A phenomenological study of the Si-H infrared spectra in porous and amorphous silicon

It is observed that Si-H stretching mode vibrational spectra in porous sili con and in hydrogenated amorphous silicon: (i) is broad with a full width a t half maxima of approximate to 20 - 40 cm(-1); (ii) has a long low energy tail; and (iii) has a peak value shifted by 100 cm(-1) from 2000 cm(-1) (cr ystalline silicon case) to 2100 cm(-1). We propose a simple phenomenologica l model to account for the above features. The model invokes a narrow distr ibution in the Si-H bond distances. The first feature namely the broadening can be satisfactorily explained. Although our model yields a low energy ta il, it is not as pronounced as the experimental tail. Our model can be show n to be consistent with the third feature, namely the peak shift.