Photoluminescence of Cd1-xMnxTe-CdTe multiple-quantum-well structures and superlattices in a magnetic field.

Abstract

The photoluminescence of ${\mathrm{Cd}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Mn}}_{\mathrm{x}}$Te-CdTe multiple-quantum-well structures and superlattices in magnetic fields up to 15 T has been studied in both emission and excitation. The samples were prepared by molecular beam epitaxy with use of growth rates of 0.2--0.8 A\r{}/sec and substrate temperatures of 300--325 \ifmmode^\circ\else\textdegree\fi{}C. Luminescence spectra were obtained for samples with different CdTe quantum-well layer thicknesses ${L}_{Z}$ and different Mn concentrations in the ${\mathrm{Cd}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Mn}}_{\mathrm{x}}$Te barrier layers. The Mn concentration determines both the depth of the conduction-band quantum wells and the strain in the two types of layers. Application of a magnetic field provided additional information on the magnetic interactions in this system. The luminescence spectra of shallow-quantum-well samples contain sharp (1--2 meV) exciton lines. In contrast to this, the luminescence spectra of samples having deep quantum wells are dominated by a single broad peak (16--40 meV), which we associate with interface states.