X-ray diffraction and electron paramagnetic resonance study of porous 6H-SiC

The article presents the results of porous SiC (PSiC) characterizations using x-ray diffraction (XRD) and electron paramagnetic resonance (EPR) techniques. Two types of PSiC samples, electrochemically as-etched and electrochemically etched and reactive ion treated, have been investigated. The XRD study shows that original SiC wafers and porous SiC layers have mainly the 6H-SiC crystal type with inclusions of 4H-SiC and 15R-SiC polytypes. With increasing porosity and porous layer thickness a new XRD band appears and grows that is assigned to the phase of amorphous graphite at the PSiC surface. The EPR spectra of PSiC layers measured at room temperature reveal low intensity signal in the g -value region of g=2.0027 and a peak-to-peak width of about 0.24-0.42 mT. The intensity of this signal increases simultaneously with the rise of PSiC thickness. The EPR study shows that the carbon dangling bond centers at and near the 6H-SiC/ SiO2 interface are the dominant defects for electrochemically etched porous 6H-SiC samples.