Stability of a-Si:H solar cells and corresponding intrinsic materials fabricated using hydrogen diluted silane

We report on a study in which properties of p(a-SiC:H)/i(a-Si:H)/n(μc-Si) a-Si:H solar cells and their i-materials prepared with hydrogen dilution are investigated and compared with films and cells prepared without hydrogen dilution. The cells and the corresponding intrinsic films were fabricated in a multi-chamber PECVD system with pure silane (SiH₄) and silane diluted with hydrogen in the ratio [H₂]/[SiH₄]=10. The initial performance of both types of cells (~4000 Å thick) fabricated without optical enhancement are quite similar but the diluted cells are significantly more stable. Despite the reported importance of the interface regions in determining their solar cell characteristics, a direct correlation between the degradation of the diluted solar cells and their intrinsic films is observed in this study. Both diluted cells and films reach a steady state of degradation under AM1 illumination within 100 hours. Distinctly different kinetics from the undiluted materials and cells and the ability to reach steady state degradation in less than 100 hours offer a new probe for improving our understanding of the mechanisms limiting cell performance