Electroluminescence imaging for determining the influence of metallization parameters for solar cell metal contacts

Electroluminescence imaging (EL) is a widely used technique to evaluate the quality of the electrical contacts of solar cells. This paper investigates the ability to detect problems after the metallization process for front and back contacts. For the back contact formation process we investigate cells which had direct contact with the furnace belt. This fact is crucial because contact between, the printed aluminum and the belt could determine the inhomogeneity of the back contact. For front contact the series resistance distribution for the quick process at different belt speeds and peak temperatures is determined. The series resistance of samples was also measured using the method called the Corescan. In both cases, a detailed description of the process parameters, especially the temperature distribution characteristics, are presented. The EL method is non-destructive and gives a greater resolution of images, which allows a more precise evaluation of electrode imperfections after the metallization process. The Corescan method gives detailed potential jump values which are proportional to the contact resistance.