Deposição e caracterização de filmes Finos de perovskitas

Abstract

This work reports the synthesis, the deposition and the optical and topographic characterization of perovskite oxide films of Barium Titanate (BTO) on fluoride doped oxide (FTO) substrates. The BTO was synthesized by the Hydrothermal Microwave Assisted (HAM) method. The deposition process of the films was done by DipElectro-Coating

(DEC). In order to perform the deposition of BTO films, precursor solutions of 1% wt, 1.5% wt and 2% wt of BTO in Isopropanol were prepared. Film deposition was varied at the withdrawal rate and at the immersion time, which followed a time series of 2 n min, where n = 1, 2, 3, 4 and 5, keeping the tension between the electrodes constant. The structural properties of the films were characterized by X-ray Diffraction, the topography by Scanning Electron Microscopy and by White Light Interferometry (WLI); finally, the optical properties were characterized by UV-Visible Spectroscopy. The films exhibit surface uniformity. Gradual variations in thickness and roughness occur according to the deposition time and the withdrawal rate. The optical measurements agree with the WLI measurements showing increased reflectance and reduced transmittance with increased thickness and roughness. The absorption of light in the film obeys BeerLambert's

law and the absorption coefficient seems to vary with the topography. There was no significant variation of the band gap energy due to the thickness variation and the distinct topographies. The DEC method proved to be efficient for the deposition of BTO on the FTO substrate and the characterizations indicated an optimal thickness limit for the application of these films in photovoltaic devices.