We have observed room-temperature erbium-ion electroluminescence in erbium-doped amorphous silicon. Electrical conduction through the structure is controlled by thermally activated ionization of deep D(-) defects in an electric field and the reverse process of capture of mobile electrons by D(o) states. Defect-related Auger excitation (DRAE) is responsible for excitation of erbium ions located close to dangling-bond defects. Our experimental data are consistent with the mechanisms proposed. (C) 1998 Elsevier Science B.V. All rights reserved.