Comparison of different dielectric passivation layers for application in industrially feasible high-efficiency crystalline silicon solar cells

Due to the trend towards thinner and higher efficient crystalline silicon solar cells, it is substantial to decrease the surface recombination velocity and to increase the internal optical reflection at the rear surface. Therefore, dielectric passivation of the rear surface is a key technology for the next generation of industrial solar cells. This paper presents a study on the applicability of different dielectric layers and stack systems ranging from high-temperature thermal oxides via silicon nitrides to low-temperature amorphous silicon. It is pointed out that a low surface recombination velocity in lifetime measurements is only one necessary condition for a high-quality rear structure. Due to its high thermal stability and good surface passivation quality, silicon carbide layers have been used as rear surface passivation in high-efficiency cell structures and efficiencies of more than 20% are reported for the first time.