Low-energy femtosecond pulsed laser deposition of cerium (IV) oxide thin films on silicon substrates

Abstract

Cerium (IV) oxide (CeO2, ceria, or cerium dioxide) has been investigated for various applications due to its excellent physical and chemical properties. Since high-precision processing of such functional material can be conceived through pulsed laser deposition (PLD) with a low-energy, ultrashort pulsed laser, we report the low-energy (∼ 8.0 nJ) femtosecond PLD (fs-PLD) of CeO2 thin films on silicon (Si) substrates. The CeO2 thin films are deposited for 2.0 to 5.0 h at room temperature with background oxygen (O2) gas and then annealed at 1000 °C for 0.5 h in ambient air. The as-deposited CeO2 film is amorphous and featureless due to the low-energy laser pulse and room-temperature deposition but exhibits good stoichiometry due to the background gas. The film properties likewise improve with post-deposition annealing coupled with a longer deposition time. Despite the change in stoichiometry, the annealed CeO2 films exhibit improved reflectivity and enhanced crystallinity. Although other deposition parameters need to be optimized further and the film stoichiometry entails additional examination, our results show the viability of low-energy fs-PLD for the fabrication of CeO2 thin films and similar functional materials.