Effects of Sc Composition and Lattice Constraint on Polarization Switching of Sc _<i>x</i> Al _{1− <i>x</i>} N Alloys: A First‐Principles Study

Herein, investigations for clarifying the effects of Sc composition and lattice constraint on polarization switching of Sc x Al 1− x N alloys by means of first‐principles calculations are presented. The calculations for polarization‐switching energy barriers, using the nudged‐elastic band technique in Sc 0.125 Al 0.875 N, Sc 0.25 Al 0.75 N, and Sc 0.375 Al 0.625 N alloys in wurtzite structure, demonstrate that homogeneous switching with low energy barrier is possible for Sc x Al 1− x N alloys with high Sc concentrations. Furthermore, the calculations assuming homogeneous switching suggest that the energy barrier deceases with Sc composition and is reduced by the lattice constraint of substrate which induces tensile strain in Sc x Al 1− x N alloys. The difference in energy barriers depending on Sc composition and lattice strain originates from the formation fivefold‐coordinated Sc atoms as well as the contribution of lattice strain in the initial/final state as well as the transition state during polarization switching. The calculated results offer some insights for understanding the polarization switching in Sc x Al 1− x N alloys which can be controlled by Sc composition and lattice constraint of growth substrate.