Highly uniform characteristics of GaN nanorods grown on Si(111) by metalorganic chemical vapor deposition

Gallium nitride (GaN) nanorod (NR) arrays were grown on a gold-coated Si(111) substrate by metalorganic chemical vapor deposition (MOCVD). The synthesized single GaN NRs were characterized by field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX) spectroscopy, high-resolution transmission electron microscopy (HR-TEM), and cathodoluminescence (CL) analysis. The HR-TEM images and selected area electron diffraction (SAED) patterns demonstrated that the GaN NRs were of high quality with a single-crystal wurtzite structure and free from defects. The GaN NRs were observed to have a uniform diameter ranging from 40 to 70 nm, length of up to 1μm, and a sharp symmetrical pyramid-like tip at the top. The pyramid-like tip was attributed to the dissociation of nitrogen atoms by the cracking of ammonia (NH₃) at the elevated growth temperature. Furthermore, there was no sign of any metal or alloy cluster at the end of the NRs. Thus, the growth of the GaN NRs does not occur by the typical vapor-liquid-solid (VLS) mechanism.