On the hydrogenation of Poly-Si passivating contacts by Al2O3 and SiN thin films
Bas W. H. van de Loo, Bart Macco, Manuel Schnabel, Maciej K. Stodolny, A.A. Mewe, David L. Young, William Nemeth, Paul Stradins, W. M. M. Kessels
Abstract
Doped polycrystalline silicon (poly-Si), when coupled with a thin SiO2 interlayer, is of large interest for crystalline silicon (c-Si) solar cells due to its outstanding passivating contact properties. To reach high levels of surface passivation, it is pivotal to hydrogenate the poly-Si and the underlying c-Si/SiO2 interface. This can be done by capping the poly-Si with a hydrogen-containing dielectric layer such as Al2O3 or SiNx, followed by a thermal anneal. On the basis of recent research, this work addresses several aspects of such hydrogenation by dielectric materials, including the effect of the annealing ambient, the thermal stability and reversibility of hydrogenation, the poly-Si doping level and c-Si surface texture. Additionally, the implementation of hydrogenation of poly-Si by dielectric materials in solar cells is discussed.