Evidence of field-induced nucleation switching in opal: V02 composites and V02 films.

We show that electrical switching in opal-V02 composites is governed by the electric field rather than voltage or current. This makes it similar to switching in chalcogenide glasses with the underlying mechanism identified as the field induced nucleation. However, the observed bias dependence of switching delay time is found to be noticeably different from that of standard V02 films on "smooth" substrates. This difference is attributed to the disorder effects in polycrystalline structures. The model of field induced nucleation is shown to apply when properly modified to account for that disorder. [ABSTRACT FROM AUTHOR]