Development of Full-Area Passivating Contacts for Solar Cells Application

The state-of-the-art PERC solar cell is passivated with Al2O3 or H:SiNx.these dielectrics must be opened locally to extract the generated photo currentby a direct metal-semiconductor contact. These contacts induce a highdensity of interface states, known for increasing the surface recombinationvelocity and decreasing the solar cell efficiency. To circumvent the directmetal-semiconductor contact, this thesis investigates a cell concept, whichbased on a full-area passivation by Al2O3 or H:SiNx without local openings.On the one hand, such a passivating and non-conductive dielectric has tobe thin enough to extract the photo current with lowest possible ohmiclosses. On the other hand, the passivation has to suppress the charge carrierrecombination at the Si/dielectric interface as much as possible. Withrespect to these criteria, Al2O3 and H:SiNx layers were deposited with optimizedprocess parameters. In conjunction with these passivation layers,also a transparent conductive oxide was developed, which enables a certaincarrier selectivity to extract just one type of charge carriers, i.e. electrons orholes. This study focuses on the development of TiOx as electron-selectivecontact and NiO or WOx as contact. The deposited contacts are examinedwith respect to their structural, electrical and optical properties. The findingsare used to form an optimized full-area carrier selective contact. Both,the thin passivation layers and the carrier selective contact, are combinedto form a full-area passivating contact for p-doped as well as for n-dopedSi. The developed full-area contacts exhibit the potential to replace thetypical metal-semiconductor contacts in state-of-the-art PERC solar cells.

Pagina's: 194, Editie: Eerste editie, Paperback, BoD - Books on Demand