A Quaternary Magnetic Alloy Semiconductor (Ga,In,Mn)N

Abstract

The physical properties of the III-N-based quaternary magnetic alloy semiconductor (Ga,In,Mn)N prepared by RF-plasma-assisted molecular beam epitaxy are reported. Epilayers are either highly resistive or n-type, and exhibit paramagnetic behavior. Magnetic circular dichroism (MCD) spectra show the presence of spin-polarized band-to-band transition (3–3.5 eV), the Mn2+ d-d * intra-ionic transition (∼2.3 eV), and the transition associated with rather deep Mn acceptor level (∼1.7 eV). Green-emission band (∼2.3 eV) is observed in photoluminescence experiments for In-containing samples. Near-band-edge emission (∼3.4 eV) is also obtained from multiple-quantum-well structures. n-type samples show negative magnetoresistance at RT, from which strong s,p-d spin exchange interaction is inferred.

Magneto-Optical Studies of Ferromagnetic Cr-Doped GaN Films Grown by Molecular Beam Epitaxy

“…Similar results were also obtained in Mn-doped GaN. 18,20) A clear MCD peak around the GaN band gap shows that this paramagnetic material should have a common band structure with GaN. Thus, we can conclude that the sample contains a paramagnetic DMSs (Ga,Cr)N. Disagreement between the ferromagnetic SQUID data and the paramagnetic MCD data suggests strongly that Cr-doped GaN itself is not responsible for the observed ferromagnetism, but unidentified small amounts of ferromagnetic precipitates included in the grown layers are likely responsible.…”