Femtosecond pulsed laser deposition of CeO2 thin films on silicon (100) substrates

Abstract

Cerium oxide (CeO₂) thin film was successfully deposited on silicon (100) via femtosecond pulsed laser deposition (fs-PLD). The deposition was carried out at varying deposition pressure at ambient temperature. The absence of defined CeO₂ peaks in the X-ray diffraction (XRD) spectra for as-deposited samples imply that the film is amorphous. All the films show the circular colored fringes due to thin-film interference. The pattern indicates that a radial variation in film thickness caused by the distribution of the ablated material in the plasma plume. The laser-produced plasma evolving pattern caused this variation. Comparison of the as-deposited samples thicknesses were done via reflectance spectroscopy. Background gas pressure affects the deposition rate of the grown film. One sample was post-annealed at 1000°C for 2 hours to improve the thickness uniformity and crystal structure. The XRD spectra of this film shows an enhancement in its crystallinity. Five peaks attributed to CeO₂ crystal phase indicate the cubic structure of the film.