Metamaterials-based broadband absorption in long-wave infrared frequency enabled by multilayered ENZ films on metal-coated patterned silicon

Abstract

Large-scale, and high-throughput produced devices with strong ultrabroadband absorption and high angular tolerance are in demand for applications such as thermal imaging, energy harvesting, and radiative cooling. Despite long-standing efforts in design and fabrication, it has been challenging to achieve all these desired properties simultaneously. Here, we create a metamaterial-based infrared absorber fabricated from thin films of epsilon-near-zero (ENZ) materials grown on metal-coated patterned silicon substrates that exhibit ultrabroadband infrared absorption in both p- and s-polarization at angles ranging from 0° to 40°. The results show that the structured multilayered ENZ films exhibit high absorption (> 0.9) covering the entire 8∼14 µm wavelengths. In addition, the structured surface can be realized via scalable, low-cost methods on large-area substrates. Overcoming the limitations on angular and polarized response improves performance for applications such as thermal camouflage, radiative cooling for solar cell, thermal image and et., al.