Fundamental studies of excitonic properties in II-VI semiconductors

The optical properties of wide bandgap 11-VI semiconductors are governed by excitons, bound electron hole pairs, over a wide range of temperatures and the main mechanism of exciton ionisation at room temperature is scattering with LO phonons. The suppression of this scattering process is of interest from a fundamental point of view as well as for potential device applications. Fundamental properties of two new materials systems, ZnSe quantum wells in MgS and ZnS quantum wells in ZnMgS, are investigated by a variety of spectroscopic techniques. New material parameters such as bandgaps and deformation potentials are obtained by fitting reflectivity and photoluminescence spectra and magneto-optical studies provide a direct measurement of exciton binding energies in these materials that are compared with numerical calculations. The interaction of excitons with LO phonons is investigated in these systems, where it is possible to achieve a difference in 1s to 2s exciton binding energies larger than the LO phonon, in temperature dependent absorption experiments. (author)Available from British Library Document Supply Centre-DSC:DXN042528 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo