  Using three-dimensional k.p calculation including strain and
piezoelectricity, we showed that the size of the quantum dot (QD) in the growth
direction determines the influence of the (In,Ga)As capping layer on the
optical properties of [11k] grown InAs QDs, where k=1,2,3. For flat dots,
increase of In concentration in the capping layer leads to a decrease of the
transition energy, as is the case of [001] grown QDs, whereas for large dots an
increase of the In concentration in the capping layer is followed by an
increase of the transition energy up to a critical concentration of In, after
which the optical transition energy starts to decrease.
