A comparison of defects in helium implanted alpha- and beta-SiC

Specimens of alpha- and beta -SiC were implanted homogeneously at room temp erature with helium to about 30% of their thickness to concentrations up to 2450 atppm. Lattice straining was determined from the bending radius of th e specimens by surface profilometry after implantation and during subsequen t annealing. Evolution and annealing of straining in alpha- and beta -SiC w ere remarkably similar. Above 1300 degreesC specimen volume increased, whic h, according to transmission electron microscopy, was ascribed to the growt h of helium clusters. Microstructural investigations showed bubbles along g rain boundaries and disk-shaped clusters of bubbles in the grain interior o n (0 0 0 1) habit planes in hexagonal alpha -SiC and on (Ill)in cubic beta -SIC. (C) 2000 Elsevier Science B.V. All rights reserved.