Raman spectroscopic study of He ion implanted 4H and 6H-SiC

In the present study, the surface morphology using atomic force microscopy (AFM) and the optical properties by Raman Spectroscopy has been used to understand the modification in the 4H-SiC and 6H-SiC wafers due to the low energy He ion implantations. The AFM results show that the He implantation manifests swelling of the surface of the samples. It is also observed that the surface roughness of the 4H-SiC is approximately three times higher than the 6H-SiC after He implantation. The Raman spectra show enhancement in the second order optical modes which are stronger in the 4H-SiC and are complimentary to the observed surface roughness. This optical enhancement is also associated with the sp2/sp3 hybridization of the carbon. The Raman spectra also indicate the presence of monoatomic lattice of Si atoms from the enhancement of the acoustic phonons.