EXCITONIC PROPERTIES IN ZN1-XCDXSE ZNSE MULTIQUANTUM-WELL STRUCTURES BY ONE-PHOTON AND 2-PHOTON SPECTROSCOPY/

A detailed investigation of excitonic states by means of one- and two- photon absorption photoluminescence excitation spectroscopy in Zn1-xCd xSe/ZnSe multi-quantum wells is reported. Ground state and excited hea vy- and light-hole excitons associated with the n=1,2 subbands have be en selectively probed exploiting the different selection rules governi ng one- and two-photon absorption processes. Experimental exciton tran sition energies are found to be in good agreement with theoretical pre dictions when strain and confinement effects are included. The compari son between experiments and theory allowed us to single out a well def ined set of band parameters and to gauge the band-offsets in these het erostructures. Furthermore, the absorption band edge clearly evident i n the two-photon absorption photoluminescence excitation spectra allow ed us to directly measure excitonic binding energies with good accurac y. (C) 1996 American Institute of Physics.