Green cathodoluminescence (CL), photoluminescence (PL) and electroluminescence (EL) have been obtained from Er-doped amorphous AIN thin films, 200 nm thick, prepared by rf magnetron sputtering. All films were activated by annealing at 750 degreesC for 10 min in a nitrogen atmosphere. Three sharp bands at about 479, 538 and 559 nm corresponding to the F-4(7/2)--> I-4(15/2),H-2(11/2)--> I-4(15/2) and S-4(3/2) --> I-4(15/2) transitions are observed. Fine structure is seen on the major transitions that does not change with temperature indicating that this structure is related to different local environments of the Er3+ ion. The PL spectrum revealed sharp peaks from Er3+ ions and a broad spectral profile that might be from defect states in the amorphous AIN. The results from EL measurements show that Er-doped amorphous AlN films can be used as a phosphor layer in alternating-current thin-film electroluminescent (ACTFEL) devices.