Electronic structures in single pair of InAs/GaAs coupled quantum dots with various interdot spacings

The electronic structures in a single pair of InAs/GaAs coupled quantum dots (CQDs) with various interdot spacings are investigated by performing photoluminescence (PL) and photoluminescence excitation (PLE) measurements. Luminescence from the bonding (X+) and antibonding (X-) states caused by electron-wave-function coupling was observed in the micro-PL spectra of the CQDs. We indicate the contribution of the hole excited states to the PL spectra in QDs based on the results for the spectral dependence on circularly polarized light and the structures of PLE spectra. PLE spectra reveal the electronic structures of the CQD system at higher energy states where both the common excited levels due to the level sharing between the electron excited states and the individual excited levels related to the hole excited states coexist. In addition, we mention that the energy-level mixing due to the strong-wave-function coupling between two QDs influences the decoherence of the carrier relaxation processes. (c) 2006 American Institute of Physics.