Piezoelectricity of ordered (Ga0.5In0.5)N alloys

First-principles calculations are performed to compare the e33 and e31 piezoelectric coefficients of GaN and InN with those of the (Ga0.5In0.5)N alloy exhibiting an alternation of Ga and In planes along the c axis. The magnitude of e33 and e31 in the ordered alloy is found to be (15%–28%) smaller than the magnitude of the corresponding coefficients resulting from the compositional average over the GaN and InN parent compounds. The microscopic origins for this downward deviation of piezoelectricity from a linear behavior with composition are revealed and discussed.