Modeling self-assembled quantum dots by the effective bond-orbital method

Systematic studies of the electronic and optical properties of InAs/GaAs self-assembled quantum dots are performed via the effective bond-orbital model employed with an efficient algorithm. Four different sizes of pyramid and one truncated pyramid with (110) sidewall quantum dots (QD's) are studied. Microscopic strain distributions have been taken into account via valence-force-field model. We find that charge density distribution and optical properties are quite different with and without including the piezoelectric effect. Without the piezoelectric effect, variation in dot size can lead to a substantial change in the strain distribution and hence the charge distribution, which gives rise to qualitatively different optical properties. Including the piezoelectric effect, hole-state wave functions are stretched along the [1 (1) over bar0] axis and hence interband optical transitions become polarized along [1 (1) over bar0] and the polarization ratio increases with dot size. Our results of the energy levels and optical polarization are in good agreement with experimental and other theoretical results. Our calculations of truncated pyramid QD's indicate that the truncation of the pyramid tip has a negligible effect on the photoluminescence properties of QD's.