Optical gain in (Zn,Cd)SeZn(S,Se) quantum wells as a function of temperature

We have investigated the mechanism of stimulated emission in ZnCdSeZnSSe quantum wells through measurements of the optical gain spectrum between 77 and 270 K. We also calculated the optical gain using a model which included many-body effects and found excellent agreement with our measurements. Our results are inconsistent with an excitonic gain mechanism and we conclude that the stimulated emission arises from an electron—hole plasma in our samples. However, we find that the electron-hole Coulomb interaction is still significant at room temperature in II–VI heterostructures.