Crystallization mechanism in films along GeTe-SbTe pseudo-binary line

Abstract

The aim of this work is to compare the isothermal crystallization kinetic in the films along GeTe-Sb ₂ Te ₃ line with composition Ge ₂ Sb ₂ Te ₅ , Ge ₁ Sb ₂ Te ₄ , Ge ₁ Sb ₄ Te ₇ and Ge ₄ Sb ₁ Te ₅ using mainly Johnson-Mehl-Avrami-Kolmogorov (JMAK) model. Results obtained have shown different crystallization mechanism in the investigated films. In Ge ₂ Sb ₂ Te ₅ and Ge ₁ Sb ₂ Te ₄ films the analysis of the kinetic results (Avrani coefficient) showed that at the beginning of crystallization a metastable phase appeared with the Ge ₁ Sb ₄ Te ₇ composition, this is followed by the nucleation and growth of the stable fcc phase up to full crystallization. In contrast Ge ₄ Sb ₁ Te ₅ and Ge ₁ Sb ₄ Te ₇ films show diffusion control growing from small dimension grains with decreasing nucleation rate.