Applied Science and Convergence Technology 2021; 30(3): 74-77
Published online May 30, 2021
Copyright © The Korean Vacuum Society.
aDepartment of Physics, Mokpo National University, Chonnam 58554, Republic of Korea
Correspondence to:E-mail: firstname.lastname@example.org
CoIn2S4. thin films were grown onto glass substrates by a spray pyrolysis method. For the growth, the substrate temperature was varied between 250 and 320 °C, and the spray rate was fixed at 6 ml/min. The grown thin films were characterized X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM), and optical spectroscopy. The XRD analysis showed that the thin films grown at 320 °C were well crystallized in cubic spinel structure. The FE-SEM results demonstrated that the thin films have a uniform and homogeneous surface. The direct band gap energy was first obtained from the measurement of optical absorption spectra near the fundamental absorption edge at 292 K, and was founded to be 1.59 eV. We also observed two group absorption bands in the near-infrared region, which originate in cobalt ions of the constituent elements of CoIn2S4.. The absorption bands were well assigned as due to the crystal-field transitions of Co2+ ions occupying tetrahedral sites of the cubic spinel CoIn2S4. host lattice.
Keywords: CoIn2S4., Thin films, Optical absorption, Band gap, Tetrahedral Co2+, Spray pyrolysis method