Raman scattering study of ZnO:Ti and ZnO:Mn bulk crystals

We report on Raman scattering spectra of two systems ZnO:Ti and ZnO:Mn. The spectra have been measured vs. temperature, excitation laser light wavelength, and light polarization. A new, strongly temperature dependent Raman peak has been found in the ZnO:Ti system as a satellite of the E2 (high) phonon peak. The peak is interpreted as an A1 electronic transition strongly coupled to the phonon spectrum of the crystal. Several new phonon bands are found in both materials. The new peaks are interpreted either as the disorder activated phonon modes or local vibrations of Ti and Mn related complexes in ZnO.