Influence of oxygen content on the 1.54 μm luminescence of Er-doped amorphous SiOx thin films

Er-doped amorphous SiOx thin films with different oxygen contents (0⩽x⩽2) were prepared by co-evaporation of Si and SiO2. The evolution of the structure of the annealed films was followed by infrared absorption spectrometry. With annealing treatment, a phase separation process occurs, leading to the formation of amorphous silicon domains mixed with a SiO2 phase. Photoluminescence (PL) experiments were performed in the visible range to observe the PL of the silicon domains and in the near-infrared range to observe the Er emission. The optical properties were correlated to the evolution of the structure. The SiO1.0 alloy annealed at 800 °C exhibits the highest Er-related signal, which can be explained by an indirect excitation of the Er3+ ions by amorphous silicon clusters.