Toward applications of near-field radiative heat transfer with micro-hotplates

Abstract

Bringing bodies close together at sub-micron distances can drastically enhance radiative heat transfer, leading to heat fluxes greater than the blackbody limit set by Stefan–Boltzmann law. This effect, known as near-field radiative heat transfer (NFRHT), has wide implications for thermal management in microsystems, as well as technological applications such as direct heat to electricity conversion in thermophotovoltaic cells. Here, we demonstrate NFRHT from microfabricated hotplates made by surface micromachining of $$\hbox {SiO}_2$$ SiO 2 /$$\hbox {SiN}$$ SiN thin films deposited on a sacrificial amorphous Si layer. The sacrificial layer is dry etched to form wide membranes ($${100}\,\upmu \hbox {m} \times {100}\,\upmu \hbox {m}$$ 100 μ m × 100 μ m ) separated from the substrate by nanometric distances. Nickel traces allow both resistive heating and temperature measurement on the micro-hotplates. We report on two samples with measured gaps of $${610}\,\hbox {nm}$$ 610 nm and $${280}\,\hbox {nm}$$ 280 nm . The membranes can be heated up to $${250}\,^{\circ }\hbox {C}$$ 250 ∘ C under vacuum with no mechanical damage. At $${120}\,^{\circ }\hbox {C}$$ 120 ∘ C we observed a 6.4-fold enhancement of radiative heat transfer compared to far-field emission for the smallest gap and a 3.5-fold enhancement for the larger gap. Furthermore, the measured transmitted power exhibits an exponential dependence with respect to gap size, a clear signature of NFRHT. Calculations of photon transmission probabilities indicate that the observed increase in heat transfer can be attributed to near-field coupling by surface phonon-polaritons supported by the $$\hbox {SiO}_2$$ SiO 2 films. The fabrication process presented here, relying solely on well-established surface micromachining technology, is a key step toward integration of NFRHT in industrial applications.

Resonant enhancement of the near-field radiative heat transfer in nanoparticles

“…47 , Ecs. (3)(4)(5)(6)(7)(8)(9)(10)16). On the other hand, the part associated with propagating waves conduces to the textbook result Q T = 1/π 2 ∞ 0 dωΘ(ω, T P )k 3 0 Im(α E ) for the energy emitted by a nanoparticle of a nonmagnetic material in absence of external surfaces (r s = r p = 0), see Ref.…”

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A nanoscale photonic thermal transistor for sub-second heat flow switching

“…Thermal radiation plays an important role in heat-to-electricity conversion 1 – 3 , near-field heat transfer 4 – 7 , and photonic cooling 8 – 10 . Further, theoretical work 11 – 17 has also explored how radiative thermal transistors can be created.…”

An analytical method to design annular microfilaments with uniform temperature

“…The main component of these devices is a micromachined membrane suspending a heater filament in its centre. Although the first silicon technology compatible microheaters appeared in the late 80s (Nuscheler 1986), still play important role in today's commercial electronics and scientific instruments, such as in gas sensors (Ru ¨ffer et al 2018;White 2014;Yunusa et al 2014), in flow-and accelerometers (Kuo et al 2012), in actuators (Ishaku et al 2021;vanHorn and Zhou 2016), in IR sources (Popa and Udrea 2019;Ishihara et al 2017;Lochbaum et al 2017), in nano-calorimeters (Hartman et al 2021;Mele et al 2016;Queen and Hellman 2009), and are used in studying of heat transfer properties of materials (Marconot et al 2021). During the last decades many different filament designs were fabricated on full or perforated membranes or in cantilever form (Lee and King 2007), on a large variety of substrate materials, such as ceramics (Roslyakov et al 2021), glass (Vauchier et al 1991), gallium-arsenide (Hotovy et al 2008) and silicon (Graf et al 2007;Hierlemann 2005).…”