Tailoring the diameter of decorated C-N nanotubes by temperature variations using HF-CVD

Patterned films of decorated nitrogenated carbon (C-N) nanotubes were catal ytically synthesised by hot filament chemical vapour deposition (HF-CVD) in a nitrogen-methane-ammonia environment. The systematic study of a transiti on between different kinds of C-N nanostructures as a function of the local substrate temperature ranging from 700 up to 820 degreesC is presented. Th e morphology, the diameter as well as the properties of the generated tubul ar structures showed strong dependence on this parameter. By means of elect ron microscopy a now type of decoration covering all tubular structures was observed. Buckled lattice fringes revealed the disordered graphitic-like c haracter of the hollow C-N nanotubes. Raman spectroscopy confirmed a transi tion in the microscopic order as a function of temperature. Furthermore fie ld emission in vacuum was studied and showed a spectacular correlation to t he deposition temperature and therefore the diameter of the kC-N tubes. For arrays of tubes thinner than 50 nm an onset field below 4 V/ mum was obser ved. (C) 2001 Elsevier Science Ltd. All rights reserved.