Determination of band offset using continuous-wave two-photon excitation in a ZnSe quantum-well waveguide structure

We investigate exciton subband transitions in a ZnSe/Zn1-xMgxSySe1-y multiple-quantum-well grown by molecular beam epitaxy waveguide structure by photoluminescence excitation and two-photon excitation spectroscopy. A continuous-wave two-photon absorption is realized by an efficient waveguide coupling scheme within the cryostat. From the energetic position of the 1s and 2p exciton transitions exciton binding energies of 33 and 38 meV are deduced for heavy and light-hole excitons, respectively. With these values we are able to determine the strain free and dimensionless conduction-band-offset parameter to Qc=0.3±0.1