Irradiation-induced microstructural change in helium-implanted single crystal and nano-engineered SiC

Abstract

Microstructural evolution induced by helium implantation and subsequent heavy ion irradiation has been investigated in single crystal and nano-engineered (NE) 3C SiC. Implantation with 65keV He+ ions was performed at 277°C, and the helium depth distribution was determined by elastic recoil detection analysis (ERDA). Transmission electron microscopy (TEM) could not resolve the presence of bubbles in any of the helium-implanted single crystal SiC. However, helium platelets and small dislocation loops (∼50nm in diameter) were observed in the single crystal sample with the highest implantation fluence after 1h annealing at 700°C. Following irradiation with 9MeV Au3+ ions at 700°C, no bubbles were observed in the helium-implanted single crystal SiC, regardless of helium fluence. For the helium-implanted NE SiC, subsequent irradiation with 9MeV Au ions to a dose of 10dpa at 700°C resulted in the formation and growth of bubbles, and a bimodal helium bubble size distribution was observed at the highest helium concentration (8000appm) in the NE SiC.