Synthesis of thin carbon films on 4H-SiC by low temperature extraction of Si with HCl

Carbon films as thin as 5 nm were synthesized by graphitization of 4H-SiC substrates at 1200-1350 °C, in a dilute HCl/Ar atmosphere at a pressure of 0.8 bar. These films formed at significantly lower temperatures and higher pressures than conventional synthesis of epitaxial graphene by sublimation of Si. Graphitization rates of 0.08-1.40 nm/min were observed. The activation energy for graphitization was approximately 460 kJ/mol. Raman spectroscopy indicated that the material was highly disordered with D-peak to G-peak ratios ranging from 0.70 to 1.43, compared to high quality graphene which does not exhibit the disorder induced D-peak.