Search Results (19)

Today, many electronic circuits are required to be able to work effectively, even in environments exposed to ionizing radiation. This work examines the effects of ionizing radiation on shift registers realized in a bulk 16 nm FinFET technology, focusing on Single-Event Upset (SEU). An SEU occurs when a charged particle ionizes a sensitive node in the circuit, causing a stored bit to flip from one logical state to its opposite. This study estimates the saturation cross-section for the 16 nm FinFET technology and compares it with results from a 28 nm planar CMOS technology. The experiments were conducted at the SIRAD facility of INFN Legnaro Laboratories (Italy). The device under test was irradiated with the ion sources ⁵⁸$Ni$ and ²⁸$Si$, both with different tilt angles, to assess the number of SEUs with different LET and range values. Additionally, the study evaluates the effectiveness of the radiation-hardened by design technique, specifically the Triple Modular Redundancy (TMR), which is a technique commonly employed in planar technologies. However, in this particular case study, TMR proved to be ineffective, and the reasons behind this limitation are analyzed along with potential improvements for future designs. Full article

Enhancing the performance of organic solar cells (OSCs) is essential for achieving sustainability in energy production. This study presents an innovative strategy that involves fine-tuning the thickness of the bulk heterojunction (BHJ) photoactive layer at the nanoscale to improve efficiency. The organic blend D18:L8-BO is utilized to capture a wide range of photons while addressing the challenge of minimizing optical losses from low-energy photons. The research incorporates SnO₂ and ZnO as electron transport layers (ETLs), with PMMA functioning as a hole transport layer (HTL). A comprehensive analysis of photon absorption, charge carrier generation, localized energy fluctuations, and thermal stability reveals their critical role in enhancing the efficiency of D18:L8-BO active films. Notably, introducing SnO₂ as an ETL significantly decreased losses and modified localized energy, achieving an impressive efficiency of 19.85% at an optimized blend thickness of 50 nm with low voltage loss (ΔV_oc) of 0.4 V within a J_sc of 28 mA cm⁻² by performing an optoelectronic simulation employing “Oghma-Nano 8.1.015” software. In addition, the SnO₂-based structure conserved 88% of the PCE at 350 K compared to room temperature PCE, which describes the high thermal stability of this structure. These results demonstrate the potential of this methodology in improving the performance of OSCs. Full article

This work investigates the relationship between the mean diameter of palladium (Pd) nanoparticles and their surface energy, specifically in the context of alkaline ethanol electro-oxidation for fuel cell applications. Employing a recent generalization of the classical Laviron equation, we derive crucial parameters such as surface energy (σ), adsorption–desorption equilibrium constant (K_eq), and electron transfer coefficient (α) from linear voltammograms obtained from Pd-based nanoparticles supported on Vulcan carbon. Synthesized using two distinct methods, these nanocatalysts exhibit mean diameters ranging from 10 to 41 nm. Our results indicate that the surface energy of the Pd/C nanocatalysts spans σ ~ 0.5–2.5 J/m², showing a linear correlation with particle size while remaining independent of ethanol bulk concentration. The adsorption–desorption equilibrium constant varies with nanoparticle size (~0.1–6 × 10⁻⁶ mol⁻¹) but is unaffected by ethanol concentration. Significantly, we identify an optimal mean diameter of approximately 28 nm for enhanced electrocatalytic activity, revealing critical size-dependent effects on catalytic efficiency. This research contributes to the ongoing development of cost-effective and durable fuel cell components by optimizing nanoparticle characteristics, thus advancing the performance of Pd-based catalysts in practical applications. Our findings are essential for the continued evolution of nanomaterials in fuel cell technologies, particularly in improving efficiency and reducing reliance on critical raw materials. Full article

This paper presents a Doherty power amplifier (DPA) integrated circuit (IC) designed to have enhanced gain, efficiency, and AM-AM characteristics through a dynamic power dividing technique, which can control the power dividing ratio according to the input power. Since this multi-purpose dynamic power dividing network also provides the phase offset and impedance matching at the interstage network needed for appropriate DPA operation, the active IC area could be reduced. To verify the proposed technique and its analysis, the DPA was implemented with a 28 nm bulk CMOS process for the fifth-generation (5G) new radio (NR) millimeter-wave frequency band of 23.5–27.5 GHz. The measured results showed a gain of 20.3–21.9 dB, saturated output power of 14.0–15.2 dBm, power added efficiency (PAE) of 22.8–26.7% at the peak power, and PAE of 14.6–17.6% at the 6 dB output power back-off (OBO). Full article

The water ingress plays an important role in building materials’ degradation. The use of lightweight aggregates is interesting in terms of sustainability, because they reduce the density of cement-based materials, among other advantages. The development and use of new lightweight aggregates, such as cork granulates, is a current research topic. In the present work, water ingress performance of sustainable mortars which combined expanded and natural cork aggregates and cements with slag, fly ash and limestone has been studied. Mortars produced with sand and expanded clay were also prepared. Bulk density, water absorption, drying capacity and gel and capillary pores were studied. Tests were carried out at 28 days and 1 year. A good behavior has been generally observed when an addition was incorporated to the binder, especially slag or fly ash. Regarding the new non-standardized lightweight cork aggregates, mortars with natural cork showed lower water absorption and lower volume of permeable pore space in the long term than mortars with expanded cork. At one year, natural cork mortars had an adequate water absorption performance compared to those with expanded clay, which may be due to the high volume of small capillary pores (100 nm–1 µm) in natural cork mortars. Full article

The use of lignin, an abundant phenolic bio-polymer, allows us to transform our fossil-based economy into a sustainable and bio-based economy. The transformation of bulk lignin into colloidal lignin particles (CLPs) with well-defined surface chemistry and morphology is a possible way to cope with the heterogeneity of lignin and use it for material applications. These CLPs can be used as emulsifiers in so-called Pickering emulsions, where solid particles stabilise the emulsion instead of environmentally harmful synthetic surfactants. This work investigates the application of CLPs produced from various bulk lignins as a stabiliser in o/w Pickering emulsions with two different oil phases (solid and liquid state). The CLPs had a primary particle size of 28 to 55 nm. They were successful in stabilising oil-in-water Pickering emulsions with high resistance to coalescence and a strong gel-like network. This enables novel applications for CLPs in the chemical and cosmetic industries, and can replace fossil-based and synthetic ingredients. Full article

This paper reviews the near-equilibrium ammonothermal (NEAT) growth of bulk gallium nitride (GaN) crystals and reports the evaluation of 2″ GaN substrates and 100 mmbulk GaN crystal grown in our pilot production reactor. Recent progress in oxygen reduction enabled growing NEAT GaN substrates with lower residual oxygen, coloration, and optical absorption. The oxygen concentration was approximately 2 × 10¹⁸ cm⁻², and the optical absorption coefficient was 1.3 cm⁻¹ at 450 nm. Maps of full-width half maximum (FWHM) of X-ray diffraction rocking curveswere generated for grown crystals and finished wafers. The X-ray rocking curve maps confirmed high-quality and uniform microstructure across the entire surface of the bulk crystals and substrates. The average FWHM of the 50 best bulk crystals from the recent batch was 28 ± 4 arcsec for the 002 diffraction and 34 ± 5 arcsec for the 201 diffraction, with an average radius of curvature of 20 m. X-ray topography measured on both sides of the bulk crystals implied that the density of dislocations wasreduced by one order of magnitude during the NEAT growth. A typical NEAT GaN substrate shows dislocation density of about 2 × 10⁵ cm⁻². Full article

Low-invasive and battery-less implantable medical devices (IMDs) have been increasingly emerging in recent years. The developed solutions in the literature often concentrate on the Bidirectional Data-Link for long-term monitoring devices. Indeed, their ability to collect data and communicate them to the external world, namely Data Up-Link, has revealed a promising solution for bioelectronic medicine. Furthermore, the capacity to control organs such as the brain, nerves, heart-beat and gastrointestinal activities, made up through the manipulation of electrical transducers, could optimise therapeutic protocols and help patients’ pain relief. These kinds of stimulations come from the modulation of a powering signal generated from an externally placed unit coupled to the implanted receivers for power/data exchanging. The established communication is also defined as a Data Down-Link. In this framework, a new solution of the Binary Phase-Shift Keying (BPSK) demodulator is presented in this paper in order to design a robust, low-area, and low-power Down-Link for ultrasound (US)-powered IMDs. The implemented system is fully digital and PLL-free, thus reducing area occupation and making it fully synthesizable. Post-layout simulation results are reported using a 28 nm Bulk CMOS technology provided by TSMC. Using a 2 MHz carrier input signal and an implant depth of 1 cm, the data rate is up to 1.33 Mbit/s with a 50% duty cycle, while the minimum average power consumption is cut-down to 3.3 μW in the typical corner. Full article

This paper proposes a series of approximate square root circuit designs with high accuracy, low latency, low area, and low power dissipation requirements. The proposed designs are constructed using an array of controlled add–subtract cell elements with both exact and approximate versions. The utility of the proposed designs are evaluated by utilizing them in an example image contrast enhancement application with demonstrably satisfactory results and large peak signal-to-noise ratios and structural similarity values. The accuracy and hardware characteristics of the proposed square root designs are also analyzed and compared with previously proposed state-of-the-art approximate square root designs. When applied to a 16-bit radicand (the number under the square root symbol), the proposed designs have the lowest error rates, normalized mean error distances, and mean relative error distances by at least 1.8x when compared to all previous methods using the same number of approximate cells. When the designs were synthesized using Synopsys Design Compiler with a 28 nm bulk CMOS process, the delay, area, power, and power-delay-product characteristics outperform all previous designs in all but a few cases. These results demonstrate that the proposed designs permit the use of a flexible range of approximate designs with varying accuracy and hardware overhead characteristics, and a suitable design can be selected based on the user design requirements. Full article

This is the first of two papers about the synthesis and microstructure properties of the Geo–rGO–TiO₂ ternary nanocomposite, which was designed to suit the criteria of a pervaporation membrane for seawater desalination. The performance and capability of Geo–rGO–TiO₂ as a seawater desalination pervaporation membrane are described in the second paper. A geopolymer made from alkali-activated metakaolin was utilized as a binder for the rGO-TiO₂ nanocomposite. A modified Hummer’s method was used to synthesize graphene oxide (GO), and a hydrothermal procedure on GO produced reduced graphene oxide (rGO). The adopted approach yielded high-quality GO and rGO, based on Raman spectra results. The nanolayered structure of GO and rGO is revealed by Transmission Electron Microscopy (TEM) images. The Geo–rGO–TiO₂ ternary nanocomposite was created by dispersing rGO nanosheets and TiO₂ nanoparticles into geopolymer paste and stirring it for several minutes. The mixture was then cured in a sealed mold at 70 °C for one hour. After being demolded, the materials were kept for 28 days before being characterized. Fourier Transform Infrared (FTIR) and X-ray Diffraction (XRD) measurements revealed that the geopolymer matrix efficiently bonded the rGO and TiO₂, creating nanocomposites. Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS) was used to examine the morphology of the outer layer and cross-sections of nanocomposites, and the results displayed that rGO were stacked on the surface as well as in the bulk of the geopolymer and will potentially function as nanochannels with a width of around 0.36 nm, while TiO₂ NPs covered the majority of the geopolymer matrix, assisting in anti-biofouling of the membranes. The pores structure of the Geo–rGO–TiO₂ were classified as micro–meso pores using the Brunauer–Emmet–Teller (BET) method, indicating that they are appropriate for use as pervaporation membranes. The mechanical strength of the membranes was found to be adequate to withstand high water pressure during the pervaporation process. The addition of rGO and TiO₂ NPs was found to improve the hyropobicity of the Geo–rGO–TiO₂ nanocomposite, preventing excessive seawater penetration into the membrane during the pervaporation process. The results of this study elucidate that the Geo–rGO–TiO₂ nanocomposite has a lot of potential for application as a pervaporation membrane for seawater desalination because all of the initial components are widely available and inexpensive. Full article

A two-stage CMOS transconductance amplifier based on the inverter topology, suitable for very low supply voltages and exhibiting rail-to-rail output capability is presented. The solution consists of the cascade of a noninverting and an inverting stage, both characterized by having only two complementary transistors between the supply rails. The amplifier provides class-AB operation with quiescent current control obtained through an auxiliary loop that utilizes the MOSFETs body terminals. Simulation results, referring to a commercial 28 nm bulk technology, show that the quiescent current of the amplifier can be controlled quite effectively, even adopting a supply voltage as low as 0.5 V. The designed solution consumes around 500 nA of quiescent current in typical conditions and provides a DC gain of around 51 dB, with a unity gain frequency of 1 MHz and phase margin of 70 degrees, for a parallel load of 1 pF and 1.5 MΩ. Settling time at 1% is 6.6 μs, and white noise is 125 nV/$\sqrt{Hz}$. Full article

This work primarily focuses on the degradation degree of bulk current (I_B) for 28 nm stacked high-k (HK) n-channel metal–oxide–semiconductor field-effect transistors (MOSFETs), sensed and stressed with the channel-hot-carrier test and the drain-avalanche-hot-carrier test, and uses a lifetime model to extract the lifetime of the tested devices. The results show that when I_B reaches its maximum, the ratio of V_GS/V_DS values at this point, in the meanwhile, gradually increases in the tested devices from the long-channel to the short ones, not just located at one-third to one half. The possible ratiocination is due to the ON-current (I_DS), in which the short-channel devices provide larger I_DS impacting the drain junction and generating more hole carriers at the surface channel near the drain site. In addition, the decrease in I_B after hot-carrier stress is not only the increment in threshold voltage V_T inducing the decrease in I_DS, but also the increment in the recombination rate due to the mechanism of diffusion current. Ultimately, the device lifetime uses Berkley’s model to extract the slope parameter m of the lifetime model. Previous studies have reported m-values ranging from 2.9 to 3.3, but in this case, approximately 1.1. This possibly means that the critical energy of the generated interface state becomes smaller, as is the barrier height of the HK dielectric to the conventional silicon dioxide as the gate oxide. Full article

This paper presents a transistor-level design with extensive experimental validation of a Content Addressable Memory (CAM), based on an eXclusive OR (XOR) single-bit cell. This design exploits a dedicated architecture and a fully custom approach (both in the schematic and the layout phase), in order to achieve very low-power and high-speed performances. The proposed architecture does not require an internal clock or pre-charge phase, which usually increase the power request and slow down data searches. On the other hand, the dedicated solutions are exploited in order to minimize parasitic layout-induced capacitances in the single-bit cell, further reducing the power consumption. The prototype device, named CAM-28CB, is integrated in the deeply downscaled 28 nm Complementary Metal-Oxide-Semiconductor (CMOS) Bulk (28CB) technology. In this way, the high transistor transition frequency and the intrinsic lower parasitic capacitances allow the system speed to be improved. Furthermore, the high radiation hardness of this technology node (up to 1Grad TID), together with the CAM-28CB high-speed and low-power performances, makes this device suitable for High-Energy Physics experiments, such as ATLAS (A Toroidal LHC ApparatuS) at Large Hadron Collider (LHC). The prototype operates at a frequency of up to 100 MHz and consumes 46.86 µW. The total area occupancy is 1702 µm² for 1.152 kb memory bit cells. The device operates with a single supply voltage of 1 V and achieves 0.41 fJ/bit/search Figure-of-Merit. Full article

Glycerol monooleate (GMO), casein and whey proteins are surfactants that can stabilize emulsion systems. This study investigates the impact of instantized GMO powders on creaming stability and oxidative stability in protein-stabilized emulsions. Model emulsions with bulk GMO, two instantized GMO powders, and two controls (without GMO) were produced by microfluidization. The droplet size, ζ-potential, viscosity, and creaming index of the emulsions were measured, while oxidative stability was evaluated by analysis of volatile compounds during storage (28 days, 45 °C) using gas chromatography mass spectrometry. Emulsions with GMO produced smaller average droplet sizes (180.0 nm) with a narrower distribution (polydispersity index of 0.161) compared to the controls (197.6 nm, 0.194). The emulsion stability of instantized emulsions was as good as bulk GMO, which were both better than controls. Based on the relative abundance of 3-octen-2-one, 2,4-heptadienal isomer 2, and 3,5-octadien-2-one isomer 1, the oxidative stability of the instantized emulsions was not significantly different from controls; however, bulk GMO emulsion showed significantly lower stability than controls. Instantized GMO powders can successfully produce physically stable protein-stabilized emulsions with good oxidative stability in a convenient powdered format. Full article

To optimize the thermal design of AlGaN-GaN high-electron-mobility transistors (HEMTs), which incorporate high power densities, an accurate prediction of the underlying thermal transport mechanisms is crucial. Here, a HEMT-structure (Al_0.17Ga_0.83N, GaN, Al_0.32Ga_0.68N and AlN on a Si substrate) was investigated using a time-domain thermoreflectance (TDTR) setup. The different scattering contributions were investigated in the framework of phonon transport models (Callaway, Holland and Born-von-Karman). The thermal conductivities of all layers were found to decrease with a temperature between 300 K and 773 K, due to Umklapp scattering. The measurement showed that the AlN and GaN thermal conductivities were a magnitude higher than the thermal conductivity of Al_0.32Ga_0.68N and Al_0.17Ga_0.83N due to defect scattering. The layer thicknesses of the HEMT structure are in the length scale of the phonon mean free path, causing a reduction of their intrinsic thermal conductivity. The size-effect of the cross-plane thermal conductivity was investigated, which showed that the phonon transport model is a critical factor. At 300 K, we obtained a thermal conductivity of (130 ± 38) Wm⁻¹K⁻¹ for the (167 ± 7) nm thick AlN, (220 ± 38) Wm⁻¹K⁻¹ for the (1065 ± 7) nm thick GaN, (11.2 ± 0.7) Wm⁻¹K⁻¹ for the (423 ± 5) nm thick Al_0.32Ga_0.68N, and (9.7 ± 0.6) Wm⁻¹K⁻¹ for the (65 ± 5) nm thick Al_0.17Ga_0.83N. Respectively, these conductivity values were found to be 24%, 90%, 28% and 16% of the bulk values, using the Born-von-Karman model together with the Hua–Minnich suppression function approach. The thermal interface conductance as extracted from the TDTR measurements was compared to results given by the diffuse mismatch model and the phonon radiation limit, suggesting contributions from inelastic phonon-scattering processes at the interface. The knowledge of the individual thermal transport mechanisms is essential for understanding the thermal characteristics of the HEMT, and it is useful for improving the thermal management of HEMTs and their reliability. Full article