Convective self-assembled processed multiwall carbon nanotube thin films for semi-transparent microelectronic applications

A self-assembled convective setup was utilized to manufacture multiwall carbon nanotube (MWCNTs) thin films at room temperature on glass substrates. The extracted X-ray diffraction patterns revealed that the manufactured MWCNTs films have a crystal structure with observed peaks at 2θ = 26.61°, 43.45°, and 53.1°, and are related to the (002), (101) and (004) planes, respectively, confined to graphite of a hexagonal structure. The Raman spectroscopic behavior of the samples was investigated, and the intensity of the D:G band ratio was utilized to estimate the crystallinity degree of carbon in the MWCNTs samples (~ 0.81). The SEM images of the films showed that the topographical properties of the films are retained and densely packed, confirming a network distribution. Briefly, the films are significantly influenced to have a rod-like shape of the MWCNTs. The analyzed HR-TEM images of the films have a uniform structure with cylindrical-shaped MWCNTs. When the energy of the probe waves was  ~ 3.95 eV, the reflected and transmitted probe wave vanished. The fabricated MWCNTs films may play an essential role as a real absorber with an absorption coefficient α(hυ = 3.5 eV) ≈ 5.36 × 10⁵ cm⁻¹. The manufactured MWCNTs films are found to support the interpretation of a direct bandgap; the evaluated energy gap is \({E}_{g}^{OPT}\) =3.748 eV as a result of the carbon atoms impurities; and a direct transition at low energy is estimated by \({E}_{g}^{Onset}=0.59 \mathrm{e}\mathrm{V}\). The performance of the fabricated films is predicted and analyzed by the complex parameters: dispersion, n*, optical dielectric, ε*, and optical conductivity, σ*. The manufactured MWCNTs provide a pathway to fabricate a broadband stable behavioral absorptive layer for photovoltaic devices and optical switching optoelectronics (at low reflectance and transmittance with high absorbance).