Effect of inert gas on pulsed laser deposition of rare earth doped fluoride thin films

The realization of crystalline sub micrometric films of Nd3+:LiYF4 fluorides on pure LiYF4 substrates by pulsed laser deposition is reported. The films were obtained by laser ablation with 355 nm photons of a bulk LiYF4 crystal doped with Nd3+ ions at 1.5% atomic concentration. Both low and high laser ablation fluency regimes were checked. The fundamental contribution of He inside a vacuum chamber to obtain crystalline Nd3+:LiYF4 films was demonstrated. The optical characteristics of the films were analyzed via recording the emission spectra following IR excitation, polarized both with E || and E ⊥ to the substrate c-axis. Lifetime measurements of the fundamental Nd3+ ion transition in the films were also performed. All the results were compared with those obtained in the Nd3+:LiYF4 bulk crystal under the same experimental conditions. The scanning electron microscope pictures of the depositions gave indications about the film surface morphology.