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

Abstract

We investigate exciton subband transitions in a ${\mathrm{Z}\mathrm{n}\mathrm{S}\mathrm{e}/\mathrm{Z}\mathrm{n}}_{1\ensuremath{-}x}{\mathrm{Mg}}_{x}{\mathrm{S}}_{y}{\mathrm{Se}}_{1\ensuremath{-}y}$ 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 ${Q}_{c}=0.3\ifmmode\pm\else\textpm\fi{}0.1.$