The tin doping effect on the physicochemical and nonlinear optical properties of the manganese oxide (Mn₃O₄: Sn) thin films

Abstract

Undoped and tin doped manganese oxide, Mn3-xSnxO4, (x=0, 2, and 4 at %) thin films were successfully elaborated by the chemical route defined in the spray pyrolysis technique and deposited on glass substrates at a temperature of 350 °C. The physicochemical characterization of the thin films was performed using an X-ray diffractometer (XRD) that showed a polycrystalline tetragonal structure for all thin films. Raman measurement confirmed the vibrational mode, A1g, and the XRD results with the presence of no secondary phases. Scanning electron microscopy coupled with energy dispersive X-ray spectroscopy depicted the surface morphology and the elemental composition (Mn, O, and Sn) of the elaborated thin films. Finally, the optical analysis was carried out, and it showed an increase in the average transmittance of the Mn3O4: Sn (0, 2, and 4 at %) from 57.6 % to 62.2 % for 700 nm and an increase of their optical band gap from 3.27 eV to 3.61 eV. We note also a decrease of their dispersive energy parameter Ed from 5.44 eV to 4.86 eV, of their static refractive index n0 from 2.02 to 1.86, as well as for their nonlinear optical parameters presented by the nonlinear refractive index n2 from 1.14 10-11 to 0.51 10-11 and the third order susceptibility χ3 from 6.14 10-13 esu to 2.49 10-13 esu. These values can be correlated to the poor crystallinity and the tensile strain of the Mn3O4: Sn (0, 2, and 4 at %) thin films, as well as to the high order of the optical bandgap energy and the decrease of the linear refractive index of these films. Hence, these thin films can be used as material for nonlinear optical applications.