Device Applications Research Articles

"V"-Shaped Changing Electronic Performance of Iodinene-Based Nanoflakes as a Function of Width.

Special structures and prominent performance make 2D iodinene more appealing and valuable at the molecular level. Here, new-type electronic devices have been constructed with iodinene-based nanoflakes in different sizes and are theoretically studied for electronic transport properties. Our findings reveal that iodinene-based nanoflakes possess great electron transport suppression, achieving the same function as SiO2 on single molecule scale. Such transport suppression shows surprisingly nonlinear "V"-shaped trend with the width of the iodinene-based nanoflake. The medium-width iodinene-based nanoflake exhibits the strongest electron transport suppression, while the narrowest and widest ones display the largest electron transmission coefficients due to delocalized transmission eigenstates. Essentially, the weakest electron transport originates from an extremely small DOS and wide HOMO-LUMO gap. Specifically, increasing the width would diminish the extension of electronic states for the dominant transport orbitals, resulting in more butterfly-like electronic states. In non-equilibrium, negative differential resistance effect can be observed in iodinene-based devices, caused by the weakening and staying away from the Fermi level of transmission peaks influenced by the bias. Our findings provide insights into the relationship between the width of iodinene-based nanoflake and electronic transport properties, and lay a foundation in the device design and applications in molecular insulators and controllable-functional devices.

Tunable enhanced chiroptical response of a twisted L-shaped plasmon nanoparticle system

Chiroptical responses in plasmon systems have aroused widespread interest, manifesting potential application in fields including physics, biology, and pharmacy, as well as other disciplines. However, the enhancement and tunability of chiroptical responses by strong plasmon coupling, which have been seldom discussed, remain wanting. In this paper, we propose a stacked and twisted L-shaped nanoparticle system, which exhibits an enhanced chiroptical response and the dynamic modulation of chiroptical response. By adjusting the twist angle and the gap between L-shaped nanoparticles, the anisotropy factor g, which quantifies the relative strength of the chiroptical response, can reach up to −1.5, and the peak position and linewidth of the g spectrum can be modified. Furthermore, in instances where the chiroptical response is weak, we construct a finite-size 1D chain by using the proposed system as the unit cell. By harnessing the global interaction among the unit cell of the 1D chain, the maximum value of g can be effectively improved and adjusted. Such an L-shaped nanoparticle system as a fundamental structure has potential applications in tunable chiroptical devices and also extends methods for device design.

Optical and sign-flipping nonlinear optical properties of NiO/PMMA/PANI nanocomposite films

In this study, we introduce an efficient nanocomposite system to enhance optical properties of Nickel oxide (NiO) integrated with two polymers matrix. NiO nanoparticles is prepared using chemical co-precipitation method and its nanocomposite films (NCFs) were prepared with poly methyl methacrylate (PMMA) and polyaniline (PANI) using drop-casting method on glass substrate and was optimized by changing the concentration of NiO. The prepared NCFs were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), ultraviolet (UV)-visible absorption spectroscopy, photoluminescence (PL) spectroscopy and X-ray photoelectron (XPS) spectroscopy. The open-aperture z-scan method is employed for nonlinear optical investigations, utilizing a nanosecond pulsed laser with a wavelength of 532 nm for excitation. The findings indicate that the NCFs exhibit sign-flipping nonlinear behavior, indicating a transition from saturable absorption to reverse saturable absorption. This suggests that our NCFs exhibit optical limiting properties and potential for applications in photonic devices, such as optical switches and laser protection systems.

Doping dependent magnetic and thermoelectric response of perovskite BaGeO3 for spintronics and energy applications

Using ab-initio simulations, we have investigated the magnetic and thermoelectric response of the pristine and Mn-, Ni-, and In-doped BaGeO3 at Ge-site. The dopants Mn, Ni, and In can be doped at Ge-site due to lower formation energies. The dopants significantly alter the electronics properties of BaGeO3. Interestingly, the In-BaGeO3 exhibits half-metallic nature. Furthermore, our doped system exhibit the magnetic behaviour with 100 % polarization near Fermi level. Additionally, the spin orientation favors the ferromagnetic (FM) states for Mn-BaGeO3. Furthermore, the realization of magnetic anisotropy energy (MAE) may pave the way to use BaGeO3 for applications in magnetic devices. Moreover the zT (0.95) is enhanced for In-BaGeO3. Thus, our studied configuration could potential candidate for thermoelectric insulation as well as thermoelectric cooling applications. We are expecting that our findings could open the ways to utilize the BaGeO3 in the domain of spintronics and magnetic semiconductor devices applications.

Stretchable printed circuit boards using a silicone substrate of variable stiffness and conventional PCB fabrication methods

Abstract Stretchable printed circuit boards (S-PCBs) offer unique advantages over rigid PCBs such as enabling conformability to changing environments and ergonomic designs with increased lifetime under dynamic loads. This study introduces an innovative fabrication method and a cost-effective solution for rapid prototyping S-PCBs using commercially available materials. By utilizing silicone substrates with different levels of stiffness and structured copper sheets for electrical connections, the S-PCBs feature ‘stiff islands’ embedded in a flexible base material. This fabrication method helps alleviate mechanical strain on strain-sensitive components while allowing local deformation of the S-PCB. The proposed fabrication method does therefore enable to integrate surface mount device components into S-PCBs and facilitates complex circuit designs while maintaining stretchability and fatigue resistance. Through material characterization, video strain analysis, as well as quasi-static and cyclic loading tests, this article demonstrates the efficacy of our approach. Based on the experimental results, we provide insights into failure modes and suggest design principles to further enhance the durability of S-PCBs fabricated with our method. We then conclude by presenting a soft wearable S-PCB demonstrator. The S-PCBs fabricated with this method withstood mechanical strains up to 100% and cyclic loads with 30% strain up to 625 cycles. The results are very promising for applications in soft robotics, wearable devices, and soft sensors and actuators. Overall, our study offers a comprehensive toolkit for fast S-PCB prototyping, paving the way for advancements in stretchable electronics with a high degree of complexity and stretchability.

Effect of Temperature on TiO2/P‐Si‐Based Memristor Devices as Optical/Electrical Synapse

Light‐based modulation on resistive switching has opened a new route for development of the devices for advanced applications like integrated switching with memory functionality, neuromorphic computing, and humanoid robotics. This article presents the wafer‐scalable process to fabricate titanium dioxide (TiO2)/porous silicon (P‐Si)‐based heterostructures for memristor applications. The resistive switching performance of the memristor is analyzed using electrical/optical stimulation. The fabricated devices offer enhanced performance metrics during optical stimulation when compared to electrical stimulation. The memristor device offers the paired pulse facilitation (PPF) index of ≈519% (during optical stimulation), which is 3.4 times of the electrical stimulation. Further, the stability and reliability measurements are performed at different temperatures especially (room temperature to 348 K) under 450 nm illumination. The testing results prove that the developed TiO2/P‐Si‐based memristors are suitable for the next‐generation computation systems development.

Electrospinning Recombinant Spider Silk Fibroin-Reinforced PLGA Membranes: A Biocompatible Scaffold for Wound Healing Applications.

Polylactide-polyglycolide (PLGA) is one of the most attractive polymeric biomaterials used to fabricate medical devices for drug delivery and tissue engineering applications. Nevertheless, the utilization of PLGA in load-bearing applications is restricted due to its inadequate mechanical properties. This study examines the potential of recombinant silk fibroin (eADF4), a readily producible biomaterial, as a reinforcing agent for PLGA. The PLGA/eADF4 composite membranes were developed by using the process of electrospinning. The spinnability of the electrospinning solutions and the physicochemical, mechanical, and thermal properties of the composite membranes were characterized. The addition of eADF4 increased the viscosity of the electrospinning solutions and enhanced both the mechanical characteristics and the thermal stability of the composites. This study demonstrates that PLGA membranes reinforced with recombinant spider silk fibroin are noncytotoxic, significantly enhance cell migration and wound closure, and do not trigger an inflammatory response, making them ideal candidates for advanced wound healing applications.

2D Embedded Ultrawide Bandgap Devices for Extreme Environment Applications.

Ultrawide bandgap semiconductors such as AlGaN, AlN, diamond, and β-Ga2O3 have significantly enhanced the functionality of electronic and optoelectronic devices, particularly in harsh environment conditions. However, some of these materials face challenges such as low thermal conductivity, limited P-type conductivity, and scalability issues, which can hinder device performance under extreme conditions like high temperature and irradiation. In this review paper, we explore the integration of various two-dimensional materials (2DMs) to address these challenges. These materials offer excellent properties such as high thermal conductivity, mechanical strength, and electrical properties. Notably, graphene, hexagonal boron nitride, transition metal dichalcogenides, 2D and quasi-2D Ga2O3, TeO2, and others are investigated for their potential in improving ultrawide bandgap semiconductor-based devices. We highlight the significant improvement observed in the device performance after the incorporation of 2D materials. By leveraging the properties of these materials, ultrawide bandgap semiconductor devices demonstrate enhanced functionality and resilience in harsh environmental conditions. This review provides valuable insights into the role of 2D materials in advancing the field of ultrawide bandgap semiconductors and highlights opportunities for further research and development in this area.

Thermodynamic analysis of the inverse electrocaloric effect in ferroelectric thin films

Abstract Inverse electrocaloric (i-EC) effect occurs in ferroelectrics when the applied electric field aligns anti-parallel to polarization. In this study, the dependence of the i-EC effect on temperature and misfit strain is formulated and applied to clamped BaTiO3 thin films using the Landau–Ginzburg–Devonshire formalism. It is found that an interplay exists between the pyroelectric coefficient and the maximum possible inverse electric field. We demonstrate that the temperature change is strongly dependent on the inverse field amplitude and is maximal at lower temperatures away from the ferroelectric-paraelectric transition for a given misfit strain. Such an outcome is opposite to the direct electrocaloric effect, where it is desirable to remain near the transition temperature for the maximum electrocaloric temperature change. The fact that the i-EC effect can be maximum at lower temperatures could allow for the potential tailoring of this effect in strained films at moderate temperatures for device applications.

Charged Impurity Scattering and Electron-Electron Interactions in Large-Area Hydrogen Intercalated Bilayer Graphene.

Intercalation is a promising technique to modify the structural and electronic properties of 2D materials on the wafer scale for future electronic device applications. Yet, few reports to date demonstrate 2D intercalation as a viable technique on this scale. Spurred by recent demonstrations of mm-scale sensors, we use hydrogen intercalated quasi-freestanding bilayer graphene (hQBG) grown on 6H-SiC(0001), to understand the electronic properties of a large-area (16 mm2) device. To do this, we first analyze Shubnikov-de Haas (SdH) oscillations and weak localization, permitting determination of the Fermi level, cyclotron effective mass, and quantum scattering time. Our transport results indicate that at low temperature, scattering in hQBG is dominated by charged impurities and electron-electron interactions. Using low- temperature scanning tunneling microscopy and spectroscopy (STS), we investigate the source of the charged impurities on the nm-scale via observation of Friedel oscillations. Comparison to theory suggests that the Friedel oscillations we observe are caused by hydrogen vacancies underneath the hQBG. Furthermore, STS measurements demonstrate that hydrogen vacancies in the hQBG have an extremely localized effect on the local density of states, such that the Fermi level of the hQBG is only affected directly above the location of the defect. Hence, we find that the calculated Fermi level from SdH oscillations on the millimeter scale agrees with the value measured locally on the nanometer scale with STS measurements.

Theoretical studies of the bipolar properties of ScAlN/AlGaN/GaN heterostructures for enhanced device applications

Abstract Here, we describe a systematic theoretical study of ScAlN/AlGaN/GaN heterostructures for enhanced high-electron-mobility transistors (HEMTs). We have investigated the carrier distributions and energy-band diagrams by solving the coupled Schrödinger and Poisson equations self-consistently. When the heterostructure is in the “off” state, the two-dimensional electron gas (2DEG) becomes increasingly depleted as the ScAlN thickness is increased to the critical thickness, at which point the two-dimensional hole gas (2DHG) appears. This critical thickness depends on the Sc content. Increasing the AlGaN thickness or Al content causes a simultaneous increase in the 2DEG and 2DHG sheet densities. In addition, when the HEMT is in the “on” state, 2DEG sheet density increases as ScAlN thickness increases, so long as the Sc content is less than 0.3; when the Sc content exceeds 0.4, this trend is reversed. For a given Sc content, double channels are produced when the ScAlN thickness exceeds the critical thickness.

Criterion for vanishing valley asymmetric transmission in dual-gated bilayer graphene

Abstract Realizing valley asymmetric transmission(VAT) for incoming valley unpolarized Dirac carriers across an electrostatically modulated confinement potential(ECP) step, which is located at the interface of the unipolar ($n-n'$) junction in dual-gated Bernal-bilayer graphene(BBG), has caught growing attention because it provides a platform to study the valley polarizer. Such a junction, however, seems to preclude from supporting vanishing VAT. Based on the effective two-band Hamiltonian of BBG with wave matching approach, we demonstrate theoretically that VAT through the $n$/$ n'$ interface vanishes in the following conditions: (i) the disappearing electrostatically modulated interlayer potential difference(EPD), or (ii) the invariance condition of the sum or difference of ECPs and EPDs, which physically corresponds to the zero band offset of the conduction or valence band in the band alignment of $n-n'$ junction. Guided by this, it is worth mentioning that the we can derive simple, analytical valley-independent expressions for the reflection and transmission probabilities. We further find the appearance of the nearly vanishing VAT for the four-band model in bilayer graphene with 'Mexican hat'-like band. As a byproduct, we apply these findings to suggest the best design for the valley-dependent selection of momenta based on dual-gated BBG connected to two pristine BBG electrodes in which ECPs of the two outer regions are distinguishable and show that the sign of valley polarization can be switched via varying EPD. We expect our results can provide guidance for future device applications relying on ballistic and valley-selective transport.

Modelling of Cut-off Frequency of Armchair Graphene Nanoribbon Tunnel Field Effect Transistor Using Transfer Matrix Method

Graphene is considered as a promising two-dimensional material for electronic device applications due to its high charge carrier mobility and it is extremely thin in size. As a material, graphene has great potential for the development of high-speed nano electric devices. Graphene can be used as a channel material in Tunnel Field Effect Transistor (TFET). In this study, the cut-off frequency of the armchair graphene nanoribbon tunnel field effect transistor (AGNR-TFET) device was modelled quantum mechanically. The solution of the Dirac-like Hamiltonian and Poisson equations self-consistently is used to determine the potential profile of device and the transmittance is calculated using the transfer matrix method (TMM). The Landauer formulation with the help of Gauss Legendre Quadrature Method (GLQM) is used to calculate the tunnelling current and the cut-off frequency of AGNR-TFET. The calculation results showed that the cut-off frequency increased as the drain voltage increased, while the increase in channel length and the N-index graphene made the cut-off frequency decreased. Moreover, the thicker the oxide layer could increase the cut-off frequency and the higher the temperature on the device would reduce the cut-off frequency.

Modeling of the metal–insulator transition temperature in alio-valently doped VO2 through symbolic regression

The correlated semiconductor vanadium dioxide (VO2) exhibits an insulator–metal transition (IMT) near room temperature, which is of interest in various device applications. Precise IMT temperature control is crucial to determine the use cases across technologies such as thermochromic windows, actuators for robots or neuronal oscillators. Doping the cation or anion sites can modulate the IMT by several tens of degrees and control hysteresis. However, modeling the effects of control parameters (e.g., doping concentration, type of dopants) is challenging due to complex experimental procedures and limited data, hindering the use of traditional data-driven machine learning approaches. Symbolic regression (SR) can bridge this gap by identifying nonlinear expressions connecting key input parameters to target properties, even with small data sets. In this work, we develop SR models to capture the IMT trends in VO2 influenced by different dopant parameters. Using experimental data from the literature, our study reveals a dual nature of the IMT temperature with varying tungsten (W) doping concentrations. The symbolic model captures data trends and accounts for experimental variability, providing a complementary approach to first-principles calculations. Our feature-driven analysis across a broader class of dopants informs selectivity and provides qualitative insights into tuning phase transition properties valuable for neuromorphic computing and thermochromic windows.

Multiple Conformal-Contact Transfer of Large-Area Crack-Free Transition Metal Dichalcogenide Stacks

Abstract Atomically-thin two-dimensional (2D) transition metal dichalcogenides (TMDs) have emerged as an ideal platform for both physics investigation and device applications. By stacking different layers into homo- or hetero-structures, an extra degree of freedom is involved in further tuning their properties, thereby boosting scenarios in twistronics, moiré photonics and optoelectronics. However, interfacial imperfections such as contaminations and cracks, frequently occur during the layer stacking sequence and accumulate layer by layer, greatly degenerating the interface quality. In this study, we developed a multiple conformal-contact transfer method to construct TMD stacks with crack-free intrinsic interfaces. The design of a deformable buffer layer is crucial to guarantee the conformal contact and intact transfer of each layer, contributing to the successful construction of centimetre-scale TMD stacks up to 8 layers. Precise control over spatial location and interlayer twist angle is also feasibly achieved, evidenced by the stacking-dependent interlayer exciton effects in WS2-WSe2 heterostructures. This work provides a facile and precise approach for architecting 2D stacks with perfect interfaces, which will further accelerate the customized design for their device functionalization.

Theoretical Insights into Off-Stoichiometric Zr(x)Ti(1-x)IrSb Half-Heusler Alloys: A First Principle Calculations.

This study presents a theoretical investigation into the phase stability, electronic, and optical properties of off-stoichiometric Zr_{x}Ti_{1-x}IrSb (x = 0, 0.0625, 0.1875, 0.25, 0.50, 0.75, 1) compounds. Using first-principles calculations, we explore how varying Zr and Ti concentrations can tune the electronic and optical properties of these half-Heusler alloys. The Structural, optical, and electronic properties were meticulously analyzed with both the GGA-PBE and Meta-GGA-SCAN approximations, as implemented in the Vienna Ab initio Simulation Package (VASP). The dynamical stability of these compounds was assessed using the Phonopy package. Our findings reveal that these alloys exhibit semiconductor behavior with tunable band gaps, and their optical properties show significant variation across different compositions, particularly in the visible light range. The compounds also demonstrate robust dynamical stability, indicating their potential for practical applications in electronic and optoelectronic devices. These results underscore the versatility of Zr_{x}Ti_{1-x}IrSb alloys and highlight their promise for next-generation technology.

Flexibility, Dispersion Property, and Giant Sunlight Absorption of Monolayer MX2 (M = Zr, Hf; X = S, Se) and Related Janus MXY (M = Zr, Hf; X = S, Y = Se)

IVB–VIA transition metal dichalcogenides (TMDs) MX2 (M = Zr, Hf; X = S, Se) and related Janus MXY (M = Zr, Hf; X = S, Y = Se) have garnered significant attention due to their unique optoelectronic properties. To further explore their potential in flexible photonics, their mechanical, band dispersion, and optical dielectric properties using orbital hybrid theory are investigated. The results reveal that the out‐of‐plane linear compression resistance of these materials is considerably lower than their in‐plane resistance, primarily because van der Waals interactions are much weaker compared to ionic bond interactions. This characteristic makes them less susceptible to external pressure and torsional forces, positioning them as promising candidates for flexible optoelectronic devices. Furthermore, the presence of multiple energy bands at the same momentum state suggests a tendency toward metal–insulator transitions. Notably, the materials exhibit a high photon flux, indicating robust photoelectric conversion capabilities, making them suitable for applications in photoelectric transducers. This study not only deepens the understanding of the optoelectronic and mechanical properties of IVB–VIA TMD materials, but also offers theoretical guidance for the development and application of flexible optoelectronic devices based on IVB‐VIA TMDs and related Janus materials.

Stability‐Enhanced Variable Stiffness Metamaterial with Controllable Force‐Transferring Path

AbstractSelf‐contact variable stiffness (SVS) metamaterial offers specific patterns of elastic strain energy storage by changing its force‐transferring path. The change of the elastic strain energy storage patterns further influences the stiffness variation of the SVS metamaterials. However, challenges still arise because typically fabricated SVS metamaterials inevitably contain structural irregularities, eccentricities, and defects. These microstructural imperfections impede the stable generation of designed strain energy storage patterns in the metamaterial, implying that the SVS metamaterials cannot achieve expected stiffness variations. To address this burning question, an SVS metamaterial/meta‐structure design paradigm with eccentric unit designs is proposed, which can realize both stable stiffness variations and high load‐bearing. The theoretical, simulation, and experimental results demonstrate that the SVS chain meta‐structure achieves ≈110 times stiffness variation between the low and high loading conditions. Its load‐bearing can reach more than 1500 N when the meta‐structure falls into the high stiffness stage. Furthermore, some typical functions are demonstrated using the stability‐enhanced SVS metamaterial, including customized mechanical protections for human joints and information transformation regulated by remote mechanical input signals. The results can provide a useful solution for generating a more feasible stability‐enhanced SVS metamaterial/meta‐structure and promote their potential applications in aerospace, medical devices, and robotics.

Multifunctional optoelectronic devices based on two-dimensional tellurium/MoS2 heterojunction

Two-dimensional van der Waals heterojunctions consisted of p–n-type semiconductors have been rapidly developed owing to their built-in electric field which can facilitate the separation of photogenerated electron–hole pairs and properties like current rectification and negative differential transconductance. Benefitting from these advantages, we have prepared an air-stable multifunctional p-tellurium (Te)/n-MoS2 heterostructure working both as a self-driven broadband photodetector and as an optically switchable complementary metal-oxide-semiconductor inverter. For photodetection, this device exhibits wavelength-modulated positive/negative optical response with large responsivity (1.51 A/W at 520 nm and 642.92 mA/W at 1550 nm, Vds = 0 V) and fast response speed, showcasing its prospects for optical encoding communication. Moreover, the device has been demonstrated to function as an inverter that will be shut down by illumination. Our multifunctional device possesses the compactness of integrated modules, widens the application scope of Te-based heterojunctions, and provides a reference for the application of Te-based devices in the field of integrated circuits.

КЕРУВАННЯ ДИНАМІКОЮ ІМПУЛЬСНОГО ПЕРЕТВОРЮВАЧА З М’ЯКИМ ПЕРЕМИКАННЯМ, ЩО ПРАЦЮЄ НА ДУГОВЕ НАВАНТАЖЕННЯ

Issues of design and research of energy-efficient and reliable semiconductor DC voltage converters for wide application in power supply devices of arc plasmatrons used in plasma metal cutting installations are considered. An estimated structural dynamic model of a soft-switching DC converter with a closed-loop control system combining the power part and the control system, intended for use as part of the latter as a digital module, was built. A technique is proposed and methods of controlling the converter are found, which provide the specified duration of transient processes, the permissible value of load current pulsations in a quasi-steady mode and the astatism of the output current, which confirms the correctness of the proposed technique. A prototype of a pulse stabilizer with digital control was made. The results of experimental studies of the sample confirm the effectiveness of the developed control device, namely the achievement of the specified duration of transient processes caused by a step change in the load current, close to 10-12 periods of conversion and astatism of the output current. It is shown that the application of a pulse stabilizer, in which a digital control loop is used, has significant advantages compared to analog options and has the advantages of a strategic plan. The use of combined control allows you to significantly reduce the requirements for the overall gain of the main control channel, which greatly facilitates the choice of sequential digital correction. Research results may be of interest to specialists in the field of power electronics, power supply systems of autonomous objects and control systems. References 14, figures 11. Key words: automatic control system, digital controller, external disturbance, plasma, robustness, optimization.