Vibrational local modes of a-Si1−xCx:H alloys and variation of local modes in different local environments

The vibrational density-of-states for various bonding structures in a-Si1−xCx:H are calculated. The local modes induced by the SiHn and CHn groups are identified. The bending modes of SiHn group have large variation between the a-Si1−xCx:H and a-Si:(H,C) alloys. The bending modes induced by the CHn groups are almost the same in the above two different alloys. The C-dangling bond has the effect of shifting the Si–C vibrational mode toward lower frequency.