Luminescent and structural characteristics of Y2O3:Tb3+ thin films as a function of substrate temperature

An inexpesive synthesis of terbium and yttrium β diketonates from acetylacetone and metal chlorides was carried out. Later, the β diketonates were used as precursors for the synthesis of Y₂O₃:Tb ³⁺thin films by the ultrasonic spray pyrolysis technique. The β diketonates are sometimes preferred as precursors for thin films because they lead to high quality films; such as a very low surface roughness and a high homogeneity. With the later idea films of Y₂O₃:Tb ³⁺ were deposited on c-Si substrates at temperatures in the 400-550°C range. Yttrium β diketonate was used as precursor of Y ₂O₃ host lattice and terbium β diketonate was used as source of Tb³⁺ activator. The optical and structural characterization of the thin films were carried out by means of photoluminescence (PL) and cathodoluminescence (CL) spectroscopies, infrared spectroscopy (IR), ellipsometry, atomic force microscopy (AFM), energy dispersive spectroscopy (EDS), and X ray diffraction (XRD). From PL and CL spectra, the luminescence intensity depended strongly on substrate temperature, the thickness of the film, and the Tb³⁺-activator concentration. Y₂O₃:Tb³⁺thin films exhibited one main band centered at 547 nm which was due to the well-known ⁵D₄ →⁷F₅ electronic transition. In addition, a concentration quenching of the luminescence intensity was observed. At high temperatures the cubic crystalline phase of Y₂O₃ was obtained as well as a reduction of organic residues. Additionally, at elevated temperatures,a low average surface roughnesswas obtained in the films with a high density and a high transparency.