Local structural change of amorphous Ge–Sb–Te thin film on annealing

Structures of amorphous Ge–Sb–Te film included in phase change optical disk have been examined using transmission electron microscopy. Cross-sectional high-resolution electron microscopy (HREM) observation indicated that locally ordered regions as small as ∼2 nm exist in the amorphous Ge–Sb–Te thin film. These ordered regions grew in size after annealing at 160 °C for 120 min. On the basis of the HREM and nano-beam electron diffraction, it was concluded that the atomic structure of the locally ordered regions is similar to that of crystalline Sb.