Controllable multilevel resistance state of superlattice-like GaSb/Ge2Te films for ultralong retention phase-change memory

The superlattice-like (SLL) GaSb/Ge2Te multilayer thin films were proposed for multilevel ultralong-retention phase-change memory (PCM). Multiple resistance states can be achieved by tuning the thickness ratio between GaSb and Ge2Te layers. The intermediate resistance state could be maintained at a large temperature gap over a wide range from 270 to 355 °C, which guarantee the substantial reliability of the multilevel storage. The high crystallization temperature and 10-years data-retention temperature indicate the high thermal stability of the GaSb/Ge2Te films. After crystallization, the density of the GaSb/Ge2Te multilayer thin films increased slightly. It is in favor of the high reliability for the multilevel PCM. The two crystallization processes and three resistance states support a multilevel storage in the GaSb/Ge2Te-based test cell. The multiple resistance states originate from the localization of the electronic states, which result from the disorder as a result of doping element migrating from neighbor layer. The minimum energy necessary for RESET operation of GaSb/Ge2Te (3.7 × 10− 11 J) is lower than that of Ge2Sb2Te5 (8.1 × 10− 10 J) cell. GaSb/Ge2Te-based cell exhibited lower power consumption, high thermal stability and fast switching speed, suggesting GaSb/Ge2Te being one of the potential materials for multilevel PCM.