INTERPRETATION OF THE SILICON-HYDROGEN STRETCHING DOUBLET IN A-SIH HYDROGENATED AMORPHOUS-SILICON

We studied the correlation between the infrared integrated absorption strengths of the wagging, bending and stretching modes for four hydrog enated amorphous silicon (a-Si:H) series, deposited by rf glow dischar ge. The strength of these modes was varied by changing the deposition temperature while keeping other parameters fixed. For the first time i t is shown that a straightforward correlation exists between these thr ee modes. It is argued that the 2100-cm-1 mode is due to SiH2 bonds an d that there is no contribution of SiH species on the inner surface of voids. The vibrational spectrum of a-Si:H can be well described by co nsidering the vibrating dipole as a harmonic oscillator with an effect ive charge e=0.44 electrons.