Observation of a nanoscale phase separation in blue-emitting Ce-doped SiO1.5 thin films

Jennifer Weimmerskirch-Aubatin (1) , Mathieu Stoffel (1) , Xavier Devaux (1) , Alexandre Bouché (1) , Georges Beainy (2) , Etienne Talbot (2) , Philippe Pareige (2) , Yannick Fagot-Révurat (1) , Michel Vergnat (1) , Hervé Rinnert (1)

1 IJL - Institut Jean Lamour
2 GPM - Groupe de physique des matériaux

Both the optical and structural properties of Ce-doped SiO1.5 thin films were investigated. The Ce-related blue luminescence, which can be seen even at room temperature for as-grown films, exhibits a rather complex evolution with the annealing temperature. In particular, a strong decrease is observed when the films are annealed at 900 degrees C. Structural characterizations combining scanning transmission electron microscopy and atom probe tomography reveal the formation of Si- and Ce-rich clusters at this temperature, thus demonstrating that the decreasing Ce-related luminescence is due to concentration induced quenching. For annealing temperatures higher than 900 degrees C, the Ce-related luminescence increases. The different structural characterizations provide clear experimental evidence of a phase separation occurring at the nanoscale between pure Si nanocrystals and Ce-rich clusters having a stoichiometry close to the cerium silicates Ce2Si2O7 or Ce-4.667(SiO4)(3)O. The latter compounds are optically active thereby explaining the increased Ce-related luminescence observed at the highest annealing temperature.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Jennifer Weimmerskirch-Aubatin, Mathieu Stoffel, Xavier Devaux, Alexandre Bouché, Georges Beainy, et al.. Observation of a nanoscale phase separation in blue-emitting Ce-doped SiO1.5 thin films. Journal of Materials Chemistry C, 2015, 3 (48), pp.12499-12506. ⟨10.1039/c5tc02722e⟩. ⟨hal-01271639⟩