Fig. 7

Phase variations on solar cell with CIGS of high Cu content (a, b) Intensity line profiles showing the phase variation (green lines) which is extracted from the regions A \(_{1}\), A \(_{2}\), B \(_{1}\) , and B \(_{2}\) marked in Fig. 6a, b. Below, the intensity profiles extracted from the same regions (A, B) in the HAADF-STEM image (Fig. 6a, b), are shown (a, b, yellow lines). In order to correct for residual background gradients in the phase images, a linear background was subtracted from the phase variation line profiles (A \(_{1}\), A \(_{2}\), B \(_{1}\) , and \(B_{2}\)). The relative thickness variation, measured by HAADF-STEM and the absolute thickness variation, measured by the phase images are given in (c, d). The EDX line profile corresponding to region A is depicted in (e) showing relative concentration variations. The EDX line profile which is shown in (f) stems from a region close to B. The copper signal in the ZnO region originates from stray electrons that impinge on the copper grid. Further a significant amount of Mg and O is measured in the CIGS region. These are artifacts due to the overlap of the Se L-lines with the K-lines of Mg and the Cr L-lines (Cr is present in the TEM specimen holder) with the O K-lines. In addition to the EDX profiles of the present elements, also the relative variation of GGI and CGI is qualitatively shown in the graph