Hole Transport in Silicon Thin Films with Variable Hydrogen Content

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Abstract
The hole transport characteristics of Si:H(F) thin films with variable hydrogen contents, prepared by hydrogen-radical-enhanced chemical vapour deposition (HRCVD), were evaluated by the time-of-flight method. The drift mobility conforms with a multiple-trapping model derived from an exponential energy distribution of the valence band tail states, and increases as hydrogen contents decrease from 15 to 2 at.%. The characteristic temperatures provided by the above model show a significant decrease over the same compositional interval. These results were interpreted on the basis of the packing density of the films and the film growth processes during deposition.