Electron-irradiation-induced crystalline-to-amorphous transition in ?-SiC single crystals

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Abstract
An electron-irradiation-induced crystalline-to-amorphous (C-A) transition in β-SiC single crystals has been studied as a function of irradiation temperature by means of ultra-high-voltage electron microscopy. The C-A transition can be induced at temperatures below 340 K. The dose of electrons required for the C-A transition is essentially constant at temperatures below 250 K, while at temperatures above 250 K the electron dose increases quickly with temperature until no amorphization can be induced any more at the critical temperature Tc of 340 K. At temperatures below Tc , chemical disordering occurs in every case and always precedes a complete C-A transition, while at temperatures above Tc the degree of chemical disordering is greatly reduced and there is no amorphization. Based on the results obtained, the roie of chemical disordering in the C-A transition is discussed in terms of the energy increases due to the production of anti-site defects. The thermal stability of the irradiation-produced amorphous SiC has been also studied and it is revealed that the amorphous SiC crystallizes into fine-grained polycry-stalline (β-SiC at temperatures above 1298 ± 25K.