Plasma-produced ultra-thin platinum-oxide films for nanoelectronics: physical characterization

We present a detailed experimental characterization of ultra-thin platinum-oxide films formed on metallic Pt surfaces using O-2 plasma treatment. A monotonic consumption of the metallic Pt by the O-2 plasma is demonstrated by electrical resistance measurements of micron- wide, ultra-thin metallic Pt wires for the range of O-2 plasma exposure times explored in this study. Conversely, angle-resolved X-ray photoelectron spectroscopy (AR-XPS) of the plasma-treated Pt reveals that the oxide layer formed on the Pt surface maintains a constant thickness over these exposure times. In combination, these data demonstrate that the O-2 plasma treatment of Pt simultaneously forms and etches an ultra-thin platinum-oxide layer on the Pt surface. In addition, the AR-XPS data also reveals the oxide layer to be composed of two different platinum - oxygen compounds. Detailed analysis demonstrates a stratified structure for the ultra-thin platinum oxide, with the oxide 'bulk' being composed of PtO2, likely with PtO defects, and the exposed oxide surface being Pt(OH)(y approximate to 2) terminated after exposure to ambient conditions. The potential utility of using plasma oxidization to form ultra-thin platinum ( or other metal) oxide films on nanoscale metal structures for nano- and molecular-electronic applications is discussed, along with other promising applications in technologies such as sensors and catalysts.