Study On Near-field Radiative Heat Transfer Of Black Phosphorus Materials Based On Fluctuation-dissipation Theorem

Thermal radiation is the process by which an object radiates electromagnetic waves due to thermal fluctuations and quantum fluctuations.In the far field region,radiative heat transfer is realized mainly through the propagation mode of electromagnetic wave.However,as the distance between two objects decreases,the contribution of propagation mode will be weaker and weaker,while the contribution of evanescent wave will gradually increase.In the near-field region(when the distance between two objects is less than the thermal wavelength),thermal radiation between the objects is transmitted mainly by evanescent mode of electromagnetic wave,and the radiative power between them is much larger than the limit of blackbody radiation given by Planck's law.In particular,the near field radiation between them can be greatly enhanced when the materials can support some surface modes,such as surface plasmons polaritons and surface phonon polaritons.With the development of micro-nano processing technology,near-field radiative heat transfer has a broad application prospect in the fields of thermal photovoltaic devices,heatassisted magnetic storage and thermal scanning microscope.This research topic has attracted extensive attention from researchers at home and abroad.As a new two-dimensional material with excellent electronic and optical properties,black phosphorus material has attracted the interest of researchers in materials science,physics and other fields in recent years.Some optoelectronic devices based on black phosphorus have also been produced.Since black phosphorus can also support surface plasmons polaritons,it is natural to study the properties of near-field radiative heat transfer between black phosphorus and micro-nano structures based on black phosphorus,and to explore the use of these properties to provide theoretical guidance for the production of electronic and optoelectronic devices.The characteristics of black phosphorus band gap such as layer control,field control and pressure control provide many possibilities for the management and control of near-field radiative heat transfer.The strong coupling of black phosphorus plasmons and hyperbolic plasmons in the near field provides an effective method forenhancing the heat transfer in the near field.At the same time,the composite structure of black phosphorus can further improve near-field radiative heat transfer.The main research contents of this paper can be summarized as follows:First,based on the classical damped oscillator model,the response characteristics of the interaction between matter and electromagnetic fields at different frequencies are analyzed.Based on maxwell's equation,linear response theory,fluctuation dissipation theory and green's function method,the relation of radiative heat transfer between parallel planes is deduced.Second,black phosphorus and silicon carbide composite structure is studied from the spectral distribution of plasmons,dispersion relations and its relationship with electronic doping,found black phosphorus plasmons and silicon carbide surface phonon polaritons simultaneously existed on the surface,and with the increase of electronic doping concentration,mixed polarization mode move toward high frequency direction.On this basis,the heat transfer coefficient of the composite structure of black phosphorus and silicon carbide with the change of electron doping was analyzed,and it was found that the change of heat transfer coefficient with the change of electron doping was similar in different directions.In the case of high doping,surface plasmons in the x direction dominates,and in the case of low doping,surface plasmons in the y direction dominates.The relationship between the thermal transfer coefficient of black phosphorus and graphene with electron doping and chemical potential was also analyzed.Third,a hyperbolic metasurface based on the black phosphorus ribbon is designed,and the characteristics of plasmons on the metasurface are analyzed.On this basis,the dependence of heat transfer coefficient on electron doping is calculated under the condition of fixed strip,and under the condition of fixed electron doping,heat transfer coefficient as a function of ribbon width is also calculated,found that for the hyperbolic metasurface with wider strip width,black phosphorus plasmons plays a more important role on heat transfer at low electron doping,while hyperbolic plasmons dominates to the heat transfer at high electron doping.For hyperbolic metasurface with narrower ribbon,the contribution from black phosphorous plasmon is weakened,while hyperbolic metasurface plasmons playmore and more important role to heat transfer.