Investigation of compositional inhomogeneities in complex polycrystalline Cu ( In , Ga ) Se 2 layers for solar cells

In-depth resolved composition inhomogeneities of polycrystalline Cu ( In , Ga ) Se 2 (CIGS) complex layers for high efficiency solar cells were investigated with Raman scattering measurements. In-depth resolved analysis of the frequency of the main CIGS Raman mode in the spectra measured after sputtering of the layers at different depths lead to identification of different compositions across the layer thickness. These data are in good agreement at both qualitative and quantitative levels with the in-depth resolved composition analysis of the samples by sputtered neutral mass spectroscopy. In addition, Raman measurements also allow detection of additional phases as ordered vacancy compounds.