Interpretation of the silicon-hydrogen stretching doublet in a-Si:H hydrogenated amorphous silicon

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Abstract
We studied the correlation between the infrared integrated absorption strengths of the wagging, bending and stretching modes for four hydrogenated amorphous silicon (a‐Si:H) series, deposited by rf glow discharge. The strength of these modes was varied by changing the deposition temperature while keeping other parameters fixed. For the first time it is shown that a straightforward correlation exists between these three modes. It is argued that the 2100‐cm−1 mode is due to SiH2 bonds and 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 considering the vibrating dipole as a harmonic oscillator with an effective charge e*=0.44 electrons.