Phase transition behavior and electronic properties of GaSb/Ge${}_2$Sb${}_2$Te${}_5$ superlattice-like structure thin films

We have fabricated GaSb/Ge${}_2$Sb${}_2$Te${}_5$ (GST) superlattice-like structure thin films for phase change memory by magnetron sputtering method, and investigated their phase transition behavior and electrical properties. The experimental results show that increasing the thickness ratio of the GaSb layer to the GST layer can increase the crystallization temperature and reduce the threshold voltage, which is conducive to improving the thermal stability of the GaSb/GST thin films. By analyzing the differences in morphology, thickness and element distribution during phase transition, it is found that the volume of the GaSb layer decreases with the increase of annealing temperature, while the volume of the GST layer expands gradually. However, the volume change range of GaSb/GST thin films is not obvious. Controlling the volume change of the GaSb/GST thin films during phase transition can prolong the service life of the device. By observing the diffusion of interface elements in GaSb/GST superlattice films during annealing, we have found that the interface mixing of Ge element is the most obvious, and Te element have a clear trend of aggregation to adjacent GaSb layers.