Temperature dependent optical properties of stacked InGaAs/GaAs quantum rings

In this paper we describe the results of temperature dependent photoluminescence intensity and decay time measurements of In(Ga)As/GaAs quantum rings where the depth of barrier is varied from sample to sample. The activation energy found for the reduction of the exciton decay time as a function of the temperature is approximately half the value of the thermionic escape energy of excitons. The temperature dependant behaviour is ascribed to the carriers lost via the excited state to the WL.The time resolved PL study indicates that thermal escape mechanisms is not so affected by reducing the spacer thickness, but it's influenced essentially by the excited state recombination.