Role of Al2O3 intermediate layer for improving the quality of polycrystalline-silicon film in inverted aluminum-induced layer exchange

A thin Al2O3 intermediate layer prepared by atomic layer deposition was introduced into inverted aluminum-induced layer exchange (inverted-ALILE) to form high-quality polycrystalline silicon (poly-Si) thin layer. It was demonstrated that the continuity and quality of poly-Si were obviously improved by the Al2O3 layer. The fraction of (1 0 0)-oriented crystals reached 93%, and the average grain size of 28 μm with uniform surface morphology and low defect density were achieved at the optimal Al2O3 thickness of 4 nm. It was also found that an a-AlOx layer always existed at the poly-Si/Al interface after inverted-ALILE process, which is independent on the original surface states. The results suggested that the thin poly-Si layer would be a promising epitaxial template for Si based thin film solar cells.