Optical and Dynamic Properties of ZnGa<sub>2</sub>S<sub>4</sub>
Saida G. Asadullayeva, Z. A. Jahangirli, T. G. Naghiyev, Dunyamali A. Mammadov
Abstract
ZnGa 2 S 4 luminescent compound is prepared by solid‐state reaction, which is confirmed by X‐ray diffraction to have a tetragonal structure. The photoluminescence (PL) emission and excitation spectra, infrared (IR) reflectivity and Raman scattering of the defective ZnGa 2 S 4 compound are studied experimentally. High stability of the shape and peak positions of the PL spectra is observed in a wide range temperature range (100–290 K). It was determined that PL intensity increases with decreasing temperature. Higher correlated color temperature (CCT) value >6000 K implies the suitability of using this material for light emitting diodes. Five modes of optical phonons are found in both IR reflectance and Raman spectra of ZnGa 2 S 4 and identified from point group symmetry analysis. The calculations of the dynamic properties are carried out within the framework of the density functional theory (DFT) with full optimization of the lattice parameters. Results of calculations show that, the phonon‐dispersion curve is sensitive to S–Se replacement in ZnGa 2 S 4 and gives rise to clearly pronounced energy gaps in the phonon spectrum.