Switching Applications Research Articles

Complementary Superwetting Structures Treated by a Femtosecond Laser for Simultaneous Spontaneous Directional Transport of Water Droplets and Underwater Bubbles.

The control of fluid transport is crucial and has broad applications in the fields of intelligent systems and microfluidics. However, current studies usually focus on the spontaneous directional transport of a single type of fluid or require complex preparation processes. In this paper, the single femtosecond laser direct processing of complementary superwetting structures using polyimide/polytetrafluoroethylene is proposed, for the first time, to realize simultaneous spontaneous directional transport of water droplets and underwater bubbles without any additional energy or chemical treatment. The flexible laser fabrication enables the creation of diverse transport structures, facilitating the achievement of linear and curvilinear fluid transport on superwetting structures. In addition, relevant applications in self-transporting chemical reactions and bubble switching are presented. This technique provides a novel approach to fabricate patterned superwetting surfaces for applications in intelligent transport, microbiology, and chemistry.

Tuning properties of binary functionalization of Sc2C MXenes for supercapacitor electrodes

Surface functionalization of two-dimensional (2D) materials like Sc2C MXenes offers a promising avenue for tailoring their properties for various applications. At the same time, significant research has focused on pure terminations involving oxygen (-O), fluorine (-F), or hydroxyl (-OH) groups. Binary surface functionalization still needs to be explored. Our work addresses this gap by investigating binary functionalized Sc2C monolayers, specifically Sc2CFN and Sc2COS. Using first-principles calculations, we explore the structural, electronic, and quantum capacitance (CQ) properties of pristine Sc2C and functionalized Sc2CFN and Sc2COS. The CQ measurements reveal distinctive electronic behaviour, with Sc2CFN and Sc2COS exhibiting indirect bandgaps of 0.90 and 1.48 eV, respectively. Introducing functional groups induces a metal-to-semiconductor transition, enhancing charge storage at the cathode and increasing the CQ to 371.64 and 341.23 μF/cm2 for Sc2CFN and Sc2COS, respectively. As far as energy applications are concerned, we also calculate the Shockley-Queisser (SQ) efficiency, which is a widely accepted quantity to get an estimate of the photovoltaic efficiency of 28.77 % for Sc2CFN and 32.97 % for Sc2COS materials. Additionally, we analyze the current-voltage (IV) characteristics, uncovering negative differential conductance (NDC) effects in Sc2COS, indicative of its potential for fast molecular switching applications. Our study provides valuable insights into the properties of binary functionalized Sc2C MXenes, paving the way for their utilization in energy storage and nanoelectronic devices.

Demonstration of normally OFF beta-gallium oxide monolithic bidirectional switch for AC switching applications

In this work, we report on the beta-gallium oxide (β-Ga2O3) monolithic bidirectional switch. The as-fabricated switch works on enhancement mode operation with a threshold voltage of ∼4 V. Maximum drain current density of 1.93 mA/mm is obtained with a drain voltage of 5 V. The bidirectional switch in a bidirectional mode has an ON/OFF current ratio of ∼107 with ON-resistance of 1.11 and 1.09 kΩ · mm in forward and reverse direction, respectively. However, in diode mode, the device shows an ON/OFF current ratio of 1.6 × 108 and 1.4 × 108 in forward and reverse conduction modes, respectively. The fabricated β-Ga2O3 monolithic bidirectional switch is then used to chop a 60 Hz Alternating Current signal at a chopping frequency of 1 kHz, indicating its potential applications in a range of converters.

First-principles studies of strain-tunable InN monolayer: applications for switching and optoelectronic devices

Abstract Two-dimensional (2D) materials are attracting significant attention for their potential applications in the post-Moore era. In this work, we systematically investigate the effect of strains on the electronic structure, transport and optoelectronic properties of 2D Indium nitride (InN) monolayer using density functional theory and non-equilibrium Green’s function methods. The results show that strains can modulate the electronic properties. Specifically, biaxial strain triggers the transition from semiconductor to metal and indirect to direct band gap. On this basis, the constructed InN-based nanodevice exhibits current switching ratios up to 1010. In addition, the optoelectronic device based on InN monolayer exhibits a robust photoelectric response in the red light. Meanwhile, biaxial strain can improve the optoelectronic performance of InN-based optoelectronic devices. The compressive strains blue-shift the photocurrent peaks of the InN monolayer, which effectively modulates its detection range in the visible light region. These findings underscore the potential applications in nanotechnology, particularly in nano-switches and optoelectronic devices.

Fabrication of Tungsten/n-CdSe/Pyrographite/Brass sandwiched electronic device and transport characterization for its resistive switching applications

Fabrication of Tungsten/n-CdSe/Pyrographite/Brass sandwiched electronic device and transport characterization for its resistive switching applications

Turning four-wave mixing on and off in elliptically birefringent fibers via narrow frequency detuning.

Controlling four-wave mixing (FWM) is vital for several applications, including fiber optical communication, optical signal processing, optical amplification, and frequency generation. This paper presents a novel, to our knowledge, approach to control unidirectional FWM in elliptically birefringent fibers. By leveraging the frequency-dependent polarization eigenmodes of these fibers and detuning the optical frequency of one of the pump fields by a few megahertz, we can turn the FWM interaction on and off, thus controlling the generation of signal and idler fields. Moreover, this approach allows us to turn off the FWM interaction at any desired frequency, enabling all-optical switching and narrowband filtering applications.

Strain engineering for the interfacial thermal resistance of few-layer graphene with porous defects

As electronic devices continue to advance toward higher integration, thermal management issues have become a bottleneck, limiting device performance at the nanoscale. In this study, we reveal the bistable structural characteristics of circular hole defects in few-layer graphene, exhibiting both adhered and separated states, through molecular dynamics simulations. We propose a mechanical model that considers the interplay between the bending energy and cohesive energy to determine the critical size of the hole defect, at which the structure transits between the adhered and separated states. We further demonstrate that strain engineering can adjust the interfacial thermal resistance by more than fivefolds, which drives the structure transit between bistable states. The strain effect on the interfacial thermal resistance of the structure can be accurately described using analytical models. These findings illustrate that strain engineering is an effective method for precisely controlling the interfacial thermal resistance in few-layer graphene and provide new insights into possible thermal switch applications.

Device to circuit level implementation of JL-NSFET for DC/analog/RF applications at sub-5nm technology node: design optimization and temperature analysis

Abstract This manuscript introduces, for the first time, a novel approach that incorporates a comprehensive analysis of sheet variations (1–5) and every individual sheet wise temperature variation, and as well as an investigation of various GS high-k gate dielectrics in Junction-less (JL) Nanosheet FET (JL-NSFET). The study starting from device level (Digital/Analog/Radio Frequency) to circuit (CMOS Inverter and ring oscillator) as a whole package is investigated through well calibrated TCAD simulation and the results portrayed. NSFETs are the ultimate choice for integrated circuits (ICs) at sub-5 nm technology node. The notion of this paper is to design and optimization of NSFET with GS high-k gate dielectrics (Al2O3, HfO2, ZrO2 and TiO2) Initially. The switching/analog and RF metric revels that HfO2 is superior in terms SS, switching applications and more compactable with CMOS process. Further, adding number of sheets and temperature variation has been done later. As number of sheets increases, the effective channel width increases, electric field distribution takes place evenly and enhanced gate control owing to improved I O N , I O N / I O F F r a t i o , SS and DIBL. However, increasing the number of vertical channel layers (sheets) more than 2 results into diminished analog/RF performance of JL-NSFET owing to increased parasitic capacitances. Further, the impact of temperature variations (250 K to 450 K) studied for different sheet variations (1 to 5) and noticed that analog/RF such as gm, gds, fT, TFP and GTFP are enhanced by 40.82%, 28.76%, 40.69%, 64.62% and 70.59%, respectively at lower temperature (250 K) when compared to high temperature (450 K). These enhancements make the device is ideal for applications in cryogenic computing systems, satellites, deep space probes, and other aerospace technologies. Furthermore, as the circuit level implementation CMOS inverter and 5-stage ring oscillator (RO) are examined for different sheets and observed as sheets increase delay and EDP increases. For a CMOS inverter the NMH (0.295 V) and NML (0.280 V) are better at 2 sheets with a highest gain of 9.38 V/V. Hence, it is advised to use two or three sheets-based JL-NSFETs for high-performance and lower-power analog/RF applications.

Ultra-wideband terahertz absorber with switchable multiple modes based on graphene and vanadium dioxide metamaterials

This article proposes a dynamic switchable broadband absorber based on graphene and vanadium dioxide (VO2). The temperature could adjust the conductivity of VO2, and external voltage could alter the conductivity of graphene. Therefore, they can be used for broadband absorption that can be switched between low and high frequencies and for achieving coupled ultra-wideband absorption. When the Fermi level of graphene is 0.9eV and VO2 is in a non-metallic state, the absorber can achieve absorption of over 90% in the range of 2.55THz-4.86THz. When the Fermi level of graphene is 0.1eV and VO2 is in a metallic state, the absorber can achieve absorption of over 90% in the range of 4.30THz-9.40THz. When the Fermi level of graphene is 0.6eV and VO2 is in a metallic state, the absorber can achieve absorption of over 90% in the range of 2.32THz-9.80THz. The absorber only partially depends on the incident angle of the incident light, simulation results show that when the incident angle is below 50 degrees, more than 90% of the absorption bandwidth changes less. The absorber has no relation to the polarization angle of the incident light, and can keep its original property at any polarization angle. This structure has potential applications in electromagnetic wave stealth devices, optical switches and filters.

Design and application of inertia switch with the zero-time trigger sensor for projectile overload impulse

The paper introduces a novel inertial trigger sensor featuring a multi-layer stacked single-arm brass beam pendulum, aimed at applications in automotive and aerospace fields, etc. It employs the Lagrangian equation for dynamic modeling and finite element analysis to achieve precise inertia force measurements. The design incorporates advanced fabrication techniques and a high-precision latching mechanism that combines circuit self-locking with mechanical triggering. Validated through simulations and testing, The results of the live ammunition tests indicate that, apart from failures of the Inertia Switch due to errors in the manufacturing process, all other inertial switches functioned normally. This demonstrates that the inertial sensor provides an adjustable trigger time of 0–5 ms and reliably withstands extreme overloads of up to 15000 g. This work significantly enhances the performance of inertial sensors in high-stress environments.

Nonlinear Optical Properties of La3+-Doped Tellurite-Zinc Glasses: Impact of Chemical Bonding and Physical Properties via Raman and XPS

Understanding the connection between the local environments of lanthanum ions in tellurite glasses and their nonlinear optical (NLO) properties is essential for various technological applications. Rare earth ions can serve as probes for the local environments of the host material if the structure-property correlations are well understood. In this study, we investigated glasses with compositions 70TeO2 - (30-x)ZnO - (x)La2O3 (mol%) (x = 0, 5, 7, 9) fabricated by the melt-quenching technique. The capabilities of combined Raman and X-ray photoemission (XPS) spectroscopy were used to identify these glasses and define spectral deconvolution for distinguishing them in the formation of bridging oxygens (BO) and non-bridging oxygens (NBO). NLO properties were evaluated using open-aperture (OA) and closed-aperture (CA) Z-scan measurements with femtosecond (fs) laser pulses (∼220 fs, 750 Hz) at wavelengths ranging from 600 to 1500 nm. Raman spectra revealed a shift to higher frequencies from 731 to 746 cm-1, with increasing of La3+ ions, indicating the conversion of TeO4 polyhedra to TeO3 structural units, affecting the Te-O- Zn2+ or Te=O bonds and resulting in a variation of the polarizability. Besides the conventional analysis of oxidation state and chemical shifts of the core-level peaks, XPS spectroscopy included a careful analysis of the type oxygen bridges and metal-oxygen bond length to distinguish otherwise similar spectral contributions of different TZL glasses. Glasses with a high fraction of Zn2⁺ ions bonded with oxygen form NBO and modify the local structure of the glass network, while La³⁺ ions coordinate with oxygen atoms or interact with the lone pairs of tellurium atoms. By analyzing the correlation in different concentrations of La3+ ions, the Te-O bonds and NBO/(BO+NBO) ratio were clearly demonstrated. These findings suggest charge compensation between the Zn2⁺ and La³⁺ ions, for maintaining structural stability within the glass network. This study also reveals an enhancement of NLO properties as a function of La3+ ions concentration in TZL glasses under fs laser excitation due to resonant nonlinearity. The third-order optical nonlinearities showed an increase in the two-photon absorption coefficient (β) from 0.26×10-2 cm GW-1 (TZL5) to 0.62×10-2 cm GW-1 (TZL9), along with an increase in the nonlinear refractive index (n2) from 0.32×10-18 m2 W-1 to 0.65×10-18 m2 W-1. This enhancement is attributed to the increased number of NBOs and the high polarizability of La3+ ions. For all-optical switching (AOS) applications, two figures of merit were applied using the n2, α0, and β coefficients. The results suggest that the TZL glasses studied are potential candidates for AOS devices. Thus, this work not only elucidates the factors underlying the NLO properties but also highlights the promising potential of these glasses for use in AOS devices.

Effect of Substrate Thinning on Temperature Rise in Ga2O3 Rectifiers

The low thermal conductivity of β-Ga2O3 is a concern for the high-power switching applications envisaged for this ultra-wide bandgap semiconductor. In this work, we examine the effect of substrate thinning to reduce the temperature rise in rectifiers under high power conditions and also reduce the on-resistance. The Ga2O3 substrates on which the rectifiers were fabricated were thinned from the original thickness of 630 μm to a lowest value of 50 μm and transferred to a brass heat sink. Experimentally, we observed that the on-resistance was reduced from 5.66 to 5.17 mΩ.cm2 when thinning to 50 μm, in excellent agreement with simulations. The calculated peak temperature rise was roughly halved for rectifiers on such thin substrates over a broad range of power densities (500–1500 W.cm2), a result supported by thermal imaging.

Fano resonance based on ENZ mode in multilayer film and its optical switch application

This paper proposes a multilayer film structure consisting of an Au film, a Dysprosium-doped cadmium oxide (CdO:Dy) layer, and a SiO2 dielectric layer. The epsilon-near-zero (ENZ) mode is indirectly excited by the surface plasmon polariton (SPP) mode, and Fano resonance can be excited by the coupling of the two modes. The higher the wavelength-sensitivity of the real part of the dielectric constant of the ENZ material at the ENZ wavelength, the narrower the bandwidth of Fano resonance in the reflection spectrum. The indium tin oxide (ITO) is used to replace CdO:Dy as a switching material, and the ENZ wavelength is dynamically controlled by bias voltage. The ON and OFF states of the reflection spectrum can be switched at the wavelength of 1410 nm, achieving an insertion loss of 0.56 dB, an extinction ratio of 13.44 dB, and a figure of merit of 23.48 at this wavelength. This multilayer film structure has potential applications in the field of optical switches.

Phase transition studies of a fluorinated antiferroelectric liquid crystal probed by temperature dependent Raman spectroscopy

Fluorinated liquid crystals (LCs) have emerged as a valuable option for display technologies, rapid switching applications, and photonic devices. Addition of fluorine atoms in the LCs change the electronic distribution within the molecule, introducing required LC properties for various display techniques. In this study, the structural properties of an antiferroelectric LC, (S)-octan-2-yl 2,3-difluoro-4′’-((6-((2,2,3,3,4,4,5,5,6,6,7,7,7-tridecafluoroheptanoyl)oxy) hexyl) oxy)-[1,1′,4′,1′’-terphenyl]-4-carboxylate is investigated using Raman spectroscopy. This LC exhibits a unique orthoconic antiferroelectric arrangement along with chiral smectic C (SmC*) and smectic A (SmA*) phases. Raman spectra were recorded over a temperature range of 20 °C to 130 °C, covering the spectral region of 500–3500 cm−1. Additionally, theoretical Raman spectra at room temperature is simulated using density functional theory (DFT) with the B3LYP functional and 6-31G (d, p) basis set, showing good agreement with experimental results. Through meticulous fitting of the spectral features using Lorentzian profiles, precise values for peak positions, linewidths, and integrated intensities of selected Raman bands are obtained. Changes in Raman spectral parameters at the crystalline-SmCA*, SmCA*-SmC*, SmC*-SmA*, and SmA*-isotropic phase transitions are analyzed in terms of molecular alignment and intra/intermolecular interactions. The Raman spectral results provide a detailed understanding of the molecular and structural behaviour of the liquid crystal as it undergoes various phase transitions with increasing temperature.

Electrochemically-Switched Microwave Response of MXene in Organic Electrolyte.

The increasingly complex electromagnetic (EM) environment necessitates advanced electrically controllable electromagnetic interference (EMI) shielding materials that can adapt to varying EM conditions. This study develops a flexible electrochemically tunable EMI shielding device based on ultrathin Ti3C2Tx MXene films, exhibiting reversible shielding effectiveness (SE) modulation from 18.9 to 26.2dB in X band at 0.1 and -1.5V. Unlike the previously reported mechanism relying on interlayer spacing adjustments, the work leverages transformations of charging state and surface chemistry for tunability during the electrochemical process. The Ti3C2Tx flake size is also evidenced to play a crucial role, with smaller flakes offering higher absorption modulation despite lower SE modulation, enabling the device with high designability. When integrated with Salisbury screen structure, the device achieves adjustable absorption from 93.560% at 0.1V to 99.996% at -1V, showing a tunable reflection suppression ratio up to 32dB with an effective bandwidth of 4.2GHz. Additionally, incorporating resonant cavity structure enables absorption-dominated (over 90%) microwave-responsive switching at 0.1 and -1.5V. This work highlights significant potential of adaptive EMI shielding materials for applications in smart electronic protection, EM switch, and radar camouflage.

Elliptic Hermite-Gaussian soliton and transformations in nonlocal media induced by linear anisotropy.

Elliptic Hermite-Gaussian (HG) soliton clusters in nonlocal media with anisotropic diffractions are studied comprehensively. The relations among solitons parameters, diffraction indices, and the degree of nonlocality are derived analytically with the Lagrangian method. Stable elliptic HG soliton clusters can be obtained when linear diffraction is anisotropic. When the solitons are launched with an initial orientation angle, we also demonstrate numerically mode transformations between HG and Laguerre-Gaussian (LG) solitons induced by linear anisotropy. Our results will enrich the soliton phenomenon with linear anisotropic diffraction and may lead to novel applications in all-optical switching, interconnection, etc.

Progress and Prospect of Liquid Crystal Droplets

Liquid crystal (LC) droplets are highly attractive for applications in privacy windows, optical switches, optical vortices, optical microresonators, microlenses, and biosensors due to their ease of fabrication and easy alignment at surfaces. This review presents the latest advancements in LC droplets, which have nematic, chiral nematic, and twist–bend nematic and ferroelectric nematic phases, or blue phases. Finally, it discusses the challenges and opportunities for applications based on LC droplets. The main challenges encompass the precise control of internal structures and defects to meet diverse application requirements, enhancing stability and durability across various environments, reducing large-scale production costs to improve commercial feasibility, increasing response speeds to external stimuli to adapt to rapidly changing scenarios, and developing tunable LC droplets to achieve broader functionalities.

Thermal Responsiveness of 1,2,4-Triazolium-Based Poly(ionic liquid)s and Their Applications in Dye Extraction and Smart Switch.

Triazoliums are a family of five-membered heterocyclic cations that contain three nitrogen and two carbon atoms. In contrast to the widely studied imidazolium cations, triazoliums are less explored. In terms of the chemical structure, triazolium replaces a carbon atom in the imidazolium cation ring with an electron-withdrawing nitrogen atom, which makes the triazolium more polarized. Among the many physical properties, the thermal responsiveness of triazoliums is of particular interest to us but has been rarely investigated. In this contribution, we prepared a series of 1,2,4-triazolium-based poly(ionic liquid)s (PILs) with varying alkyl substituents and counteranions and studied their thermal-responsive behavior. We found that 1,2,4-triazolim-based PILs with a polymeric backbone structure similar to that of polyimidazoliums exhibited opposite thermal phase transition processes in solvents. For example, methyl-substituted 1,2,4-triazolium-based PILs exhibited an upper-critical-solution-temperature (UCST)-type phase transition in methanol when the counterion was I- and a lower-critical-solution-temperature (LCST)-type phase transition in acetone when the counterion was PF6 -. The thermal responsiveness was reversible and concentration-dependent. Interestingly, the thermal response of 1,2,4-triazolim-based PILs could be retained in the organogel form, which was applied in the pretreatment of anion-containing organic waste liquids and temperature-controlled "smart" switches.

GaN-on-sapphire JTE-anode lateral field-effect rectifier for improved breakdown voltage (>2.5 kV) and dynamic RON

In high-power switching applications such as electric grids, transportation, and industrial electronics, power devices are supposed to have kilo-voltage (kV) level blocking capability. In this work, 1200-V gallium nitride (GaN) lateral field-effect rectifiers (LFERs) are demonstrated. The GaN-on-sapphire epitaxial structure is adopted to prevent vertical breakdown. To address electric field crowding, a p-GaN/AlGaN/GaN junction termination extension (JTE) is embedded in the anode region of the LFER. Comparing to the conventional LFER (Conv-LFER) fabricated on the same wafer, the JTE-anode LFER (JTE-LFER) achieves an improved breakdown voltage (>2.5 kV) and a lower dynamic ON-resistance (RON). The proposed p-GaN/AlGaN/GaN JTE offers a semiconductor-based solution (contrasted to the dielectric-based solution, i.e., field plate) to mitigate the high electric field, which is highly desirable for wide bandgap semiconductor power devices as it enhances the dielectric reliability.

Tunable and polarization-dependent electromagnetically induced transparency analogy in graphene-based terahertz metasurfaces

In this paper, we theoretically and numerically demonstrate a tunable and polarization-dependent electromagnetically induced transparency analogy based on graphene terahertz metasurfaces. The unit cell of the metasurface consists of three-layer graphene strips embedded in a silicon grating. The dynamic adjustment of the transparent window can be achieved by changing the coupling distance between the graphene layers and the polarization direction of the incident lights. The operation mechanism behind the phenomenon can be attributed to the near-field interaction and electromagnetic coupling of modes in graphene strips. Furthermore, the full wave electromagnetic simulations obtained by the finite-difference time-domain method agree well with the theoretical fitting results based on the three-harmonic oscillator model. In addition, by changing the Fermi levels, it can not only realize the outstanding slow-light effects with a maximum group index of 3750 but also obtain the four-frequency asynchronous optical switch function in terahertz regions. Therefore, our proposed metamaterial device may have potential applications in image switching, optical switches, slow-light device, optical communication, and optical storage.