In situ $3ω$ techniques for measuring thermal conductivity of phase-change materials

Knowledge of the thermal conductivity of phase-change materials is essential for accurate modeling of nonvolatile memory devices that incorporate them. The “$3ω$ method” is a well-established and sensitive technique for measuring this property. We report two new extensions of the $3ω$ technique that feature in situ monitoring of the phase-change material as it transitions from the as-deposited amorphous phase to the crystalline phase. One technique crystallizes the entire sample in a vacuum oven, while using the $3ω$ voltage to monitor the phase transition. The other technique uses the $3ω$ heater to crystallize only the material in the region of measurement.