Large-scale synthesis of n-type gallium nitride nanowires using NiI2-decorated carbon nanotubes as a reactant

This study demonstrates the first example of the use of NiI2-filled carbon nanotubes (CNTs) for the synthesis of GaN nanowires (NWs). Large quantities of single crystal and n-type GaN NWs were synthesized after NiI2-decorated CNTs reacted with Ga2O3 in NH3. Comparatively few short GaN NWs (<1 μm) were synthesized in the absence of CNTs, and GaN NWs were found to be synthesized with a reasonable yield using graphite as a reactant. Therefore, CNTs play no role as a template in the growth of NW, but this growth is assisted by NiI2 nanocrystals via a vapour–liquid–solid mechanism in which the presence of carbon materials facilitates the reduction of Ga2O3 to Ga2O and Ga, thus providing a constant Ga source during the growth of the NW. Furthermore, the use of NiI2-filled single wall carbon nanotubes results in a higher NW yield at a low growth temperature (600 °C), indicating that NiI2-filled single wall CNTs can serve as an effective reactant for the synthesis of GaN NWs.