Structural, Optical and Electrical Properties of Pure and Ag, Mn co doped ZnO Thin Films for Photovoltaic Applications

Abstract

In this work, thin layers based on pure-ZnO and Ag-Mn co-doped-ZnO (AMZO) were elaborated with rapid thermal evaporation (RTE) technique. According to the X Rays diffraction analysis (XRD), both layers present hexagonal wurtzite-structure, however a small shift in the lattice parameters values (a, c) is observed, which confirms the distortion of these lattices. Layers observation surfaces by scanning-electron microscopy (SEM) shows the films morphology change by the doping, pure ZnO and $A M Z O$ films have a nanostructured surface with spherical form. The incorporation of $\mathrm{Ag}^{+}, \mathrm{Mn}^{2+}$ in the place of $\mathrm{Zn}^{2+}$ leads to the decrease of the nanospherical structures diameter as compared with pure $\mathbf{Z n O}$ films. Ultraviolet visible spectroscopy (Uv-Vis) analysis shows a good transparency of the layers and the band-gap decreases with ZnO doping from 3.84 to 3.75eV. The electrical properties confirm the semiconductor nature of ZnO films with sheet resistance around $10^{7} \Omega / \mathrm{sq}$, and with $A g-M n$ co-doping these films become conductors with sheet resistance of $10^{3} \Omega / \mathrm{sq}$.