A metal-chalcogenide layer, SnSe, was inserted between the memory layer GeTe and the top electrode to form a phase change memory cell. The GeTe layer exhibited ovonic threshold switching at a threshold field of ~ 110V/μm. For subsequent implementation into applications and reliability, material interdiffusion and sublimation were examined in bilayer phase change films of GeTe/SnSe. Transmission electron microscopy and parallel electron energy loss spectroscopy analyses revealed Sn migration to the GeTe layer, which was responsible for lowering the rhombohedral to cubic structural transformation temperature in GeTe. Incongruent sublimation of SnSe and GeTe was observed at above 500C. Severe volatilization of Se resulted in the separation of a metallic Sn phase. The use of Al2O3 as a capping layer was found to mitigate these effects.

Investigation of Inter-Diffusion in Bilayer GeTe/SnSe Phase Change Memory Films. A.Devasia, D.MacMahon, S.Raoux, K.A.Campbell, S.K.Kurinec: Thin Solid Films, 2012, 520[11], 3931-5