Figure 1

The scheme of fabricating axial p–n junction Si NWs—a An as-grown p–i NW b scanning electron microscope (SEM) image of an as-grown p–i NW. c A NW with the Au cap removed d SEM image of a NW with the Au cap removed. e P ion implantation on a NW coated with the spin-on-glass (SOG) silicon dioxide. The top intrinsic part is converted to n-type f SEM image of an SOG-coated NW. g Ap–n junction NW after the P ion implantation and removal of the SOG. h SEM image of a p–n junction NW