P-55 Synthesis of High-quality GaN Nanowires and their Optical, Field Emission Properties

GaN nanowires are a new type of field emission materials which have been amacting increasing attention in recent years!'.21 In this paper, high-quality GaN nanowires have been synthesized by a chloride-assisted vapor phase epitaxy method, which were deposited on Co-coated Si substrate using gallium and N&Cl as precursors. Their structural and optical properties were examined by X-ray diffraction, scanning and transmission electron microscopy, Raman spectrum and photoluminescence. The GaN nanowires were single crystalline with a uniform diameter of about 100 nm and a length of several micrometers. The nanowires were observed over the entire Si substrate with high density and most of them have triangular cross section. The Raman photon modes showed a little down-shift and asymmehy, which might result from the internal stress due to the geometrical confinement. Photoluminescence measurement indicated that two emission peaks were centered at 358 and 410~1, revealing the good optical properties of this material. Field emission measurements of the GaN nanowires were also performed in the vacuum chamber at the pressure of 1xlO~'Torr at the ambient temperature and the promising emission properties were obtained and discussed.