Raman scattering spectroscopy has been performed on high quality Co-doped ZnO epitaxial films, which were grown on Al2O3 (0001) by oxygen-plasma assisted molecular beam epitaxy. Raman measurements revealed two local vibration modes (LVMs) at 723 and 699 cm1 due to the substitution of Co2_in wurtzite ZnO lattice. The LVM at 723 cm(-1) is found to be an elemental sensitive vibration mode for Co substitution. The LVM at 699 cm(-1) can be attributed to enrichment of Co2bound with oxygen vacancy, the cobalteoxygen vacancyecobalt complexes, in Zn1 xCoxO films associated with ferromagnetism. The intensity of LVM at 699 cm 1, as well as saturated magnetization, enhanced after the vacuum annealing and depressed after oxygen annealing. (C) 2014 Elsevier B. V. All rights reserved.