Investigation of Low-Energy H and He Implanted 4H-SiC using X-Ray and Neutron Reflectivity

The atomic number density profiles extracted from grazing angle x-ray and neutron reflectivity are relatively unexplored for investigating ion implantation. Here they are used to explore the effects of low energy implantation of light ions, H and He, into 4H-SiC with energies in the range of 360 to 2000 eV and fluences up to 2x10^17 ions/cm^2. For both ions, combined x-ray and neutron reflectivity measurements reveal a top layer of SiC having a reduced density of 60-65% while the thickness of this layer increases with fluence. Atomic force microscopy imaging (AFM) shows topographic defects which appear to be etch pits. Our results indicate that these implanted light ions do not form gas bubbles below the surface of SiC and we discuss how these combined AFM and reflectivity measurements provide insight on the interaction of the light ions with SiC.