Investigation of phase transition in stacked ge-chalcogenide/snte phase-change memory films

Phase transitions in stacked GeTe/SnTe and Ge2Se3/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 Ge2Se.-i 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 GexSni.xTe solid solution.In the GeiSes/SnTe stack, the phase transition starts with the separation of a SnSe phase due to the migration of Sn ions into the Ge2Se3 layer.SnSe is believed to facilitate the crystallization of Ge2Se3-SnTe solid solution at ~360°C, which is much lower than the crystallization temperature of Ge2Se3, therefore consuming less power during the phase transition.