Charged and neutral exciton complexes in individual self-assembledIn(Ga)Asquantum dots

Charged ${(X}^{*})$ and neutral (X) exciton recombination is reported in the photoluminescence spectra of single In(Ga)As quantum dots. Photoluminescence excitation (PLE) spectra show that the charged excitons are created only for excitation in the barrier or cladding layers of the structure, consistent with their charged character, whereas the neutral excitons in addition show well-defined excitation features for resonant excitation of the dots. The PLE spectra for X and $X^{*}$ exhibit a clear anticorrelation in the region of the wetting layer transition, showing that they compete for photocreated carriers.