Synthesis and characterization of europium doped zinc selenide thin films prepared by photo-assisted chemical bath technique for luminescence application

ZnSe:x% Eu³⁺ (0 ≤ x ≤ 2.0) thin films were deposited using the photo-assisted chemical bath technique. All the films samples revealed wurtzite phase and the diffraction peak intensities decreased with increased Eu³⁺ concentration, due to loss of crystallinity. Raman spectroscopy revealed two optical phonon peaks due to first and second order longitudinal modes. The films morphological transformed from flakes to spherical grains with an increased Eu³⁺ concentration. The presence of the anticipated elements was confirmed by energy dispersive X-ray spectroscopy. Atomic force microscopy showed an increase in surface roughness with increased Eu³⁺ concentration, which however decreased at x = 2.0%. The ultraviolet–visible spectroscopy results showed increased band gap energy with an increase in Eu³⁺ concentration. There was a blue shift in the transmittance edge with respect to the undoped sample due to the decrease in crystallite size. The undoped sample showed four luminescence peaks, which are due to the band-to-band and defects within the host material. Although there was no evidence of emission from the Eu³⁺ ions, increasing the Eu³⁺ doping concentration resulted in enhancement of the emission peak intensities. Chromaticity analysis showed that the blue emission color is not significantly influenced by the Eu³⁺ concentration.