Microwave Annealing for Fast and Effective Hydrogen Activation in Polycrystalline Silicon Passivating Contacts

Hydrogenation is a crucial step in the fabrication of high‐efficiency silicon solar cells. In this study, the effectiveness of hydrogen activation is demonstrated via microwave annealing of hydrogen‐rich dielectrics coated on poly‐Si passivating contacts. This method is compared with conventional hydrogenation techniques, such as annealing in N 2 in the presence of a hydrogen‐rich source (such as hydrogenated aluminum oxide (AlO x :H), hydrogenated silicon nitride (SiN y :H), or a AlO x :H/SiN y :H stack). Key improvements observed include a reduction in J 0 from 30 to <5 fA cm − 2 , an increase in iV oc from 690 to >730 mV, and an enhancement in effective lifetime ( τ eff ) from 0.6 to ≈3.5 milliseconds on phosphorus‐doped poly‐Si/SiO 2 passivating contact samples. With a very short annealing time of ≈1–2 min, the samples passivated by AlO x :H, SiN y :H, or the stack show similar performance to samples subjected to 30 min of nitrogen annealing. Photoluminescence (PL) spectra corroborate the findings regarding the hydrogenation of the poly‐Si layer and the c‐Si substrate, with an increase in PL intensity after microwave annealing. Ultimately, this work suggests that microwave annealing could be a promising addition, offering flexibility to traditional firing hydrogenation processes.