Characterization of Sn/CuO interface by x-ray photoelectron spectroscopy

The Sn/CuO interface has been investigated by the techniques of x-ray photoelectron spectroscopy and atomic force microscopy. Thin films of tin were deposited on CuO at room temperature by e-beam method. The thickness of the tin film was varied between 3 Å and 10 Å. The tin 3d, oxygen 1s, and copper 2p regions were recorded by XPS. The spectral data show the absence of the high binding energy satellite in the copper 2p regions. This corresponds to the reduction of CuO to elemental copper. The tin overlayer is observed to get oxidized to SnO₂. The thickness of oxidized tin was found to depend upon the initial thickness of the tin overlayer. The reaction is observed to continue until the tin overlayer exceeds a thickness of 7 Å. Beyond this thickness unreacted tin is observed. The AFM study shows nonuniformity of the SnO₂ film on copper.  The study provides a means of preparing SnO₂ of nano-dimensions.