Field emission properties of carbon nanotubes on Ni islands created on tin oxide substrate
S.S. Roy, P.K. Yadav and J.A. McLaughlin
University of Ulster, UK
nickel islands, carbon nanotubes, field emission
In many experimental situations in the study carbon nanotube base devices, in particular when some nanoscale characteristics of the materials are of interest, it is essential to grow catalyst (such as Ni, Co or Fe) island/dots. In recent past several attempts have been made to study the role of the catalyst size on the growth of carbon nanotube and their device performance.
In this report Ni films were deposited on tin oxide substrate with the range of thickness from 1-15 nm. We produced micro and nano islands of Nickel (Ni) by photo lithographic and thermal annealing of Ni films. In the first case various micro size of Ni islands were made by means of conventional photolithography and wet etch process. In the second instance irregular nano islands were obtained by annealing the Ni film at temperature up to 600C. The optimum conditions (photo resist thickness, prebake setting, UV exposure time, developer chemistry, developing time and hard-baking time) for producing micro islands were identified. On the other hand the size and distribution of the islands depends critically on the annealing temperature and the thickness of the Ni layer. Carbon nanotubes were grown on the top of micro and nano Ni islands. We observed that the Ni islands size controls the dimension, growth rate and density of the carbon nanotube. The field emission performances were obtained from the diode-type electrode configuration in terms of emission current and field enhancement factors.
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Nanotech 2006 Conference Program Abstract