XPS AND NEXAFS STUDIES OF RARE-EARTH-DOPED AMORPHOUS SOL-GEL FILMS

Information about the structural environment of rare-earth (RE) ions i n different host matrices is necessary in order to select a glass comp osition with optimized spectral properties for integrated optic device s, such as lasers or amplifiers. The present study is aimed at determi ning the influence of co-dopant elements (P and Al) on the structural environment around (RE) cations (Nd3+ and Er3+) in amorphous silica-ti tania matrices. For this purpose, thin film samples in the SiO2-TiO2-P 2O5-Nd2O3 and SiO2-TiO2-Al2O3-Er2O3 systems were prepared by sol-gel p rocessing and studied by Xray photoemission spectroscopy (XPS) and nea r edge X-ray absorption fine structure (NEXAFS), after being densified at 900 degrees C. These measurements allowed the determination of the concentrations of the different types of oxygen atoms present in the Si-O-Ti, Si-O-P and Si-O-Al bonding sequences and these were found to reach maximum total values for compositions containing similar to 10 m ol% of the PO2.5 or AlO1.5 co-dopants. (C) 1998 Elsevier Science B.V. All rights reserved.