MAGNETOOPTICAL STUDY OF HEAVY-HOLE AND LIGHT-HOLE EXCITONS IN CDTE/(CD, MN)TE SINGLE QUANTUM-WELLS

We report experimental and theoretical investigations of excitons in CdTe/Cd1-xMnxTe single quantum wells with high manganese content x = 0.20 and various well widths. The Zeeman splitting of the excitonic transitions is measured by photoluminescence excitation in an external magnetic field up to 7.5 T. We have developed an extended model describing the Zeeman splitting of quantum well excitons, including the exchange interaction, the intrinsic g-factor of electron and hole and the Coulomb interaction in an external magnetic field. The calculation allows the interpretation of both light- and heavy-hole excitons. From the Zeeman splittings we deduce the natural valence band offset Q(V) in the strain-free limit. Due to the small valence band offset, a magnetic field-induced type I to type II transition occurs for the heavy-hole state. We show that the main contribution to this transition comes from the excitonic effects, which nearly compensate for the large decrease of the confinement energy. In wide quantum wells with high manganese content we found an enhanced paramagnetic exchange interaction, which is discussed in terms of interface effects.