Thin film p-i-n poly-Si solar cells directly converted from p-i-n a-Si structures by a single shot of flash lamp

Abstract

We propose a novel production method to fabricate high-efficiency thin-film poly-Si solar cells using flash lamp annealing (FLA) for crystallization of micrometer-order-thick p-i-n amorphous silicon (a-Si) structure, prepared by catalytic chemical vapor deposition (Cat-CVD, Hot-Wire CVD) on low-temperature glass substrates and following high-pressure water vapor annealing for defect passivation. The FLA enables us to crystallize a-Si films with only one pulse of less than 10 ms duration, and use of Cat-CVD provides a-Si cost-effectively because of high deposition rate of a-Si over 10 nm/s. Secondary ion mass spectroscopy (SIMS) profiles reveal that diffusion of dopants in p- or n-type layers is sufficiently suppressed after FLA, indicating possibility of simultaneous crystallization of p-i-n stacked a-Si films. High-pressure water vapor annealing (HPWVA) enhances the minority carrier lifetime of the poly-Si up to about 10 μs and drastically improves diode properties of the p-i-n poly-Si structure. No light-induced degradation is observed in the solar cell property of the poly-Si solar cell after 24-hour 1-sun light soaking.