An electrical probe of the phonon mean-free path spectrum

TL;DR

This paper introduces a novel electrical method to measure the phonon mean-free path spectrum, offering advantages over optical techniques and revealing a broader phonon spectrum in gallium arsenide.

Contribution

The paper presents a new electrical probing technique for the MFPAF that is insensitive to interfacial impedance and compatible with various experimental setups.

Findings

Phonons in gallium arsenide have a wider mean-free path spectrum than previously believed.

The electrical probe effectively measures the MFPAF without optical methods.

Analysis using the enhanced Fourier law supports the broader phonon spectrum.

Abstract

Most studies of the mean-free path accumulation function (MFPAF) rely on optical techniques to probe heat transfer at length scales on the order of the phonon mean-free path. In this paper, we propose and implement a purely electrical probe of the MFPAF that relies on photo-lithographically defined heater-thermometer separation to set the length scale. An important advantage of the proposed technique is its insensitivity to the thermal interfacial impedance and its compatibility with a large array of temperature-controlled chambers that lack optical ports. Detailed analysis of the experimental data based on the enhanced Fourier law (EFL) demonstrates that heat-carrying phonons in gallium arsenide have a much wider mean-free path spectrum than originally thought.