Contact Formation of Silver Paste and Atmospheric Pressure Chemical Vapor Deposition (n) Poly-Silicon Passivating Contacts on Planar and Textured Surfaces

Abstract

One of the main challenges for the industrialization of the passivating contact approach for Si solar cells is the metallization with screen-printed paste while maintaining the low saturation current density. Using a non-commercial Ag paste to metallize atmospheric pressure chemical vapor deposition (APCVD) (n) poly-Si, the metal contact formation for passivating contacts on planar and textured substrates is investigated. The paste creates deep imprints caused by silver crystallite formation at the pyramid tips of textured silicon wafers. In contrast, on planar wafers, the silver crystallite growth stops at the interface between poly-Si and the Si wafer. Similar contact resistivities are determined by comparing textured and planar Si samples. On planar samples, a contact resistivity of 4.6(14) mΩcm2 and a saturation current density of only 141(10) fA cm−2 for the metallized contact area are demonstrated. Textured samples with a contact resistivity of 2.7(17) mΩcm2 show a higher saturation current of 480(40) fA cm−2. This etching behavior is investigated by structural and elemental analyses using scanning electron microscopy.