Direct Measurement of Room Temperature Non-diffusive Thermal Transport Over Micron Distances in a Silicon Membrane

Abstract

The "textbook" phonon mean free path (MFP) of heat carrying phonons in silicon at room temperature is ~40 nm. However, a large contribution to the thermal conductivity comes from low-frequency phonons with much longer MFPs. We present a simple experiment demonstrating that room temperature thermal transport in Si significantly deviates from the diffusion model already at micron distances. Absorption of crossed laser pulses in a freestanding silicon membrane sets up a sinusoidal temperature profile that is monitored via diffraction of a probe laser beam. By changing the period of the thermal grating we vary the heat transport distance within the range ~1-10 μm. At small distances, we observe a reduction in the effective thermal conductivity indicating a transition from the diffusive to the ballistic transport regime for the low-frequency part of the phonon spectrum.

6 pages plus References and Supplementary Material (14 pages total)

References in corpus (1)

• Energy Dissipation and Transport in Nanoscale Devices

Cited by in corpus (10)

• Frequency-dependent phonon mean free path in carbon nanotubes from non-equilibrium molecular dynamics
• A new regime of nanoscale thermal transport: collective diffusion counteracts dissipation inefficiency
• Superdiffusive heat conduction in semiconductor alloys -- I. Theoretical foundations
• Superdiffusive heat conduction in semiconductor alloys -- II. Truncated Lévy formalism for experimental analysis
• Electron-Phonon Coupling and Thermal Conductance at a Metal-Semiconductor Interface: First-principles Analysis
• Radial Quasiballistic Transport in Time-Domain Thermoreflectance Studied Using Monte Carlo Simulations
• Phonon heat conduction in layered anisotropic crystals
• Size Effects in Thermal Conduction by Phonons
• Quantum bounds on heat transport through nanojunctions
• Length Dependent Thermal Conductivity Measurements Yield Phonon Mean Free Path Spectra in Nanostructures