The effects of oxygen flow ratio on the properties of AgxO thin films grown by radio frequency magnetron sputtering

Abstract

The Ag_xO thin film with various oxygen flow ratios (R[O₂]%) deposited by radio frequency magnetron sputtering (RFM-SPT) has been studied. While adjusting R[O₂]% from 0% to 30%, the Ag_xO thin film transitioned from metal to semiconductor and/or insulator with different transparent appearances on the surface observed using X-ray diffraction (XRD) and transmittance measurement. At high oxygen flow ratios, the Ag_xO film is multi-phased as a mixture of Ag^(II)O and Ag₂^(III)O₃. In addition, the work function (ϕ) of those samples changes from 4.7 eV to 5.6 eV as measured by photoelectron yield spectroscopy (PYS). The compositional and chemical state changes that occur at the Ag_xO surface during the increments of R[O₂]% are evaluated by the relative peak intensities and binding energy shifts in X-ray photoelectron spectroscopy (XPS). With the incorporation of more electrons in chemical bonding, the oxygen-induced band forms. And combining all the results from transmittance (band gap confirmation), PYS (work function confirmation), and XPS (valence band position confirmation), the estimated band diagrams are given for the oxidation state of Ag_xO with various oxygen flow ratios.