Irradiation-induced amorphization: Effects of temperature, ion mass, cascade size, and dose rate - art. no. 024105

An empirical model based on cascade "quenching" and epitaxial recrystalliza tion has been developed to describe the accumulation of the amorphous fract ion during ion beam irradiation experiments. The model is based on the assu mption that the amorphous fraction that remains after the formation of a ca scade is related to a crystallization efficiency parameter A. For low value s of A, as would be expected at low temperatures, for heavy-ion irradiation s, or for materials that are good glass formers, the accumulation of the am orphous fraction as a function of dose is an exponential function. For high values of A, as would be expected at elevated temperatures, for light-ion irradiations, or for materials that are poor glass formers, the accumulatio n of the amorphous fraction as a function of dose is a sigmoidal function. Amorphization dose varies as a function of temperature and is reflected by the temperature-dependent crystallization efficiency. The effects of ion ma ss and energy on critical amorphization dose and temperature are discussed in terms of the cascade size. The dose-rate effect on the critical temperat ure of amorphization is derived considering the thermal annealing of the da maged material.