In situ IR spectroscopic study of a-Si:H films growing under photo-chemical vapor deposition condition

Polarization modulation infrared spectroscopy has been successfully applied for in situ observations of a-Si:Hfilms growing under photo-chemical vapor deposition conditions. The thin films exhibited absorption bands arising fromSiH₃or SiH₂species, depending upon the substrate temperature. Whereas the mass thickness of thefilm deposited at 293 K increased in proportion to the deposition time, the IR absorption intensity of SiH₃species decreased in rate when the film grew beyond 15 Å in thickness, showing that the concentration of the SiH₃species becomes reduced with the deposition time. Although the band ascribable to the Si-O stretching vibration could not be observed during the deposition, it grew when the film was exposed to air. This fact suggests that theorigin of the oxygen incorporated in the film is mainly atmospheric oxidizing agents.