Structural and Optical Properties of Sm-doped BaMoO₄ Phosphor Thin Films Deposited by Radio-Frequency Magnetron Sputtering

Abstract

BaMoO₄:Sm³⁺ phosphor thin films were prepared using radio-frequency magnetron sputtering at several growth temperatures, followed by rapid thermal annealing. All the phosphor thin films revealed tetragonal structures with preferential (112) orientation. The emission and the excitation intensities, transmittances, and band gap energies of the phosphor thin films were found to depend significantly on the growth temperature. The excitation spectrum consisted of a strong broad band centered at 261 nm in the range 210–310 nm arising from charge transfer transitions between O⁻² and Sm³⁺ and three weak bands, one each at 370, 406, and 475 nm. The emission spectra of the phosphor thin films under excitation at 267 nm showed six emission bands located at 451, 558, 595, 640, 700, and 762 nm, respectively which were due to the typical 4f − 4f transitions of Sm³⁺ ions. The highest emission intensity of the BaMoO₄:Sm³⁺ phosphor thin film was achieved at a growth temperature of 400 °C, where the optical band gap was 4.70 eV and the color chromaticity coordinate was (0.492, 0.353). These results suggest that the BaMoO₄:Sm³⁺ phosphor thin film is a promising candidate for application in red-light-emitting devices.