Thin Films Deposited by Chemical Vapor Deposition and Their Arsenic Diffusion

By employing Neodymium-hexafluoro-pentanedionate and Iron-pentanedionate as chemical precursors, we are able to grow (Nd,Fe)O_1-yF_1+2y thin films by aerosol assisted chemical vapor deposition with different Nd:Fe atomic ratios (Nd_1-xFe_x; 0 ≤ x ≤ 1). The X-ray diffraction and energy dispersive experiments, indicate that for compositions of x ≤ 0.5, the as grown films crystallize in the tetragonal off-stoichiometry Nd-oxyfluoride structure (NdO_1-yF_1+2y, spatial group P4/nmm), while for x >; 0.5 the films develop an amorphous phase. Given that we are able to grow films with x≈0.5, the (Nd,Fe)O_1-yF_1+2y films with this particular Nd/Fe concentration have been employed in diffusion experiments to try to introduce arsenic and develop the NdFeAsO_1-yF_y. The preliminary results indicate that the arsenic is not efficiently incorporated into the precursor film; however the diffusion promotes the recrystallization of the as grown films in the stoichiometric Nd_1-xFe_xOF rhombohedral phase (spatial group R-3m). The electrical characterization of those films indicates that most of them are semiconductors.