Hydrogenation characteristics of p-type poly-Si passivating contacts on textured surface for double-sided TOPCon devices
Anna Damm, Mathias Bories, Jan Benick, Mario Hanser, Armin Richter, AnYao Liu, Zhongshu Yang, Stefan Lange, Paul‐Tiberiu Miclea, Jana‐Isabelle Polzin
Abstract
An effective hydrogenation process for polycrystalline silicon based passivating contacts (TOPCon) is crucial to achieve a very high level of surface passivation. This work examines the hydrogenation characteristics of p-type TOPCon on textured surface morphology by applying dielectric layers such as AlO x , SiN x and stacks thereof followed by an activation in a furnace anneal or by fast-firing. In a direct comparison with n-type TOPCon, p-type TOPCon requires higher activation temperatures and a higher activation energy. For a successful integration of n-type and p-type TOPCon into bottom cell precursors with 726 mV implied V oc for tandem devices, stacks featuring AlO x are beneficial to increase the thermal stability especially for n-type TOPCon. With regards to fast-firing processes, the influence of an additional pre- or post-annealing step is investigated. The peak firing temperature can significantly be reduced when applying an annealing step beforehand and a post-firing anneal improves surface passivation to recombination current densities J 0s as low as 7.9 fA/cm 2 for p-type TOPCon on textured surface which is one of the lowest reported in literature. • Higher hydrogenation activation temperatures are necessary for p-TOPCon than n-TOPCon. • Higher hydrogenation activation energy of p-TOPCon likely associated to smaller grain size. • Hydrogenation process successfully integrated into TOPCon 2 bottom cell precursors. • Combination of annealing and fast-firing is beneficial for surface passivation. • Low J 0s of 7.9 fA/cm 2 for p-type TOPCon on textured surface.