Fabrication of High-Density GaN Nanowires through Ammoniating $Ga_2O_3//Nb$ Films

High-density GaN nanowires were successfully synthesized on Si(111) substrates through ammoniating $Ga_2O_3//Nb$ films under flowing ammonia atmosphere at 950°C. The as-synthesized GaN nanowires are characterized by X-ray diffraction, selected-area-electron diffraction, Fourier transform infrared, scanning electron microscopy, and field-emission transmission electron microscopy. The results show that the synthesized nanowires are single-crystal hexagonal wurtzite GaN with diameters ranging from 30 to 100 nm and lengths up to several microns. The photoluminescence spectra measured at room temperature only exhibit a strong and broad emission peak at 367.8 nm. Finally, the growth mechanism of GaN nanowires is discussed.