Photoluminescence excitation spectroscopy of the lasing transition in II-VI laser structures allows direct observation of the absorption edge during laser operation. We have investigated a set of Zn0.8 Cd0.2Se/ZnSe multiple quantum well structures with well widths ranging from 30 to 120 Å and the photoluminescence at low excitation levels consistently shows the n = 1 heavy hole exciton transition, while above threshold the lasing peak is observed to be red-shifted with a localization energy which is always much greater than the Stokes shift due to inhomogeneities. Excitonic absorption features can be observed up to the highest excitation energies and the localization energy for all well widths remains around 30 meV suggesting that the optical gain above lasing threshold involves exciton-LO phonon emission. © 1994.
|Number of pages||5|
|Journal||Journal of Crystal Growth|
|Publication status||Published - 2 Apr 1994|