Characterisation of solar cell nanolayer interfaces using time-of-flight elastic recoil detection analysis

The understanding of hydrogen and chemical interfaces in passivating contact stacks is critical for advancing high-efficiency silicon solar cells. This work employs time-of-flight elastic recoil detection analysis (ToF-ERDA) to profile elemental depth distributions, particularly the unambiguous characterisation of hydrogen, in key surface passivation dielectric nanolayers—SiN x , AlO x , and Al-doped ZnO (AZO). By leveraging the high mass resolution and low fluence of ToF-ERDA, combined with Monte Carlo simulations (MCERD), our work resolves hydrogen distributions and distinguishes overlapping signals from Si and Al, enabling precise analysis of interface composition. SiN x layers exhibit hydrogen contents up to 21 at.%, with redistribution and performance degradation observed after high-temperature annealing. In contrast, AlO x shows lower hydrogen content (∼2 at.%) but significant lifetime improvements post-annealing, indicating dominant field-effect passivation. For SiN x /AlO x double-layer stacks, enhanced hydrogen diffusion into AlO x was observed, suggesting SiN x as a hydrogen source. AZO/AlO x stacks demonstrated excellent passivation (iV OC > 730 mV) post-anneal, with hydrogen predominantly located in the AZO, challenging conventional views of AlO x as the main hydrogen source. These findings underline the value of ToF-ERDA for evaluating passivation mechanisms and demonstrate the tools versatility and usefulness in characterising dielectric nanolayers. • ToF-ERDA accurately depth profiles hydrogen in solar cell passivation layers. • An onset for rapid effusion of hydrogen in SiNx layers occurs at >600C, linked to reductions in surface passivation. • AlO x layers gain hydrogen from SiN x , showing effectiveness as a H diffusion source. • AZO/AlO x stacks show excellent passivation, potentially with AZO as primary H source. • MCERD simulations refine depth profiles and deconvolute overlapping Si and Al.