Thermal characterization of dielectric and phase change materials for the optical recording applications

Advances in the phase change optical recording technology strongly depend on the optical and thermal optimizations of the metal/ZnS–SiO2/phase change multilayer structure, which requires accurate modeling and thermal characterization of the phase change media structure. In the present work, the thermal conductivities of the amorphous and crystalline Ge4Sb1Te5 phase change and ZnS–SiO2 dielectric layers of thicknesses in the range of 50–300nm have been measured using the transient thermoreflectance technique. The data are between factors of 2–4 different from the previously measured values for thin film and bulk samples. The thermal boundary resistance at a metal/ZnS–SiO2 interface is found to be around 7×10−8m2W−1. This might have serious implications for the future phase change recording application which attempts to achieve the high writing speeds by decreasing the thickness of a ZnS–SiO2 dielectric layer.