Ion-implantation-induced extended defect formation in (0001) and (11 2̄ 0) 4H-SiC

We study the effect of substrate orientation namely (11 2̄ 0) and (0001) oriented crystals on defect formation in 4H-SiC. The microstructure of the various samples, as-implanted with P and annealed, were studied by Rutherford backscattering spectrometry and channeling and transmission electron microscopy in an attempt to understand the damage evolution and defect structures resulting from different crystal orientations and different implantation damage. The annealing of the damage results in a range of different defects including dislocation loops, voids and precipitates in both a -cut and c -cut crystals. For the c -cut crystals, we observe the formation of (a) Frank prismatic (0001) loops previously reported in implanted SiC, and (b) a second type of defects showing stacking fault contrast consistent with (i) pure Shockley partials and/or (ii) (0001) sheared interstitial defects bounded by a Shockley partial dislocation. A mechanism for the formation of the latter defects in SiC is proposed and the relative stacking fault energies of the proposed defects are estimated using calculated parameters for the axial next-nearest-neighbor Ising (ANNNI) spin model from the literature. For the a -cut crystal, we note the presence of two types of dislocation loops, with two habit planes, namely small dislocation loops located on the basal plane (0001) and large (11 2̄ 0) prismatic loops. In addition, larger conglomerated loops which do not necessarily have a (11 2̄ 0) habit plane and may be a larger variant of the (11 2̄ 0) prismatic loops are also observed in the a -cut sample. Small precipitates are observed pinned to these loops. Elemental profiling of the implanted species before and after annealing by secondary ion mass spectrometry revealed a correlation between precipitation close to dislocation networks and the agglomeration of phosphorus at certain depths.