Strain and ferroelectricity in wurtzite ScxAl1−xN materials

Abstract

Density functional theory predicts an abrupt drop in the stability, in the kinetic barrier for polarization reversal and spontaneous polarization of a ScxAl1−xN wurtzite phase, when the Sc:Al ratio approaches 50:50. The same effect is obtained by the application of a tensile strain. The resulting polarization reversal barrier correlates with experimental coercive fields, and highly textured film measurements exhibit polarization values close to the theoretically predicted ones. Film thickness below 5 nm has a significant impact on the elastic properties.