Platform and Framework for Time-Resolved Nanoscale Thermal Transport Measurements in STEM

TL;DR

This paper presents a novel STEM-based system combining laser excitation and high-resolution EELS to enable time-resolved, nanoscale thermal transport measurements, providing new insights into heat conduction at the nanometer scale.

Contribution

The authors developed an integrated laser-STEM-EELS platform with temporal resolution around 50 ns for direct measurement of nanoscale thermal properties.

Findings

Measured thermal conductivity of amorphous carbon: 1.24 W/m·K

Determined heat capacity of amorphous carbon: 821 J/kg·K

Framework enables time-resolved thermal transport studies

Abstract

Understanding heat transport at the nanometer scale is critical for semiconductor devices, quantum materials, and thermal management of nanostructures, yet direct local measurements of thermal conductivity and heat capacity remain scarce. We developed a laser-excitation system integrated into a scanning transmission electron microscope (STEM) for nanoscale thermal transport measurements using ultra-high-resolution electron energy-loss spectroscopy (EELS). A fiber-coupled laser is introduced via a modified aperture mechanism, enabling flexible holder geometries and large tilt angles without optical elements in the polepiece gap. Synchronization of pulsed laser excitation with an externally gated direct electron detector provides temporal resolution about 50 ns at <10 meV energy resolution. Local temperatures are determined via the principle of detailed balance, and thermal transport parameters are extracted by fitting a forward-time central-space heat diffusion model including radiative losses. For amorphous carbon films, we obtain a thermal conductivity of 1.24 $\frac{W}{m\cdot K}$ and a heat capacity of 821 $\frac{J}{kg\cdot K}$, consistent with literature. This framework enables time-resolved nanoscale measurements of thermal transport in materials and devices.