Unusual optical properties of type-II InAs/GaAs0.7Sb0.3 quantum dots by photoluminescence studies

The optical properties of type-II InAs/GaAs0.7Sb0.3 quantum dots (QDs) were investigated by photoluminescence (PL). It is found that the peak position of PL spectra exhibits a significant blueshift under a moderate excitation level. The observed blueshift can be well explained by the band bending effect due to the spatially separated photoexcited carriers in a type-II band alignment. We also found that the PL spectra exhibit a strong in-plane polarization with a polarization degree up to 24%. The observed optical anisotropy is attributed to the inherent property of the orientation of chemical bonds at InAs/GaAs0.7Sb0.3 heterointerfaces.