Characterization of Titanium Oxide Films Prepared by the Template-Stripping Method

Abstract

Titanium is a widely used biomaterial, and there is, therefore, considerable interest in studying the processes occurring at its surface. A suitable in situ investigation technique is atomic force microscopy (AFM), which, however, requires very flat substrates. In the case of gold, the so-called “template-stripping method” has allowed the successful preparation of surfaces that are atomically flat over large areas. The method is based on the evaporation of gold onto atomically flat surfaces of freshly cleaved mica, which is subsequently stripped off. Cacciafesta et al. (Langmuir 2000, 16, 8167−8175) have applied this method for preparing model titanium (oxide) surfaces for AFM investigation. The focus of the present study was the characterization of the chemical and topographical characteristics of the resulting surface. In particular, it was found that mica could not be completely removed from the titanium during the stripping step unless a thin layer of carbon was present between the titanium and the mica. In this study, a layer of amorphous carbon was artificially introduced between the two materials, but it is possible that the carbon naturally present in the micas can play a similar role. Detailed investigation by spectroscopic (angle-resolved X-ray photoelectron spectroscopy, depth profiling, X-ray photoelectron diffraction) and imaging methods (AFM) lead to the conclusion thaton samples without a carbon interfacethe mica layer is at most a few unit cells thick and is nearly confluent.