Tuning of g-factor in self-assembled In(Ga)As quantum dots through strain engineering -: art. no. 205301

We have investigated the effect of strain on the g-factors of self-assembled In(Ga)As dots by single-dot spectroscopy and an eight-band effective mass calculation taking into account the influence of the strain distribution and the Zeeman effect. The strain and its distribution in and around the quantum dots are varied by thermal annealing or by introducing an strain reducing layer. Thermal annealing produces a graded composition profile due to In-Ga intermixing. The graded composition profile reduces both hydrostatic and biaxial strain near the bottom of the dot; and enhances them near the top. This strain variation results in a large reduction of the absolute hole g-value and a small reduction of the absolute electron g-value. On the other hand, the covering of InAs dots with an In0.17Ga0.83As strain reducing layer decreases mainly the hydrostatic strain. The variation of the strain and the band edge alignment enhance the electron g-value while they reduce the hole g-value. These results should provide insights to control the g-factors in pyramidal self-assembled dots.