ITO:n-ZnO:p-NiO and ITO:n-ZnO:p-NZO thin films: Study of crystalline structures, surface statistical metrics, and optical properties.

Abstract

The article presents results on fabrication and characterization of transparent, oxide-based junction diodes on quartz substrates. The devices are made by radio frequency magnetron sputtering in the form of sandwich structures: ITO:n-ZnO:p-NiO (homojunction) and ITO:n-ZnO:p-NZO (heterojunction). The microstructure, crystalline structure, and micromorphology features of deposited samples are studied by means of X-ray diffraction, Atomic Force Microscopy, and Scanning Electron Microscopy. Obtained results are used to derive statistical, fractal and functional surface characteristics that exhibited secondary alignment patterns. Apart from that, optical and electrical measurements are carried out as well. Optical transmittance peaked at 80% in visible range, but substantially increased after annealing. Due to structural differences, heterojunction was found to follow linear current-voltage dependence specific of ohmic contacts, whereas homojunction was found to follow non-linear characteristics as in junction diode.