Isothermal crystal growth kinetics in Se90Te10 and Se80Te20 thin films was studied by microscopy and in situ X-ray diffraction (XRD) measurements. The spherulite-like crystals grew linearly with time. In a narrow temperature range of between 65 and 85°C, crystal growth rates exhibit simple exponential behavior with activation energies E G=193±4kJ mol-1 for Se90Te10 and EG=195±4kJ mol-1 for Se80Te 20. The crystal growth in both compositions is controlled by liquid-crystal interface kinetics and can be described by a screw dislocation growth model. From the XRD data, the crystallization fraction was estimated. The crystallization data were described by Johnson-Mehl-Avrami (JMA) model with Avrami exponents m=1.4±0.3 for Se90Te10 and m=1.6±0.4 for Se80Te20. Activation energies were estimated from the temperature dependence of rate constant evaluated from the JMA model. The activation energies of nucleation-growth process were found to be Ec=184±21kJ mol-1 for Se90Te 10 and Ec=179±7kJ mol-1 for Se 80Te20, and are comparable with activation energies of crystal growth.
ASJC Scopus subject areas
- Physics and Astronomy(all)