Broadband Visible and Near-Infrared Absorbers Implemented with Planar Nanolayered Stacks

Jaeyong Kim, Harim Oh, Beomseung Kang, Jongill Hong, Jong Joo Rha, Myeongkyu Lee

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)


Broadband light absorbers are highly desirable in various applications including solar-energy harvesting, thermo-photovoltaics, and photon detection. The Fabry–Perot (F–P) cavity comprising metal–insulator–metal (MIM) layers has attracted enormous interest as a lithography-free structure for realizing planar super absorbers. However, typical F–P cavity exhibits a narrow absorption band, and efforts have thus been made to increase the absorption bandwidth. This study demonstrates that near-perfect absorption over a broad spectral range can be obtained from the MIM structure by using thermally evaporated Ag and Au thin films whose dielectric and optical properties are much different from bulk-state properties because of their nanoscale features. A 55 nm thick SiO2 spacer sandwiched between a 10 nm Ag top layer and a 100 nm Al back reflector exhibits absorption >95% in the visible range of 400–700 nm. The broad absorption band shifts to a near-infrared range of 650–1000 nm by replacing the top layer with a 10 nm thick Au film and increasing the SiO2 spacer thickness to 115 nm. The experimental results are supported by finite-difference time-domain simulation. The large absorption bandwidth is attributed to the lossy nature of the nanostructured top metallic layer combined with the resonant absorption of the MIM cavity.

Original languageEnglish
Pages (from-to)2978-2986
Number of pages9
JournalACS Applied Nano Materials
Issue number3
Publication statusPublished - 2020 Mar 27

Bibliographical note

Funding Information:
This work was supported by the R&D convergence program of the National Research Council of Science & Technology of the Republic of Korea (CAP-16-10-KIMS).

Publisher Copyright:
Copyright © 2020 American Chemical Society

All Science Journal Classification (ASJC) codes

  • Materials Science(all)


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