Vibrational properties of SiO and SiH in amorphous SiOx:H films (0 ≤ x ≤ 2.0) prepared by plasma-enhanced chemical vapor deposition

The stretching and bending absorptions arising from SiO and SiH bonds in amorphous SiOx:H films, prepared by rf glow discharge decomposition of a SiH4O2 mixture at 300°C, have been investigated by infrared absorption measurements as a function of the O content, x. Changes in the profiles of the SiH stretching absorption as a function of x were examined on the basis of a random-bonding model. A charge-transfer model is employed to derive the oscillator strength of the SiH stretching absorption and the peak frequencies of the SiH and SiO stretching absorption, for the Si(Si4−nOn)(n = 1−4) and HSi(Si3−nOn)(n = 0−3) bonding configurations. The absorption over the range 500–900 cm−1, related to the SiH and SiO bending motions, can be decomposed into five components around 650, 780, 800, 840 and 880 cm−1. It is found that the intensities of the 780, 840 and 880 cm−1 bands are closely correlated with those of the SiH stretching absorptions at 2115, 2200 and 2260 cm−1, respectively. The origins of these absorption bands along with the 650 and 800 cm−1 bands are discussed.