Selective Area Growth and Characterization of GaN Nanorods Fabricated by Adjusting the Hydrogen Flow Rate and Growth Temperature with Metal Organic Chemical Vapor Deposition

GaN nanorods are successfully fabricated by adjusting the flow rate ratio of hydrogen (H_2)/nitrogen (N_2) and growth temperature of the selective area growth (SAG) method with metal organic chemical vapor deposition (MOCVD). The SAG template is obtained by nanospherical-lens photolithography. It is found that increasing the flow rate of H_2 will change the GaN crystal shape from pyramid to vertical rod, while increasing the growth temperature will reduce the diameters of GaN rods to nanometer scale. Finally the GaN nanorods with smooth lateral surface and relatively good quality are obtained under the condition that the H_2:N_2 ratio is 1:1 and the growth temperature is 1030^\circ\!C. The good crystal quality and orientation of GaN nanorods are confirmed by high resolution transmission electron microscopy. The cathodoluminescence spectrum suggests that the crystal and optical quality is also improved with increasing the temperature.