The influence of the two-dimensional sinusoidal gratings on the near-field radiative heat flux between two doped silicon films

The near-field radiative heat flux between two two-dimensional sinusoidal grating surfaces made of doped-silicon is investigated by the finite difference time domain (FDTD) method. The parameter Λ, which is defined as the ratio of the amplitude to the period of the two-dimensional sinusoidal grating surface, is used to characterize the surface feature. When the amplitude is much smaller than the period, the surface effect is not significant to modify the near-field radiative heat flux between two smooth films. However, when the amplitude is comparable with the period, the near-field radiative heat flux between two smooth films can be enhanced remarkably. The coupling of the localized surface modes between the may be responsible for the variation of the near-field radiative heat flux when the parameter Λ is changed. Moreover, the effect of the lateral displacement of the films on the near-field radiative heat flux is also studied. The results indicate that the near-field radiative heat flux will achieve the maximum value when the peaks of the sinusoidal gratings are aligned. This work will be valuable to research on contactless thermal management in nanoscale.