Preparation and characterization of carbon nanotubes encapsulated GaN nanowires

A novel two-step catalytic reaction is developed to synthesize gallium nitr ide nanowires encapsulated inside carbon nanotubes (GaN@CNT). The nanowires are prepared from the reaction of gallium metal and ammonium using metals or metal alloys as a catalyst. After the formation of the nanowires, carbon nanotubes are subsequently grown along the nanowires by chemical vapor dep osition of methane. The structural and optical properties of pure GaN nanow ires and GaN@CNT are characterized using scanning electron microscopy, tran smission electron microscopy, X-ray diffraction, energy dispersive X-ray sp ectroscopy and Raman spectroscopy. The results show that GaN nanowires are indeed encapsulated inside carbon nanotubes. The field emission studies sho w that the turn-on field of GaN@CNT is higher than that of carbon nanotubes , but substantially lower than that of pure GaN nanowires. This work provid es a wide route toward the preparation and applications of new one-dimensio nal semiconductor nanostructures. (C) 2001 Elsevier Science Ltd. All rights reserved.