Characterization and device application of indium doped ZnO homojunction prepared by RF magnetron sputtering

Undoped and Indium doped Zinc Oxide (IZO) nanocrystalline thin films were synthesized via RF magnetron sputtering techniques using home-made cold pressed powder targets. The morphology, crystal structure, elemental analyses were studied using FESEM, AFM, XRD, EDS and XPS techniques. All the films showed hexagonal wurtzite structure, and revealed appreciable variations in (100), (002) and (101) peak intensities with indium doping. The incorporation of In into the ZnO films was confirmed by both EDS and XPS measurements. XPS and Photoluminescence (PL) studies of doped films demonstrated significant reduction of oxygen vacancies (Vo) after incorporation of indium in ZnO lattice at substitutional sites. PL spectra showed convoluted peaks, which correspond to band to band transitions and defect level emissions. The optical studies showed high transmittance of over 90% in the UV–vis region and exhibited the absorption edge near 380 nm. The band gap energy of the films increased from 3.27 eV to 3.42 eV, with In content. In addition, typical rectifying I–V characteristics of SZO/IZO homojunction layers were demonstrated.