Characterization of SiC Nanostructures in Crystalline and Porous Silicon Formed by Ion Beam Synthesis

We have investigated the optical properties of 3C-SiC nanocrystals formed by implanting high-fluence carbon ions into a crystalline silicon (c-Si) substrate. Si (100) samples were implanted by 200-keV carbon ions for a fixed fluence of 1.6 × 1017 cm−2 at different temperatures of room temperature (RT), 500 ℃ and 800 ℃ followed by post-implantation annealing at 1050 ℃ for 2 h in a pure nitrogen ambient. A photoluminescence (PL) spectrum with a peak at 525 nm (2.36 eV)could be observed only in the case of implantation at the elevated temperature (800 ℃, followed by high-temperature thermal annealing. The formation of precursors to 3C-SiC nano-crystals seems to be allowed only in the case of high-temperature implantation. X-ray diffraction (XRD) and cross-sectional transmission electron microscopy (XTEM) measurements showed that the 3C-SiC nano-crystals of 5 - 8 nm in diameter were mostly aligned with the (100) silicon substrate, with the SiC (111) planes parallel to the sample surface. We have also investigated the room-temperature PL characteristics of porous silicon (PS) implanted with carbon. PS samples made by anodizing were implanted with 200-keV carbon ions at a fluence of 1.6 × 1017 cm−2 at room temperature and 800℃ and were subsequently annealed at temperatures of 300 - 1050 ℃ in a nitrogen ambient. The typical intense red-orange light (~650 nm) from the porous Si surface disappeared markedly after implantation, and a considerable blue light appeared after thermal annealing. The formation of 3C-SiC could be confirmed by X-ray photoelectron spectroscopy (XPS) and XTEM measurements,and the effects of different implantation and annealing temperatures on the light-emission properties of the implanted porous silicon could be described. KCI Citation Count: 3