Magnesium indium oxide (MgIn2O4) spinel thin films: Chemical spray pyrolysis (CSP) growth and materials characterizations

MgIn2O4, which has an inverse spinel structure, has been adopted as the transparent material in optoelectronic device fabrication due to its high optical transparency and electrical conductivity. Such a technologically important material was prepared by the spray pyrolysis technique. Precursors prepared for the cationic ratio Mg/In = 0.5 were thermally sprayed onto glass substrates at 400 and 450 °C. We report herein the preparation and characterization of the films by X-ray diffraction (XRD), energy-dispersive absorption X-ray spectroscopy (EDAX), and atomic force microscopy (AFM). The XRD results showed the single phase formation of the material that revealed the presence of Mg2+ and In3+ in the inverse spinel-related structure. The FTIR and EDAX results further confirmed that the nanocrystalline films were mainly composed of magnesium, indium, and oxygen, in agreement with XRD analysis. We surmised from the AFM micrographs that the atoms have enough diffusion activation energy to occupy the correct site in the crystal lattice. For the 423-nm-thick magnesium indium oxide films grown at 400 °C, the electrical conductivity was 5.63×10−6 Scm−1 and the average optical transmittance was 63% in the visible range (400–700 nm). Similar MgIn2O4 films deposited at 450 °C have a conductivity value of 1.5×10−5 Scm−1 and an average transmittance of 75%. Hall coefficient observations showed n-type electrical conductivity and high electron carrier concentration of 2.7×1019 cm−32.7×1019 cm−3.

Graphical abstractMgIn2O4 thin films have been prepared using the chemical spray pyrolysis technique. Prepared films were polycrystalline and preferentially oriented along the (311) plane as revealed from the X-ray diffraction spectrum.Figure optionsDownload full-size imageDownload as PowerPoint slide