GaN nanowires were synthesized on silicon, nickel nitrate [Ni(NO3)2]-dispersed silicon, and a nickel-dispersed alumina (Ni/Al2O3) composite under an argon atmosphere containing a low partial pressure of ammonia (PNH3 = 10 kPa). GaN nanowires were formed on the Ni(NO3)2-dispersed silicon and Ni/Al2O3 composite substrates. Two kinds of nanowires with different morphologies were observed. Initially, the formation of rough-surfaced nanowires occurred, which was followed by the formation of smoothsurfaced nanowires. In the case of the Ni/Al2O3 composite, GaN nanowires with rough surfaces were formed after 15 min at 1000°C, and the number of nanowires increased with the holding time. TEM observations showed that the nanowires grew in the  direction, which supported the proposed vapor-liquid-solid growth mechanism.
- Gallium nitride
- Gallium oxide