Jacques O'Connell

Investigation of radiation damage and hardness of H- and He-implanted SiC

In this study, an investigation was conducted in order to determine the effects of high-dose H and He ion implantation on the structure of 3C-SiC and 6H-SiC as well as the effects on material hardness in order to understand the role of H and He produced in SiC by neutron-induced transmutations as described by Heinisch et al. [J. Nucl. Mater. 2004, 327, 175–181.]. H and He ions were implanted into polycrystalline 3C-SiC on a Si substrate and single-crystal bulk 6H-SiC, respectively, at an ion energy of 100 keV, and the total dose that was used for both species was 1017 ions/cm2 in the temperature range of 473–573 K. The specimens were annealed at 1000°C for 20 min in an inert Ar atmosphere. The damaged region in the He-implanted 6H-SiC had a high density of small bubbles, but no cracks were observed. Severe cracking was observed along the damaged region in the H-implanted 3C-SiC specimens as well as a high density of hydrogen platelets. Neither specimen displayed any amorphization. Nanoindentation hardness measurements showed a marked increase in the hardness of the annealed He-implanted 6H-SiC, which was ascribed to the creation of point defects inhibiting interplanar slip. There was also a large decrease in hardness corresponding to the depth of the ion damage.