LAUSR

Photoluminescence properties of InAs/GaAs1−xSbx quantum dots (QDs) are investigated with respect to the Sb-composition of x = 0, 0.15, and 0.25. The QDs demonstrate a type-II band alignment for x = 0.15 and 0.25. In contrast, with well-defined InAs/GaAs QDs, the InAs/GaAs1−xSbx QDs exhibit overlapping spectral features with increasing laser excitation intensity, which are determined to be the result of different carrier recombination routes, including both type-I and type-II pathways. Our investigation indicates that the optical behavior and the carrier dynamics in these InAs/GaAs1−xSbx QDs are much more complicated than in the InAs/GaAs QD counterparts. It provides very useful information for understanding the band structure and carrier dynamics of type-II InAs/GaAs1−xSbx QDs.