Thermal Barrier Phase Change Memory.

Phase change memory is widely considered as the most promising candidate as storage class memory (SCM), bridging the performance gaps between dynamic random access memory and flash. However, high required operation current remains the major limitation for the SCM application, even after using defect engineering materials, for example, Ti-doped SbTe. Here, we demonstrate that ∼87% current can be reduced by spatially separating SbTe and TiTe layers, thanks to semimetallic TiTe serving as a thermal barrier in the reset process. Moreover, the stable crystalline TiTe layer provides an ordered interface to speed up the crystallization process of the amorphous SbTe layer, enabling ∼10 ns ultrafast crystallization speed. An outstanding device lifetime, up to ∼2 × 10 cycles, has been obtained, which is twice as long as that of alloy-based cells. Correlative electron microscopy and atom probe tomography provide evidence that the TiTe/SbTe multilayer can keep a layer-stacked structure, avoiding phase segregation found in alloys and strong element intermixing in the GeTe/SbTe superlattice, which enables excellent cyclability. This study suggests that adding a semimetallic layer in the phase change layer, such as TiTe and TiSe, can yield a phase change memory with superior properties.