Microwave absorption properties of pyrolytic carbon nanofilm

Abstract

We analyzed the electromagnetic (EM) shielding effectiveness in the Ka band (26 to 37 GHz) of highly amorphous nanometrically thin pyrolytic carbon (PyC) films with lateral dimensions of 7.2 × 3.4 mm2, which consists of randomly oriented and intertwined graphene flakes with a typical size of a few nanometers. We discovered that the manufactured PyC films, whose thickness is thousand times less than the skin depth of conventional metals, provide a reasonably high EM attenuation. The latter is caused by absorption losses that can be as high as 38% to 20% in the microwave frequency range. Being semi-transparent in visible and infrared spectral ranges and highly conductive at room temperature, PyC films emerge as a promising material for manufacturing ultrathin microwave (e.g., Ka band) filters and shields.

Fluorination as Effective Method for Tuning the Electromagnetic Response of Graphene

“…Recently, we demonstrated that nano‐thin conductive carbon and graphene films could be highly absorptive ability at certain thickness which is inversely proportional to their conductivity . The idea of this communication is to present a tunable EMI shielding layer based on fluorinated graphene.…”

Transmission characteristic of graphene/TiO2 paper measured at Ka-band

“…Millimeter wave absorbers are mainly in metamaterial structure by tailoring shape, geometry, size, orientation and arrangement (see for examples [4][5][6]). Some interesting reports for application of graphene at Ka-band (27-40 GHz) can be found in [7][8][9].…”

Electromagnetic Properties of Graphene-like Films in Ka-Band

“…However, since deposition of graphene on dielectric surfaces of arbitrary shape is still a difficult task, attention of scientists and engineers is currently focused on composite materials filled with graphene nanoplatelets, nanoribbons and flakes that also demonstrate remarkable mechanical, thermal and electromagnetic properties (see [4] and references therein). We have recently suggested an interesting alternative to graphene-based materials by demonstrating that 25 nm thick pyrolytic carbon (PyC) film, which is morphologically close to the nanographite, being many thousands times thinner than skin depth can attenuate a significant part of incident microwave radiation [5]. In contrast to graphene, PyC films can be easily synthesized not only on metal, but also on dielectric substrate [6] of arbitrary shape which makes it very attractive from the technological point of view.…”

“…The frequency dependence of transmittance/reflectance in K a -band, 26-37 GHz, for 25 nm thick PyC film was measured in [5]. An experiment demonstrated surprisingly high absorbance (~30%) despite the small sample thickness, which was many thousands times less than the skin depth in metals.…”