Competitive carrier interactions influencing the emission dynamics of GaAsSb-capped InAs quantum dots

The optical properties of InAs/GaAs quantum dots capped with a GaAsSb quantum well are investigated by means of power-dependent and time-resolved photoluminescence. The structure exhibits the coexistence of a type-I ground state and few type-II excited states, the latter characterized by a simultaneous carrier density shift of the peak position and wavelength-dependent carrier lifetimes. Complex emission dynamics are observed under a high-power excitation regime, with the different states undergoing shifts during specific phases of the measurement. These features are satisfactorily explained in terms of band structure and energy level modifications induced by two competitive carrier interactions inside the structure. (C) 2012 American Institute of Physics. (http://dx.doi.org/10.1063/1.4769431)