Density and structural changes in SiC after amorphization and annealing

The density of amorphous SiC layers formed by 2 MeV Si+ implantation into single-crystalline 6H–SiC was measured by x-ray reflectometry and compared with the results of step height measurements. Reactive ion etching was used to investigate the density as a function of depth. The density of the as-amorphized SiC is about 12% less than that of the crystalline material. Within experimental accuracy, the density reduction is homogeneous across the whole layer thickness. Low-temperature annealing leads to the formation of relaxed amorphous SiC with a density about 7% below the crystalline one. These large density changes are in contrast to results in amorphous Si. They can be explained by the high atomic density of SiC and the chemical disorder in the amorphous state of SiC.