Abstract
Aluminum-induced crystallization (AIC) process was used to prepare the cheaper and has large grain poly-silicon films for thin film solar cell. But it is observed that the high density of intragrain defects form in the poly-Si film during AIC process, that will enhance the carrier recombination probability, and such that directly influence the efficiency of solar cell. To solve this problem, we use TEM to investigate the nucleation and growth of silicon grain in a series of time length of AIC process. Using sputtering method, 300 nm poly-Al layer was deposited onto glass substrate, then the sputtering chamber was exposed to atmosphere for 2 min in order to obtain a native oxide layer. Finally 600 nm amorphous silicon layer was deposited using a sputter, to get Al/Al2O3/α-Si stacking structure. After deposition processes, the samples were annealed in a tube furnace under Ar ambient and N2 mixed H2 ambient at 400℃ different times, respectively. The nucleation and growth mechanism of poly-Si grains are investigated with TEM. We found that twin has existed at initial state of silicon grains. The twin density decreases with increasing the annealing time, and will also be influenced in different annealing atmosphere. It was also found that AIC processed poly-Si grains has {100} preferred orientation. This promotes us to study the grain orientation in the poly-Si thin film at initial stage of annealing. The nuclei Si tends to growth at Al/ Al2O3 interface, resulting the phenomenon of {100} preferred orientation.