On the growth mechanism of polycrystalline silicon thin film by Al-induced layer exchange process

We attempted to clarify controlling mechanisms of Al-induced layer exchange process of Al and amorphous silicon (a-Si) and microstructures in resultant polycrystalline silicon (poly-Si) thin film by utilizing in situ observation of the growth process. Introduction of a few nm-thick germanium adlayer remarkably reduces crystallization time and affects the grain size of poly-Si films. This is likely to be accompanied by the growth mode transition as suggested by change of Avrami constant. Control of the Al/a-Si interface is of crucial importance to control the growth process.

► Impact of Ge thickness inserted at a-Si/Al on Al-induced layer exchange process was investigated by in situ monitoring.
► Drastic increase of the grain size of poly-Si was observed by insertion of only 1 nm Ge.
► Drastic reduction of the processing time was realized by further increase of Ge thickness.
► Growth mode changeover occurred at a critical thickness of Ge.