Crystallization of GST225 thin film induced by a single femtosecond laser pulse: Experimental and theoretical study

Amorphous to crystalline phase transition in Ge2Sb2Te5 film under the influence of a single femtosecond laser pulse is studied. Two-dimensional temperature calculations and kinetic model for crystallization were used to support experimental results and then to explain the fast mechanism of crystallization. Based on comparison with the experimental data, the theoretical Time-Temperature-Transformation diagram was calculated, that allowed to define the range of cooling rates at which crystallization is possible. The distribution of crystalline fraction in the thin film was calculated using these rates. Reflectance of the simulated structures turned out to be in good agreement with experimental observations.