We report a visible luminescence of Er3+ ions in an amorphous-nanocrystalline AlN:Er thin film prepared by co-deposition using AlN, Er, and SiO2 targets. A PL emission spectrum of Er3+ in the AlN:Er film annealed at 750 degrees C showed a strong bluish green emission of Er3+ in the amorphous-nanocrystalline AlN:Er thin film, which is attributed to the intra-4fEr3(+) transitions of H-2(11/2 ->) I-4(15/2) and 4 F-7/2 -> I-4(15/2). It was found that crystallite diameters were between 3 and 5 nm by high-resolution transmission electron microscopy. The occurrence of the strong Er3+ emission in the annealed AIN:Er thin film with a mixture of amorphous and nanocrystalline phases may be contributed to an increase in the number of excitation Er3+ centers and a presence of oxygen related to Er3+ excitation and recombination process in the AIN:Er thin film. (c) 2006 Elsevier B.V. All rights reserved.