Synthesis and field emission studies of 1-D nanostructures



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1-D Nanostructures are attractive candidates for electron emitters in vacuum microelectronic devices because of their sharp tip radii and high aspect ratio. With advances in nanotechnology, various strategies have been reported for controlled synthesis of nanostructures including 1-D variants (nanowires and nanotubes). While various functional electronic/optoelectronic devices and circuits have been demonstrated using nanostructures, this work is focused on the synthesis and field emission studies of 1-D nanostructures of three materials systems, namely carbon nanotubes, silicon nanowires and graphitic nanocones. The potential applications of 1-D nanostructures as electron emitters are varied and include displays, microwave amplifiers, x-ray sources, holography, multiple e-beam lithography, electronic cooling. The carbon nanotubes (CNTs) are grown in anodic alumina templates by thermal chemical vapor deposition (CVD). The Silicon Nanowires (Si NWs) are grown by atmospheric pressure CVD (APCVD) via hydrogen reduction of silicon tetrachloride with an Au thin film acting as the catalyst for the Vapor-Liquid-Solid (VLS) process. Further post-growth processing was employed in the case of Si NWs, namely in-situ annealing and cesiation, to improve the field emission characteristics. Finally, field emission characterization of individual tubular graphitic nanocones (TGCs) was carried out. The TGCs were grown on iron needle by microwave plasma assisted CVD of C2H2 + N2. An individual nanocone emitted a current as high as 80 µA, corresponding to a current density of ~ 108 A/cm2 , without breakdown. Individual emitters would be of interest for applications in holography and as coherent electron sources.