Le Journal de Physique IV 03 (1993) C5-397-C5-400
Optical properties of single magnetic quantum wells in an external magnetic fieldS. WESTON1, T. STIRNER1, P. HARRISON1, J.E. NICHOLLS1, W.E. HAGSTON1 and D.E. ASHENFORD2
1 Department of Applied Physics, University of Hull. HU6 7RX, U.K.
2 Engineering, Design and Manufacture, University of Hull. HU6 7RX, UK.
Photoluminescence measurement performed on magnetic Cd1-xMnxTe quantum wells surrounded by Cd1-yMny Te barriers ([MATH]), grown by M. B. E. and 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. Characteristic features of the samples are either the large ([MATH]18meV) Stokes' shift and/or the width of the P. L. lines ([MATH]11meV). These are to be contrasted with the values in comparable non-magnetic 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. Arguments 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 band attributed to excitons bound to donors. It is observed experimentally that this donor-bound exciton emission disappears with increasing magnetic field. A theoretical interpretation of the observed properties of this band is given in terms of excitons bound to donors which are situated at different positions in the well and barrier region.
© EDP Sciences 1993