Optical Characterization of Tb³⁺:BaHfO₃ Thin Films by Means of Photoacoustic Spectroscopy

In this work, the synthesis and optical characterization of Al₂O₃/Tb³⁺:BaHfO₃/Al₂O₃ heterostructure, grown by ultrasonic spray pyrolysis technique are reported. The X-ray diffraction patterns corroborate that the scintillator layer structure corresponds to perovskite structure, while the elemental chemical composition of it is close to the optimal stoichiometry, but showing barium vacancies. The empirical determination of the optical bandgap energy, achieved by means of the photoacoustic spectroscopy technique, set a principal direct band gap in 3.8 eV, but evidencing the existence of a larger indirect bandgap also. The photoluminescent spectroscopy measurements show that the heterostructure has an intense fluorescent response, congruent to the principal emission lines of trivalent terbium, as was intended to.