Influence of ammoniating time on the microstructure of Mg-doped GaN nanowires

Mg-doped GaN nanowires have been successfully grown on Si(1 1 1) substrates by magnetron sputtering through ammoniating Ga2O3/Mg thin films at 900 °C for 15 min. The growth of the GaN nanowires was investigated as a function of ammoniating time so as to study the influence of ammoniating time on the structural properties of GaN samples in particular by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), FT-IR spectrophotometer, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (TEM), and photoluminescence (PL) spectrum. The results demonstrate that ammoniating time has great influence on the microstructure, morphology and optical properties of GaN nanowires. GaN nanowires ammoniated at 900 °C for 15 min are straight and smooth with uniform thickness along spindle direction and high crystalline quality, 50 nm in diameter and 20 μm in length with good emission properties, and the growth direction of the nanowire is parallel to [1 0 0] orientation. A clear blue-shift of the band-gap emission has occurred due to Mg doping.