The infrared transmittance and reflectance spectra of amorphous fluorinated silicon films (a-Si: F) have been measured as a function of a ratio of SiF4/(SiF4+ Ar) partial pressure and annealing temperature. The absorption bands were assigned: 1,015 cm-1 (SiF4 stretching), 965 cm-1 (Si-F3 stretching), 920 cm-1 (Si-F2 stretching), 870 cm-1 ((Si-F2)2 stretching), 825 cm-1 (Si-F stretching), 600 cm-1 (Si-C stretching or Si 2LA mode), 515 cm-1 (Si TO mode), 380 cm-1 (SiF4 bending), and 300 cm-1 (Si LA mode). SiF4 molecules incorporated into a-Si: F films are observed in samples prepared with high SiF4 partial pressures, but in samples prepared lower SiF4 partial pressures dangling bonds seem to be saturated by fluorine atoms. The transition from Si-F, Si-F2, and Si-F3 groups to SiF4 molecules occurs above annealing temperatures (600 �C). The total fluorine content is constant until crystallization, and a-Si: F films are found to be more stable than a-Si: H films.
ASJC Scopus subject areas
- Physics and Astronomy(all)