Damaged structures of α-SiC below and above the critical temperature of amorphization (Tc) under high-energy electron irradiation were studied by means of transmission electron microscopy and electron energy-loss spectroscopy. Above Tc, crystal fragmentation took place due to local lattice strains caused by preferential displacements, subsequent outward diffusion of C atoms and the formation of Si nano-clusters. On the other hand, the amorphous structure formed below Tc could be well-characterized by the formation of Si–Si, Si–C and sp3 C–C covalent bonds with the tetrahedral coordination locally retained and uniformly distributed. The primary amorphization process under electron irradiation could be interpreted by the defect-accumulation model, in which displaced atoms were frozen at interstitial sites before long-distance diffusion by reconstructing the surrounding structure to relax the local strains. Accordingly, the amorphization process was controlled essentially by the mobility of displaced C and Si atoms, and chemical disordering seemed to play a minor role in triggering the amorphization.

Local Structures and Damage Processes of Electron Irradiated α-SiC Studied with Transmission Electron Microscopy and Electron Energy-Loss Spectroscopy. S.Muto, T.Tanabe: Journal of Applied Physics, 2003, 93[7], 3765-75