Stable chalcogenide Ge-Sb-Te heterostructures with minimal Ge segregation

Matching of various chalcogenide films shows the advantage of delivering multilayer heterostructures whose physical properties can be tuned with respect to the ones of the constituent single films. In this work, (Ge-Sb-Te)-based heterostructures were deposited by radio frequency sputtering on Si(100) substrates and annealed up to 400 °C. The as-deposited and annealed samples were studied by means of X-ray fluorescence, X-ray diffraction, scanning transmission electron microscopy, electron energy loss spectroscopy and Raman spectroscopy. The heterostructures, combining thermally stable thin layers (i. e. Ge-rich Ge_5.5Sb₂Te₅, Ge) and films exhibiting fast switching dynamics (i. e. Sb₂Te₃), show, on the one side, higher crystallization-onset temperatures than the standard Ge₂Sb₂Te₅ alloy and, on the other side, none to minimal Ge-segregation.