Magnetic and structural properties of Fe ion-implanted GaN

The magnetic and structural properties of Fe ion-implanted GaN was investigated by various measurements. XRD results did not show any peaks associated with second phase formation. The magnetization curve at 5K showed ferromagnetic behavior for 900 degrees C-annealed sample. In zero-field-cooled (ZFC) and field-cooled (FC) magnetization measurements, the irreversibility and a cusp-like behavior of the ZFC curve were observed for 900 degrees C-annealed sample. These behaviors are typically observed in superparamagnetic or spin glass phase. While the temperature dependence magnetization of 800 degrees C-annealed sample showed non-Brillouin-like curve and it is not exhibited ferromagnetic hysteresis at 5K. In XPS measurement, the coexistence of metallic Fe (Fe-0) and Fe-N bond (Fe2+ and Fe3+) for Fe 2p core level spectra is observed in as-implanted sample. But 700-900 degrees C-annealed samples showed only Fe-N bond (Fe2+ and Fe3+) spectra. For Ga 3d core level spectra only Ga-N bonds showed for as implanted with 700-900 degrees C-annealed samples. From XPS results, it could be explained that magnetic property of our films originated from FeN structures. (c) 2007 Elsevier B.V. All rights reserved.