Current research is focused on the standardization of grazing incidence/exit XRF (GI-XRF/GE-XRF) and X-ray reflectometry (XRR) methodologies. These techniques are applied mostly at synchrotron facilities to characterize structural (thickness, roughness, density), compositional (elemental abundance versus depth) and chemical (redox state versus depth) properties of thin nanolayered systems deposited or deep implanted on semiconductors (Si, Ge). Nanomaterials have emerging interdisciplinary applications for example in nanoelectronics, in energy storage and conversion technologies, etc. Relevant research activities are carried out through different collaborative schemes, for example with the Technical University of Athens, INFN-LNS and colleagues from Institutions worldwide. Open research challenges refer to the development of scanning-free GE-XRF analytical methodologies, the optimization and validation of appropriate software codes which combine GIXRF/XRR results to achieve optimum description of experimental data, but also towards a proper evaluation of optical constants which are mostly appropriate to describe the continuously developed novel nano-layered systems.
Previous research in this field employed combined Ion Beam Analysis (IBA) based methodologies to characterize the in-depth elemental profile of thin film Cu(In, Ga)Se2 solar cells at the Ruđer Bošković Institute in Zagreb, Croatia. In copper indium gallium diselenide Cu(In1-X,GaX)Se2 (CIGSe, 0<X<1), thin films the inter-diffusion of the elements during film growth creates a gradient in the In/Ga concentration along the depth of the absorber that affects the band gap and carrier density and thus it determines the photovoltaic properties (efficiency) of the solar cell. The proposed IBA methodology based on dual energy alpha beam RBS spectrometry combined with PIXE measurements demonstrated the analytical potential to resolve the in-depth elemental profiles in thin solar cells Cu(In, Ga)Se2 and revealed interesting features such as the diffusion of In within the ZnO window layer.