Magnetic and Optical Properties of MN Doped GaN

Abstract : Mn:doped GaN films, a dilute magnetic semiconductor material, are grown on (0001) sapphire substrates by metal organic vapor deposition. Optical properties are investigated by transmission measurements and two absorption bands are found to be dominating the transmission spectra. The first absorption band was at Ev+1.5 eV and was attributed to the formation of a Mn related deep level energy band above the valence band of GaN. The second band extended from 2.0 eV to the bandedge of GaN. Absorption at these bands scaled with thickness and composition of the films. Co-doping of these films by n-type (Si) and p-type dopants (Mg) also greatly enhanced or reduced the absorption at these bands, indicating a change in the Fermi level in the crystal. The magnitude of the saturation magnetization was also a function of the Fermi level, which was probed by transmission measurements. Therefore, a correlation between optical properties and saturation magnetization has been established.