Synthesis and optical characterizations of pure In2O3 and mixed Mn2O3–In2O3 nanomaterials on fluorine-doped tin oxide substrates

Pure In2O3 and mixed Mn2O3–In2O3 nanomaterials were synthesized via vapor transport method. The X-ray diffraction patterns demonstrated the cubic crystalline phase for pure In2O3 sample, whereas a combination of cubic In2O3 and orthorhombic Mn2O3 phases were observed for the mixed sample. The scanning electron microscopy images revealed the formation of randomly oriented nanorods for pure In2O3 sample, while assemblies of nanorods with different lengths and diameters were reported for the mixed sample. The transmittance spectrum of pure In2O3 was greater than 80% over the visible spectral range, while the transmittance of the mixed Mn2O3–In2O3 nanostructured film was 32%. The obtained band gap values for pure In2O3 and mixed Mn2O3–In2O3 nanostructured thin films were 3.92 and 3.37 eV, respectively. The mixed Mn2O3–In2O3 nanostructured thin film has higher refractive index, higher optical conductivity, and lower electrical resistivity than those for pure In2O3 film. Two obvious emission peaks were observed for the pure and the mixed samples. The photoluminescence intensity of the mixed Mn2O3–In2O3 nanostructured thin film is higher than that of pure In2O3 indicating its validity to be used in optoelectronic applications such as light-emitting diodes.