Analysis of Raman modes in Mn-doped ZnO nanocrystals

Mn-doped ZnO was synthesized using a co-precipitation technique. X-ray diffraction (XRD) measurements and photoluminescence (PL) spectra show that Mn ions are doped into the lattice positions of ZnO. The modes at 202, 330, and 437 cm-1 in the Raman spectrum are assigned as 2E2 (low), E2 (high)-E2 (low), and E2 (high) modes of ZnO base, respectively. The mode at 528 cm-1 is ascribed to a local vibrational mode related to Mn. The mode at 580 cm-1 should be an intrinsic mode of ZnO and assigned to E1 longitudinal optical (LO). Its reinforcement should result from a combination of resonance at the excitation wavelength and impurity-induced scattering.