We present a spectroscopic study of single quantum dot molecules (QDMs) formed by two closely stacked In0.5 Ga0.5 As layers. The exciton fine structures as well as direct and indirect excitonic species associated with QDMs were identified by power dependent and polarization resolved microphotoluminescence measurements. As the temperature was increased, a directional energy transfer between the direct and indirect excitons in single QDMs was observed. A rate-equation model was developed to explain our data. We show that a phonon-assisted nonresonant tunneling of the hole between the two adjacent dots is responsible for such directional energy transfers in QDMs.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - 13 Jun 2008|