Cd0.3Zn0.7S/ZnS multiple-quantum-well strained-layer superlattices with a range of well widths can produce excitonic emissions around 3.4 eV at room temperature (RT), due to the quantum confinement of excitons in the CdZnS wells. The emission spectra of a 41 angstrom Cd0.3Zn0.7S well were extensively studied under high optical excitation. We found a non-linear dependence of the spontaneous RT exciton-emission intensity on the excitation intensity for high excitations. With increasing excitation density, the emission line moves to slightly the lower-photon energy and in addition its linewidth is broadened. A shoulder on higher-energy side of the excitonic spectrum appears above about 100 kW/cm2, which is related to an optical transition associated with a higher excited-level state of the electrons confined in the conduction-band potential well.
