Thermal oxidation of gallium nitride nanowires

The thermal oxidation of gallium nitride (GaN) nanowires in dry air was investigated by using thermogravimetric and transmission electron microscopy. The oxidation strongly depends on the oxidation temperature and the nanowire diameters. At temperatures lower than 700 degreesC, the oxidation is dominantly controlled by an oxygen absorption reaction. A chemical oxidation reaction occurs upon further increasing the temperature, accompanied by the formation of monoclinic gallium oxide (Ga2O3). The crystalline Ga2O3 can form a dense protective shell on the surfaces of GaN nanowires with large diameters, whereas Ga2O3 could not crystallize into one-dimensional morphology on the initial GaN nanowires with small diameters. (C) 2003 American Institute of Physics.