We have applied extended X-ray absorption fine structure (EXAFS) analyses and ab initio molecular dynamics (AIMD) simulations to study the structure of Ag-doped (up to 42%) Ge1Sb2Te4 alloys. The computer models are consistent with EXAFS experiments, and reveal that the Ge environment is significantly modified by Ag doping, whereas those of Sb and Te are barely affected (except for high Ag concentrations), and suggest that Ag prefers bonding with Te. Doping with Ag promotes the conversion of Ge from tetrahedral to octahedral, and enhances the speed of crystallization of Ge–Sb–Te (GST) alloys as predicted by MD simulation. Our study sheds light on the atomistic mechanism of rapid crystallization of GST alloys, and enhancement by Ag doping.
Mean-square displacements (MSDs), depicting the hopping of individual silver atoms in the silver-doped GeSbTe phase-change memory material (PCMM).