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 irradiation ion fluxes greatly enhances the nucleation rate of crystalline silicon in an amorphous matrix, but has a negligible effect on the growth rate of crystalline grains. In situ electron microscopy during ion irradiation was employed to quantitatively analyze transient and steady-state crystal nucleation. Termination of ion irradiation during transient 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 changes in the transient nucleation rate also enables evolution of the subcritical cluster distribution, which has to date defied direct observation, to be inferred.