Polarity-dependent resistance switching in crystalline Ge1Sb4Te7 film

Phase-change memory (PCM) utilizes the fast reversible phase transition between crystalline and amorphous chalcogenide phase-change materials to achieve the data storage. The rather large density difference between crystalline and amorphous phases will induce device failure with repeated switching. Further, the melting-quenching process induced amorphous-crystalline phase-change needs high energy consumption. In this work, reversible resistance switching is observed in crystalline Ge1Sb4Te7 ribbons driven by voltage polarity, without amorphous-crystalline phase-change. Consequently, the large density variation and the high energy consumption are avoided, which overcomes those two restrictions of PCM. Moreover, on the basis of ab initio calculations, the underlying mechanism is further analyzed and it is concluded that this switching is induced by the reversible swapping of antimony between its lattice site and the center of the Te-Te van der Waals bilayers.