Deep ultraviolet Raman scattering characterization of ion-implanted SiC crystals

Multiple energy phosphorous ions were implanted into 4H-SiC at room temperature and at an elevated temperature (500 °C) followed by annealing at various temperatures. Deep ultraviolet Raman microscopy was used to analyze the effect of the implantation dose and postannealing temperature on the recovery of surface layers damaged by the implantation. The Raman analysis showed that the recovery rate of the crystallinity increased with an increase in the annealing temperature. However, for highly dosed samples, recovery was not complete even with annealing temperatures up to 1700 °C. With room-temperature implantation, part of the implanted layer was converted into a 3C structure with heavy stacking faults. New Raman bands were observed at below 500cm−1 in samples heavily dosed with 4.0×1016cm−2 after annealing, which revealed that excess phosphorus precipitates. A downshift of the phonon Raman bands and a reduction in the LO–TO-phonon frequency splitting were observed in as-implanted samples and ones that are not completely recovered by annealing. This feature is discussed based on several mechanisms.