Piezoelectric coupling constant in epitaxial Mg-doped GaN

Abstract

Although surface acoustic wave (SAW) devices using quartz and LiNbO3 have proven highly successful, manufacturability would be considerably eased if SAW devices could be readily integrated with semiconductor devices. In a recent paper, Lee et al. proposed Mg-doped epitaxial GaN as suitable for SAW devices integrated with other III-V materials. The piezoelectric constant, or electromechanical coupling factor (k2), is one important parameter determining the acoustic behavior of a material. A large k2 eases the design of wide-bandwidth low-loss SAW transducers. The piezoelectric constants are also of great interest in the design of strained-layer devices. For Mg-doped GaN, Lee et al. found k2 = (4.3 plusmn 0.3)%. If confirmed, this would represent one of the highest values of k2 ever reported, and would revolutionize the design of acoustic devices integrated with III-V materials, since other III-V materials have much smaller k2. For example, GaAs has k2 = 0.04%