Effect of SHI irradiation and high temperature annealing on the microstructure of SiC implanted with Ag

Scanning electron microscopy (SEM), Raman spectroscopy and Rutherford backscattering spectrometry (RBS) were used to study the influence of swift heavy ion (SHI) irradiation and annealing on the microstructure of polycrystalline SiC implanted with silver (Ag). Polycrystalline SiC specimens were first implanted with 360 keV Ag + ions at room temperature (RT) to a fluence of 2 × 1016cm−2. Thereafter, some of the implanted samples were irradiated with Xe ions of 167 MeV (SHI) at room temperature to a fluence of 3.4 × 1014 cm−2 and 8.4 × 1014 cm−2. Both the as-implanted and implanted then irradiated samples were annealed in vacuum at temperatures ranging from 1100 to 1400 °C in steps of 100 °C for 5 h. Raman and SEM results showed that implantation of silver (Ag) resulted in complete amorphization of the near surface region of the SiC substrates. However, SHI irradiation of the as-implanted SiC resulted in partial recrystallization of the initially amorphized layer. The as-implanted samples exhibited more crystallinity after annealing at 1100 °C as compared to SHI irradiated samples annealed at same conditions. This poor recrystallization of the SHI irradiated SiC samples was due to the amount of impurities (i.e. concentration of Ag atoms) retained after annealing at 1100 °C. Raman and SEM results showed that annealing of the as-implanted samples at 1100 °C resulted in larger average crystal size compared to the SHI irradiated samples annealed in the same conditions. The intensity of the longitudinal optical (LO) phonon in Raman spectra increases with the increasing the average crystal sizes of SiC.