Investigation of crystalline orientation factor in microcrystalline silicon thin film deposition

Crystalline orientation factors in microcrystalline silicon (µc‐Si) deposition are investigated by the triode‐plasma enhanced chemical vapor deposition (PECVD) method and conventional diode‐PECVD with optical emission spectroscopy (OES). The existence of more important factors for the orientation than the ion and the [H]/[SiHx] ratio on the growing surface is suggested from the SiH4 flow rate and the mesh‐electrode gap dependence of the orientation and the crystallinity in triode‐PECVD. Improvement of the crystallinity and the independent orientation of the following film on the seed‐layer offer the deposition radicals to act a key role for the crystalline growth direction. The oligomerized‐silane radical (probably dimeric radical) is proposed as an orientation factor by the relation of SiH* emission intensity on the deposition rate and the orientation.