Ultra-broadband absorbance of nanometer-thin pyrolyzed-carbon film on silicon nitride membrane

• Published in: Nanotechnology Vol. 35; no. 30; pp. 305705 - 305711
• Main Authors: Jorudas, Justinas, Rehman, Hamza, Cojocari, Maria, Pashnev, Daniil, Urbanowicz, Andrzej, Kašalynas, Irmantas, Bertoni, Benedetta, Vicarelli, Leonardo, Pitanti, Alessandro, Malykhin, Sergei, Svirko, Yuri, Kuzhir, Polina, Fedorov, Georgy
• Format: Journal Article
• Language: English
• Published: England IOP Publishing 22.07.2024
• Subjects: near-infrared; pyrolytic carbon; terahertz; thin-film absorber; ultra-broadband absorption; thin-film absorber; ultra-broadband absorption; near-infrared; terahertz; pyrolytic carbon
• ISSN: 0957-4484; 1361-6528
• DOI: 10.1088/1361-6528/ad4157

Fifty percents absorption by thin film, with thickness is much smaller than the skin depth and optical thickness much smaller than the wavelength, is a well-known concept of classical electrodynamics. This is a valuable feature that has been numerously widely explored for metal films, while chemically inert nanomembranes are a real fabrication challenge. Here we report the 20 nm thin pyrolyzed carbon film (PyC) placed on 300 nm thick silicon nitride (Si N ) membrane demonstrating an efficient broadband absorption in the terahertz and near infrared ranges. While the bare Si N membrane is completely transparent in the THz range, the 20 nm thick PyC layer increases the absorption of the PyC coated Si N membrane to 40%. The reflection and transmission spectra in the near infrared region reveal that the PyC film absorption persists to a level of at least 10% of the incident power. Such a broadband absorption of the PyC film opens new pathways toward broadband bolometric radiation detectors.