Growth and magnetic properties of self-assembled (In, Mn)As quantum dots

Self-assembled In_0.79Mn_0.21As quantum dots were successfully grown on GaAs (001) substrates by low-temperature molecular beam epitaxy. Atomic force microscopy and high-resolution transmission electron microscopy confirm the formation of quantum dots. High-resolution lattice image suggests that In_0.79Mn_0.21As dots are single phase with zinc-blend structure. The dots exhibit typical ferromagnetic state at 5 K and demonstrate a Curie temperature of ∼290 K which is much higher than those of (In, Mn)As diluted magnetic semiconductor alloys ever reported. The significant increase in Curie temperature can be attributed to the much higher Mn content in the dots, and the possible enhancement of the hybridization strength between the quantum-confined holes in the dots and the itinerant holes in the semiconductor valence band.