Thermal Chemical Vapor Deposition of Superblack Randomly Oriented Carbon Nanotube Coatings

Abstract

Multi‐walled carbon nanotubes (CNTs) are deposited via thermal chemical vapor deposition using cobalt catalyst and MgO promoter. A systematic investigation of the major processing parameters such as temperature (390–620 °C), pressure (3–10 mbar), injection (4–10 ms), and deposition times is performed. The impact of these parameters on the film density and optical properties of CNT coatings is discussed. Irrespective of the growth parameters, a homogeneous deposition of CNTs and a negligible impact on the CNTs’ quality are observed. Total hemispherical reflectance (THR) reveals a threshold thickness of 3 μm, above which the CNT films behave as an efficient black absorber in the UV–vis–near‐infrared (NIR) and mid‐infrared (MIR) spectral regions. Spatial and spectral integrations of THR show a reflection below 1% in the 250 nm–2.5 μm spectral range. The low reflection observed in the NIR is retained in the MIR up to λ = 10 μm.