1H/29Si cross-polarization dynamics in amorphous hydrogenated silicon

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Abstract
A modified cross‐polarization method is used to simplify the solid‐state magic‐angle spinning 2 9Si‐NMR spectrum of a‐Si:H. At least three magnetically distinct environments are resolved. A microscopic model for the cross‐polarization dynamics is used to assign the components of the spectrum. Contrary to expectations from solution state studies of low‐molecular‐weight silanes, the signals from 2 9Si bonded directly to hydrogen are shifted to a lower field compared to quaternary Si. This observation is rationalized on the basis of theoretical models and photoemission spectroscopy results published by other groups. A suggestion for the nature of shallow states is offered on the basis of the NMR results.