Layered configuration of graphene-Si 3 N 4 films for strongly absorbent incident radiation in a wide wavelength range of 1–14 µm

A type of infrared (IR) broadband metamaterial absorbers with several typical features, such as a relatively strong IR radiation absorption, an ultrathin functioned architecture, and a layered configuration of graphene-Si 3 N 4 films, are proposed. The principal metamaterial absorbers are constructed by alternating configuring the core film consisting of a graphene sheet and a Si 3 N 4 dielectric layer, which are also back attached by a thin Cu substrate. The layered graphene-Si 3 N 4 /Cu architecture already experimentally achieves an average IR absorption of ∼86.71% in a wide wavelength range of 1-14 µm according to simulations and actual measurements. And their IR absorbance can also be easily adjusted by suitably matching the layer number of the graphene-Si 3 N 4 film or applying a set of bias voltages over the functioned graphene sheets constructed. The developed metamaterial absorbers can tolerate a relatively wide beam incident angle range of 0°-80°. The improved IR absorbing architecture also presents a polarization-independent character. Finally, it is given that the addition of various superstructures to the incident surface of the structure guarantees a very high average absorption of the structure while changing the absorption peak of the structure. It is discussed that this design can be used as a substrate for different super-surface structures to ensure their very high absorption in the infrared band. The proposed IR absorbing approach will highlight the continuous development of the IR radiation absorption technique in a broad application field.