Switching the wires: p‐Type α‐Fe2O3 nanowires with ordered oxygen vacancies were synthesized without additional annealing. After a process of annealing in a reductive ambient, a p‐type to n‐type transition was achieved in a nanowire device (see graph and image). The observation of a p–n transition suggests potential applications for these nanowires in future nanodevice technologies.

Very dense and uniformly distributed nitrogen-doped tungsten oxide (WO(3)) nanowires were synthesized successfully on a 4-inch Si(100) wafer at low temperature. The nanowires were of lengths extending up to 5 mum and diameters ranging from 25 to 35 nm. The highest aspect ratio was estimated to be about 200. An emission peak at 470 nm was found by photoluminescence measurement at room temperature. The suggested growth mechanism of the nanowires is vapor-solid growth, in which gaseous ammonia plays a significant role to reduce the formation temperature. The approach has proved to be a reliable way to produce nitrogen-doped WO(3) nanowires on Si in large quantities. The direct fabrication of WO(3)-based nanodevices on Si has been demonstrated.