Characterization of ferromagnetic Ga[sub 1-x]Mn[sub x]N layers grown on sapphire (0001) substrates.

Ga[sub 1-x]Mn[sub x]N epilayers with a well-ordered ferromagnetic structure were grown on sapphire (0001) substrates, using the plasma enhanced molecular-beam epitaxy technique. Ga[sub 1-x]Mn[sub x]N films were found to be homogeneous, and to exhibit n-type conductivity and ferromagnetic ordering with a Curie temperature (T[sub C]) above room temperature. This was confirmed by transmission electron microscopy, x-ray diffraction, and by magnetometry using a superconducting quantum interference device. The high-temperature (T=300 K) photoluminescence (PL) spectra exhibited Mn-related free-to-acceptor pair transitions for Ga[sub 1-x]Mn[sub x]N layers with x≈0.2% and x≈0.6%. A Mn acceptor level of a Ga[sub 1-x]Mn[sub x]N layer with low Mn content was found to be located around 330 meV above the top of the valence band, suggesting that Mn-bound holes in group-III nitrides exhibit effective-masslike behavior. The excitation and temperature-dependent PL provided convincing evidence of a band-edge exciton to acceptor transition. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]