The Dependence of the Magnetic Properties of GaMnN on Codoping by Mg and Si

Abstract

The magnetic properties of GaMnN, grown by metalorganic chemical vapor deposition, depend on the addition of dopants; where undoped materials are ferromagnetic, and n -type (Si-doped) and p -type (Mg-doped) films are either ferromagnetic or paramagnetic depending on dopant concentration. The ferromagnetism of this material system seems correlated to Fermi level position, and is observed only when the Fermi level is within or close to the Mn energy band. This allows ferromagnetism-mediating carriers to be present in the Mn energy band. The current results exclude precipitates or clusters as the origin of room temperature ferromagnetism in GaMnN.

Temperature dependence of the optical properties in GaMnN

“…A variety of methods have been reported to synthesize single-phase GaMnN, including diffusion, 6 ion implantation, 10 ammonothermal, 11 as well as epitaxial growth by molecularbeam epitaxy ͑MBE͒, 7 hydride vapor-phase epitaxy 8 ͑HVPE͒, and metal-organic chemical-vapor deposition ͑MOCVD͒. 9 So far, a great deal of emphasis has been placed on the origin of the ferromagnetic behavior in GaMnN. Kronik et al 12 have predicted theoretically that the ferromagnetic properties are related to the occupancy of Mn energy band and the position of the Fermi level related to this band, while relating experimental work is currently under way to understand the mechanism of the ferromagnetism.…”

“…Kronik et al 12 have predicted theoretically that the ferromagnetic properties are related to the occupancy of Mn energy band and the position of the Fermi level related to this band, while relating experimental work is currently under way to understand the mechanism of the ferromagnetism. 9 Besides the magnetic characteristics, another crucial step towards the realization of GaMnN-based devices is to clearly understand the structural, optical, and electrical properties of GaMnN, especially the Mn related phenomenon. X-ray diffraction ͑XRD͒, transmission electron microscopy, and extended x-ray-absorption fine-structure measurements have been employed to examine the effects of Mn doping on structural properties, and to determine whether Mn substituted for Ga on lattice positions or presented as Mn clusters.…”