Splitting of excitons and biexcitons in coupled InAs quantum dot molecules

Coupling in laterally coupled InAs quantum dot molecules has been observed by conventional microscopic photoluminescence spectroscopy. At low excitation intensity, splitting of exciton emission is observed, and this is ascribed to recombination of bonding and antibonding states when two quantum dots are coupled. With increasing excitation intensity, splitting of biexciton emission because of coupling is observed on both sides of the exciton peaks. The splitting of both exciton and biexciton peaks increases with increasing energy, which implies a large wave function overlap at high energy.