Infrared-transmission spectra and hydrogen content of hydrogenated amorphous silicon

In this paper, two kinds of methods of calculating the hydrogen content of a-Si:H thin film by means of the wagging mode and the stretching modes of infrared-transmission spectra, are investigated. The reason for the difference in these two calculation results is analyzed. If the contents of SiH2 and (SiH2)n are indicated in terms of a structure factorF=(/840+/880)//2000, it is shown that the calculation results obtained from the two different methods are almost equal when the refractive indexn is approximately 3.4 or the fitting thickness is between 0.71 and 0.89 μm in the case of a smallF. It is shown that the ways of fabrication of thin film can influences silicon-hydrogen bonding configuration of a-Si: H film, and different ways of fabrication can lead to different contents of SiH2 and (SiH2)n. The uniformity of the thin film with a bigF is bad. In this case, there is great difference between the thickness measured by the SurfCom408A surface profile apparatus and the thickness obtained by fitting the fringes; and the hydrogen contents of a-Si:H films obtained by means of the wagging mode and the stretching modes are different, too. But the fabrication of the MWECR CVD assisted by CAT CVD can effectively restrain the formation of SiH2 and (SiH2)n.