DEPENDENCE OF EXCITON LINEWIDTH ON THE COMPOSITION OF ZNXMG1-XSE LAYERS GROWN BY MBE

This work deals with the study of the photoluminescence and reflectivi ty properties of ZnxMg1-xSe epilayers grown by molecular beam epitaxy on (001)GaAs and (111)ZnTe substrates. The photoluminescence spectra o f ZnxMg1-xSe layers grown on GaAs and ZnTe substrates are dominated by blue emission bands. The energetical positions and relative intensiti es of the bands depend on Mg contents in the epilayers. The shift of t he maxima of blue emission toward higher photon energies and a simulta neous steep increase in the linewidth with an increase in Mg concentra tion are observed. A small amount of Mg added to ZnSe leads to a sharp increase in the linewidth from 2 meV in pure ZnSe layer grown on GaAs substrate to about 180 meV in Zn0.78Mg0.22Se.