Formation of negatively-charged excitons and charge transfer in quantum dots

Negatively-charged excitons were assigned in AlGaAs/GaAs modulation-doping structures (MOD) with AlInAs quantum. Peaks observed at zero bias decreased or disappeared with increasing negative bias and new peaks were seen to grow up. These two-group peaks were reasonably assigned respectively as negatively-charged excitons and neutral excitons, since the excess electrons were considered to be extracted from the dot region and formation of negatively-charged excitons was suppressed under high bias.