GeTe/Sb2Te3 Super-Lattices: Impact of Atomic Structure on the RESET Current of Phase-Change Memory Devices

Abstract

Phase change memories (PCMs) are at the heart of modern memory technology, offering multi-level storage, fast read/write operations, and non-volatility, bridging the gap between volatile DRAM and non-volatile Flash. The reversible transition between amorphous and crystalline states of phase-change materials such as GeTe or Ge₂Sb₂Te₅ is at the basis of PCM devices. Despite their importance, PCM devices face challenges including high power consumption during the RESET operation. Current research efforts focus on improving device architecture and exploring alternative phase-change materials such as GeTe/Sb₂Te₃ super-lattices (SLs), for which a reduced programming power consumption is observed compared with standard PCMs. Herein, by combining X-ray diffraction and scanning transmission electron microscopy imaging of SL thin films with the study of the same SL in PCM devices, it is shown that it is possible to significantly decrease RESET energy of the device, without modifying the SL composition, by reducing the amount of structural defects through annealing treatment. The best device properties are obtained after transforming the SL into a defect-free, highly out-of-plane oriented rhombohedral phase. These results offer a promising avenue for further improving the performance of SL-based PCM devices through structural optimization.