Device Characteristics Research Articles

TaPaFuzz: Hardware-accelerated RISC-V bare-metal firmware fuzzing using rapid job launches

Fuzz testing serves as a key technique in software security aimed at identifying unexpected program behaviors by repeatedly executing the target program with auto-generated random inputs. Testing is integral to IoT device security but is hampered by the minimal observability features of typical in-market IoT devices. Moreover, the slow nature of a RISC-V software emulation on x86 host CPUs and the inaccuracies introduced by compiling IoT applications to a different ISA for execution on host systems pose significant challenges. Our software-hardware co-design surmounts these hurdles. Fuzzing jobs are prepared and evaluated on a host computer, while the actual execution with high-throughput tracing is performed on an FPGA. Advances in the host-to-FPGA interface together with an accelerated reset procedure between Fuzzer jobs effectively hide the costly host-FPGA communication, increasing the single-thread fuzzing performance by up to factor 11.7x that of the leading QEMU-based fuzzer AFL++ running on a very fast x86 CPU. We demonstrate practical usability by evaluating our framework on a collection of bare-metal applications.

Rapid deposition analysis of inhaled aerosols in human airways

A rapid data-driven method for determining regional deposition of inhaled medication aerosols in human airways is presented, which is patient specific. Inhalation patterns, device characteristics, and aerodynamic particle size distribution of medications are considered. The method is developed using dimensional analysis and Buckingham Pi theorem, and provides total, regional, and lobar distributions of aerosol deposition. 34 dimensionless quantities are selected, of which 22 encode features of the airway trees and segmented lobes, 14 pertain to the device and the drug formulation, and 13 the inhalation profile of the subject. The dimensionless correlations are obtained using a large database of computational fluid dynamics results on patient specific airways. The intraclass correlation coefficient between the current method and its training dataset is 0.92. The difference between the predicted average lobar deposition in the six asthma patients and the in-vivo data is 1.3%. The model has the potential to offer insights into the effectiveness of personalized drug delivery in clinical settings and can aid in drug development cycles.

(Dis)connecting families: Parents’ versus children's perspectives on the role of mobile devices within family interactions

The characteristics of mobile technology devices have enabled new ways of integrating technology in familial interactions. This study aimed to investigate (1) differences in perspectives of technoference and family-oriented mobile technology use between parents and children, (2) the relation between parent–child interactions that take place via mobile technology and the quality of the parent–child relationship, and (3) its association with the well-being of parents and preadolescents separately. Structural equation modelling was performed on cross-sectional data from 390 parent–child dyads. The findings revealed discrepancies in child technoference perceptions and varying associations of the different types of mobile technology use with the parent–child relationship and parents' and children's well-being. From children's perspective, both parent and child technoference was negative for the parent–child relationship, whereas family-oriented mobile technology use when physically together was beneficial for the relationship and the child's well-being. From parents’ perspective, only child technoference was negatively related to the parent–child relationship and parent's well-being. Overall, the findings underline that mobile technology use can be both detrimental and beneficial, however, the effects can differ depending on the family member and the type of technology use.

Novel electrical characteristic measurement system of semiconductor films for estimating device characteristics

We proposed a novel measurement method and system to measure the electrical characteristics of non-patterned semiconductor films to estimate the final device’s properties. The proposed method is based on measuring bottom-gate structure thin-film transistor (TFT) using the probe pins as source and drain electrodes. We carefully designed the array structure and material of the probe pin to effectively detect extremely low-level currents without patterned electrodes on the semiconductor film. The contact pressure was also carefully controlled through continuous monitoring using an implemented pressure sensor to ensure the reliability and reproducibility of the measured data. In addition, we developed a method of extracting device parameters, such as the threshold voltage and field-effect mobility, from the measured data, considering the geometric factor of the proposed method. Comparative analysis between the measurement results of the film sample using the proposed system and that of the final TFT sample exhibited similar results with slight deviations. Furthermore, the proposed system provided similar results under repetitive measurements. Consequently, the proposed method and system successfully demonstrated the estimation of the final TFT’s properties by measuring the electrical characteristics of the non-patterned semiconductor film with excellent reliability, highlighting the possibility of effectively reducing costs for development and fabrication.

Simulation study of a novel GaN on Si Quasi‐Vertical Reverse‐Conducting Insulated Gate Bipolar Transistor

Abstract In this paper, a novel GaN on Si quasi-vertical reverse conducting insulated gate bipolar transistor(RC-IGBT) with a new NPN structure is proposed and simulated by Silvaco TCAD. The distinctive feature of this structure lies in fabricating the original bottom P-Collector on the wafer surface. In comparison to conventional IGBT devices with PNPN structures, this NPN structure overcomes two major challenges: the difficulty in forming ohmic contacts due to the activation difficulty of the bottom P-GaN and the necessity of creating backside through-holes for electrode formation. Simultaneously, the N-GaN in the emitter and reverse-conducting regions can be selectively regrown through Metal-Organic Chemical Vapor Deposition (MOCVD) or Molecular Beam Epitaxy (MBE), avoiding the etching effect of top-layer N-GaN on P-GaN during the fabrication of P-type electrodes. This approach demonstrates a high level of process feasibility. In this paper, Silvaco TCAD is used to simulate the static and dynamic characteristics of this novel quasi-vertical RC-IGBT device. The simulation results reveal that the device has a high saturation current(Ion,sat) density of 18224.67A/cm2 at Vge=14V,a threshold voltage (Vth) of 5V,a breakdown voltage of 828V,a latch-up voltage of 800V ,and a switching speed of nanoseconds. In addition, the selection of device parameters is studied in this paper.

Analysis of ultrasonic device influence on the ultrasonic thickness measurement of the steel grade

ABSTRACT Ultrasonic thickness measurement depends on the capability of the equipment and its operating characteristics, as well as on the auxiliary means used to adjust the system and analyse the obtained results. The characteristics of the ultrasonic device commonly used as a flaw detector are crucial for achieving accurate and precise results and are very important for the reliability of the results obtained in the measurement process, especially in production systems. This article aims to determine the quantitative variations in thickness caused by influencing parameters of the ultrasonic device and chosen ultrasonic probe, their quantification of interactions, and the significance of their influence on the accuracy and precision of the results. In the experimental part of the research, a factorial plan of the experiment was carried out to determine the influence of the ultrasonic device and the type of ultrasonic probe on the variability of the results of the ultrasonic thickness measurement. The parameters of the ultrasonic device and probes were analysed, and the experimental plan for developing the regression model was elaborated. The response surface methodology was applied, and the in-service measurement process was simulated using Monte Carlo simulation.

Efficiency limit for diamond metal/intrinsic/p-type Schottky barrier-based betavoltaic cells

Diamond materials hold great potentials with favorable characteristics for betavoltaic cells, thanks to their simple structure, high conversion efficiency, and radiation robustness. However, to explore its efficiency limit is greatly hindered by the material growth, doping techniques, and device design as well. In this work, a device model based on a diamond metal/intrinsic/p-type (MIP) Schottky barrier architect is analyzed for an accurate prediction of the efficiency limit for the betavoltaic cell based on such a structure. The study takes various factors of significance into account on the betavoltaic cell device characteristics, including the radiation source, thickness and doping concentration of the intrinsic layer, metal work function, as well as the metal/diamond interface traps and traps in the bulk. The current–voltage characteristics and fundamental parameters of the betavoltaic cells are thoroughly analyzed. According to our results, an open-circuit voltage of 2.04 V, a short-circuit current density of 87 nA·cm−2, and a fill factor of 0.9 for the diamond MIP betavoltaic cell can be achieved, which give a maximum energy conversion efficiency of 10.7%, at optimal conditions using 50 nm thick Al metal as the contact layer, 9 μm thick and 1 × 1014 cm−3-doping intrinsic layer, and 10 μm thick and 2 × 1017 cm−3-doping p-layer under a 2 μm 63Ni irradiation. This work also discusses the impact of the interface/bulk traps on the barrier heights of practical Schottky diodes and the device's performance as well.

A MODEL FOR PHYSICS PRACTICAL WORK USING MOBILE LEARNING AND LEARNING MANAGEMENT SYSTEM (LMS) IN HIGHER EDUCATION: DESIGN, VALIDATION, AND EVALUATION

Despite the importance of physics practical work in higher education, its implementation is often hampered by various constraints and problems. Technology, such as learning management systems (LMS) and mobile learning, can offer solutions to some of these problems and enrich students' learning experiences. Therefore, this research proposes a model called Practical Works in Physics via Mobile Learning and LMS (PWP-MLMS) that exploits features of LMSs and mobile devices to overcome specific challenges encountered in physics practical works and improve students' performance in these works. The model was designed, validated, and evaluated within the teaching context of a Moroccan university. To assess the model's effectiveness,128 students in the Bachelor of Education, Physics-Chemistry specialization were randomly divided into two groups of 64 students each: an experimental group using the model for practical work on the topic of rectification and filtering in the electronics module, and a control group following the conventional method for the same practical work. The results of the evaluation showed that the proposed model can significantly reduce the time required to complete the practical work, have a positive influence on the students' technical skills, and improve the quality of their laboratory reports. Keywords: mobile learning, LMS, practical work, physics education, higher education

Closed Circuit of 3-Dimensional Polymer Powders

This article describes the most important stages of testing the levels of innovative readiness of a new machine and material construction solutions for closed loops of polymer powders in 3D additive manufacturing. The aim of this study was to indicate the state and directions of development of the technology of geometric recycling of polymer powders in 3D additive manufacturing, the need to control the geometric quality of the powders, and the quality of the design of machines for their processing in a closed circuit. The method was aimed at creating a strategy and verifying the stages of development of a new idea for stabilizing the geometric and dynamic design features of polymer powders for additive manufacturing (3D printing). Connections and relationships of the variable design features of powders, machines and devices with variable postulated states of products and processes allowed for the analysis, knowledge, description and development of variables for stabilizing geometric features of polymer powders in recycling. The results show the possibilities of supporting innovative creativity according to the adopted method, allow for determining the level of compliance of the quality of the products of the technical system, the effectiveness of preparatory processes for recycling and the non-toxicity of the products and processes of the new technology and their closed loop. The goal of developing useful design values, according to an integrated method of analysis, assessment and environmental development, was achieved, including the proposal of design features of razor blade shredders, supported by genetic algorithms, and devices for stabilizing polymer powders in additive manufacturing with recycling.

High Performance Self‐Powered p+‐GaN/n−‐ZnO/Au UV Heterojunction Phototransistor with 3D Interconnected ZnO Nanowire Network for Solar‐Blind Imaging and Optical Communication

AbstractHeterojunction phototransistor (HPT) is considered the most promising detector technology in weak ultraviolet (UV) signal detection due to its inherent internal gain through transistor action. However, achieving high‐performance self‐powered UV HPTs remains a significant challenge. In this study, a high‐performance self‐powered p+‐GaN/n−‐ZnO/Au UV HPT with ZnO serving as the floating base is cleverly designed. The device features a unique back‐to‐back configuration of the p+‐GaN/n−‐ZnO heterojunction and n−‐ZnO/Au Schottky junction, along with an ultrathin ZnO base layer of a 3D nanowire network structure. This design enables the fabricated p+‐GaN/n−‐ZnO/Au UV HPT to operate in a self‐powered mode with exceptional performance metrics. Under zero bias, the device exhibits outstanding characteristics including ultralow dark current of 1.7 × 10−13 A, remarkable Iphoto/Idark ratio of 106, fast response speed (tr = 150 µs / tf = 250 µs), high responsivity of 9.74 A W−1, and detectivity of 1.58 × 1014 Jones, representing the best result achieved for UV HPTs thus far at zero bias. Moreover, the fabricated UV HPT is successfully demonstrated in solar‐blind imaging and UV communication systems without the need for an external power supply. This work presents effective and practical design strategies for achieving high‐performance self‐powered UV HPTs.

FIB-fabrication of superconducting devices based on Bi2Se3 junctions

Recent advances in quantum technologies are highly influencing the current technological scenario. Hybrid devices combining superconductors and topological insulators represent an excellent opportunity to study the topological superconducting phase, which offers interesting features that might have significant implications in the development of quantum sensing and quantum computing. Furthermore, focused ion beam techniques, whose versatility enables to create sophisticated devices with high degree of customization, can enhance the creation of complex devices. Here, we develop a novel approach for creating single-crystal devices that is applied to the fabrication of superconducting devices based on topological insulator Bi2Se3 in a geometry characteristic of a superconducting quantum interference device. Characterization of these devices reveals that superconductivity is induced in our crystal and the supercurrent is modulated by applying an external magnetic field. These results open the way to tailoring the response of hybrid devices that combine superconductors and topological insulators by focused ion beam techniques.

On the Origin of Signal and Bandwidth of Converse Magnetoelectric Magnetic Field Sensors

AbstractConverse magnetoelectric sensors enable the detection of low‐frequency and low‐amplitude magnetic fields over a bandwidth of several kilohertz by combining the electrical excitation of a magnetoelectric resonator via a piezoelectric layer with an inductive readout. Here, a comprehensive sensor model is presented to further foster the development of this promising sensor concept. The model relates the output signal to the device characteristics, taking into account the magnetoelastic and electromechanical properties, the resonator geometry, and operating conditions. The sensor system is thoroughly experimentally analyzed to validate the model. Based on the analysis, the sensor concept is explained in detail, including the origin of its loss and bandwidth and their connection with the magneto‐mechanical loss in the magnetostrictive layer. Significant advances have been made in the comprehensive understanding of converse magnetoelectric sensors, providing a solid basis for future improvements in magnetoelectric sensor systems.

A hybrid electro-thermochemical device for methane production from the air

Coupling direct air capture (DAC) with methane (CH4) production is a potential strategy for fuel production from the air. Here, we report a hybrid electro-thermochemical device for direct CH4 production from air. The proposed device features the cogeneration of carbon dioxide (CO2) and hydrogen (H2) in a single compartment via a bipolar membrane electrodialysis module, avoiding a separate water electrolyzer, followed by a thermochemical methanation reaction to produce CH4. H2-induced disturbances lead to efficient CO2 extraction without pumping requirement. The energy consumption and techno-economic analysis predict an energy reduction of 37.8% for DAC and a cost reduction of 36.6% compared with the decoupled route, respectively. Accordingly, CH4 cost is reduced by 12.6%. Our proof-of-concept experiments show that the energy consumption for CO2 release and H2 production is 704.0 kJ mol−1 and 967.4 kJ mol−1, respectively with subsequent methanation achieving a 97.3% conversion of CO2 and a CH4 production energy of 5206.4 kJ mol−1 showing a promising pathway for fuel processing from the air.

Reconfigurable Homojunction Phototransistor for Near-Zero Power Consumption Artificial Biomimetic Retina Function.

Semiconductor photodetectors integrating preliminary signal-processing functions play a vital role in artificial biomimetic retina systems. Herein, we propose a tungsten diselenide (WSe2) phototransistor with a dual-layer gate dielectric and an asymmetric graphene insert structure. This phototransistor exhibits a bidirectional self-powered photocurrent by controlling the gate voltage via the formation of reconfigurable p+-p and n-p homojunctions in the channel from the asymmetric graphene insert. At the same time, the nonvolatile electron and hole stored in the dual-layer gate dielectric are generated using a temporary gate voltage, which can replace the gate voltage to regulate the channel charge. Moreover, the photocurrent shows a linear relation with the temporary programming gate voltage. The phototransistor exhibits a rectification ratio of >4 orders of magnitude without the gate voltage, indicating its significant capability to operate in a fully self-powered mode with near-zero power consumption. Based on the device characteristics, we successfully simulate the biological functions of the photoreceptor layer and bipolar cell layer in the retinal receptive field. The identification of the object motion direction in the receptive field can be realized by integrating three programmable devices on the chip. Furthermore, edge enhancement of the image is achieved by independently modulating the light response of each pixel in the sensor by varying the programming gate voltage. This study will promote the developing progress of future artificial biomimetic retina systems.

Important Notes for Preventing Entrapment of Distal Filter-based Embolic Protection Device in Carotid Artery Stenting.

Failure to retrieve a distal filter-based embolic protection device (EPD) is a potential complication of carotid artery stenting. This may be caused by trapping of the proximal marker of the EPD within the stent tip marker. Maintaining an adequate distance between the two can prevent this. We examined the behavior of several stent-filter-based EPD combinations, focusing on their propensity to become trapped or disengage in vitro. Four physicians subjectively rated the force required to result in trapping using a 5-point scale. Moreover, the force required to disengage trapped devices was evaluated. The Casper stent-Spider FX EPD combination was difficult to disengage when entrapment occurred, which suggested that this phenomenon tended to occur with this combination. The stent tip marker of the closed-cell stents advanced as they shortened, which may be a unique feature of closed-cell stents. Although trapping is uncommon, it can cause serious complications. To prevent these complications, device characteristics should be well understood before they are used in patients.

An efficient device model for ferroelectric thin-film transistors

Ferroelectric thin-film transistors (Fe-TFTs) have promising potential for flexible electronics, memory, and neuromorphic computing applications. Here, we report on a physics-based efficient device model for Fe-TFTs that effectively describes memory switching and device I–V characteristics. This model combines a stochastic multi-domain description of FE switching dynamics with a virtual source treatment of TFT device characteristics. It demonstrates that the memory window of Fe-TFTs depends on the amplitude and duration of the applied voltage pulses, thus suggesting quantitative means of programming and control. Additionally, we introduce a machine-learning-enabled method to automatically generate optimal voltage pulses for accurately programming multiple intermediate FE states, which is crucial for multi-bit memory and neuromorphic computing applications. To showcase the model’s applications, we simulate a 4×4 crossbar array circuit based on Fe-TFTs, highlighting its utility in performing multiply-accumulate computing operations. This small array can achieve a high speed of ∼1.28 tera operations per second (OPS) and a power efficiency of ∼0.43 W/PetaOPS. The model developed here is valuable for exploring the capabilities of Fe-TFTs in future flexible memory and computing technologies.

On the stability of the dislocation structure of speckle fields

The features of propagation in free space of light beams with a dislocation structure of the wavefront are considered. The stability to the influence of diffraction of small-scale dislocation systems providing spatial super-resolution is analyzed. Based on a comparison of the characteristics of various dislocation formations, a conclusion is made about the greatest structural stability of systems with special type screw dislocations. Such dislocations can be obtained by azimuthal rotation of edge dislocations characterized by a sharp phase jump of light oscillations along the singular line. The obtained results will find application in optimizing the characteristics of optical devices with ultra-high spatial resolution, as well as in developing software for the operation of spatial light modulators forming beams with a specified amplitude-phase profile.

Rubbing-induced site-selective deposition of 2D material patterns on nanomembranes

2D-layered materials (e.g., graphene and transition metal dichalcogenides) have attracted huge attention due to their unique mechanical and electrical properties. Emerging research efforts, which seek to combine device characterization and high-resolution electron micrography analysis for 2D-layered device features, demand nano/microlithographic techniques capable of producing ordered 2D material patterns on ultrathin membranes with nanoscale thicknesses. However, such membranes are so fragile that most conventional lithographic techniques can be hardly performed on them to generate 2D material patterns. Our previous works have demonstrated that the rubbing-induced site-selective (RISS) deposition method can produce arbitrary 2D semiconductor (e.g., MoS2 and Bi2Se3) patterns on regular device substrates. This fabrication route prevents the vulnerable 2D-layered structures from the detrimental damage introduced by plasma etching and resist-based lithography processes. In this work, we explore the applicability of RISS for directly producing 2D material patterns on nanomembranes. Specifically, this work shows that a polymeric interfacing layer on the rubbing template features, which can effectively prevent stress concentration during the rubbing process, is crucial to successful implementation of RISS processes on nanomembranes. Furthermore, we carried out the mechanics simulation of the Von Mises stress and pressure distribution on the RISS-processed membrane to identify the optimal rubbing load, which can generate sufficient triboelectric charge for material deposition but no damage to the membrane. Using this approach, we have successfully demonstrated the deposition of Bi2Se3 patterns on 25 nm SiOx nanomembranes and high-resolution transmission electron micrography characterization of the crystallographic structures.

Advancing Multi-Ion Sensing with Poly-Octylthiophene: 3D-Printed Milker-Implantable Microfluidic Device.

On-site rapid multi-ion sensing accelerates early identification of environmental pollution, water quality, and disease biomarkers in both livestock and humans. This study introduces a pocket-sized 3D-printed sensor, manufactured using additive manufacturing, specifically designed for detecting iron (Fe2+), nitrate (NO3 -), calcium (Ca2+), and phosphate (HPO4 2-). A unique feature of this device is its utilization of a universal ion-to-electron transducing layer made from highly redox-active poly-octylthiophene (POT), enabling an all-solid-state electrode tailored to each ion of interest. Manufactured with an extrusion-based 3D printer, the device features a periodic pattern of lateral layers (width = 80µm), including surface wrinkles. The superhydrophobic nature of the POT prevents the accumulation of nonspecific ions at the interface between the gold and POT layers, ensuring exceptional sensor selectivity. Lithography-free, 3D-printed sensors achieve sensitivity down to 1ppm of target ions in under a minute due to their 3D-wrinkled surface geometry. Integrated seamlessly with a microfluidic system for sample temperature stabilization, the printed sensor resides within a robust, pocket-sized 3D-printed device. This innovation integrates with milking parlors for real-time calcium detection, addressing diagnostic challenges in on-site livestock health monitoring, and has the capability to monitor water quality, soil nutrients, and human diseases.

Novel 4H–SiC MESFET with high ability in gate capacitances control for high frequency applications

The ability to control the gate capacitances is crucial for high-frequency applications, as it affects the device's frequency characteristics, gain and power handling capabilities. We present a 4H–SiC metal-semiconductor field-effect transistor (MESFET) with high gate capacitance control ability for high-frequency applications. The proposed structure (GCC-MESFET) consists of a step gate and a SiC well for adjusting the channel depletion layer and modifying the channel charges. Therefore, the gate capacitances will be controlled (GCC-MESFET). The proposed structure significantly improves the cut-off frequency (fT) and maximum oscillation frequency (fmax). The fT has increased from 23.5 GHz to 33 GHz and the fmax from 50.1 GHz to 54.4 GHz in the proposed structure compared to a conventional structure (C-MESFET). The results show that the DC maximum output power density (Pmax), DC transconductance (gm), cut-off frequency (fT) and maximum oscillation frequency (fmax) of GCC-MESFET improve in comparison with a conventional structure (C-MESFET). It is necessary to mention that the drain current and the breakdown voltage of the proposed structure increase by 48 % and 20 % respectively, compared with the C-MESFET structure due to modifying the channel charges and adjusting the electric field. So, the proposed structure can be used for high current, high voltage, high-power and high frequency applications.