Strong electrically tunable exciton $g$ factors are observed in individual (Ga)InAs self-assembled quantum dots and the microscopic origin of the effect is explained. Realistic eight-band $\mathbf{k}·\mathbf{p}$ simulations quantitatively account for our observations, simultaneously reproducing the exciton transition energy, dc Stark shift, diamagnetic shift, and $g$ factor tunability for model dots with the measured size and a comparatively low In composition of $x_{\text{In}}~35\%$ near the dot apex. We show that the observed $g$ factor tunability is dominated by the hole, with the electron contributing only weakly. The electric-field-induced perturbation of the hole wave function is shown to impact upon the $g$ factor via orbital angular momentum quenching, with the change of the In:Ga composition inside the envelope function playing only a minor role. Our results provide design rules for growing self-assembled quantum dots for electrical spin manipulation via electrical $g$ factor modulation.

• Received 22 October 2010

DOI:https://doi.org/10.1103/PhysRevB.83.161303