Synthesis and luminescence properties of erbium silicate thin films

We have studied the structure and the room temperature luminescence of erbium silicate thin films deposited by rf magnetron sputtering. Films deposited on silicon oxide layers are characterized by good structural properties and excellent stability. The optical properties of these films are strongly improved by rapid thermal annealing processes performed in the range of temperature 800-1250 degrees C. In fact through the reduction of the defect density of the material, a very efficient room temperature photoluminescence at 1535 nm is obtained. We have also investigated the influence of the annealing ambient, by finding that treatments in 02 atmosphere are significantly more efficient in improving the optical properties of the material with respect to processes in N-2. Upconversion effects become effective only when erbium silicate is excited with high pump powers. The evidence that all Er atoms (about 10(22) cm(-3)) in erbium silicate films are optically active suggests interesting perspectives for optoelectronic applications of this material. (C) 2007 Elsevier B.V. All rights reserved.