This paper presents the design and fabrication of a broadband microstrip attenuator, operating at 1-20 GHz, based on few layer graphene flakes. The RF performance of the attenuator has been analyzed in depth. In particular, the use of graphene as a variable resistor is discussed and experimentally characterized at microwave frequencies. The structure of the graphene-based attenuator integrates a micrometric layer of graphene flakes deposited on an air gap in a microstrip line. As highlighted in the experiments, the graphene film can range from being a discrete conductor to a highly resistive material, depending on the externally applied voltage. As experimental evidence, it is verified that the application of a proper voltage through two bias tees changes the surface resistivity of graphene, and induces a significant change of insertion loss of the microstrip attenuator.

The paper presents the experimental and modeling results of a microwave slot antenna in a coplanar configuration based on graphene. The antennas are fabricated on a 4 in. high-resistivity Si wafer, with a ∼300 nm SiO₂ layer grown through thermal oxidation. A CVD grown graphene layer is transferred on the SiO₂. The paper shows that the reflection parameter of the antenna can be tuned by a DC voltage. 2D radiation patterns at various frequencies in the X band (8–12 GHz) are then presented using as antenna backside a microwave absorbent and a metalized surface. Although the radiation efficiency is lower than a metallic antenna, the graphene antenna is a wideband antenna while the metal antennas with the same geometry and working at the same frequencies are narrowband.

This paper introduces a novel technique in which Maxwell equations, discretized by the transmission line matrix method in a 3-D domain, are coupled to the Schrodinger equation and simultaneously solved. The aim is to develop a method that accounts for deterministic electromagnetic field dynamics together with the quantum phenomena, which are typical of nanodevices.

For future miniaturization of electronic systems using 3D chip stacking, new fine-pitch materials for through-silicon-via (TSV) applications are likely required. In this paper, we propose a novel carbon nanotube (CNT)/copper nanocomposite material consisting of high aspect ratio, vertically aligned CNT bundles coated with copper. These bundles, consisting of hundreds of tiny CNTs, were uniformly coated by copper through electroplating, and aspect ratios as high as 300:1 were obtained. The resistivity of this nanomaterial was found to be as low as ∼10 ⁻⁸ Ω m, which is of the same order of magnitude as the resistivity of copper, and its temperature coefficient was found to be only half of that of pure copper. The main advantage of the composite TSV nanomaterial is that its coefficient of thermal expansion (CTE) is similar to that of silicon, a key reliability factor. A finite element model was set up to demonstrate the reliability of this composite material and thermal cycle simulations predicted very promising results. In conclusion, this composite nanomaterial appears to be a very promising material for future 3D TSV applications offering both a low resistivity and a low CTE similar to that of silicon.

MoO₃ and MoO₂ systems have attracted particular attention for many widespread applications thanks to their electronic and optical peculiarities; from the crystallographic point of view, MoO₃ adopts a thermodynamically stable orthorhombic phase (α-MoO₃) belonging to the space group Pbmn, while MoO₂ assumes a monoclinic arrangement characterized by space group P2₁/c. In the present paper, we investigated the electronic and optical properties of both MoO₃ and MoO₂ by using Density Functional Theory calculations, in particular, the Meta Generalized Gradient Approximation (MGGA) SCAN functional together with the PseudoDojo pseudopotential, which were used for the first time to obtain a deeper insight into the nature of different Mo–O bonds in these materials. The calculated density of states, the band gap, and the band structure were confirmed and validated by comparison with already available experimental results, while the optical properties were validated by recording optical spectra. Furthermore, the calculated band-gap energy value for the orthorhombic MoO₃ showed the best match to the experimental value reported in the literature. All these findings suggest that the newly proposed theoretical techniques reproduce the experimental evidence of both MoO₂ and MoO₃ systems with high accuracy.