Magnetic properties of Mn-doped GaN and p-i-n junctions

We report on the growth and magnetic properties of GaMnN films and p-i-n junctions grown by metalorganic, chemical vapor deposition. The magnetic properties of MOCVD grown GaMnN were found to depend upon the type and concentration of the co-dopant. Si or Mg co-doping of GaMnN films led to either ferromagnetic or paramagnetic behavior depending on the concentration. The magnetic properties within the GaMnN material system appear to correlate with the position of the Fermi level. Ferromagnetism was observed only when the Fermi energy level was within or very close to the Mn energy band. The presence of the Fermi energy level within the Mn energy band allows the presence of carriers that mediate ferromagnetism. These results further confirm that the ferromagnetic properties result from a solid solution of Mn in the GaN. Mn-doped GaN p-i-n junctions which were grown to study the effect of the magnetic properties on the IN characteristics. These devices consist of GaN:Si/GaMnN/GaN:Mg layers grown by metal-organic chemical vapor deposition. The carrier concentrations for the n and p-type layers are similar to 5x10(18)/cm(3) and 1x10(18)/cm(3) respectively, where the GaMnN i layer is approximately 0.2-0.45 mu m thick with up to 0.5% Mn.