Defect Diagnostics of Scribing Failures and Cu-Rich Debris in Cu(In,Ga)Se$_2$ Thin-Film Solar Modules With Electroluminescence and Thermography

We study the appearance of both scribing failures and Cu-rich debris, formed during Cu(In,Ga)Se (CIGS) co-evaporation, in electroluminescence (EL) and dark lock-in thermography (DLIT) images. We observe that for most of the defect types, there is a characteristic appearance of EL and DLIT that allows reliable diagnostics. We also point to defect scenarios where different defects appear similar. With regard to scribing defects, we find that the reliability of defect identification increases with the length of the line interruption, while for Cu-rich debris, we find that the geometrical size and position within the cell significantly determine its defect appearance and, therefore, the ability to diagnose it.