Redistribution dynamics of optically generated charges in In ( Ga ) As ∕ GaAs self-assembled quantum dots

We investigate a quantum-dot-based field-effect device allowing selective optical charging (electrons or holes) of a sub-ensemble of InGaAs ∕ GaAs self-assembled quantum dots using resonant excitation. The dynamics of the photogenerated charge distribution is studied as a function of excitation energy and lattice temperature. Thermally activated redistribution of charge among the quantum dot ensemble is shown to occur, over a microsecond time scale, only at elevated ( T ∼ 100 K ) temperatures. An activation energy analysis demonstrates that the two-dimensional wetting layer is the main charge redistribution channel and provides information about the single-particle energy structure of the quantum dots.