Nitrogen-doped tungsten oxide nanowires: Low-temperature synthesis on Si, and electrical, optical, and field-emission properties

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 μm 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 WO₃ nanowires on Si in large quantities. The direct fabrication of WO₃-based nanodevices on Si has been demonstrated.