Fig. 5: Energy analysis of the phase segregation.
From: Ab initio molecular dynamics and materials design for embedded phase-change memory
a The energy difference Ediff of amorphous Ge-rich GST with respect to amorphous Ge1Sb2Te4 and amorphous Ge as a function of the Ge concentration, as defined in the text. Each data point is averaged over three samples of a specific Ge-rich GST alloy, three samples of amorphous Ge1Sb2Te4 and three samples of amorphous Ge. The large error bars are mostly contributed by the energy fluctuations of amorphous Ge1Sb2Te4 and amorphous Ge models, due to their limited system size. b The sketches of separated GST phase and homogeneous GST phase. Positive Ediff values reveal an intrinsic tendency toward phase separation into amorphous Ge1Sb2Te4 and amorphous Ge, while negative Ediff values indicate that the amorphous models are energetically favorable in the homogeneous phase.
