Ultrafast Tunable Near-Field Radiative Thermal Modulator Made of Ge3Sb2Te6

We show numerically the phase change material Ge3Sb2Te6 (GST) with special configuration as a heat modulator in the regime of near-field radiative heat transfer (NFRHT). The ability of GST to allow ultrafast reversible switch between two phases endows it great potential in practical modulation application. By designing silicon carbide (SiC) nanoholes (NHs) filled with GST, this configuration could achieve a considerable modulation effect and large near-field radiative heat flux. The underlying mechanism can be explained by the observation that the entire configuration supports either hyperbolic modes or surface phonon polaritons (SPhPs) resonance modes and even the combination of both modes, thereby resulting in the remarkable modulation effect. In addition, the effects of the volume filling factor and graphene coverage are also investigated at the vacuum gap distance of 100 nm. With graphene coverage, the modulation factor can be further improved to as high as 0.72 achieved at the volume filling factor of 0.6 with temperature difference of 20 K. The proposed configuration has the potential to effectively modulate heat in the near-field regime for designing heat modulation applications in the future.