Tight-binding analysis of the optical matrix element in wurtzite- and zincblende-GaN quantum wells

The polarization dependence of the optical matrix element in wurtzite- and zincblende-GaN quantum wells (QWs) is theoretically investigated, based on the sp(3) tight-binding model which takes into account the spin-orbit interaction and crystal field splitting. The optical matrix element in wurtzite-GaN QWs has no dependence on the wave number due to its anisotropy along the c axis. We also show that the optical matrix element for the conduction-light hole transition in wurtzite-GaN QWs is about three times larger than that for bulk zincblende GaN. These results suggest that wurtzite GaN will be useful for light emitting devices due to its apparent high optical transition.