Characterization of Femtosecond laser-irradiation crystallization and structure of multiple periodic Si/Sb₈₀Te₂₀ nanocomposite films by coherent phonon spectroscopy.

Multiple parameters of nanocomposite Si/Sb₈₀Te₂₀ multilayer films are possibly optimized simultaneously to satisfy the development of ideal phase-change memory devices by adjusting chemical composition and physical structure of multilayer films. The crystallization and structure of the films are studied by coherent phonon spectroscopy. Laser irradiation power dependence of coherent optical phonon spectroscopy reveals laser-induced crystallization of the amorphous multilayer film, while coherent acoustic phonon spectroscopy reveals the presence of folded acoustic phonons which suggests a good periodic structure of the multilayer films. Laser irradiation-induced crystallization shows applicable potentials of the multilayer films in optical phase change storage.