Synthesis of aligned GaN nanorods on Si(111) by molecular beam epitaxy

Straight and well-aligned GaN nanorods have been successfully synthesized by molecular beam epitaxy (MBE) method. The GaN nanorods have been characterized by field-emission scanning electron microscopy (FE-SEM) equipped with energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). SEM images show that GaN nanorods are constituted with two parts of which shapes are different from each other. The upper part of the nanorod is very thin and its lower part is relatively thick. The XRD and EDS analysis have identified that the nanorods are pure hexagonal GaN with single crystalline wurtzite structure. The TEM images indicate that the nanorods are well crystallized and nearly free from defects. The XRD, HRTEM, and SAED pattern reveal that the growth direction of GaN nanorods is 〈0001〉. The photoluminescence (PL) spectra indicate the good emission property for the nanorods. Finally, we have demonstrated about the two-step growth of the nanorods.