Synthesis And Luminescence Properties Of GaN Nanowires Array Via CVD Method

Gallium nitride, an important Ⅲ-Ⅴ semiconductor compound material, has been extensively applied in microelectronic and optoelectronic fields due to its excellent properties such as chemical stability, high electron mobility, high melting point, high thermal conductivity and broad band-gap. In this work, we reported the synthesis of high-quality GaN nanowires, GaN nanowire array and Sb/P co-doped GaN nanowires via chemical vapor deposition (CVD) method. In the synthetic process of GaN nanowires, different substrates, temperatures, airflows and buffering layers were used. The GaN nanowire array and Sb/P co-doped GaN nanowires were synthetized in a three temperature zone furnace to realize precise temperature control during the synthetic process. The as-synthesized samples were analysed by scanning electron microscope (SEM), X-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive spectrum (EDS) and room-temperature cathodoluminescence (CL). The microstructures, CL properties and growth mechanism have been investigated. The main results are as follows:(1)The morphological evolution of GaN nanostructures depends strongly on the Ga/N reactant ratios in the reaction system. There are variable Ga/N reactant ratios near the reaction boat which results in the film has a complicated morphology of GaN nanostructures. On the contrary, Ga/N reactant ratios near the graphite support are stable due to the long distances transport of the source precursors. Therefore, the morphology of as-synthesized GaN samples located on graphite support was uniform.(2)The epitaxial growth of GaN nanowire array grown on Sap/Al substrate can only be realized on the substrate surface with defect owing to the absence of nucleation center. On the Sap/Au/Al substrate, GaN nanowire arrays with large yield were successfully synthesized via AlN buffer layer and Au catalyst. No Au catalyst was observed on the top of GaN nanowires, indicating the formation of GaN nanowire arrays follows the vapor-solid (VS) growth mechanism. The near band-edge cathodoluminescence peak of GaN nanowire arrays has a slight redshift compared with intrinsic emission and a yellow luminescence is found.(3) Sb was successfully doped into GaN nanowires via Sb/P co-dope process. The crystal structure of Sb/P co-doped GaN nanowires remains wurtzite-type hexagonal structure. Room-temperature cathodoluminescence measurements indicated that the Sb/P co-doped GaN nanowires have a broad near band edge (NBE) emission and a redshift of visible emission.