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 DRAM and Flash. However, high required operation current remains the major limitation for the SCM application, even after using defect engineering materials, e. g. Ti-doped Sb2Te3. Here, we demonstrate ~87% current can be reduced by spatially separating Sb2Te3 and TiTe2 layer thanks to the semimetallic TiTe2, severing as a thermal barrier in the Reset process. Moreover, the stable crystalline TiTe2 layer provides ordered interface to speed up the crystallization process of amorphous Sb2Te3 layer, enabling ~10 ns ultrafast crystallization speed. Outstanding device lifetime, up to ~ 2×107 cycles, has been obtained, twice as long as alloy-based cell. Correlative electron microscopy and atom probe tomography evidence that TiTe2/Sb2Te3 multilayer can keep layer-stacked structure, avoiding phase segregation found in alloy and strong element intermixing in GeTe/Sb2Te3 superlattice, which enables excellent cyclability. This study suggests adding semimetallic layer in the phase change layer, like TiTe2 and TiSe2, can yield a phase change memory with superior properties.