Annual ring-like grain growth in Ni-mediated crystallization of amorphous silicon by pulse annealing

We studied annual ringlike grain growth in Ni-mediated crystallization of amorphous silicon (a-Si). Ni particles were sputtered onto a-Si and then the sample was crystallized in a pulse lamp annealing system. The crystallization of a-Si proceeds circularly from the seed at the center of a grain. The Ni atoms on the a-Si aggregate together and then from a NiSi2 crystallite, which is a seed for inducing crystallization. The crystallization proceeds from these nuclei, and then the diskshaped grain grow laterally with increasing the number of heating cycles. An annual ring appears after Secco etch of a disklike grain even though the crystallization temperature is fixed. The explosive crystallization over 1μm results in annual ring, which is more clear when pulse heating is used for crystallization. Polycrystalline silicon with a grain size of 103μm was achieved in the present work.