Phosphonate-anchored thin films on titanium and niobium oxide surfaces: Fabrication and characterization

Phosphonate-anchored thin films form on various metal oxide substrates. This paper compares structural details of these covalently anchored films on the oxidized surfaces of titanium, niobium and a Ti45Nb alloy. This is made possible by a sample configuration wherein the alkylphosphonates are coated onto a thin film of metal which is sputtered onto a double-side-polished silicon wafer and then oxidized. Samples are flat and reflective and are suitable for ellipsometry, wetting measurements, X-ray Photoelectron Spectroscopy, Atomic Force Microscopy, and Fourier Transform Infrared-Attenuated Total Reflectance Spectroscopy. Deposition from heated tetrahydrofuran produces ordered films with measurable differences among deposition protocols and among metal oxide substrates. These substrates enable identification of the mildest deposition procedures that still provide uniform, robust surface coatings.