Device Scaling Research Articles

Efficiency scaling of inductively coupled plasmas for radio frequency propulsion systems

AbstractA generalized inductively coupled plasma (ICP) efficiency model is derived, which may be used to predict plasma generation efficiency with many types of radio frequency (RF) electric propulsion system. The analytical ICP discharge model is used to examine device scaling, and investigate trends in ICP performance as a function of geometry and system inputs. The ICP efficiency model is applied to an analytical RF cathode model to predict device behavior. Results from the updated RF cathode model show improvements in agreement with experimental data.

Cooperative Nernst effect of multilayer systems: Parallel circuit model study

Transverse thermoelectric power generation has emerged as a topic of immense interest in recent years owing to the orthogonal geometry which enables better scalability and fabrication of devices. Here, we investigate the thickness dependence of longitudinal and transverse responses in film-substrate systems, i.e., the Seebeck coefficient, the Hall coefficient, the Nernst coefficient, and the anomalous Nernst coefficient in a unified and general manner based on the circuit model, which describes the system as the parallel setup. By solving the parallel circuit model, we show that the transverse responses exhibit a significant peak, indicating the importance of a cooperative effect between the film and the substrate, arising from circulating currents that occur in these multilayer systems in the presence of a temperature gradient. Finally, on the basis of realistic material parameters, we predict that the Nernst effect in bismuth thin films on doped silicon substrates is boosted to unprecedented values if the thickness ratio is tuned accordingly, motivating experimental validation. Published by the American Physical Society 2024

Intralayer/Interlayer Codoping Stabilizes Polarity Modulation in 2D Semiconductors for Scalable Electronics.

2D semiconductors show promise as a competitive candidate for developing future integrated circuits due to their immunity to short-channel effects and high carrier mobility at atomic layer thicknesses. The inherent defects and Fermi level pinning effect lead to n-type transport characteristics in most 2D semiconductors, while unstable and unsustainable p-type doping by various strategies hinders their application in many areas, such as complementary metal-oxide-semiconductor (CMOS) devices. In this study, an intralayer/interlayer codoping strategy is introduced that stabilizes p-type doping in 2D semiconductors. By incorporating oppositely charged ions (F and Li) with the intralayer/interlayer of 2D semiconductors, remarkable p-type doping in WSe2 and MoTe2 with air stability up to 9 months is achieved. Notably, the hole mobility presents a 100-fold enhancement (0.7 to 92 cm2 V-1 s-1) with the codoping procedure. Structural and elemental characterizations, combined with theoretical calculations validate the codoping mechanism. Moreover, a CMOS inverter and more complex logic functions such as NOR and XNOR, as well as large-area device arrays are demonstrated to showcase its applications and scalability. These findings suggest that stable and straightforward intralayer/interlayer codoping strategy with charge-space synergy holds the key to unlocking the potential of 2D semiconductors in complex and scalable device applications.

Video Game-Based Trunk Exercises for Rehabilitation in Chronic Stroke Survivors: A Mixed-Methods Feasibility Study.

Aim: To assess the feasibility of video game-based trunk exercises using the Valedo® system in a chronic stroke population. Method: Ten chronic stroke survivors (eight males and two females, mean age 63 ± 15 years) were asked to complete 18 intervention sessions, each lasting 45 min., over 6-8 weeks. Feasibility was evaluated quantitatively using the Psychosocial Impact of Assistive Devices Scale (PIADS) as well as through recruitment, retention, adherence, and safety measures. Qualitative data on feasibility were collected through post-intervention semi-structured interviews. Descriptive analysis was used to summarize participant characteristics, recruitment, retention, and adherence. Qualitative data were analyzed using thematic analysis of the interviews. Results: Twelve stroke survivors were recruited from Southampton (United Kingdom) and Riyadh (Kingdom of Saudi Arabia), with two participants dropping out after the baseline assessment session. The remaining ten participants completed the study with a mean adherence of 96.11% to the planned sessions. No serious adverse effects were reported, however, four participants did experience trunk muscle tightness and fatigue. Post-intervention interviews revealed that participants encountered some physical and cognitive challenges while playing the Valedo video games. However, they felt that the implementation of trunk exercises using video games was safe, as the exercises were performed in a secure environment and in safe positions. Conclusions: The findings suggest that the Valedo system is feasible for delivering trunk exercises to chronic stroke survivors. Several factors should be considered when implementing this type of intervention in the future.

Narrowband Electroluminescence from Color Centers in Hexagonal Boron Nitride.

Defects in wide bandgap materials have emerged as promising candidates for solid-state quantum optical technologies. Electrical excitation of single emitters may lead to scalable on-chip devices and therefore is highly sought after. However, most wide bandgap materials are not amenable to efficient doping, posing challenges for electrical excitation and on-chip integration. Here, we demonstrate narrowband electroluminescence from visible and near-infrared color centers in hexagonal boron nitride (hBN). We harness van der Waals tunnel junctions of graphene-hBN-graphene. Charge carriers are electrically injected into hBN, exciting localized defects that emit nonclassical light, as characterized by the second order correlation measurement. Remarkably, the devices operate at room temperature and produce robust, narrowband emission spanning from visible to the near-infrared. Our work marks an important milestone in vdW materials and their promising attributes for integrated quantum technologies and on-chip photonic circuits.

An intensive eye-tracking intervention in children with dyskinetic cerebral palsy: a multiple case study

This study aimed to explore the effects of a four-week intensive eye-tracking intervention on children with dyskinetic cerebral palsy (DCP), focusing on goal attainment, communication competencies, stress levels, subjective workload, and caregivers’ perception of psychosocial impact. A multiple case study design with non-concurrent, staggered multiple baselines was employed, involving three children aged 7, 12, and 13 years. The study included a randomized baseline period of two or three weeks, an intensive eye-tracking intervention, and a six-month follow-up. Two individual eye-tracking goals were identified and assessed using the Goal Attainment Scale, while communication competencies were evaluated with the Augmentative and Alternative Communication Profile: A Continuum of Learning. Stress levels were monitored through Heart Rate Variability measured by the Bittium Faros 360° ECG Holter during eye-tracking tasks. Subjective workload and psychosocial impact were assessed using pictograms and the Psychosocial Impact of Assistive Devices Scale, respectively. Descriptive statistics were applied for analysis. All participants attained and retained their eye-tracking goals, regardless of their initial functional profiles or prior experience with eye-tracking technology. Post-intervention improvements in communication competencies were maintained at the six-month follow-up. Variations in stress levels, subjective workload, and psychosocial impact were observed among participants across different phases of the study, aiding the interpretation of the results. The study concludes that a structured, tailored, four-week intensive eye-tracking intervention can yield successful results in children with DCP, irrespective of their baseline communication abilities or functional profile. Recommendations for future research, including more robust methodologies and reliable computerized tests, are provided.

Synthesis of chemical bath deposited Manganese oxide thin films for high performance supercapacitor

The present study addresses the growing need for high-performance supercapacitors, emphasizing the benefits of Manganese oxide (MnO2) thin film as a promising electrode material. Thin film deposition of MnO2 is achieved through Chemical Bath Deposition (CBD) method by varying the deposition time on the stainless steel substrate. In order to investigate impact of deposition time on various physico-chemical properties of MnO2 thin films, different characterizations were carried out like X-ray diffraction, Scanning electron microscopy, Energy dispersive X-ray analysis, X-ray photoelectron spectroscopy, cyclic voltammetry, Galvanostatic charge–discharge analysis. The deposited MnO2 thin films are subsequently studied for their electrochemical properties in a 1 M KOH electrolyte solution. Remarkably, the best specific capacitance is obtained about 296.5 F/g at current density of 0.5 A/g, with 86.42 % retention after 5000 cycles, highlighting the excellent electrochemical performance of the MnO2 thin films deposited at 6 hrs of reaction time. This work highlights valuable insights into the CBD deposited MnO2 thin films for supercapacitor applications, providing a foundation for the development of an efficient, low-cost, and scalable energy storage devices.

Compact design of universal gates with non-aligned gate technology and assessment of its performance in a TCAD Environment

ABSTRACT This paper proposes a technology computer-aided design (TCAD) of a compact single-device NAND and NOR logic gates in 215 nm device length along with speed and power performance results. The universal gates are designed with non-aligned double gate technology, and this helps to reduce the transistor count, giving a compact design structure. The static characteristics and input pattern sensitivity of the NAND and NOR structures are investigated in this work. By using graphical method, the optimal supply voltage of the universal gates was determined. The optimal supply voltage of the NAND gate and NOR gate was 0.9 V and 0.84 V, respectively, at an input frequency of 1 GHz. Further, the device scalability of the proposed structures was analysed. When compared to the past work, the proposed NAND gate and NOR gate improves delay performance by 25.02% and 35.63%, respectively. Additionally, a reduction of 10% and 16% in its supply voltage is achieved. Therefore, the proposed gate has potential to operate at higher frequency with reduced supply voltage, making them suitable in circuit applications.

Scaling of N-Type Field-Effect Transistors Based on Aligned Carbon Nanotube Arrays.

Wafer-scale aligned carbon nanotubes (A-CNTs) are promising candidate semiconductors for building high-performance complementary metal-oxide-semiconductor (CMOS) transistors for future integrated circuits (ICs). A-CNT-based p-type field-effect transistors (P-FETs) have demonstrated excellent performance and scalability down to sub-10 nm nodes. However, the development of A-CNT n-type FETs (N-FETs) lags far behind, in regard to their electronic performance and device scaling. In this work, we fabricated top-gated N-FETs based on A-CNTs with a scandium (Sc)-contacted source and drain. High-performance A-CNT N-FETs were demonstrated with record on-state current (Ion) exceeding 1 mA/μm and peak transconductance (gm) of 0.4 mS/μm. Interestingly, the A-CNT N-FETs exhibited abnormal scaling behavior owing to the lateral oxidation of low-work function source/drain contacts, leading to formidable challenges to scale both the gate length (Lg) and the contact length (Lc) at the same time. Understanding of the abnormal scaling behavior contributes to seeking solutions for high-performance A-CNT N-FETs, and it paves the way for future CNT CMOS digital IC technology.

Development of surface-activated La0.6Ca0.4MnO3 perovskite-type electrodes using oxygen plasma for highly stable supercapacitor application

This study introduces a novel and efficient approach for synthesizing perovskite-type nanoparticles and advanced plasma surface activation to significantly improve the supercapacitor's performance. High-purity La0.6Ca0.4MnO3 (LCMO) perovskite nanoparticles with a crystalline structure were synthesized using a facile coprecipitation technique, followed by an innovative low-pressure DC glow-discharge plasma treatment in an oxygen atmosphere. This plasma surface activation process enhances the surface properties of the nanoparticles and boosts their electrochemical performance, representing a transformative modification method for energy storage materials. Detailed analysis of the synthesized and surface-activated LCMO (SA@LCMO) nanoparticles revealed a well-defined cubic morphology with a remarkable surface area of 95 m2/g, as confirmed by TEM and BET analysis. The plasma-treated SA@LCMO electrodes demonstrated superior supercapacitor performance, delivering an impressive specific capacitance of 453 F/g at a current density of 1 A/g more than doubling the 225.8 F/g achieved by untreated LCMO electrodes. Additionally, the SA@LCMO electrodes exhibited exceptional cycle stability, retaining 87 % of their capacitance and achieving a coulombic efficiency of 95.2 % after 10,000 GCD cycles. The material also showed promising energy storage capabilities, with a maximum energy density of 3.92 Wh/kg at a power density of 170.6 W/kg. These results highlight the transformative impact of plasma surface activation on perovskite nanomaterials, positioning the SA@LCMO as a highly promising candidate for next-generation energy storage technologies with superior energy density, durability, and performance. This study introduces new avenues for surface engineering perovskite-based materials to create scalable high-performance energy storage devices.

3D Light-Direction Sensor Based on Segmented Concentric Nanorings Combined with Deep Learning.

High-precision, ultra-thin angular detectable imaging upon a single pixel holds significant promise for light-field detection and reconstruction, thereby catalyzing advancements in machine vision and interaction technology. Traditional light-direction angle sensors relying on optical components like gratings and lenses face inherent constraints from diffraction limits in achieving device miniaturization. Recently, angle sensors via coupled double nanowires have demonstrated prowess in attaining high-precision angle perception of incident light at sub-wavelength device scales, which may herald a novel design paradigm for ultra-compact angle sensors. However, the current approach to measuring the three-dimensional (3D) incident light direction is unstable. In this paper, we propose a sensor concept capable of discerning the 3D light-direction based on a segmented concentric nanoring structure that is sensitive to both elevation angle (θ) and azimuth angle (ϕ) at a micrometer device scale and is validated through simulations. Through deep learning (DL) analysis and prediction, our simulations reveal that for angle scanning with a step size of 1°, the device can still achieve a detection range of 0∼360° for ϕ and 45°∼90° for θ, with an average accuracy of 0.19°, and DL can further solve some data aliasing problems to expand the sensing range. Our design broadens the angle sensing dimension based on mutual resonance coupling among nanoring segments, and through waveguide implementation or sensor array arrangements, the detection range can be flexibly adjusted to accommodate diverse application scenarios.

High-Performance Aqueous Supercapacitors Based on a Self-Doped n-Type Conducting Polymer.

Environmentally-benign materials play a pivotal role in advancing the scalability of energy storage devices. In particular, conjugated polymers constitute a potentially greener alternative to inorganic- and carbon-based materials. One challenge to wider implementation is the scarcity of n-doped conducting polymers to achieve full cells with high-rate performance. Herein, this work demonstrates the use of a self-doped n-doped conjugated polymer, namely poly(benzodifurandione) (PBDF), for fabricating aqueous supercapacitors. PBDF demonstrates a specific capacitance of 202 ± 3 Fg-1, retaining 81% of the initial performance over 5000 cycles at 10 Ag-1 in 2m NaCl( aq ). PBDF demonstrates rate performances of up to 100 and 50 Ag-1 at 1 and 2mgcm-2, respectively. Electrochemical impedance analysis reveals a surface-mediated charge storage mechanism. Improvements can be achieved by adding reduced graphene oxide (rGO), thereby obtaining a specific capacitance of 288 ± 8 Fg-1 and high-rate operation (270 Ag-1). The performance of PBDF is examined in symmetric and asymmetric membrane-less cells, demonstrating high-rate performance, while retaining 83% of the initial capacitance after 100000 cycles at 10 Ag-1. PBDF thus offers new prospects for energy storage applications, showcasing both desirable performance and stability without the need for additives or binders and relying on environmentally friendly solutions.

Applying Pattern Language to Enhance IIoT System Design and Integration: From Theory to Practice

The Industrial Internet of Things (IIoT) is pivotal in advancing industrial automation, offering significant improvements in connectivity and efficiency. However, the integration of heterogeneous devices within IIoT systems presents substantial challenges, primarily due to the diversity in device hardware, protocols, and functionalities. In this paper, we propose a new pattern language specifically designed to enhance interoperability and operational efficiency across industrial settings. Drawing from a case study of the State Company for Automotive Industry (S.C.A.I.) in Iraq, this study details the development and integration of eleven interrelated patterns. These patterns were carefully combined based on identified relationships, forming a comprehensive pattern language that addresses key aspects of system heterogeneity, including device communication, data security, and system scalability. The pattern language was validated using the Delphi process theory, engaging industry experts to refine and optimize the framework for practical application. The implementation of this pattern language led to significant improvements in system integration, enabling seamless communication between diverse devices and enhancing operational workflows. The case study demonstrates the practical viability of the proposed pattern language in enhancing interoperability within real-world Industrial Internet of Things (IIoT) applications. Furthermore, the replicable nature of this framework makes it a valuable resource for other industrial environments seeking to harness the power of IIoT technologies.

Unveiling the tradeoff between device scale and surface nonidealities for an optimized quality factor at room temperature in 2D MoS2 nanomechanical resonators

A high quality (Q) factor is essential for enhancing the performance of resonant nanoelectromechanical systems (NEMS). NEMS resonators based on two-dimensional (2D) materials such as molybdenum disulfide (MoS2) have high frequency tunability, large dynamic range, and high sensitivity, yet room-temperature Q factors are typically less than 1000. Here, we systematically investigate the effects of device size and surface nonidealities on Q factor by measuring 52 dry-transferred fully clamped circular MoS2 NEMS resonators with diameters ranging from 1 μm to 8 μm, and optimize the Q factor by combining these effects with the strain-modulated dissipation model. We find that Q factor first increases and then decreases with diameter, with an optimized room-temperature Q factor up to 3315 ± 115 for a 2-μm-diameter device. Through extensive characterization and analysis using Raman spectroscopy, atomic force microscopy, and scanning electron microscopy, we demonstrate that surface nonidealities such as wrinkles, residues, and bubbles are especially significant for decreasing Q factor, especially for larger suspended membranes, while resonators with flat and smooth surfaces typically have larger Q factors. To further optimize Q factors, we measure and model Q factor dependence on the gate voltage, showing that smaller DC and radio-frequency (RF) driving voltages always lead to a higher Q factor, consistent with the strain-modulated dissipation model. This optimization of the Q factor delineates a straightforward and promising pathway for designing high-Q 2D NEMS resonators for ultrasensitive transducers, efficient RF communications, and low-power memory and computing.

Tailoring magnetism in chromium-doped zinc cobalt ferrite nanostructure for advanced spintronic memory devices

Soft magnetic ferrites serve as a crucial component in a wide array of sensing and actuating applications across various industries, including consumer electronics, automotive systems, spintronics, and more. These materials also find utility in spintronics, particularly for next-generation magnetic random-access memory (MRAM) due to their excellent inductive properties, which enhance the performance and scalability of spintronic memory devices. This study focuses on fine-tuning soft magnetic ferrites for inductive applications by doping them with Cr ions. By utilizing advanced experimental techniques such as the vibrating sample magnetometer (VSM) for bulk magnetometry and X-ray magnetic circular dichroism (XMCD) alongside X-ray absorption spectroscopy for atomic studies, the research aims to investigate the structural, electronic, and magnetic properties of the nanoferrites. Addition of doping in the soft ferrites observes reduction in the general magnetic parameters, with the only exception being coercivity, which decreases from 381 Oe to 275 Oe as the doping concentration increases from x = 0 to x = 0.02, and then increases to 350 Oe at x = 0.03. Through such precise tuning of the nanoparticles, this study aims to investigate the controllable soft magnetic properties of the nanoferrites, thereby paving the way for fast access times, non-volatility, and low energy consumption, presenting a compelling alternative to conventional memory technologies.

Memristors with Monolayer Graphene Electrodes Grown Directly on Sapphire Wafers.

The development of the memristor has generated significant interest due to its non-volatility, simple structure, and low power consumption. Memristors based on graphene offer atomic monolayer thickness, flexibility, and uniformity and have attracted attention as a promising alternative to contemporary field-effect transistor (FET) technology in applications such as logic and memory devices, achieving higher integration density and lower power consumption. The use of graphene as electrodes in memristors could also increase robustness against degradation mechanisms, including oxygen vacancy diffusion to the electrode and unwanted metal ion diffusion. However, to realize this technological transformation, it is necessary to establish a scalable, robust, and cost-effective device fabrication process. Here we report the direct growth of high-quality monolayer graphene on sapphire wafers in a mass-producible, contamination-free, and transfer-free manner, using a commercially available metal-organic chemical vapor deposition (MOCVD) system. By taking advantage of this approach, graphene-electrode based memristors are developed, and all the processes used in the device fabrication incorporating graphene electrodes can be performed at wafer scale. The graphene electrode-based memristor demonstrates promising characteristics in terms of endurance, retention, and ON/OFF ratio. This work presents a possible and viable route to achieving robust graphene-based memristors in a commercially and technologically sustainable manner, paving the way for the realization of more powerful and compact integrated graphene electronics in the future.

Control of chiral damping in magnetic trilayers using He+ ion irradiation

In the forefront of spintronic advancements, structures with strong perpendicular magnetic anisotropy (PMA) such as Pt/Co/Pt are essential for the miniaturization and performance enhancement of high-density magnetic storage technologies. The robust PMA characteristic of these systems facilitates the development of scalable spintronic devices, crucial for next-generation magnetic memory applications. This study investigates the interplay between PMA and the Dzyaloshinskii-Moriya interaction (DMI)—an antisymmetric exchange interaction prevalent in non-centrosymmetric magnetic systems—and its dissipative counterpart, chiral damping. While chiral damping arises from the same broken inversion symmetry as DMI, it typically introduces an additional energy dissipation channel, reducing device efficiency. Our research examines the effects of controlled helium ion (He+) irradiation on a Pt/Co/Pt system. We find that ion beam irradiation enhances interfacial intermixing, which correlates with a decrease in PMA. However, domain wall velocity measurements indicate a concurrent reduction in both DMI and chiral damping, along with enhanced velocities as irradiation fluence increases. These observations suggest that ion beam irradiation can be judiciously applied to achieve a balance between lower DMI, chiral damping, and reasonable PMA, thereby optimizing the system for improved device performance.

Easy-to-configure zero-dimensional valley-chiral modes in a graphene point junction.

The valley degree of freedom in two-dimensional (2D) materials can be manipulated for low-dissipation quantum electronics called valleytronics. At the boundary between two regions of bilayer graphene with different atomic or electrostatic configuration, valley-polarized current has been realized. However, the demanding fabrication and operation requirements limit device reproducibility and scalability toward more advanced valleytronics circuits. We demonstrate a device architecture of a point junction where a valley-chiral 0D PN junction is easily configured, switchable, and capable of carrying valley current with an estimated polarization of ~80%. This work provides a building block in manipulating valley quantum numbers and scalable valleytronics.

Design and optimization of broadband near-perfect absorber based on transition metal nitrides thin-films for solar energy harvesting

Broadband metamaterial absorbers hold promise for solar energy harvesting, but their complex designs and use of expensive noble metals hinder scalability and thermal stability. Additionally, traditional design methods are time-consuming. We propose a novel approach that combines a genetic algorithm with the transfer matrix method to optimize both material composition and layer structure for large-scale, cost-effective, and thermally stable solar absorbers. This method enables the design of near-perfect absorbers with an average absorptance exceeding 90 % and over 80 % across a broad wavelength range (0.3–2.5 μm) within the key solar spectrum. By optimizing the arrangement of metal and insulator layers using nitride materials (e.g., vanadium nitride), we achieve superior performance compared to traditional metal–insulator and insulator–metal structures. This optimization utilizes resonant absorption and the inherent absorption of metal layers. Our work paves the way for efficient and scalable solar energy harvesting devices.

A New Paradigm for Semiconductor Manufacturing: Integrated Synthesis, Delivery, and Consumption of Source Chemicals for IC Fabrication

The semiconductor industry is being radically impacted by the placing of greater emphasis on the development of hetero-devices and systems that will act as essential drivers for a wide spectrum of technological applications. The introduction of new materials and their integration with currently used materials are projected to replace integrated circuitry (IC) design and device scaling as the key enablers to the realization of improved device performance and larger density gains. Yet material selection has been constrained by existing fabrication process technology. To date, fabrication processes have dictated material selection by limiting chemical sources or precursors to those that match existing process tools associated with chemically based vapor phase processes and their variants, which in turn limits material compositions in ICs. The processing and integration of new materials compositions and structures will require the introduction of new deposition and etching processes, and manufacturing worthy tool designs and associated protocols that provide new methods for atomic-level control. To this end, a novel manufacturing paradigm is presented comprising a method and system for real-time, closed-loop monitoring and control of synthesis, supply, and consumption of precursors in process intensification techniques including chemical vapor deposition (CVD), atomic layer deposition (ALD), atomic layer etching (ALE), and other IC manufacturing processes. This intelligent automated manufacturing approach is consistent with a central component of the semiconductor industry’s recent adoption of Industry 4.0., including vertical integration of IC manufacturing through robotization, artificial intelligence, and cloud computing. Furthermore, the approach eliminates several redundant steps in the synthesis, handling, and disposal of source precursors and their byproducts for CVD, ALD, ALE and other chemically based manufacturing processes, and thus ultimately lowers the manufacturing cost for both conventional and new IC materials. Further, by eliminating the issues associated with precursor thermal, chemical, and pyrophoric instabilities, this new paradigm enables the deposition of a myriad of new thin-film materials and compositions for IC applications that are practically unattainable with existing precursors. Preliminary and planned demonstration examples for the generation and deposition of highly toxic and unstable source precursors are provided.