Structural investigation of Ru/Pt nanocomposite films prepared by plasma-enhanced atomic layer depositions

We have fabricated Ru and Pt nanocomposite films using plasma-enhanced atomic layer deposition (PE-ALD), and characterized their structure by means of analytical electron microscopy. Pt and Ru were deposited in Ar/O2 plasma using trimethyl(methylcyclopentadienyl) platinum(IV) and bis(cyclopentadienyl)Ru(II) or bis(ethylcyclopentadienyl)Ru(II) as precursors, respectively. The resistivity of a Pt film deposited on a Si substrate at 300 °C was 16.2 μΩ cm, and that of a Ru film was as low as 11 μΩ cm, showing the film to be metallic and not oxidized. It was revealed that the film prepared by successive PE-ALDs of Pt and Ru on a thin amorphous carbon substrate for electron microscopy analysis is a nanocomposite of Ru ribbons and PtRu (7:3) alloy ribbons with 2-3 nm in width. The Ru ribbon comprised small particles with poor crystallinity of the hcp A3 structure and the PtRu ribbon comprised crystallites with good crystallinity of the fcc Al structure. The atomic layer deposition would be one of potential techniques to produce Ru/Pt nanocomposites for fuel cell catalysts.