Explosive crystallization of amorphous silicon films by flashlamp annealing

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.