Control of Morphology and Growth Direction of Gallium Nitride Nanostructures
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N11.30.1
Control of Morphology and Growth Direction of Gallium Nitride Nanostructures Seung Yong Bae, Hee Won Seo, Jeunghee Park, Department of Chemistry, Korea University, Jochiwon 339-700 Korea ABSTRACT Various shaped single-crystalline gallium nitride (GaN) nanostructures were produced by chemical vapor deposition method in the temperature range of 900 – 1200 °C. Scanning electron microscopy, transmission electron microscopy, electron diffraction, x-ray diffraction, electron energy loss spectroscopy, Raman spectroscopy, and photoluminescence were used to investigate the structural and optical properties of the GaN nanostructures. We controlled the GaN nanostructures by the catalyst and temperature. The cylindrical and triangular shaped nanowires were synthesized using iron and gold nanoparticles as catalysts, respectively, in the temperature range of 900 - 1000 °C. We synthesized the nanobelts, nanosaws, and porous nanowires using gallium source/ boron oxide mixture. When the temperature of source was 1100 °C, the nanobelts having a triangle tip were grown. At the temperature higher up to 1200 °C the nanosaws and porous nanowires were formed with a large scale. The cylindrical nanowires have random growth direction, while the triangular nanowires have uniform growth direction [010]. The growth direction of the nanobelts is perpendicular to the [010]. Interestingly, the nanosaws and porous nanowires exhibit the same growth direction [011]. The shift of Raman, XRD, and PL bands from those of bulk was correlated with the strains of the GaN nanostructures. INTODUCTION One-dimensional nanostructures such as wires (or rods), belts, and tubes are currently the subject of intense research because of a pure scientific standpoint and their technological applications in electronics and optoelectronic nanodevices, etc.1-4 These properties and applications are usually highly dependent on the size and the shape of nanostructures. In fact, the shape of nanostructures has significant influence on the physical properties that are important in many practical applications, such as light-emitting diodes and scanning-microscopy probes.5,6 Therefore the development of synthesis whose size and shape are easily controlled is of great interest in this area. Among the various nanostructured materials, wurtzite structured gallium nitride (GaN) is widely accepted as a potential material for the optoelectronic application, due to its direct large energy bandgap (Eg=3.4 eV at 300 K), high thermal stability, and strong resistance to radiation.7-9 Here we report that various 1-dimensional nanostructures of GaN were synthesized in a controlled manner via chemical vapor deposition at the temperature ranging from 900 to 1200 °C.10-14 The cylindrical and triangular shaped nanowires were synthesized using iron (Fe) and gold (Au) nanoparticles in the temperature range of 900 - 1000 °C. When the gallium (Ga) source/ boron oxide (B2O3) mixture was used to reactant, we synthesized the nanobelts, nanosaws, and porous nanowires. The results indicate that
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