This article reports on the thermal characterization of Ge-rich Ge2Sb2Te5 films and Ge2Sb2Te5/Ge-rich Ge2Sb2Te5 multilayers designed for high-temperature applications in the field of phase-change memory. The thermal conductivities of such materials and the thermal boundary resistance with the Si3N4 dielectric material are characterized by two different photothermal techniques. The phase change in Ge-rich Ge2Sb2Te5 is found to occur at a temperature higher than that of the Ge2Sb2Te5 alloy. The Ge2Sb2Te5/Ge rich Ge2Sb2Te5 multilayer has been observed to feature two phase changes corresponding to Ge-rich Ge2Sb2Te5 and Ge2Sb2Te5. Finally, it is estimated that the thermal resistance of the interface separating Ge-rich Ge2Sb2Te5 and Ge2Sb2Te5 nanolayers constitutes the multilayer structure and its contribution has been realized to be significant in enhancing the thermal resistance of the multilayer structure. © 2022 Wiley-VCH GmbH.