Chemical characterization of surfaces and thin films for the development of new materials and quality control

Abstract

Surfaces and thin films of solid materials play an important role in many technological fields like corrosion, catalysis, polymers, plasma surface engineering, coatings, tribology, implants, sensors, microelectronics, etc. Application of analytical methods with high surface and chemical sensitivity is important for a complete understanding of surface reactions, functional properties, and degradation of materials in such applications. Scanning electron microscopy - SEM in combination with EDXS is very often applied to analyze the morphology and elemental chemical composition with high lateral resolution. In this presentation, another two methods with high surface sensitivity will be presented, i.e., X-Ray photoelectron spectroscopy – XPS and Secondary ion mass spectrometry - SIMS. These methods have surface sensitivity in the range of 1-5 nm, making them unique surface probes. The XPS analyses can give information on chemical composition, oxidation states (identification of Cu(0)/Cu(1+)/Cu(2+), Ti(0)/Ti(3+)/Ti(4+)) and bonding of elements (C-C/C-O/O=C-O) at surfaces and thin films. The SIMS method allows the identification of a type of molecules and molecular structure at surfaces, which is particularly important for analyses of organic materials. The XPS and SIMS methods can be combined with ion etching to remove the surface layers and analyze subsurface chemical composition up to one micron. In such a way, a depth distribution in thin films and multilayer structures can be obtained. In this presentation, we will show typical applications of surface analytical methods XPS and SIMS in our laboratory for the development of new catalytic materials based on doped TiO2, a study of corrosion inhibitors, the application of graphene-based materials, and the degradation of perovskite solar cells. Also, examples of surface analyses for quality control as support for industrial partners in Slovenia will be presented.