Determination of C54 nucleation site density in narrow stripes by sheet resistance measurements and μ-Raman spectroscopy

The kinetic of the C49-C54 phase transformation at 730 °C in TiSi2 narrow strips for width in the 0.5-1.3-μm range was investigated by resistance measurements and μ-Raman spectroscopy. With this last technique a growth rate of 0.15 μm/s and a nucleation density of about 0.035 sites/μm2 were obtained. The fraction of the transformed material as measured by resistance follows the Johnson-Mehl-Avrami equation, with an exponent equal to 1 for all of the analyzed linewidths. Nucleation site saturation occurs and the growth is one-dimensional along the length of the strip. The characteristic time increases as 1/W, W being the width of the strip, and, taking into account the growth rate obtained by μ-Raman spectroscopy, the nucleation density resulted 0.034 sites/μm2 in excellent agreement with the μ-Raman results.