IN-SITU ANALYSIS OF IRRADIATION-INDUCED CRYSTAL NUCLEATION IN AMORPHOUS-SILICON - A MICROSCOPE FOR THERMODYNAMIC PROCESSES IN NUCLEATION

Ion irradiation (600 keV Xe+ ) at high temperatures and [ow irradiatio n ion fluxes greatly enhances the nucleation rate of crystalline silic on in an amorphous matrix, but has a negligible effect on the growth r ate of crystalline grains. In situ electron microscopy during ion irra diation was employed to quantitatively analyze transient and steady-st ate crystal nucleation. Termination of ion irradiation during transien t nucleation produces changes in the nucleation rate that can best be accounted for by irradiation-induced modification of the thermodynamic barrier to crystal nucleation. Observation of irradiation-induced cha nges in the transient nucleation rate also enables evolution of the su bcritical cluster distribution, which has to date defied direct observ ation, to be inferred.