Photoluminescence of Samarium-Doped Aluminosilicate Thin Films Deposited by RF Sputtering with a Ceramic Target

Samarium-doped aluminosilicate thin films were prepared by rf magnetron sputtering in both pure argon and in a mixture of argon and hydrogen at the substrate temperatures of 25, 200 and 300°C. A hot-pressed ceramic disk was used as a target with a nominal composition of Sm2O3⋅5Al2O3⋅88SiO2. X-ray photoelectron spectroscopy revealed that the samarium and aluminum contents in the films deposited in both sputtering gases increased with increasing substrate temperature at the expense of silicon. The photoluminescence intensity of Sm2+ ions increased with increasing substrate temperature and with decreasing sputtering pressure, due to the increase in activated Sm2+ ions. Hydrogen gas mixed with argon enhanced the reduction of Sm3+ to Sm2+ at the substrate temperatures of 25 and 200°C. The addition of an aluminum chip on the ceramic target during deposition increased the absorbance of the films and the photoluminescence intensity of Sm2+, whereas that of aluminum oxide did not. These results are attributed to the shifts in the UV edge of the films.