Structure evolution in CIGS deposition: An X-ray diffraction analysis with Rietveld whole-pattern refinement

We have used Rietveld whole pattern refinement methods to extract quantitative structural information from powder X-ray diffraction analyses of CIGS (copper indium gallium diselenide) photovoltaic materials. Samples produced by single-stage co-evaporation generated a single-phase CIGS XRD pattern that yielded Ga/In relative site occupancies that were in good agreement with X-ray fluorescence measurements. In contrast, samples extracted during a three-stage deposition sequence showed complex behavior: an initial (Ga,In)₂Se₃ layer that evolved into two distinct CIGS phases. Other changes, such as the dependence of the lattice parameter of the α-Mo back contact layer with process conditions, were observed via whole pattern Rietveld refinement.