Excitonic properties of ZnS quantum wells - art. no. 155321

The excitonic properties of cubic ZnS quantum wells in ZnM-S are studied by reflectivity and magnetooptics. A remarkable improvement in the quality of the samples grown by molecular-beam epitaxy on GaP substrates has allowed the observation of heavy- and light-hole exciton transitions with values fo r the full width at half maximum as narrow as 5 meV. The 2s state of the he avy-hole exciton is identified and exciton binding energies of as high as 5 5 meV are deduced, indicating that for quantum wells narrower than 3.5 nm t he exciton-LO phonon scattering can be suppressed. Zeeman splittings of the order of 10 meV for both the light- and heavy-hole exciton transitions app ear in magnetoreflectivity spectra in magnetic fields up to 54 T. Large lig ht-hole exciton g values of the order of 4 for all quantum wells are obtain ed due to the light hole being the uppermost valence band in these tensile- strained quantum wells. A strong reduction in the diamagnetic shifts for na rrow wells is observed due to increasing quantum confinement.