Damage in Xe-implanted 4H-SiC under severe conditions

Xenon ions were implanted in 4H-SiC at 400 and 700 °C with fluences of 1 × 10 ¹⁶ and 3 × 10 ¹⁶ cm ⁻² , respectively. Transmission Electron Microscopy (TEM) experiments were carried out to study the resulting microstructure and its evolution after a 1400 °C annealing. Observations show that the temperature of implantation plays an active role in the formation of as-generated defects. The implantation temperature of 400 °C is too low to allow the formation of visible defects and only a strongly damaged band is observed in the ion stopping range. The post-implantation annealing results in the formation of nanometric cavities along the ion path. In the buried ion stopping region, xenon solid cavities or nano-precipitates of about 10 nm in diameter are present. Other types of defects were also formed during annealing, a high density of stacking faults is observed among the solid cavities and black spot defects are observed beyond the implanted area. At a temperature of 700 °C, the vacancies become mobile enough to cause the formation of nanocavities all along the ions path, i.e. voids in the near surface region and full-gas cavities in the xenon stopping range. At this temperature stacking faults were also formed as well as the defect band at the back. The annealing only causes a slight growth of the solid cavities.