Single crystal thin films of LiNbO3:Er co-doped with ZnO have been grown on (001) LiNbO3 substrate by liquid phase epitaxy method. The Er2O3 concentration in the melt of ZnO co-doped LiNbO3:Er was fixed at 1 mol% and ZnO concentrations were varied from 3 to 5 mol%. The crystallinity of ZnO co-doped LiNbO3:Er films became better than the LiNbO3 substrate. At ZnO 5 mol% concentration, the surface of ZnO co-doped LiNbO3:Er film is affected by compressive stress along both the perpendicular and the parallel direction. The surface of ZnO 3 mol% co-doped LiNbO3:Er film is smoother than the original LiNbO3 substrate surface. (C) 2002 Elsevier Science B.V. All rights reserved.