Optical Detection of the Charging of InAs Quantum Dots with Different Backgate Configurations

ABSTRACTWe investigate self-assembled InAs quantum dots by photoluminescence (PL) and capacitance spectroscopies. By employing specially designed backelectrode configurations, we can control the number of electrons, which are confined in the quantum dots. With PL experiments we study the dependence of the s-s transition on the electron occupation of the quantum dots. We observe a characteristic redshift of the s-s transition when the s-shell is filled with electrons. However, if the p-shell of the quantum dots starts to fill, the samples with different backelectrode configurations show a different behavior. In one type of samples, the signal stays redshifted, while in the other it blueshifts again. The effect can be explained by different hole capture processes in both types of samples.