Fig. 3: Non-equilibrium phonon dynamics across the interface under forward (AlN → SiC) and reverse (SiC → AlN) heat flow.
From: Probing phonon transport dynamics across an interface by electron microscopy
a,b, Experimentally reconstructed temperature maps for forward and reverse heat flow conditions. c,d, EEG spectra acquired under forward and reverse heat flow. e,f, Corresponding EEL spectra. Overlaid lines denote the relative intensity of AlN TO phonon peak (81–85 meV): solid white line from EEG spectra and dashed grey line from EEL spectra. g, Extracted phonon spectra at SiC (red line), AlN (blue line) and interface (green shade) from panels c–f. Calculated phonon DOS is shown at the bottom. h, Interface residual spectra after removing the spectral components of bulk SiC and AlN using the least-squares fitting (see Methods). i, Calculated spatial distribution of phonon modal temperatures near the interface. The thick solid line represents the averaged modal temperature profile. j, Schematic illustration of non-equilibrium phonon transport across the interface. Dispersion lines are colour-coded by calculated modal temperatures along the ΓA direction (heat flow direction). The central coloured band plots depict the interface residual spectra from the experimental EEG data, representing the interface mode population. Arrows denote the three-phonon scattering processes associated with the α and β modes: green for absorption, grey for emission. Solid arrows indicate enhanced processes and open arrows denote suppressed processes. a.u., arbitrary units.
