Synthesis of gallium nitride nanostructures by nitridation of electrochemically deposited gallium oxide on silicon substrate

Gallium nitride (GaN) nanostructures were successfully synthesized by the nitridation of the electrochemically deposited gallium oxide (Ga 2 O 3 ) through the utilization of a so-called ammoniating process. Ga 2 O 3 nanostructures were firstly deposited on Si substrate by a simple two-terminal electrochemical technique at a constant current density of 0.15 A/cm 2 using a mixture of Ga 2 O 3 , HCl, NH 4 OH and H 2 O for 2 h. Then, the deposited Ga 2 O 3 sample was ammoniated in a horizontal quartz tube single zone furnace at various ammoniating times and temperatures. The complete nitridation of Ga 2 O 3 nanostructures at temperatures of 850°C and below was not observed even the ammoniating time was kept up to 45 min. After the ammoniating process at temperature of 900°C for 15 min, several prominent diffraction peaks correspond to hexagonal GaN (h-GaN) planes were detected, while no diffraction peak of Ga 2 O 3 structure was detected, suggesting a complete transformation of Ga 2 O 3 to GaN. Thus, temperature seems to be a key parameter in a nitridation process where the deoxidization rate of Ga 2 O 3 to generate gaseous Ga 2 O increase with temperature. The growth mechanism for the transformation of Ga 2 O 3 to GaN was proposed and discussed. It was found that a complete transformation can not be realized without a complete deoxidization of Ga 2 O 3 . A significant change of morphological structures takes place after a complete transformation of Ga 2 O 3 to GaN where the original nanorod structures of Ga 2 O 3 diminish, and a new nanowire-like GaN structures appear. These results show that the presented method seems to be promising in producing high-quality h-GaN nanostructures on Si.