Raman scattering study of gallium nitride heavily doped with manganese

Small MnxGa1−xN crystals grown by the resublimation method have been characterised by Raman scattering technique. It has been shown, that for small concentration of manganese the concentration of free electrons in the material is high as in typical free standing GaN crystals, but for higher contents of manganese the concentration of free carriers in the alloy has been substantially reduced. The measured Raman spectra have been compared with the calculated phonon density of states, and it has been shown that the Raman peaks correspond to the peaks of the phonon density of states. In consequence the new Raman peaks found in the material are ascribed to disorder activated phonon modes.