Inductive effect of phosphorus atoms on the formation of graphite-like clusters in silicon carbide during irradiation

The inductive effect of phosphorus (P) atoms on the formation of graphite-like clusters in silicon carbide (SiC) was investigated by using confocal micro-Raman spectroscopy. SiC samples containing P atoms at concentrations of 1.0 x 10(20) and 1.0 x 10(21) cm(-3) were prepared by P ion implantation. The P-containing and P-free SiC samples were irradiated simultaneously with 1.25 MeV Si5+ ions at a fluence of 1.0 x 10(16) cm(-3) at room temperature, 300 degrees C, and 500 degrees C. Two prominent peaks at 1385 and 1562 cm(-1), which correspond to the breathing vibration of six-membered carbon (C) rings and stretching vibration of sp(2) C-C bonds, respectively, are observed in the Raman spectra of as-irradiated P-containing SiC. These results demonstrate that P atoms can effectively promote the aggregation of C atoms into graphite-like clusters during irradiation. The formation of graphite-like clusters follows an inductive aggregation mechanism. The graphite-like cluster nucleus is tentatively identified as a C-si(Pc)(2) complex. For comparison, argon (Ar)-ion irradiation of magnesium (Mg)-containing SiC was also performed, where graphite-like clusters were not formed. (C) 2019 Elsevier B.V. All rights reserved.