Controllable crystal growth and fast reversible crystallization-to-amorphization in Sb(2)Te-TiO(2) films

The structure evolution and crystallization processes of Sb(2)Te-TiO(2) films have been investigated. The Sb(2)Te-rich nanocrystals, surrounded by TiO(2) amorphous phases, are observed in the annealed Sb(2)Te-TiO(2) composite films. The segregated domains exhibit obvious chalcogenide/TiO(x) interfaces, which elevate crystallization temperature, impede the grain growth and increase crystalline resistance. Compared with that in conventional Ge(2)Sb(2)Te(5) film, the shorter time for onset crystallization (25 ns) and amorphization (100 ns) has been achieved in as-deposited (Sb(2)Te)(94.7)(TiO(2))(5.3) film under 60 mW laser irradiation. The corresponding recrystallization and re-amorphization can also be realized in the film. From Johnson-Mehl-Avrami (JMA) analysis, it is further found that the one-dimensional grain growth with controlled interface is dominant for the film during the fast phase-change process. Therefore, (Sb(2)Te)(94.7)(TiO(2))(5.3) film with improved crystallization mechanism is promising for high-stable and fast-speed memory applications.