High quality epitaxial ZnO films were grown on c-Al2O3 substrates with Cr2O3 buffer layer by plasma-assisted molecular beam epitaxy (P-MBE). The hexagonal crystalline Cr2O3 layer was formed by oxidation of the Cr-metal layer deposited on the c-Al2O3 substrate using oxygen plasma. The epitaxial relationship was determined to be [1 (1) over bar 0 0]ZnO//[1 1 (2) over bar 0]Cr2O3//[1 (1) over bar 0]Cr//[1 1 (2) over bar 0]Al2O3 and [1 1 (2) over bar 0]ZnO//[1 (1) over bar 0 0 ]Cr2O3//[0 0 1]Cr//[1 (1) over bar 0 0]Al2O3. The Cr2O3 buffer layer was very effective in improving the surface morphology and crystal quality of the ZnO films. The photoluminescence spectrum showed the strong near band-edge emissions with the weak deep-level emission, which implies high optical quality of the ZnO. lms grown on the Cr2O3 buffer. (C) 2008 Elsevier B. V. All rights reserved.