Characterization of polycrystalline silicon films produced by aluminum-induced layer exchange for the various thicknesses of an aluminum oxide layer

We characterized polycrystalline silicon films produced by aluminum-induced layer exchange (ALILE) for the various thicknesses of an aluminum oxide layer. The pc-Si film is fabricated by the ALILE process with a structure of glass/Al/Al₂O₃/a-Si for application to a seed layer of polycrystalline silicon (pc-Si) solar cells using dc and RF sputtering, and PECVD methods, respectively. For investigation of the effects of oxide film thickness on the crystallinity in the ALILE process, the thickness of Al₂O₃ was varied from 4 to 50 nm including native oxidation in the ambient atmosphere. For characterization OM, SEM, Raman spectroscopy analyses are carried out. As results, the crystallinity was exponentially decayed with increase of Al₂O₃ thickness. Also, the grain size is decreased with increase of Al₂O₃ layer thickness. The maximum pc-Si grain size of about 60 μm is obtained at the relatively thin oxide layer. The preferential crystal orientation was (111) and more dominant for the thinner Al₂O₃ layers. In this work the effects of Al₂O₃ film thickness on the crystallization properties of a-Si by ALILE process are closely demonstrated such as grain size, preferential crystal orientation, and crystallinity.