Coexistence of type-I and type-II band alignments in In0.46Al0.54As/ Ga0.46Al0.54As self-assembled quantum dots.

Optical properties of In_0.46Al_0.54As/ Ga_0.46Al_0.54As quantum dots (QDs) have been investigated by photoluminescence (PL). At a low temperature of 8K, the PL peak energy blue-shifts 44 meV and the linewidth broadens by 21 meV as the excitation intensity increases by four orders of magnitude. As the temperature increases, the QD spectra demonstrate a fast redshift and narrowing from 35 K. These observations have been explained by the type-II nature of QDs and the lateral carrier transfer due to electronic coupling between neighboring QDs. A special double exponential decay behavior indicates the coexistence of type-I and type-II band alignment in this QD sample. [ABSTRACT FROM AUTHOR]