Femtosecond dynamics of carrier relaxation and exciton formation in Zn1-XCdXSe/ZnSYSe1-Y multiple-quantum-well structures

We have investigated the intraband carrier relaxation and exciton formation dynamics in a Zn0.88Cd0.12Se/ZnS0.12Se0.88 multiple quantum well using a f emtosecond pump and probe method. We have analyzed the spectral shape Of th e exciton absorption band, and obtained the temporal change of the homogene ous broadening. The homogeneous width of the heavy-hole exciton absorption shows the delayed rise of similar to 1 ps and the two-component decay with decay times of similar to 10 ps and similar to 100 ps. These behaviors are dependent on temperature and pumping wavelength. The temporal behavior of t he additional broadening has been explained by the numerical simulation, ta king into account the intraband carrier relaxation and the exciton formatio n.