A stimulated emission effect has been studied in Zn1-x Cd x Se/ZnSe (x=0.3) multiquantum wells (MQWs) with the well width of 7 to 70 Å. The luminescence spectrum of the quantum well (QW) exciton at 4.2 K is shifted from the absorption spectrum by 10-12 meV to the lower-energy side. The deviation of the peak energy of the luminescence shows that the excitons in the MQW are inhomogeneously broadened by the monolayer fluctuation of the QW width. Stimulated emission is observed in the low-energy shoulder of the exciton luminescence band, which shifts to lower energies with increasing excitation intensity. The gain process is explained by the exciton-exciton scattering in the MQWs.

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Photoluminescence in Zn1-x Cd x Se/ZnSe multi-quantum wells (MOWs) have been studied under various excitation intensities and compared with the absorption spectrum. A stimulated emission by the quantum well (QW) excitons appears shifted by 8 meV from the peak of the spontaneous emission band at an excitation power density of 0.25 MW/cm2. Above 1 MW/cm2 the emission spectrum broadens and shifts further to the lower energy side. The observed stimulated emissions are interpreted by the recombination due to the exciton-exciton scattering and by the electron hole plasma recombination in the MQWs.