High-Resolution XRF Spectroscopy for Elemental Mapping of Thin-Film Layers

This thesis investigates the application of high-resolution X-ray fluorescence (XRF) spectroscopy for the elemental characterization and mapping of thin-film layers at the nanometric scale. The study focuses on the analysis of ultra-thin coatings, with thicknesses on the order of tens of nanometers, deposited on silicon wafer substrates, where signal overlap and substrate interference represent significant challenges. A field-portable XRF (FP-XRF) system was used under controlled laboratory conditions to evaluate its performance in resolving elemental distributions in thin films and spatially confined samples. Particular attention was given to optimizing acquisition parameters, including excitation energy, filtering conditions, and sample-to-detector distance, in order to enhance sensitivity to surface layers while minimizing substrate contributions. To address the intrinsic limitations of XRF in thin-film analysis, a dedicated data processing workflow was developed. This includes background correction, peak identification, and substrate subtraction to isolate the signal originating from the thin film. Furthermore, a quantitative analysis of the elemental composition was carried out by means of a calibration procedure based on reference samples with known thickness for each element, enabling the conversion of spectral intensities into physically meaningful quantities. The results demonstrate that, despite the inherent constraints of portable XRF instrumentation, it is possible to achieve reliable elemental discrimination in thin-film systems through careful optimization of measurement conditions and signal processing strategies. The study highlights both the potential and the limitations of high-resolution XRF spectroscopy for non-destructive analysis of nanoscale layered materials, providing insights for future improvements in instrumentation and methodology.