Modeling of Two Different Operation Modes of Phase Change Material for Phase-Change Random-Access Memory

Two basic models for phase-change random-access memory (PRAM) are compared for the first time. Model 1 is based on polycrystalline Ge 2 Sb 2 Te 5 , and the phase change takes place only in some of the film. Model 2 is based on amorphous Ge 2 Sb 2 Te 5 . This work indicates that model 1 has an excellent R OFF / R ON , but inferior structure and reset current. Model 2 has superior structure and reset current, but inferior R OFF / R ON . Therefore, for model 2, it is important to control the thickness of nonprogrammable volume to ensure sufficient R OFF / R ON and the proper range of the ratio of non-programmable volume and programmable volume is calculated as 0.003–1%. The simulation result shows the temperature distribution of model 2 can satisfy the actual requirement well, and the reset current can be reduced to 0.15 mA, much lower than that in model 1.