Optical anisotropy in (1 1 0)-oriented zinc-blende GaN/AlGaN quantum wells

Optical anisotropy in (1 1 0)-oriented zinc-blende GaN/AlGaN quantum wells (QWs) was investigated using the multiband effective-mass theory. The in-plane anisotropy for a (1 1 0) orientation was observed for the x'- and y'-optical matrix elements. On the other hand, in the case of the (0 0 1)- and (1 1 1)-oriented QWs, the matrix elements that corresponded to the C1–HH1 and C1–LH1 transitions for the y'-polarization were the same as those for the x'-polarization. Also, the valence-subband structures for a (1 1 0) orientation were shown to be anisotropic along the in-plane directions, k'x and k'y. The optical anisotropy calculated for the C1–HH1 and C1–LH1 transitions gradually increased with an increasing Al composition. This is attributed to the increase in the anisotropy in the valence band structure.