Decoupled thermal resistances of phase change material and their impact on PCM devices

We report the thickness and phase dependent thermal properties of Ge₂Sb₂Te₅ (GST) films using electrical Joule heating thermometry (3ω method) and validate the data with optical thermometry. The intrinsic thermal conductivity of GST increases from 0.26 W/mK for the amorphous phase to 0.57 W/mK for the crystalline phase. The thermal boundary resistance between GST and Si₃N₄ films decreases from 134 × 10^-9 m²KW^-1 to 25 × 10^-9 m²KW^-1 after the phase change. The effective thermal resistance of GST shows a nonlinear dependence on the film thickness that infers the presence of microstructural defects. We separate the contributions of defects from intrinsic thermal transport and summarize possible causes for their thickness dependent behavior. An electrothermal simulation of PCM cell estimates the potential impact of the measured properties. This work improves the quality of PCM simulations by offering detailed knowledge of the distribution of thermal resistances.