Thermal characterization of the $SiO2-Ge2Sb2Te5$ interface from room temperature up to $400°C$

The thermal conductivity of $Ge2Sb2Te5$ (GST) layers, as well as the thermal boundary resistance at the interface between the GST and amorphous $SiO2$⁠, was measured using a photothermal radiometry experiment. The two phase changes in the $Ge2Sb2Te5$ were retrieved, starting from the amorphous and sweeping to the face centered cubic (fcc) crystalline state at $130°C$ and then to the hexagonal crystalline phase (hcp) at $310°C$⁠. The thermal conductivity resulted to be constant in the amorphous phase, whereas it evolved between the two crystalline states. The thermal boundary resistance at the $GST-SiO2$ interface was estimated to be higher for the hcp phase than for the amorphous and fcc ones.