DEVELOPMENT OF A BROADBAND ELECTROMAGNETIC RADIATION ABSORBER BASED ON MULTIWALL CARBON NANOTUBES AND ITS APPLICATION IN BOLOMETRIC RECEIVERS

This work is devoted to the development of a technique for obtaining an array of multi-walled vertically aligned carbon nanotubes (VACNT) with a thickness of up to 120 μm on Si/Al2O3/Fe substrates and to the study of their absorbing properties in the THz spectral region, as well as to the assessment of their prospects as a broadband THz radiation absorber based on calculations of the spectral dependence of absorption coefficient for traditional and inverted-type bolometric devices. It is shown that the absorption of the VACNT array transferred onto the Revalpha polymer substrate reaches 70–80% in the wavelength range of 40–200 µm. Calculations show that traditional bolometers with an absorber based on VACNT have the best sensitivity at wavelengths less than 100 μm, and inverted bolometers also having a VACNT layer have the best sensitivity at wavelengths exceeding 50 μm, which makes them complementary to each other.

Piezoelectric response of aligned carbon nanotubes depending on sublayer material

The results of experimental studies of the effect of the sublayer material on the piezoelectric response and sensitivity to mechanical deformations of aligned carbon nanotubes (CNTs) are presented. It is shown that the highest piezoelectric response (136 nA at a pressing force of 4 μN) and best sensitivity are demonstrated by CNTs grown on a Mo sublayer. This dependence is probably due to the geometric parameters of CNTs and the structure of the CNT array as a whole. The results obtained can be used to develop energy-efficient nanogenerators based on CNT arrays.

Chemical Bond Formation between Vertically Aligned Carbon Nanotubes and Metal Substrates at Low Temperatures

The exceptional physical properties of carbon nanotubes (CNTs) have the potential to transform materials science and various industrial applications. However, to exploit their unique properties in carbon-based electronics, CNTs regularly need to be chemically interfaced with metals. Although CNTs can be directly synthesized on metal substrates, this process typically requires temperatures above 350 °C, which is not compatible for many applications. Additionally, the CNTs employed here were highly densified, making them suitable as interconnecting materials for electronic applications. This paper reports a method for the chemical bonding of vertically aligned CNTs onto metal substrates that avoids the need for high temperatures and can be performed at temperatures as low as 80 °C. Open-ended CNTs were directly bonded onto Cu and Pt substrates that had been functionalized using diazonium radical reactive species, thus allowing bond formation with the open-ended CNTs. Careful control during grafting of the organic species onto the metal substrates resulted in functional group uniformity, as demonstrated by FT-IR analysis. Scanning electron microscopy images confirmed the formation of direct connections between the vertically aligned CNTs and the metal substrates. Furthermore, electrochemical characterization and application as a sensor revealed the nature of the bonding between the CNTs and the metal substrates.