  Thin films of silicon oxide (SiOx) are mixtures of semiconductive c-Si
nanoclusters (NC) embedded in an insulating g-SiO2 matrix. Tour et al. have
shown that a trenched thin film geometry enables the NC to form semiconductive
filamentary arrays when driven by an applied field. The field required to form
reversible nanoscale switching networks (NSN) decreases rapidly within a few
cycles, or by annealing at 600 C in even fewer cycles, and is stable to 700C.
Here we discuss an elastic mechanism that explains why a vertical edge across
the planar Si-SiOx interface is necessary to form NSN. The discussion shows
that the formation mechanism is intrinsic and need not occur locally at the
edge, but can occur anywhere in the SiOx film, given the unpinned nanoscale
vertical edge geometry.
