IN-SITU OBSERVATION OF THE DAMAGE EVOLUTION IN BETA-SIC CRYSTALS DURING HELIUM AND HYDROGEN DUAL-ION IRRADIATIONS

In situ observations were performed on the bubble formation in beta-SiC crystals during three kinds of ion irradiations: (a) single helium ion irradiation, (b) hydrogen ion pre-irradiation followed by helium ion pre-irradiation, and (c) simultaneous irradiation of helium and hydrogen ions. The bubble formation and growth in beta-SiC, at the same level of irradiation fluences, were remarkably depressed in the case of simultaneous helium- and hydrogen-ion irradiations compared to the other two cases. The effect of simultaneous ion irradiation on the bubble formation is discussed with respect to the diffusion of the incident ions and the number of nucleation sites for helium bubbles.