ANISOTROPIC HOLE SUBBAND STATES AND INTERBAND OPTICAL ABSORPTION IN [MMN]-ORIENTED QUANTUM WELLS

摘要

Using a multiband k . p theory, we have analyzed the anisotropic hole subband states and interband optical absorption in [mmn]-oriented GaAs/AlAs quantum wells (QW's). For QW's grown in the [001] and [113] direction, the spacing of hole subbands and the slope of the subband dispersion is considerably larger than that for QW's grown in the [110] direction. Anisotropy of the dispersion is the largest for [110] grown QW's. We calculate the interband optical absorption due to free electron-hole transitions. While basic features of the absorption coefficient alpha(omega) are independent of the growth direction, we find that the in-plane anisotropy of alpha(omega) differs strongly for [110] and [113]. It is opposite in sign for heavy hole and light hole transitions. Our calculations are in good agreement with available experimental data. They indicate that in [113]-oriented GaAs/AlAs structures, the corrugation of the interfaces has a small effect on the optical anisotropy observed experimentally at the fundamental absorption edge. [References: 45]