Magneto-spectroscopy of ordered arrays of magnetic semiconductor quantum wires

Hexagonally ordered arrays of quantum wires of the diluted magnetic semiconductor Cd1-xMnxS (0 < x < 0.2) have been obtained by incorporating the semiconductor alloy into the ordered win-like pores of mesoporous silica hosts (MCM-41). Electron paramagnetic resonance measurements indicate that the crystalline structure of the Cd1-xMnxS quantum wires changes from zincblende to wurtzite with increasing x. Photoluminescence and photoluminescence excitation spectroscopy have been performed at liquid helium temperatures in external magnetic fields up to 7.5 T. The photoluminescence studies of the transitions within the half-filled Mn 3d-shell reveal the existence of at least two kinds of Mn-centres with different crystal fields. A blue shift of more than 200 meV of the absorption edge of the Cd1-xMnxS wires compared to that of bulk material is found due to the lateral quantum confinement in the nanowires. In addition, the p-d exchange-induced bowing of the band gap with x is enhanced in the wire structures due to the confinement-induced shift of the lowest valence band state towards the Mn 3d-states. (C) 2001 Elsevier Science B.V. All rights reserved.