Ultra-flat platinum surfaces from template-stripping of sputter deposited films

We report the fabrication of platinum (Pt) surfaces with single-angstrom flatness by template-stripping sputtered films from silicon wafers. For comparison, template-stripped (TS) gold (Au) is also produced from sputtered films using the same procedure. The surface wetting properties, refractive indices and extinction coefficients of the TS platinum are presented and compared against those of non-TS platinum films. The observed optical constants, as well as X-ray crystallography data, suggest that macroscopic properties of the sputtered TS platinum films are similar to previously studied evaporated platinum films [Surf. Interf. Anal. 29 (2000) 179]. Finally, scanning probe microscopy studies of the topography of TS Pt and TS Au sputtered metal surfaces are presented. Immediately after stripping, the TS platinum exhibits ∼1 Å root-mean-square roughness over one square micron and demonstrates higher fidelity to the templating silicon wafer than TS gold. The TS platinum surface also shows high physical stability in ambient laboratory conditions over the period of a week, whereas considerable topographical aging is observed in the case of the TS gold surface. The results are discussed in relation to the potential of TS platinum for use in molecular electronic systems.