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Medium-range order in pyrolyzed carbon films: Structural evidence related to metal–insulator transition

V. Meenakshi, S. V. Subramanyam
2002 Journal of Applied Physics  
Structural properties of carbon films prepared by the pyrolysis of tetra chloro phthalic anhydride are investigated in an attempt to correlate it with the metal-insulator transition observed earlier as a function of deposition temperature, from electrical transport studies. Anomalous features are observed which evolve as the pyrolysis temperature is varied from 700 to 900°C. This includes prepeaks in the x-ray diffraction pattern in the region less than 1 Å Ϫ1 providing evidence for medium
more » ... nce for medium range order, and a broad shoulder around 1200 cm Ϫ1 in the Raman spectra, which are seen in addition to the usually observed peaks in amorphous carbon films. A simple model is proposed according to which presence of "polymeric domains" containing chains of carbon atoms with single and double bond alternation ͑-CvC-͒, in a predominantly aromatic ring structure, could give rise to the anomalous features.
doi:10.1063/1.1491021 fatcat:j6nu2tpmwbbuxfl2etfxllrp7e