Electrical transport in three-dimensional ensembles of silicon quantum dots

Following our previous works in which we tried to understand the transport mechanisms below and at the conductivity percolation threshold of three-dimensional ensembles of Si quantum dots (QD's), in the present work we try to derive a comprehensive understanding of the transport mechanisms above the percolation threshold. Our conclusions are based on a systematic study of the electrical properties of Si nanocrystallite ensembles that are embedded in an insulating matrix as a function of their density. To evaluate the transport mechanisms we introduce the concept of "touching," showing that its application enables to suggest that the percolation transition is associated with the onset of extended states-like transport in a continuous disordered network. This understanding provides a framework for the discussion of the transport in ensembles of QD's in general and in ensembles of Si QD's in particular.