Enhanced thermal conduction by surface phonon-polaritons

Abstract

Improving heat dissipation in increasingly miniature microelectronic devices is a serious challenge, as the thermal conduction in nanostructures is markedly reduced by increasingly frequent scattering of phonons on the surface. However, the surface could become an additional heat dissipation channel if phonons couple with photons forming hybrid surface quasiparticles called surface phonon-polaritons (SPhPs). Here, we experimentally demonstrate the formation of SPhPs on the surface of SiN nanomembranes and subsequent enhancement of heat conduction. Our measurements show that the in-plane thermal conductivity of membranes thinner than 50 nm doubles up as the temperature rises from 300 to 800 kelvin, while thicker membranes show a monotonic decrease. Our theoretical analysis shows that these thickness and temperature dependencies are fingerprints of SPhP contribution to heat conduction. The demonstrated thermal transport by SPhPs can be useful as a previously unidentified channel of heat dissipation in a variety of fields including microelectronics and silicon photonics.

Probing nanoparticle substrate interactions with synchrotron infrared nanospectroscopy: Coupling gold nanorod Fabry-Pérot resonances with SiO2 and h−BN phonons

“…In such materials, their composite responses find origin in their bulk dielectric properties together with particle morphology and cluster geometry [4][5][6][7][8][9]. Characterizing these properties with simultaneously high spatial and spectral resolution is difficult but essential for the rational design of advanced materials with novel functionalities [10][11][12][13][14]. Today, a number of studies have made progress in this direction through a variety of near-field imaging and spectroscopy techniques [15][16][17][18][19][20][21][22][23], yet considerable work still lies ahead to better understand material design principles and characterization methods in the IR spectral regime.…”

Heat Transport Driven by the Coupling of Polaritons and Phonons in a Polar Nanowire

“…The main resonance peak of ε I at 155 Trad/s indicates that SiN absorbs a significant amount of energy from the electromagnetic field and therefore limits the propagation of SPhPs, at that frequency. By contrast, the dip of ε R occurs at 175 Trad/s, which represents the frequency at which the SPhPs exhibit the strongest confinement to the interface [23]. The yellow zone (ε R < 0), on the other hand, stands for the Reststrahlen band determined by the frequency interval (167.0; 199.5) Trad/s that contains the range of frequencies (ε R < −ε 0 ) that would support the propagation of SPhPs in absence of absorption (ε I = 0), as established by Equation (18).…”

“…The propagation and heat transport of the SPhPs along a SiN nanowire is quantified and analyzed in this section. SiN is a typical polar material able to support the propagation of SPhPs in a wide frequency range [23,34] and therefore can be considered as a good SPhP conductor. By solving the Maxwell equations under proper boundary conditions for the transverse magnetic polarization required for the existence of SPhPs [12,25], the following dispersion relation for the SPhP wavevector β along the wire axis is obtained [35]…”

“…This ballistic behavior appears due to the huge SPhP propagation length that was found to be as long as 1 m [19][20][21][22] and is hence orders of magnitude longer than the typical mean free paths of electrons and phonons. The spectral values of this propagation length is mainly determined by the material permittivity, which is nearly independent of temperature, within a wide range of temperatures lower and higher than room temperature [23]. Therefore, the ballistic heat transport of SPhPs is not necessarily restricted to low temperatures, as is the case of electrons and phonons.…”

“…Figure 2.Real and imaginary parts of the relative permittivity ε = ε R + iε I of SiN, as a function of frequency[23]. The yellow zone stands for the band in which ε R < 0.…”