Strain and built-in potentials in wurtzite polar and non-polar InGaN/GaN quantum wires

Strain and built-in potential distributions in c- and a-plane wurtzite (WZ) InGaN/GaN quantum wires (QWRs) are investigated using theory of continuum elasticity. The position dependence of ϵx′x′ and ϵz′z′ along x^′-axis in a-plane QWR is shown to be similar to that along z-axis of ϵ_zz and ϵ_xx in c-plane QWR, respectively. ϵx′x′ along x^′-axis in a-plane QWR suddenly change from compressive to tensile strain at the boundary between the QWR and the barrier. ϵz′z′ also experiences a relaxation along x^′-axis and continuously decreases with increasing distance. The decrease in the built-in potential is observed in the nonpolar QWR, which could be attributed to crystal orientation effects on piezoelectric and elastic stiffness constants. We expect that the internal efficiency can be improved by using nonpolar a-plane QWRs.