Investigation of microstructures and optical properties in Mn-doped SiC films

► Local structure and optical properties of Mn-doped SiC films were investigated. ► Mn4Si7 compounds result in the formation of the C clusters. ► Mn4Si7 compounds strongly affect the photoluminescence properties. ► The 413-nm PL peak origins from C cluster centers. Mn-doped SiC films were prepared on Si(100) substrates by RF-magnetron sputtering technique. The microstructures and composition of films have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). The XRD results show that the Mn-doped SiC films form a 3C–SiC crystal structure and some doped Mn atoms occupy the C sites of SiC lattice. The XPS results suggest that there exist SiC, CC and SiMn bonds in the films, but the signal of SiC bond decreases and that of CC bond increases with the increase of Mn concentration. The Mn K-edge XANES and EXAFS measurements show that the majority of Mn atoms form Mn4Si7 secondary phase compounds and the existence of Mn metal and MnO can be safely excluded. Then the photoluminescence (PL) properties of films are observed at room temperature. The origin of 413-nm PL peak is associated with C cluster centers, which obviously correlates with the Mn-doped concentration.