Large-grained (111)-oriented Si/Al/SiO2 structures formed by diffusion-controlled Al-induced layer exchange

We investigated inverted Al-induced crystallization (AIC) technique of amorphous Si films (thickness: 50-100 nm) for the formation of polycrystalline Si films on Al coated glass substrates at low-temperature (< 500 °C). A SiO2 interlayer was inserted in between Al and Si layers in order to control the Al-Si diffusion rate. As a result, the crystal orientation of the AIC-Si layer strongly depends on the thickness of the SiO2 interlayer: thin (1 nm) interlayer provided (100) orientation while thick (10 nm) interlayer provided (111) orientation. Meanwhile, the thicker the SiO2 interlayer, the larger the grain size of the AIC-Si layer. In particular, for a sample with 10-nm-thick SiO2 interlayer, the (111) orientation fraction reached 99% and the average grain size over 50-μm diameters. This AIC-Si layer holds promise as epitaxial templates for light-absorption layers of thin-film solar cells, as well as for functional silicide materials.