Strong enhancement of piezoelectric constants in ScxAl1−xN: First-principles calculations

We theoretically investigate the piezoelectricity of ScxAl1−xN in the entire range of x by first-principles calculations. We find that the piezoelectric constants of wurtzite-type ScxAl1−xN significantly enhance as x increases from 0 to 0.75. However, the energy stability analyses between structure phases show that the cubic-type phases become more stable than the wurtzite-type phases at x of approximately 0.5 and higher, interfering with the ability of wurtzite-type ScxAl1−xN to realize the maximum piezoelectricity. Moreover, our study on element combination dependences on piezoelectricity in A0.5B0.5N (A = Sc, Y, La and B = Al, Ga, In) indicates that Sc, Y, and La have the strongest effect on the enhancement of piezoelectric constants in AlN, GaN, and InN, respectively.