Exciton related photoluminescence stimulation in SiC nanocrystals

The paper presents the results of porous SiC characterization using scanning electron microscopy (SEM), X-ray diffraction (XRD) and photoluminescence spectroscopy techniques. XRD study shows the investigated porous 6H-SiC layers contain inclusions of 4H-SiC and 15R-SiC polytypes as well as the amorphous graphite phase. Photoluminescence study of PSiC layers with different thicknesses and SiC NC sizes reveals the intensity stimulation for exciton and defect-related PL bands. The intensity stimulation of defect-related PL bands is due to the increase, at the etching process, of the concentration of surface defects, apparently to deal with carbon. The intensity enhancement for exciton-related PL bands is attributed to the exciton recombination rate increasing due to the realization of exciton confinement and exciton-polariton effects in big size SiC NCs of different polytypes (6H-PSiC with inclusions of 15R- and 4H-PSiC).