Raman scattering investigations of semiconducting diamond-like carbon thin films and fibers obtained from camphor

Abstract

Semiconducting carbon-based thin films obtained from camphor soot were studied by microRaman spectroscopy with a laser wavelength of 632.8 nm. Different spectral contributions were identified between 1000 and 1650 cm −1 and discussed. The contributions are the D-like and G-like peaks of polycrystalline graphite at ~1345 and 1530 cm −1, respectively, with a FWHM value ~5 times larger than in a:C, and an additional feature at ~ 1240 cm −1 due to tetrahedrally-coordinated carbon of camphoric soot. Spectra obtained were typical of DLC materials with small size sp 3 clusters. This material seems to be suitable for flat panel display application using field emission by cold cathode. Thermal annealing by laser light induced a modification in the Raman spectrum. A band appears at 1591 cm −1, close to the peak associated with the in-plane stretching mode of sp 2-hybridized carbon atoms (crystalline graphite phase). Thick (20 μm) and thin (1 μm) fibers were obtained from camphor pyrolysis. Raman spectra were similar to those obtained with laser annealed thin films.