Quantum dots as a sensitive tool to monitor charge

The excitonic photoluminescence spectra reveal an abrupt change of the charge-state of single In(Ga)As/GaAs quantum dots, for a certain transformation when the excitation energy below the barrier band gap. This transform energy is dependent on the thickness of the underlying wetting layer and the crucial energy is associated with an optical transition involving an energy level of the wetting layer. The effect is proposed to be used as a tool, not only to monitor charge in quantum dots in order to study related phenomena, but also to gain new insight in the electronic structure of strained In(Ga)As/GaAs layers by using the quantum dots as charge-probes.