Manipulating heat flow in a controllable and reversible manner is a topic of fundamental and practical interest. Numerous approaches to perform thermal switching have been reported, but they typically suffer from various limitations, for instance requiring mechanical modulation of a submicron gap spacing or only operating in a narrow temperature window. Here, we report the experimental modulation of radiative heat flow by electronic gating of a graphene field effect heterostructure without any moving elements. We measure a maximum heat flux modulation of 4 ± 3% and an absolute modulation depth of 24 ± 7 mW m^(–2) V^(–1) in samples with vacuum gap distances ranging from 1 to 3 μm. The active area in the samples through which heat is transferred is ∼1 cm^2, indicating the scalable nature of these structures. A clear experimental path exists to realize switching ratios as large as 100%, laying the foundation for electronic control of near-field thermal radiation using 2D materials
