Structural, morphological, and magnetic characterization of In1−xMnxAs quantum dots grown by molecular beam epitaxy

Abstract

In this paper, we present a method to order low temperature (LT) self-assembled ferromagnetic In1−xMnxAs quantum dots (QDs) grown by molecular beam epitaxy (MBE). The ordered In1−xMnxAs QDs were grown on top of a non-magnetic In0.4Ga0.6As/GaAs(100) QDs multi-layered structure. The modulation of the chemical potential, due to the stacking, provides a nucleation center for the LT In1−xMnxAs QDs. For particular conditions, such as surface morphology and growth conditions, the In1−xMnxAs QDs align along lines like chains. This work also reports the characterization of QDs grown on plain GaAs(100) substrates, as well as of the ordered structures, as function of Mn content and growth temperature. The substitutional Mn incorporation in the InAs lattice and the conditions for obtaining coherent and incoherent structures are discussed from comparison between Raman spectroscopy and x-ray analysis. Ferromagnetic behavior was observed for all structures at 2 K. We found that the magnetic moment axis changes from [110] in In1−xMnxAs over GaAs to [1-10] for the ordered In1−xMnxAs grown over GaAs template.