Deposition of Europium Oxide on Si and its optical properties depending on thermal annealing conditions

We investigate the influence of the ambient gas during thermal annealing on the photoluminescence (PL) properties of europium compound thin films on Si substrates. The films were deposited by radio-frequency magnetron sputtering and subsequently annealed in N₂ or O₂ ambient gas by rapid thermal annealing (RTA). The results of X-ray diffraction indicate that the resulting europium compound annealed in N₂ ambient have several silicate phases such as EuSiO₃ and Eu₂SiO₄ compared to those annealed in O₂ ambient. The spectral results revealed that a broad luminescence associated with Eu²⁺ ions, with a maximum intensity at 600 nm and a FWHM of 110 nm, was observed from the thin film annealed at 1000 °C in N₂ ambient. However, a series of narrow PL spectra from Eu³⁺ ions were observed from the film annealed in O₂ ambient.