Enhanced emission of Er3+ from alternately Er doped Si-rich Al2O3 multilayer film with Si nanocrystals as broadband sensitizers

Alternately Er doped Si-rich Al2O3 (Er:SRA) multilayer film, consisting of alternate Er–Si-codoped Al2O3 (Er:Si:Al2O3) and Si-doped Al2O3 (Si:Al2O3) sublayers, has been synthesized by co-sputtering from separated Er, Si, and Al2O3 targets. The dependence of Er3+ related photoluminescence (PL) properties on annealing temperatures over 700–1100 °C was studied. The maximum intensity of Er3+ PL, about 10 times higher than that of the monolayer film, was obtained from the multilayer film annealed at 950 °C. The enhancement of Er3+ PL intensity is attributed to the energy transfer from the silicon nanocrystals in the Si:Al2O3 sublayers to the neighboring Er3+ ions in the Er:Si:Al2O3 sublayers. The PL intensity exhibits a nonmonotonic temperature dependence: with increasing temperature, the integrated intensity almost remains constant from 14 to 50 K, then reaches maximum at 225 K, and slightly increases again at higher temperatures. Meanwhile, the PL integrated intensity at room temperature is about 30% higher than that at 14 K.