Infrared Perfect Absorbers Fabricated by Colloidal Mask Etching of Al–Al2O3–Al Trilayers

We propose a combined fabrication method of reactive ion etching and large-scale colloidal mask to fabricate mid-infrared metamaterial perfect absorbers using aluminum–aluminum oxide-aluminum trilayers. The absorptivities of the fabricated samples reached as high as 98% and the absorption bandwidths were comparable to those of the absorbers based on gold or silver. Following Kirchhoff’s law, their emission spectra exhibited sharp single emission peaks indicating high potential as narrow-band infrared emitters. The results obtained here demonstrate that earth-abundant aluminum is a high-performance plasmonic materials in the mid-infrared range, and open up a route for fabricating cost-effective scalable plasmonic devices such as efficient light harvesting structures, thermal emitters, and infrared sensors.