, ZnO and Mg/sub x/Zn/sub 1-x/O (x/spl les/0.35) thin films are grown on R-plane sapphire substrates. Their SAW properties, including velocity dispersion and piezoelectric coupling, are characterized using test devices. Data for both Rayleigh and Love wave modes, propagating parallel and perpendicular to the c-axis, are presented. In piezoelectric Mg/sub x/Zn/sub 1-x/O films, the acoustic velocity increases, whereas the piezoelectric coupling decreases with increasing Mg content.