Magnetism in GaN layers implanted by La, Gd, Dy and Lu

We present a complex study of rare earth elements implanted GaN layers grown by low pressure metal-organic vapor phase epitaxy on c-plane sapphire substrates. Gd, Dy, La and Lu ions were implanted with energies of 200 keV and doses ranging from 5 × 1013 to 4 × 1017 atoms.cm− 2. The chemical composition and concentration profiles of ion-implanted layers were studied by secondary ion mass spectrometry and Rutherford back scattering. The structural properties of the layers were characterized by Rutherford back scattering/channeling and X-ray diffraction reciprocal space mapping. Gd implanted layers exhibit ferromagnetic behavior persisting up to ~ 720 K. Since the ferromagnetic behavior was not observed in the case of La and Lu implanted layers, it cannot be attributed to the structural damage of the layer. Based on the fact that the samples are electrically conducting we conclude that the ferromagnetism can be associated with doped electrons mediating the ferromagnetic interaction between local moments on Gd and Dy.