Magneto-spectroscopy of ordered arrays of magnetic semiconductor quantum wires

Hexagonally ordered arrays of quantum wires of the diluted magnetic semicon ductor Cd1-xMnxS (0 < x < 0.2) have been obtained by incorporating the semi conductor alloy into the ordered win-like pores of mesoporous silica hosts (MCM-41). Electron paramagnetic resonance measurements indicate that the cr ystalline structure of the Cd1-xMnxS quantum wires changes from zincblende to wurtzite with increasing x. Photoluminescence and photoluminescence exci tation spectroscopy have been performed at liquid helium temperatures in ex ternal magnetic fields up to 7.5 T. The photoluminescence studies of the tr ansitions within the half-filled Mn 3d-shell reveal the existence of at lea st two kinds of Mn-centres with different crystal fields. A blue shift of m ore 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 th e nanowires. In addition, the p-d exchange-induced bowing of the band gap w ith x is enhanced in the wire structures due to the confinement-induced shi ft of the lowest valence band state towards the Mn 3d-states. (C) 2001 Else vier Science B.V. All rights reserved.