Surface Functionalization of Silicon Carbide Quantum Dots

Silicon carbide (SiC) nanostructures are appealing as non-toxic, water-stable and oxidation-resistant nanomaterials. Owing to these unique properties, three-dimensionally confined SiC nanostructures, namely SiC quantum dots (QDs), have found applications in the bioimaging of living cells. Photoluminescence (PL) investigations, however, have revealed that across the polytypes: 3C-, 4H- and 6H-SiC, excitation wavelength.dependent PL is observed for larger sizes but deviates for sizes smaller than approximately 3 nm, thus exhibiting a dual-feature in the PL spectra. Additionally, nanostructures of varying polytypes and bandgaps exhibit strikingly similar PL emission centered at approximately 450 nm. At this wavelength, 3C-SiC emission is above the bulk bandgap as expected of quantum size effects, but for 4H-SiC and 6H-SiC the emissions are below bandgap. 4H-SiC is a suitable polytype to study these effects.