Theoretical predictions of the structural stability and property contrast for Sb-rich Ge3Sb6Te5 phase-change materials

Abstract

Improving the structural stability and property contrast of phase-change materials is important to make phase-change random access memories work in prolonged service stably. Based on the density functional theory and ab initio molecular dynamics simulations, we analyze the structural, electronic, and optical properties of Sb-rich amorphous Ge3Sb6Te5, in comparison with the traditional amorphous Ge2Sb2Te5. The results show that excess Sb concentration can promote the formation of wrong bonds, tetrahedrons, and fivefold rings, which are beneficial for the structural stability of amorphous phases. In addition, Ge3Sb6Te5 has a bigger difference in the bandgap and dielectric function between the crystalline and amorphous phases, indicating that excess Sb concentration can improve the electrical and optical property contrast between the two phases. Our calculation will provide a theoretical basis for applying Sb-rich Ge3Sb6Te5 to retain data stably in prolonged service.