We fabricated p+–p–p+ junctions in order to properly investigate the electrical conduction across a boron implanted silicon-on-insulator (SOI) nanostructured pattern, like photonic crystals and shallow-etched trenches. By analysis of the I–V measurements, we demonstrate that a depletion region is present and it is induced by the dry etching process of reactive ion etching. This depletion region does not depend on the geometry of the dry-etched nanostructure, but on the doping level of the substrate.