Kinetics of the C49-C54 transformation by micro-Raman imaging

The kinetics of the C49-C54 phase transition was analyzed in TiSi thin films obtained by reacting a Ti layer deposited on amorphous silicon. The C54 fraction was determined in the temperature range 680-720 °C by electrical measurements and by micro-Raman spectroscopy. The Raman spectra were acquired by scanning large silicide areas (100×50 ?m) and images showing the evolution of the C54 grains at different times and temperatures were obtained. The transformed fraction, the density and size distribution of the C54 grains were measured, and a detailed discussion of the errors associated with the micro-Raman technique is presented. The data indicate that the nucleation rate is not constant and the Johnson-Mehl-Avrami model cannot describe this transition.