Control of the initial stage of nanocrystallite silicon growth monitored by in-situ spectroscopic ellipsometry

The early stage of nanocrystallite silicon (nc-Si:H) growth from plasma-enhanced chemical vapor deposition (PECVD) was investigated through in-situ monitoring by UV-visible spectroscopic ellipsometry. The film structure was an amorphous up to about 500 Å thickness on SiO2 substrate, which was very sensitive to the selection of the substrate including its surface roughness. Especially, the thickness of the transition layer from amorphous to nc-Si phase is thicker on SiO2 substrate than that on Cr or c-Si with native oxide one under an identical plasma condition. The SiH4 gas heating technique has been proposed to enhance the crystallinity at the early stage of growth on SiO2.