Raman spectroscopy and field emission measurements on catalytically grown carbon nanotubes

We used microcontact printing to pattern a silicon surface with an iron-containing catalytic solution. Multiwall carbon nanotubes were subsequently grown on the patterned areas by chemical vapor deposition at temperatures between 650 and 1000 degreesC. We demonstrate that the diameter of the catalytically grown multiwall nanotubes increases with the deposition temperature. Raman spectroscopy has been used to investigate the crystalline character of the obtained structures, and it was found that the fraction of the nanocrystalline shell increases with the temperature. The measurement of the field-emission properties shows a correlation between the tube diameter and the emission-field values.