Investigation on Ge_5−xSb_xTe₅ phase-change materials by first-principles method

摘要

The structure stability and chemical bonding of Ge_5−x Sb _x Te₅ (x=0,1,2) phase-change alloys were studied by ab initio calculations. By analyzing formation energies, density of states and electron localization function, we have shown that the chemical bonding character of Ge₄Sb₁Te₅ is quite similar to that of GeTe and hence a NaCl crystalline state is expected. The introduction of extra electrons by Sb in Ge₄Sb₁Te₅ and Ge₃Sb₂Te₅ results in states at the Fermi Level. With increasing Sb contents as in Ge₃Sb₂Te₅, the chemical bonding becomes rather inhomogeneous.