GaP Nanostructures: Nanowires, Nanobelts, Nanocables, and Nanocapsules
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N11.26.1
GaP Nanostructures : Nanowires, Nanobelts, Nanocables, and Nanocapsules Hee Won Seo, Seung Yong Bae, Jeunghee Park* Department of Chemistry, Korea University, Jochiwon 339-700, South Korea E-mail : [email protected] ABSTRACT Various GaP nanostructures such as nanowires, nanobelts, nanocables, and nanocapsules were synthesized by sublimation of ball-milled powders. They have a single-crystalline zinc blende structure with [111] growth direction. The morphology and structure were controlled by reactant gas, growth time, flow rate, and growth temperature. The size, morphology and properties of the nanostructures were examined by scanning electron microscopy, transmission electron microscopy, electron energy-loss spectroscopy (EELS), electron diffraction, energy dispersive x-ray spectroscopy, powder x-ray diffraction, and Raman spectroscopy using a 514.5 nm argon ion laser. The photoluminescence was carried out using the 458 nm line of an argon ion laser as the excitation source. The GaP nanowires are straight, cylindrical, and smooth in surface, with mean diameter of 40 nm and length up to 300 mm. The nitrogen-doped nanobelts and nanowires were synthesized by ammonia ambient gas. EELS data reveals that the nitrogen doping occurs mainly in the surface region. The PL spectrum shows the typical isoelectronic bound exciton peaks in the range of 2.11~2.25 eV, suggesting a concentration of (1018 cm-3 nitrogen atoms. We also synthesized two types of GaP nanocables; GaP nanowire sheathed with the amorphous silicon oxide layers and with the graphite layers. The core-shell diameter is under 30 nm and the outerlayer can be removed by acid treatment to produce the 10 nm diameter GaP nanowires. The GaP encapsulated with BCN nanotubes were synthesized under the ammonia flow using the ball-milled carbon-containing boron oxide powders. The number of BCN layers is typically 10~20. INTRODUCTION Since the discovery of carbon nanotubes (CNTs), one-dimensional (1D) nanostructures have attracted much attention as well-defined building blocks to fabricate nanoscale electronic and optoelectronic devices.1-6 Recently, the modulation of the radial composition in nanowires has demonstrated their potential in nanodevice applications with diverse functions.2,6 Gallium phosphide (GaP), a wide band gap semiconductor (Eg=2.24 eV at 300 K), is a potential material for optical and high-temperature electronic devices. The GaP nanowires and nanobelts were synthesized by various methods including laser ablation, carbon nanotube-confined reaction, and sublimation.7-11 Lieber group synthesized by a laser ablation of gold-containing GaP target using 1064 nm.7 S. T. Lee and coworkers synthesized by irradiating 248 nm laser on the gallium oxide (Ga2O3)/GaP mixture target.8 They also prepared using the reaction of carbon nanotubes with Ga/Ga2O3 mixture in a phosphorus vapor atmosphere.9 Our group synthesized the GaP nanowires and nanobelts via a sublimation of ball-milled GaP powders under argon or NH3 atmosphere.10-12 However, the coaxial nanocable
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