Thermally induced evolution of optical and structural properties of Er2O3 films grown on Si substrates by thermal atomic layer deposition

Abstract Thermally induced evolution of structural and optical properties of Er2O3 films prepared by atomic layer deposition was investigated. The films were grown on Si substrates by water-assisted approach from (tris(methylcyclopentadienyl)erbium(III). As-deposited films showed cubic Er2O3 phase, and compressive stress. Isochronal (30 min) heating at 600–1100 °C in nitrogen flow caused strain relaxation, decrease of the lattice parameters and the increase of coherent domain size. Besides, in the films annealed at 1000–1100 °C, the formation of Er silicate phase was observed. This phase formed due to Si diffusion from substrate in film volume, and the presence of Si was found not only at the film/substrate interface, but also on the top surface of the film. This fact was explained by spinodal decomposition of Er silicate with the formation of Er2SiO5 phase on top surface. It was shown that both oxygen vacancies and Er3+ ions contribute to light emission, however, no energy transfer from vacancies to Er3+ ions was detected.