OPTICAL-PROPERTIES OF SINGLE MAGNETIC QUANTUM-WELLS IN AN EXTERNAL MAGNETIC-FIELD

Photoluminescence measurement performed on magnetic Cd1-xMnxTe quantum wells surrounded by Cd1-yMnyTe barriers (y > x), grown by M. B. E. an d subjected to an external magnetic field, are described. The observed excitation spectra are shown to be in agreement with calculations of exciton energies based on the envelope function approximation. Charact eristic features of the samples are either the large (approximately 18 meV) Stokes' shift and/or the width of the P. L. lines (approximately 11meV). These are to be contrasted with the values in comparable non-m agnetic wells of CdTe where the Stokes' shift is typically less than 1 meV and the halfwidth of the P. L. lines is less than 1 or 2 meV. Arg uments are presented which show that these observations, together with their magnetic field dependence, are consistent with the formation of magnetic polarons. The photoluminescence emission also contains a ban d attributed to excitons bound to donors. It is observed experimentall y that this donor-bound exciton emission disappears with increasing ma gnetic field. A theoretical interpretation of the observed properties of this band is given in terms of excitons bound to donors which are s ituated at different positions in the well and barrier region.