Article

Article

Curr. Appl. Phys. 2020; 20(12): 1321-1327

Published online December 31, 2020 https://doi.org/10.1016/j.cap.2020.08.017

Copyright © The Korean Physical Society.

Thermally stable AgCu alloy disc array for near infrared filters

Im H.-S., Sim K.-B., Seong T.-Y.

Department of Materials Science and Engineering, Korea University, Seoul, 02841, South KoreaIm, H.-S., Department of Materials Science and Engineering, Korea University, Seoul, 02841, South Korea; Sim, K.-B., Department of Materials Science and Engineering, Korea University, Seoul, 02841, South Korea; Seong, T.-Y., Department of Materials Science and Engineering, Korea University, Seoul, 02841, South Korea

Correspondence to:Seong, T.-Y.
Department of Materials Science and Engineering, Korea UniversitySouth Korea
email: tyseong@korea.ac.kr

Abstract

We investigated the thermal and optical characteristics of AgCu alloy disc (250 and 380 nm in diameter) arrays to produce an optical filter with low near infrared (NIR) transmittance, and compared their properties with those of Ag disc array. Unlike the Ag discs, the AgCu discs remained relatively stable with hillocks after annealing at 500 °C. The Ag and AgCu disc samples had similar transmittance characteristics, showing a global minimum at ~767 nm (for the 250 nm-disc samples) and at ~1081 nm (for the 380 nm-disc samples). Based on finite-difference time-domain (FDTD) simulations, the global minimum was related to localised surface plasmon resonance (LSPR). The Maxwell-Garnett model was employed to interpret the red-shift of the transmittance minima. The calculations showed that a mixture of agglomerated and stable Ag discs, resulting in different n and k values, would be responsible for the red-shift and an increase in the minimum transmittance. © 2020 Korean Physical Society

Keywords: AgCu alloy, Finite-difference time-domain simulation, Infrared filter, Localised surface plasmon, Nanodisc array, Nanoimprint lithography

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