Annealing induced inversion of quantum dot fine-structure splitting

By mapping the anisotropy fine-structure splitting of the exciton ground state in the luminescence spectra of individual Cd x Zn 1 − x Se quantum dots, treated by postgrowth rapid thermal annealing (TA), a preferred in-plane axis of Zn-Cd interdiffusion has been identified. In particular, a TA-induced sign reversal of the fine-structure splitting is demonstrated. Additionally, in the annealed quantum dots, the binding energy of the charged exciton reaches a maximum value when the fine-structure splitting is minimum. The studies demonstrate that by postgrowth thermal annealing the symmetry of individual quantum dot can be modulated.