Erbium silicate thin films that have a good morphology are synthesized by radiofrequency magnetron sputtering. Properly annealed films exhibit efficient luminescence at 1535 nm, and all of the Er ions in the material (about 10 22 cm–3) are demonstrated to be optically active. The possibility to efficiently excite Er ions also through electron–hole mediated processes is demonstrated in nanometer‐scale Er–Si–O/Si multilayers (see figure). The results are relevant to the improvement of silicon‐based devices.