Interfacial phase change memory (iPCM) devices have been shown to switch with significantly reduced power consumption, compared with conventional phase-change memory devices. These iPCMs are based on a periodic structure of nanometer-sized layers of chalcogenides called a chalcogenide superlattice (CSL). Strong temperature increases have been observed within the CSL during the switching procedure, questioning the stability of the CSL structure. In this study, we conduct a detailed quantitative analysis to investigate the evolution of the structure and composition of the sputter-deposited GeTe-Sb