Electrically adjusted infrared transmittance of a functioned silicon via an au nano‐cone metasurface

• Published in: Nano select Vol. 2; no. 2; pp. 357 - 363
• Main Authors: Wei, Dong, Hu, Chai, Chen, Mingce, Shi, Jiashuo, Luo, Jun, Wang, Haiwei, Xie, Changsheng, Zhang, Xinyu
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 01.02.2021; Wiley-VCH
• Subjects: Arrays; double cascade Schottky barrier; Electric potential; Electrons; Etching; infrared transmittance; Metal foils; Metasurfaces; nano‐cone metasurface; optical modulator; Silicon; Silicon wafers; Transmittance; Voltage
• ISSN: 2688-4011; 2688-4011
• DOI: 10.1002/nano.202000156

A type of electrically adjusted infrared transmittance material is constructed by an n‐type silicon nano‐cone metasurface coating with a 30 nm thick Au film, and then an Al foil is adhered on the back of the metasurface. Two types of nano‐cone are fabricated. The average height of both the nano‐cone structures is ∼230 nm. The top angle of each nano‐cone frame is ∼16° and ∼17°, and their arranging frequency 2 µm−1 and 1 µm−1, respectively. Through the material, a relatively wide regulation of the infrared (IR) transmittance can be achieved by electrically driving a couple of cascade Schottky barrier formed at the interface of Au film and the nano‐patterned silicon and also another interface between the Al foil tape and the bottom surface of the silicon. By applying a voltage between the top Au film and the bottom Al foil, the IR transmittance of the material can be adjusted remarkably and becomes zero as the Au film is switched to the positive. Typically, the transmittance of 2.2 µm wavelength lasers normally incident upon the nano‐patterned facet of the material can be adjusted from ∼21% to ∼65% for a voltage variance of 0 V to −5 V. The regulation of infrared transmittance obtained through gold nano‐cone metasurface are investigated. For this purpose, gold film nano‐cone is deposited on silicon nano‐cone metasurface, and then aluminum foil is adhered on the back of the metasurface. Typically, the transmittance of 2.2 µm wavelength lasers can be adjusted from ∼21% to ∼65% for a voltage of 0 V to −5 V.