Cathodoluminscent properties of pulsed laser deposited Er,Yb co-doped Y2O3 thin films

Thin Er3+, Yb3+ co-doped Y2O3 films have been grown on (001) SiO2 substrates by pulsed laser deposition from ceramic targets. The influence of the active ion concentration and processing parameters on the structure, cathodoluminescent (CL) spectra and optical properties of the films have been investigated. The films were prepared in an oxygen atmosphere at pressures of 0.01 and 0.1 mbar and at 500°C substrate temperature. Blue, green and red light emissions centred at 408 nm, 562 nm and 660 nm, respectively, and an infrared (IR) spectrum centred at 1.54 µm were measured. The intensities of the CL peaks strongly depend on the Er and Yb ion concentration in the films and their ratio. An increase in Yb content at a fixed Er concentration leads to a decrease in the CL intensity in the visible range. It is higher for the films deposited at 0.1 mbar, which correlates with the better crystallinity obtained. Despite their better crystallinity, the films prepared at 0.01 mbar have a slightly higher optical transmission in the visible and near-IR range, which corresponds to the smoother surface and lower absorption measured.