Microwave-induced nucleation of conducting graphitic domains on silicon carbide surfaces

Microwave irradiation of the C-rich (⁠$0001¯$⁠) surface of 6H-SiC is seen to rapidly induce the nucleation of conductive nanoscopic graphitic grains. Discrete graphitic islands are observed and Raman spectroscopy suggests turbostratic stacking with minimal electronic coupling between adjacent graphene layers. Ensemble Raman and near-edge x-ray absorption fine structure (NEXAFS) spectroscopies are used in conjunction with spatially resolved atomic force microscopy, scanning Kelvin probe microscopy (SKPM), and colocalized Raman imaging to characterize the topography and electronic structure of the obtained graphitic domains and to develop a mechanistic description of the nucleation process. SKPM provides a direct spatially resolved means to differentiate conductive graphitic grains from the wide-bandgap SiC semiconductor. NEXAFS spectroscopy allows for evaluation of the planar alignment of the graphitic nuclei. The microwave processing method demonstrated here provides a facile route to patterning conductive domains on a ceramic component for applications in power electronics and multilayered ceramic capacitors.