Layer exchange during aluminum-induced crystallization of silicon suboxide thin films

•Al-induced crystallization of a-SiO1.8 in the layer exchange mode was carried out.•Annealing at 550 °C led to the formation of a continuous poly-Si thin film.•The complete oxidation of Al with the formation of Al oxide inclusions embedded in a-SiO1.8.•The presence of regions of unchanged a-SiO1.8 in the upper layer.•The embedding of Al into the SiO2 substrate accompanied by its oxidation. Aluminum-induced crystallization of a-SiO1.8 in the layer exchange mode was carried out. Annealing of a “SiO2 substrate/Al/a-SiO2 membrane/a-SiO1.8” stacked structure at 550 °C led to the formation of a continuous polycrystalline Si (poly-Si) thin film on the substrate, which is characteristic of the layer exchange process. However, the upper layer formed in the process had structural features that were not previously observed for the pure and slightly oxidized amorphous silicon as a Si-containing thin-film precursor. The high oxygen content in the system led to the non-uniform transformation of a-SiO1.8 layer, namely, to the formation of Al oxide islands of submicron size nearby the interface with poly-Si thin film as a result of the complete oxidation of the Al layer, whereas the other part of the upper layer was still unchanged. In addition, the embedding of Al into the SiO2 substrate accompanied by its oxidation was observed.