Comparative structural study of Al2O3–SiO2 glasses and amorphous thin films

We compared the impact of alumina doping on the structure of Al₂O₃–SiO₂ amorphous thin films and bulk glasses using Raman spectroscopy and x-ray diffraction. In both thin films and bulk glasses, the addition of Al₂O₃ is accompanied by an increase in the mean Si–O–T angle and an evolution of the ring statistics with a decrease in the proportion of small rings. We evidenced structural differences between sputtered films and fused bulk glasses. Sputtered Al₂O₃–SiO₂ thin films are about 6%–7% denser than their equivalent Al₂O₃–SiO₂ bulk glasses. This difference is mainly due to a change in ring statistics with the formation of small rings within the sputtered thin films. These structural differences in atomic structural organization highlight the impact of the synthesis conditions and open the door to further investigation of the structure–functional property relationships in sputtered Al₂O₃–SiO₂ thin films.