Terahertz characterization of nano-scale high-entropy alloy films and their high-contrast grating applications

Chia-Yen Lu; Yi-Chen Sung; Cheng-Hsien Yeh; Yu-Hua Chen; Chen-Yun Kuan; Kuang-Teng Hung; Wei-Hsiang Chen; Wen-Dung Hsu; Chuan-Feng Shih; Chan-Shan Yang

doi:10.1063/5.0188695

AIP Advances (Mar 2024)

Terahertz characterization of nano-scale high-entropy alloy films and their high-contrast grating applications

Chia-Yen Lu,
Yi-Chen Sung,
Cheng-Hsien Yeh,
Yu-Hua Chen,
Chen-Yun Kuan,
Kuang-Teng Hung,
Wei-Hsiang Chen,
Wen-Dung Hsu,
Chuan-Feng Shih,
Chan-Shan Yang

Affiliations

Chia-Yen Lu: Institute and Undergraduate Program of Electro-Optical Engineering, National Taiwan Normal University, Taipei 11677, Taiwan
Yi-Chen Sung: Institute and Undergraduate Program of Electro-Optical Engineering, National Taiwan Normal University, Taipei 11677, Taiwan
Cheng-Hsien Yeh: Department of Electrical Engineering, National Cheng Kung University, Tainan 70101, Taiwan
Yu-Hua Chen: Institute and Undergraduate Program of Electro-Optical Engineering, National Taiwan Normal University, Taipei 11677, Taiwan
Chen-Yun Kuan: Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan
Kuang-Teng Hung: Department of Electrical Engineering, National Cheng Kung University, Tainan 70101, Taiwan
Wei-Hsiang Chen: Institute and Undergraduate Program of Electro-Optical Engineering, National Taiwan Normal University, Taipei 11677, Taiwan
Wen-Dung Hsu: Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan
Chuan-Feng Shih: Department of Electrical Engineering, National Cheng Kung University, Tainan 70101, Taiwan
Chan-Shan Yang: Institute and Undergraduate Program of Electro-Optical Engineering, National Taiwan Normal University, Taipei 11677, Taiwan

DOI: https://doi.org/10.1063/5.0188695
Journal volume & issue: Vol. 14, no. 3
pp. 035036 – 035036-8

Abstract

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We investigated the optical constants of thin films of the Nb25Mo25Ta25W25 alloy, which belongs to high-entropy alloys (HEAs), with a transmission terahertz (THz) measurement system and discovered that the refractive index, extinction coefficient, and conductivity of the HEA thin film measured in the range of 0.3–1.0 THz all increased as the thickness of the thin film increased (the thickness was maintained in the range between 10 and 40 nm). According to the experimental results, this alloy with a high refractive index is suitable for producing high-contrast gratings (HCGs). The principle behind achieving a high contrast with a high-reflection HEA grating is to harness the confined plasmonic energy within the grating, thereby enhancing the localized plasmonic energy within the grating. This work elucidates that we can not only fabricate THz components by controlling the thickness of the thin film but also utilize the high refractive index of this material to create HCGs.

Published in AIP Advances

ISSN: 2158-3226 (Online)
Publisher: AIP Publishing LLC
Country of publisher: United States
LCC subjects: Science: Physics
Website: http://aipadvances.aip.org/

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