2-PHOTON ABSORPTION-SPECTROSCOPY IN ZNSE ZNSSE STRAINED-LAYER SUPERLATTICES/

We report two-photon absorption photoluminescence excitation (TPA-PLE) measurements in ZnSe/ZnSSe strained-layer superlattices (SLS). Polari zation-dependent selection rules are observed in TPA spectra depending on the direction of the exciting field with respect to the growth axi s of the SLS. Experimental exciton transition energies have found to b e in good agreement with theoretical predictions considering strain an d confinement effects. Furthermore by means of comparative non-linear technique the TPA coefficient has been measured at different energies and compared with theoretical predictions including quasi-bidimensiona l excitonic effects. A satisfactory agreement has been shown for the o verall spectral behaviour and in some cases also for the TPA coefficie nt values.