Native defects and diffusion in amorphous silicon -- a revisit

Recent theoretical and experimental results are assessed as they relate to the structure and properties of the dominant native paramagnetic point defect (D center) and the mechanisms of H diffusion. These results lead us to propose that the D center is neither a dangling or a floating bond, but an intermediate configuration which we label "frustrated bond". Experimental results by Jackson et al. set an upper bound for the diffusivity of D centers, but are not incompatible with D centers mediating H motion. Doping- and illumination-enhanced H diffusion can be accounted for in a unifying manner in terms of excess D centers that are mobile and mediate H motion via the kick-out mechanism, without any new assumptions. © 1992.