Phase transitions in stacked GeTe/SnTe and Ge_2Se_3/SnTe thin layers for potential phase-change memory applications have been investigated by X-ray diffraction using a two-dimensional area detector system. The as-deposited underlying GeTe or Ge_2Se_3 layer is amorphous, whereas the top SnTe layer is crystalline. In the GeTe/SnTe stack, the crystallization of GeTe phase occurs near 170°C, and upon further heating, the GeTe phase disappears, followed by the formation of rocksalt-structured Ge_xSn_(1-x)Te solid solution. In the Ge_2Se_3/SnTe stack, the phase transition starts with the separation of a SnSe phase due to the migration of Sn ions into the Ge_2Se_3 layer. SnSe is believed to facilitate the crystallization of Ge_2Se_3-SnTe solid solution at ～360°C, which is much lower than the crystallization temperature of Ge_2Se_3, therefore consuming less power during the phase transition.
展开▼
