Abstract
We report the structural and magnetic properties of the Fe-doped GaSb quantum dots (QDs) (nominal Fe concentration x = 4.7%–16.6%) grown on GaAs (001) substrates by molecular beam epitaxy. The QDs with nanometer-scale dimensions consist of two areas with different crystal structures, a zinc-blende GaAsSb wetting layer and a new phase of FeGaSb alloy that has a simple cubic lattice. The size and distribution of the QDs depend on the Fe concentration, as revealed by atomic force microscopy. Magnetic force microscopy measurements at zero applied magnetic field show the presence of ferromagnetism in the QDs at room temperature with an easy axis in the 1¯10 direction, which is consistent with magnetometry measurements. The Curie temperature in these QDs is very high (>400 K), which is promising for spintronic applications at room temperature.
Highlights
QDs equipped with ferromagnetism are very promising for low-power spintronic devices or high-density information storage3 because they are known to have higher Curie temperatures (TC) and more sensitive responses to external control means such as the electric field than their bulky counterparts
Using molecular beam epitaxy (MBE), Mn-doped QDs have been realized in III–V and group-IV semiconductors
The main reason is because scitation.org/journal/apm their bulk counterparts, Mn-doped ferromagnetic semiconductors (FMSs), show TC much lower than room temperature
Summary
Quantum dot (QD) structures of semiconductors have been extensively studied because of their potential to be used in high-performance devices, such as highly efficient semiconductor lasers1 or qubit logic gates.2 In particular, QDs equipped with ferromagnetism are very promising for low-power spintronic devices or high-density information storage3 because they are known to have higher Curie temperatures (TC) and more sensitive responses to external control means such as the electric field than their bulky counterparts.4,5 In ferromagnetic MnAs QDs By using Fe as the magnetic dopant, a new class of high-TC Fe-doped III–V FMSs has been created.20–30 In particular, doping Fe into GaSb thin films at a low growth temperature resulted in the formation of the p-type FMS (Ga1−x,Fex)Sb28–30 with roomtemperature ferromagnetism.
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