Switching Applications Research Articles

Impact of Interface Trap Charges on the Performance and Reliability of Heterojunction Hetero Dielectric Vertical Non-Uniform Channel Double Gate TFET

Abstract We examined the influence of interface trap charges on the performance of the source pocket heterojunction hetero dielectric vertical non-uniform channel double gate tunnel field- effect transistor (SP-HJ-HD-VNUCDG-TFET). Specifically, the effect of donor and acceptor traps on the analog/RF performance of the device was investigated. The SP-HJ-HD-VNUCDG-TFET was designed to improve the drive current of the TFET. The results of the proposed device are compared with a source pocket heterojunction vertical non-uniform channel double gate TFET (SP-HJ-VNUCDG-TFET). Several figures of merit, including cutoff frequency fT, gain bandwidth product, and the transconductance frequency product are analysed and, based on the simulation results, it appears that the SP-HJ-HD-VNUCDG-TFET is more suitable for low power switching applications compared to the SP-HJ-VNUCDG-TFET because performance of SP-HJ-HD-VNUCDG-TFET is less affected by the interface trap charges.

KV-class vertical p-n heterojunction rectifier based on ITO/diamond

Indium tin oxide (ITO) layers were sputter-deposited onto commercially available vertical p/p+ diamond structures consisting of 5 μm thick p-type (1.3 × 1016 cm−3) drift layers deposited by chemical vapor deposition on 250 μm thick heavily B-doped (3 × 1020 cm−3) single crystal substrates. The ITO is found to form a type II band alignment allowing Ohmic contact to the p-type diamond and creating a vertical n-p heterojunction. The maximum reverse breakdown of heterojunction rectifiers was ∼1.1 kV, with an on-resistance (RON) of 13 mΩ · cm2, leading to a power figure of merit of 99.3 MW/cm2. The on-voltage was 1.4 V, diode ideality factor was 1.22, with a reverse recovery time of 9.5 ns for 100 μm diameter rectifiers. The on/off ratios when switching from −5 V forward to 100 V reverse were in the range of 1011–1012. This is a simple approach for realizing high performance vertical diamond-based rectifiers for power switching applications.

All‐Optical Spatial Self‐Phase and Cross Phase Modulation Using an NLO Active Pyrylium Dye towards an Optical OR Gate

AbstractAll‐optical modulation and optical switching with nonlinear materials are integral parts of the advancing all‐optical communication network. This report discusses the synthesis of a promising pyrylium dye, pyrylium‐NH2 for NLO based applications and probes its spatial self‐phase and cross phase modulation (XPM) properties. This dye can be effectively used for all‐optical modulation and OR logic gate operation. A 532 nm DPSS laser of tunable power is used to study the intensity dependent nonlinear refractive indices (n2) of the dye in ethanol, methanol and acetone. The dye has shown significant n2 compared to the existing literature. Concentration dependence, incident intensity dependence and temporal evolution of the far field diffraction annuli rings in these three solvents were studied. The all‐optical modulation of a weak signal beam is demonstrated using a high intensity pump beam via cross phase modulation, paving the way to optical switching applications.

A Versatile Dual-Responsive Shape-Memory Gripper via Additive Manufacturing Toward High-Performance Cross-Scale Objects Maneuvering.

Smart grippers serving as soft robotics have garnered extensive attentions owing to their great potentials in medical, biomedical, and industrial fields. Though a diversity of grippers that account for manipulating the small objects (e.g., tiny micrometer-scale droplets) or the big ones (e.g., centimeter-scale screw) has been proposed, however, cross-scale maneuvering of these two species leveraging an all-in-one intelligent gripper is still challenging. Here, a magnet/light dual-responsive shape-memory gripper (DR-SMG) is reported, based on the hybrid of Fe-nanoparticles and shape-memory polymers. Thanks to its photothermal effect, the closed-state DR-SMG switches to the open state under the synergetic cooperation of near-infrared-ray (NIR) and a circinate magnetic field, referring to the temporary state. On the other hand, once the NIR is loaded, the temporary opened DR-SMG would reconfigure to its permanent closed state owing to shape-memory effect. Leveraging this principle, DR-SMG can grasp and release diverse cross-scale objects ranging from micrometers to centimeters including metals, glass balls, polymers, and small liquids. Significantly, this versatile DR-SMG is capable of spatially delivering multifunctional chemical droplets and conductive liquid metals, thereby enabling lab-on-chip and electrical switch applications. This work provides new insights into intelligent grippers and further advances the field of soft robotics.

Extraction of power transmission parameters from PT-symmetric waveguides.

The PT-symmetric waveguides have been frequently discussed in the photonics community due to their extraordinary properties. Especially, the study of power transmission is significant for switching applications. The aim of this study is to extract the mode power transmission parameters based on the coupled mode equations and analyze the power properties of the PT-symmetric system. The equations relying on the coupled mode theory are constructed according to the two different orthogonality relations between the original and adjoint system. The results matching well with the finite difference simulations demonstrate the validity of our method, while the conventional coupled mode theory fails. The power properties in the PT-symmetric and PT-broken phases are also observed. Furthermore, a new integration is implemented from which the conserved quantity is defined and extracted, which reflects the Hamiltonian invariant of the system. Our method fully incorporates the properties of complex modes and allows the study of the power transmission properties based on the orthogonality relations, which is also applicable to other types of non-Hermitian optical systems. This work provides what we believe to be a new perspective for the power analysis of PT-symmetric waveguides and is helpful to design the switching devices.

Clinical and radiographic outcomes of extra-short implants (≤ 6 mm) in the posterior atrophic jaws: a retrospective cohort study

ObjectiveThis study aimed at investigating implant survival rate and marginal bone loss (MBL) around extra-short implants. The impact of the loading protocol and of the use of an intermediate abutment was also evaluated, to explore possible differences in terms of the outcome measures.Materials and methodsPatients with single or multiple mandibular or maxillary posterior edentulism rehabilitated using extra-short 5–6 mm long implants were included. Different prosthetic protocols were used. Clinical and radiological follow-up was 5 years. The outcomes measures were implant survival and MBL.ResultsThe analysis included 56 implants placed in 34 adults (12 males and 22 females; mean age 60 years, SD 11). Six implants failed during a median follow-up of 5 years and 4 of them were recorded in one patient at 2-year follow-up. The 5-year implant survival was 89% overall (87% in conventional and 94% in immediate loading). At univariate analysis, during follow-up immediate loading was associated with higher MBL (mean variation 0.21 mm, 95%CI 0.01 to 0.40; p = 0.02), while intermediate abutment was associated with lower MBL (mean variation -0.23 mm, 95%CI -0.39 to -0.09; p = 0.003). Multivariable analysis confirmed that immediate loading was associated with higher MBL.ConclusionWithin its limitations, this study showed that extra-short implants under immediate loading conditions can be a reliable solution. The application of horizontal and vertical platform switching with the use of intermediate abutments seems to be able to contribute to the reduction of MBL.Graphical

Polyol-mediated synthesis of strontium hexaferrite nanoparticles and their potential application for resistive switching and non-volatile memory storage devices

Polyol-mediated synthesis of strontium hexaferrite nanoparticles and their potential application for resistive switching and non-volatile memory storage devices

Novel Magnetic-Field-Free Switching Behavior in vdW-Magnet/Oxide Heterostructure.

Magnetization switching by charge current without a magnetic field is essential for device applications and information technology. It generally requires a current-induced out-of-plane spin polarization beyond the capability of conventional ferromagnet/heavy-metal systems, where the current-induced spin polarization aligns in-plane orthogonal to the in-plane charge current and out-of-plane spin current. Here, a new approach is demonstrated for magnetic-field-free switching by fabricating a van-der-Waals magnet and oxide Fe3GeTe2/SrTiO3 heterostructure. This new magnetic-field-free switching is possible because the current-driven accumulated spins at the Rashba interface precess around an emergent interface magnetism, eventually producing an ultimate out-of-plane spin polarization. This interpretation is further confirmed by the switching polarity change controlled by the in-plane initialization magnetic fields with clear hysteresis. Van-der-Waals magnet and oxide are successfully combined for the first time, especially taking advantage of spin-orbit torque on the SrTiO3 oxide. This allows this study to establish a new way of magnetic field-free switching. This work demonstrates an unusual perpendicular switching application of large spin Hall angle materials and precession of accumulated spins, and in doing so, opens up a new field and opportunities for van-der-Waals magnets and oxide spintronics.

Quantum control in size selected semiconductor quantum dot thin films

Abstract We introduce a novel technique for coherent control that employs resonant internally generated fields in CdTe quantum dot (QD) thin films at the L-point. The bulk band gap of CdTe at the L-point amounts to 3.6 eV, with the transition marked by strong Coulomb coupling. Third harmonic generation (λ 3 = 343 nm, hν = 3.61 eV) for a fundamental wavelength of λ 1 = 1,030 nm is used to control quantum interference of three-photon resonant paths between the valence and conduction bands. Different thicknesses of the CdTe QDs are used to manipulate the phase relationship between the external fundamental and the internally generated third harmonic, resulting in either suppression or strong enhancement of the resonant third harmonic, while the nonresonant components remain nearly constant. This development could pave the way for new quantum interference–based applications in ultrafast switching of nanophotonic devices.

Tailoring Spectral Response of Grating-Assisted Co-Directional Couplers with Weighting Techniques and Rational Transfer Functions: Theory and Experiment

This work addresses the tailoring spectral response of grating-assisted co-directional couplers (GADCs) in the context of wavelength filtering for fiber-to-the-home (FTTH) applications. Design methods for spectral response engineering by means of coupling profile apodization-type weighting techniques and also more advanced rational transfer functions fitting a predefined spectral window template are presented. Modeling results based on coupled mode theory are then applied for the design and experimental fabrication of InGaAsP/InP GADCs targeting 1.3+/1.3− µm diplexer application in FTTH access networks. The experimental results are found to be in good agreement with the modeling predictions. The design tools presented are quite general and can be easily adapted to other technology platforms, such as silicon photonics for the use of GADCs as add-drop wavelength division multiplexers. The field of parity–time symmetry is another avenue where these types of gain–loss-assisted GADCs as active components are of interest for switching applications, and the design methods presented here may find utility.

Stabilizing Schottky-to-Ohmic Switching in HfO2-Based Ferroelectric Films via Electrode Design.

The discovery of ferroelectric phases in HfO2-based films has reignited interest in ferroelectrics and their application in resistive switching (RS) devices. This study investigates the pivotal role of electrodes in facilitating the Schottky-to-Ohmic transition (SOT) observed in devices consisting of ultrathin epitaxial ferroelectric Hf0.93Y0.07O2 (YHO) films deposited on La0.67Sr0.33MnO3-buffered Nb-doped SrTiO3 (NbSTO|LSMO) with Ti|Au top electrodes. These findings indicate combined filamentary RS and ferroelectric switching occurs in devices with designed electrodes, having an ON/OFF ratio of over 100 during about 105 cycles. Transport measurements of modified device stacks show no change in SOT when the ferroelectric YHO layer is replaced with an equivalent hafnia-based layer, Hf0.5Zr0.5O2 (HZO). However, incomplete SOT is observed for variations in the top electrode thickness or material, as well as LSMO electrode thickness. This underscores the importance of employing oxygen-reactive electrodes and a bottom electrode with reduced conductivity to stabilize SOT. These findings provide valuable insights for enhancing the performance of ferroelectric RS devices through integration with filamentary RSmechanism.

Strategies to enhance THz harmonic generation combining multilayered, gated, and metamaterial-based architectures

Graphene has unique properties paving the way for groundbreaking future applications. Its large optical nonlinearity and ease of integration in devices notably makes it an ideal candidate to become a key component for all-optical switching and frequency conversion applications. In the terahertz (THz) region, various approaches have been independently demonstrated to optimize the nonlinear effects in graphene, addressing a critical limitation arising from the atomically thin interaction length. Here, we demonstrate sample architectures that combine strategies to enhance THz nonlinearities in graphene-based structures. We achieve this by increasing the interaction length through a multilayered design, controlling carrier density with an electrical gate, and modulating the THz field spatial distribution with a metallic metasurface substrate. Our study specifically investigates third harmonic generation (THG) using a table-top high-field THz source. We measure THG enhancement factors exceeding thirty and propose architectures capable of achieving a two-order-of-magnitude increase. These findings underscore the potential of engineered graphene-based structures in advancing THz frequency conversion technologies for signal processing and wireless communication applications.

Electric field-assisted resonance frequency tuning in free standing nanomechanical devices for application in multistate switching using a phase change material.

VO2 possesses a unique property of solid-state phase transition near room temperature wherein it transforms from monoclinic (M1) to tetragonal phase (R) that alters its physical properties, such as resistivity, mechanical modulus, and lattice strain, at an ultrafast time scale known as MIT. Such a phenomenon offers a distinct advantage to use VO2 in switching applications using heat flux as a stimulus. However, such alteration in properties can also be triggered under an electric field (E), which is known as E-MIT. A nanomechanical resonator coated with VO2 recently received traction where the resonance behavior can be modulated by taking advantage of its phase transition. Herein, we demonstrate that by fabricating a microstring of 400 μm (L) × 5 μm (W) × 240 nm (t) of suspended SiNx coated with VO2, the frequency (fr) of the resonator can be modulated by applying an electric field. We show that at room temperature, the fr of the microstring can be either reduced (by 0.5% at 15 V mm-1) or enhanced (by 2.2% at 25 V mm-1) or can be varied in a cycle under E-field. Using theoretical models, we establish the simulated results and explain the processes behind it, which demonstrate excellent mechanical tuning properties of the VO2-based microstring resonator, making it an attractive and alternative option for highly efficient MEMS-based switches and neuromorphic devices.

Solvent and counterion cooperatively induced inversion of stereocenter Δ/Λ and CPL in a mononuclear Eu(III) complex

The development of lanthanide complexes with stimuli-responsive dynamic chirality inversion holds significant potential for applications in chiroptical switches and chiral sensing. However, the variable coordination numbers and coordination geometries of...

An organic-inorganic hybrid ferroelastic with a near-room-temperature phase transition.

Organic-inorganic hybrid metal halides (OIMHs) with ferroelastic phase transition properties have recently attracted great attention due to their widespread application prospects in the fields of energy storage, sensors, switches, etc. However, most of the hybrid ferroelastics exhibit phase transition points (Tc) far beyond room temperature, which may limit their applications in mechanical switches and energy storage for daily working requirements. Herein, we synthesized a new zinc halide OIMH ferroelastic (E,E)-[BPHD]ZnBr4 (BPHD = N1,N6-bis(piperidine-1-yl) hexa-2,4-diene diamide), which experiences a 2/mF1̄ type paraelastic-ferroelastic phase transition at a near-room-temperature Tc of 285 K. It crystallizes in the monoclinic P21/c space group at 298 K, undergoing a change to the triclinic P1̄ space group in the low-temperature phase, with the number of molecules in asymmetric units doubling. Differential scanning calorimetry, variable-temperature electrical resistivity (ρ) and Raman spectrum tests confirm the occurrence of the phase transition, accompanied by a change in ρ of nearly two orders of magnitude, and reversible evolution of ferroelastic domains has been observed. In addition, (E,E)-[BPHD]ZnBr4 also exhibits remarkable compliance and softness within the category of hybrid crystals. This work will inspire further exploration of new hybrid ferroelastic materials with near-room-temperature phase transitions.

Adding multiple electrons to helicenes: how they respond?

Helicenes of increasing dimensions and complexity have recently burst into the scene due to their unique structures coupled with interesting chiral, optical, and conducting properties. The helicene-related research has quickly progressed from fundamental curiosity to a diverse range of applications in organic catalysis, optoelectronic devices, chiroptical switches, sensors, and energy storage. The in-depth understanding of electron accepting properties of helicenes should further advance their materials chemistry applications, however, previous reports only relied on spectrocopic and electrochemical studies, while their structural changes weren't extensively discussed. Therefore, we initiated a broad investigation of chemical reduction behaviour of helicenes ranging in size and properties coupled with X-ray diffraction characterization of the reduced products. The responses of helicenes with different structures to the stepwise electron addition were investigated using a combination of X-ray crystallography, spectroscopic methods, and calculations. This study revealed topology- and charge-dependent consequences of chemical reduction ranging from reversible geometry perturbation to irreversible core transformation and site-specific reactivity of helicenes in addition to original alkali metal coordination patterns. This overview is focused on the crystallographically confirmed examples stemming from chemical reduction reactions of different helicenes with alkali metals. The opened discussion should stimulate further exploration of reactivity and complexation of novel π-expanded and heteroatom-doped helicenes based on the revealed structure-property correlations, thus advancing their applications as intriguing new materials.

Manipulating Polarization via Optical Fiber Twisting for Optical Switch Applications

Manipulating Polarization via Optical Fiber Twisting for Optical Switch Applications

Improved RNA toehold switch sensitivity using the NanoLuc complementation reporter.

RNA toehold switches are powerful tools that can be used as biosensors to detect nearly any RNA sequence. In the presence of a specific RNA trigger, the toehold switch allows translation of a reporter protein. Toehold switches expressed in cell-free expression systems have been used as biosensors for several viruses and bacterial RNAs. Here we explore the use of the NanoLuc complementation reporter NanoBiT and found that it provides improved sensitivity over sfGFP. This reporter can be applied broadly across other RNA toehold switch applications.

Conversion of Flexible Spin Crossover Metal-Organic Frameworks Macrocrystals to Nanocrystals Using Ultrasound Energy: A Study on Structural Integrity by MicroED and Charge-Transport Properties.

Metal-Organic Frameworks (MOFs) attract attention for their intrinsic porosity, large surface area, and functional versatility. To fully utilize their potential in applications requiring precise control at smaller scales, it is essential to overcome challenges associated with their bulk form. This is particularly difficult for 3D MOFs with spin crossover (SCO) behavior, which undergo a reversible transition between high-spin and low-spin states in response to external stimuli. Maintaining their structural integrity and SCO properties at the nanoscale remains a significant challenge, yet these properties make them ideal candidates for sensors, data storage, and molecular switch applications. This study reports the synthesis of nanocrystals of the well-known SCO MOF [Fe2(H0.67bdt)3]·xH2O (1, x = 0-10, bdt2- = 1,4-benzeneditetrazolate), which exhibits both magnetic and charge transport properties. The nanocrystals are obtained through sonication of macrocrystals, and the preservation of their crystalline structure at the nanoscale is explored using Microcrystal Electron Diffraction (MicroED). A comparison between macro- and nanocrystals highlights the structural integrity and the preservation of charge-transport properties, underlining the potential for further miniaturization of MOFs for advanced technological applications.

Fano and Electromagnetically Induced Transparency Resonances in Dual Side-Coupled Photonic Crystal Nanobeam Cavities.

We propose two types of structures to achieve the control of Fano and electromagnetically induced transparency (EIT) line shapes, in which dual one-dimensional (1D) photonic crystal nanobeam cavities (PCNCs) are side-coupled to a bus waveguide with different gaps. For the proposed type Ⅰ and type Ⅱ systems, the phase differences between the nanobeam periodic structures of the two cavities are π and 0, respectively. The whole structures are theoretically analyzed via the coupled mode theory and numerically demonstrated using the three-dimensional finite-difference time-domain (3D FDTD) method. The simulation results show that the proposed structure can achieve several kinds of spectra, including Fano, EIT and asymmetric EIT line shapes, which is dependent on the width of the bus waveguide. Compared to the previously proposed Fano resonator with 1D PCNCs, the proposed structures have the advantages of high transmission at the resonant peak, low insertion loss at non-resonant wavelengths, a wide free spectral range (FSR) and a high roll-off rate. Therefore, we believe the proposed structure can find broad applications in optical switches, modulators and sensors.