Stimulated blue emission processes in Zn1−xCdxSeZnSe multi-quantum wells

Stimulated emissions in Zn1−xCdxSeZnSe multi-quantum well (MQW) structures have been studied under high optical excitation in the temperature range 4.2–300 K. With increasing the excitation intensity, the stimulated emission at low temperatures shows a red shift of the peak energy and a quadratic dependence of the intensity on the excitation intensity. The observed stimulated emission process is interpreted by exciton-exciton scattering in the MQWs. At room temperature, highly excited MQWs show a markedly broadened emission, the intensity of which is in proportion to the excitation intensity. We attribute the emission process to electron-hole plasma (EHP) recombination. The observed emission spectra are in good agreement with calculations by using models of exciton-exciton scattering and EHP recombination. The stimulated emission mechanisms elucidated in the present study are closely related to those taking place in ZnSe-based blue laser diodes.