Gate-Tunable Near-Field Heat Transfer

Abstract

Active control over the flow of heat in the near-field holds promise for nanoscale thermal management, with applications in refrigeration, thermophotovoltaics, and thermal circuitry. Analogously to its electronic counterpart, the metal-oxide-semiconductor (MOS) capacitor, we propose a thermal switching mechanism based on accumulation and depletion of charge carriers in an ultra-thin plasmonic film, via application of external bias. In our proposed configuration, the plasmonic film is placed on top of a polaritonic dielectric material that provides a surface phonon polariton (SPhP) thermal channel, while also ensuring electrical insulation for application of large electric fields. The variation of carrier density in the plasmonic film enables the control of the surface plasmon polariton (SPP) thermal channel. We show that the interaction of the SPP with the SPhP significantly enhances the net heat transfer. We study SiC as the oxide and explore three classes of gate-tunable plasmonic materials: transparent conductive oxides, doped semiconductors, and graphene, and theoretically predict contrast ratios as high as 225%.

Electronic Modulation of Near-Field Radiative Transfer in Graphene Field Effect Heterostructures

“…Recently, a theoretical scheme was proposed to electronically control radiative flow in a graphene field effect device, but an experimental implementation of a radiative thermal switch based on such a device has not yet been reported. 54 We implemented an experiment to demonstrate such a thermal switch using a graphene heterostructure device. As shown schematically in Figure 1a We apply a standard fluctuational electrodynamics formalism [55][56][57] to assess the potential for this sample configuration to modulate near-field radiative flow.…”

“…The spectral features from the SiO 2 only contribute to the background heat flux. 54 We obtain the total thermal conductance h by integrating over all frequencies and define a thermal switching for each sample are 197 K and 86 K for S1 and 270 K and 91 K for S2 and 269 K and 90 K for S3, respectively. For each sample, we observe a reversible change in the measured heat flux as the bias is ramped up and down.…”

“…By eliminating all conductive losses and reducing the gap spacing to 100 nm, biasing to -100 V as in these experiments would result in a heat flux modulation of 100%. Reducing the gap distance to such a value would also allow for coupling between the graphene plasmon and the phonon-polariton in the dielectric to influence heat flow 54. However, even reducing the gap to 500 nm without any change in the interface conductance would lead to modulation of 45%.…”

Near-field radiative heat transfer between topological insulators via surface plasmon polaritons

“…When two objects are brought to the micro/nano scale separations, the near-field radiative heat transfer (NFRHT) can exceed the Stefan-Boltzmann law of black-body radiation by several orders of magnitude ( Polder and Van, 1971 ; Joulain et al., 2005 ; Kim et al., 2015 ; Biehs et al., 2010 ; Cuevas and Garcia-Vidal, 2018 ), due to the tunneling effect of evanescent modes. The huge energy flux of the NFRHT has received extensive interest and opens the door to next-generation energy control and conversion technologies ( Zhang, 2020 ), including near-field thermophotovoltaics ( Ilic et al., 2012a ; Koyama et al., 2019 ; St-Gelais et al., 2017 ; Mittapally et al., 2021 ), photonic transformer ( Zhao et al., 2021 ), noncontact thermal management ( Papadakis et al., 2019 ; Ito et al., 2017 ; Otey et al., 2010 ; Ben-Abdallah and Biehs, 2014 ), and electroluminescent cooling ( Zhu et al., 2019 ; Chen et al., 2015 ). Many researches have been devoted to explore new materials to obtain greater heat flux, thereby improving the performance of the above applications ( Wu, 2021 ; Tang et al., 2020 ; Wu, Fu, and Zhang, 2018 , 2020 ; Liu et al., 2017 ; Francoeur et al., 2011 ; Wu and Fu, 2021a , 2021b ; Zhou et al., 2020 ; Shi et al., 2017 ; Li et al., 2021 ; Hu et al., 2021 ).…”

Super-Planckian Radiative Heat Transfer between Macroscale Surfaces with Vacuum Gaps Down to 190 nm Directly Created by SU-8 Posts and Characterized by Capacitance Method

“…1,2 In the near-field regime however, the radiative heat flux can exceed the blackbody limit by a few orders of magnitude due to coupling of evanescent waves or so-called photon tunneling within the subwavelength vacuum gap between the emitter and receiver. [3][4][5][6] Applications of near-field thermal radiation (NFTR) are numerous ranging from thermal imaging, [7][8][9] thermopower conversion, [10][11][12][13][14] radiative cooling, [15][16][17][18] to contactless heat flow management such as thermal rectification [19][20][21][22] and modulation [23][24][25][26][27] .…”