Thermal evolution of Er silicate thin films grown by rf magnetron sputtering

Abstract

Stoichiometric Er silicate thin films, monosilicate(Er2SiO5) anddisilicate (Er2Si2O7), have been grown on c-Si substrates by rf magnetronsputtering. The influence of annealing temperature in the range1000–1200 °C in oxidizingambient (O2) on the structural and optical properties has been studied. In spite of the known reactivityof rare earth silicates towards silicon, Rutherford backscattering spectrometry shows thatundesired chemical reactions between the film and the substrate can be strongly limited byusing rapid thermal treatments. Monosilicate and disilicate films crystallize at 1100 and1200 °C, respectively, as shown by x-ray diffraction analysis; the crystalline structureshave been identified in both cases. Moreover, photoluminescence (PL)measurements have demonstrated that the highest PL intensity is obtained forEr2Si2O7 filmannealed at 1200 °C. In fact, this treatment allows us to reduce the defect density in the film, in particular bysaturating oxygen vacancies, as also confirmed by the increase of the lifetime of the PLsignal.