Optical study of GaN doped with Mn grown by metal organic vapor phase epitaxy

The optical properties of Mn-doped GaN were investigated. The films were grown by metalorganic vapor phase epitaxy using tricarbonyl (methylcyclopentadienyl) manganese as the dopant source. Two characteristic bands were observed in the absorption spectra of Mn-doped epilayers. The low energy band had a threshold at 1.4 ± 0.05 eV with a maximum at 1.5 ± 0.02 eV, with a full width half maximum of 245 ± 10 meV at 296 K. A second higher energy band was observed as a shoulder to the band edge absorption with a threshold energy of 2.06 eV at room temperature. Using photoluminescence spectroscopy, a new broad band was observed in the infrared spectra of GaN:Mn at 1.27 ± 0.02 eV with a full width half maximum of 0.26 ± 0.01 eV at 20K. From analysis of optical absorption and emission spectra Mn forms a deep acceptor level with optical transitions at 1.4 and 2.06 eV. The deep level nature of Mn indicates that it is a potential dopant for semi-insulating GaN.