Nucleation and growth of poly-Si films deposited directly on glass substrate in reactive thermal-chemical vapour deposition

We prepared device-grade polycrystalline silicon thin films on glass substrates at 450 °C, by reactive thermal–chemical vapour deposition employing Si2H6 and F2 as source gases. The nucleation and growth of the poly-Si thin films were investigated, and the process pressures were varied from 533 to 933 Pa. Thin films with thickness of 2 to 200 nm were prepared and their crystallinity and morphological properties were characterized. The incubation time is shorter than 30 s; 533 Pa yields higher crystallinity. However a trade-off exists between growth rates and grain sizes. We proposed a model for comparing our technique with conventional low- pressure chemical vapor deposition.