Abstract
Carbon is the most well-known black material in the history of man. Throughout the centuries, carbon has been used as a black material for paintings, camouflage, and optics. Although, the techniques to make other black surfaces have evolved and become more sophisticated with time, carbon still remains one of the best black materials. Another well-known black surface is black silicon, reflecting less than 0.5% of incident light in visible spectral range but becomes a highly reflecting surface in wavelengths above 1000 nm. On the other hand, carbon absorbs at those and longer wavelengths. Thus, it is possible to combine black silicon with carbon to create an artificial material with very low reflectivity over a wide spectral range. Here we report our results on coating conformally black silicon substrate with amorphous pyrolytic carbon. We present a superior black surface with reflectance of light less than 0.5% in the spectral range of 350 nm to 2000 nm.
Highlights
Creating a superior black surface has long been a lasting challenge for many decades[1,2]
pyrolytic carbon (PyC) - similar to carbon nanotubes (CNTs) and graphene - displays strong absorption of the EM radiation in a wide spectral range spanning from UV to far-IR10–13
The deposited PyC film consists of small, lamellar graphitic ribbons with size of several nanometers and relatively small amount of amorphous carbon[16,17]
Summary
In order to demonstrate the conformal PyC deposition, we coated a bare silicon substrate and bSi with PyC films. The thickness of the fabricated PyC films is determined by the methane concentration in the hydrogen-methane gas mixture and pressure in the CVD chamber. At 1100 °C, the catalyst-free spontaneous methane decomposition starts This process is initiated by methane radicals that form new hydrocarbon molecules, which are combined into massive polycyclic aromatic structures and deposited onto substrate[2,3]. After the process both sides of the substrate were coated with the PyC film. Scanning electron microscopy was done by SEM Zeiss Supra 40 and Leo 1550 Gemini
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