Fig. 9

Phase variations at inhomogeneities in the pn-junction region. a–d Reconstructed phase images from selected sites labelled as a–d in Fig. 8. Inhomogeneous regions are visible in CdS and CIGS. The line profiles (e–j) were extracted from the marked regions 1–6, whereas profiles nr. 1,3,5, and 6 show variations in CdS and profiles 2 and 4 variations in CIGS. The extent of the absolute phase variations are indicated next to the profiles. Furthermore, the corresponding potential variation needed to cause the measured phase shift under the assumption that the thickness is constant is indicated (case ii) and also the thickness variation needed to cause the phase shift under the assumption that the potential is constant (case i)