Near-Infrared Raman Spectroscopy as a Unique Tool for Characterization of Visible Luminescent ZnS Phosphor.

Near-infrared (NIR) Raman spectroscopy has shown its unique advantages for characterization of ZnS:Cu, Al materials, emitting a strong luminescence in the visible region. We demonstrate that, because of a rapid decrease of luminescence in the NIR region, Raman spectra with 752.5-nm excitation are free from the visible luminescence, which usually masks Raman signals with visible excitations. By comparing the spectra of ZnS:Cu, Al samples with different luminescence efficiencies, we also find that crystal imperfections, including coexistence of hexagonal domains, can lead to a reduction of luminescence properties.