Growth and characterization of quaternary-alloy ferromagnetic semiconductor (In,Ga,Fe)Sb

TL;DR

This study reports the growth and detailed characterization of a quaternary ferromagnetic semiconductor (In,Ga,Fe)Sb with tunable properties, demonstrating its potential for spintronic devices.

Contribution

It introduces a method to systematically control lattice, electronic, and magnetic properties of (In,Ga,Fe)Sb via Ga concentration during low temperature molecular beam epitaxy.

Findings

Lattice constant varies linearly with Ga content.

Carrier type switches from n-type to p-type with increasing Ga.

Intrinsic ferromagnetism with Curie temperatures up to 120 K.

Abstract

We study the growth and properties of quaternary-alloy ferromagnetic semiconductor (FMS) (In0.94-x,Gax,Fe0.06)Sb (x = 5% - 30%, Fe concentration is fixed at 6%) grown by low temperature molecular beam epitaxy (LT-MBE).Reflection high-energy electron diffraction (RHEED) patterns, scanning transmission electron microscopy (STEM) lattice images, and X-ray diffraction (XRD) spectra indicate that the (In0.94-x,Gax,Fe0.06)Sb layers have a zinc-blende crystal structure without any other second phase. The lattice constant of the (In0.94-x,Gax,Fe0.06)Sb films changes linearly with the Ga concentration x, indicating that Ga atoms substitute In atoms in the zinc-blend structure. We found that the carrier type of can be systematically controlled by varying x, being n-type when x \le 10% and p-type when x \ge 20%. Characterizations using magnetic circular dichroism (MCD) spectroscopy indicate that the (In0.94-x,Gax,Fe0.06)Sb layers have intrinsic ferromagnetism with relatively high Curie temperatures (TC = 40 - 120 K). The ability to widely control the fundamental material properties (lattice constant, bandgap, carrier type, magnetic property) of (In0.94-x,Gax,Fe0.06)Sb demonstrated in this work is essential for spintronic device applications.