Carrier dynamics and lasing in graded index separate confinement Zn1-xCdxSe quantum wells

We investigated graded index separate confinement Zn1-xCdxSe/ZnSe heterostructure on In1-xGaxAs (100) substrate by using high excitation and time-resolved photoluminescence spectroscopies. The carrier dynamics in the graded barriers and the quantum well is investigated. Our measurements show the filling of quantum well states in about approximate to 30 ps by depopulation of higher energy states, and the reduction of the decay time of the photoluminescence at the onset of lasing. Lasing threshold is found to be reduced by about one order of magnitude with respect to samples without graded index profile. The threshold for lasing was in the range from approximate to 1 to 145 kW/cm(2) when the sample temperature was varied from 10 to 300 K. In short cavities we observed lasing from excited energy states.