Explosive crystallization (EC) takes place during flash lamp annealing in micrometer-thick amorphous Si (a-Si) films deposited on glass substrates. The EC starts from the edges of the a-Si films due to additional heating from flash lamp light. This is followed by lateral crystallization with a velocity on the order of m/s, leaving behind periodic microstructures in which regions containing several hundreds of nm-ordered grains and regions consisting of only 10-nm-sized fine grains alternatively appear. The formation of the dense grains can be understood as explosive solid-phase nucleation, whereas the several hundreds of nanometer-sized grains, stretched in the lateral direction, are probably formed through explosive liquid-phase epitaxy. This phenomenon will be applied to the high-throughput formation of thick poly-Si films for solar cells.

Explosive crystallization of amorphous silicon films by flash lamp annealing

https://iopscience.iop.org/article/10.1088/0268-1242/31/10/103001/pdf

A review of thermal processing in the subsecond range: semiconductors and beyond

Intense pulsed light processing for photovoltaic manufacturing

Variation of crystallization mechanisms in flash-lamp-irradiated amorphous silicon films

Thin-film polycrystalline silicon solar cells formed by flash lamp annealing of a-Si films

https://dspace.jaist.ac.jp/dspace/bitstream/10119/8167/1/Thin_Solid_Films_517_3472_2009.pdf

Precursor Cat-CVD a-Si films for the formation of high-quality poly-Si films on glass substrates by flash lamp annealing

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.

Young Rae Jang

Papers

Precursor Cat-CVD a-Si films for the formation of high-quality poly-Si films on glass substrates by flash lamp annealing

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