Tuning optical properties of high In content InGaAs/GaAs capped InAs quantum dots by post growth rapid thermal annealing

摘要

The effect of rapid thermal annealing on InAs quantum dots (QDs) capped with In_(0.4)Ga_(0.6)As/GaAs layer has been investigated by photoluminescence (PL). An unusual red shift of the PL emission peak has been observed for an annealing temperature (T_a) of 650℃ together with a pronounced improvement of the PL from the quantum well like heterocapping layer (QW). This behavior is attributed to the strain induced phase separation of the hetero-capping alloy. However, for T_a=750℃, a blue shift of the QDs PL peak has been observed with respect to that of the as-grown sample. For this annealing temperature the PL intensity of the QW exceeds that of the QDs indicating a relatively prominent In/Ga interdiffusion. When annealed at 850℃, only the PL arising from the QW can be detected in addition to a broadened low energy side band indicating the dissolution of the QDs at that temperature.