Abstract :
Multiple stacked self-assembled (In1−xMnx)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 (Tc). 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 Tc was as high as 400 K. These results provide important information on the optical and magnetic properties for enhancing the Tc of (In1−xMnx)As-based nanostructures.
