Band-edge exciton transitions temperature in multiple stacked self-assembled (In1-xMnx)As quantum dot arrays

Multiple stacked self-assembled (In(1-)xMn(x))As quantum-dot (QD) arrays were grown on GaAs (100) substrates by using molecular-beam epitaxy with a goal of producing (In1-xMnx)As QDs with a semiconductor phase and a high ferromagnetic transition temperature (T-c). Atomic force microscopy, magnetic force microscopy, high-resolution transmission electron microscopy, and energy dispersive X-ray fluorescence measurements showed that crystalline multiple stacked (In0.84Mn0.16)As with symmetric single-domain particle were formed on GaAs substrates. Near-field scanning optical spectroscopy spectra at 10 K for the (In0.84Mn0.16)As multiple stacked QDs showed that the band-edge exciton transitions were observed. The magnetization curve as a function of the magnetic field at 5 and 300 K indicated that the multiple stacked (In0.84Mn0.16)As QDs were ferromagnetic, and the magnetization curve as a function of the temperature showed that the T-c was as high as 400 K. These results provide important information on the optical and magnetic properties for enhancing the T-c of (In1-xMnx)As-based nanostructures. (C) 2005 Elsevier Ltd. All rights reserved.