Optical anisotropy in type-II (110)-oriented GaAsSb/GaAs quantum wells

The optical anisotropy of zinc-blende type-II GaAsSb/GaAs quantum wells (QWs) with (110) crystal orientation was investigated by using the multiband effective-mass theory. The optical matrix element for the y′([11̄0])-polarization rapidly decreases with increasing in-plane wave vector. On the other hand, in the case of the x′([001])-polarization, the optical matrix element is nearly independent of the in-plane wave vector. The optical anisotropy gradually increases with increasing carrier density. This can be explained by the fact that, at a higher carrier density, carriers occupy higher states above k||=0 and the optical matrix element for the x′-polarization becomes larger than that for the y′-polarization at high k||.