Total SiH4/H2 pressure effect on microcrystalline silicon thin films growth and structure

The effect of the total SiH₄/H₂ gas pressure (1–10 Torr) on the growth rate, the film crystallinity and the nature of hydrogen bonding of microcrystalline silicon thin films deposited by 13.56 MHz plasma-enhanced chemical vapour deposition (PECVD) was investigated under well-controlled discharge conditions. The deposition rate presents an optimum for 2.5 Torr, which does not follow the trend of silane consumption that increases with pressure and is attributed to an increase in plasma density. The film crystallinity increases with pressure from 1–2.5 Torr and then remains almost the same, whereas the films deposited at 1 Torr are highly stressed. On the other hand, hydrogen bonding is also drastically affected.