Switching Applications Research Articles

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 10^10. 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.

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

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

Effect of Substrate Thinning on Temperature Rise in Ga2O3 Rectifiers

Abstract 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.

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

Abstract 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 variations, 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-5nm 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_ON, I_ON/I_OFF ratio, 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 (250K to 450K) 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 (250K). Furthermore, as the circuit level implementation CMOS inverter and 5-stage RO are examined for sheets increase, delay and EDP increases. For a CMOS inverter the NMH (0.295V) and NML (0.280V) 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.

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.

An efficient and improved algorithm for generating an equivalent planar architecture of the data vortex switch

The data vortex (DV) switch was originally designed as an all optical interconnection network for high performance computing (HPC) applications. It was highly scalable with low latency and high throughput, compared to traditional switches used for optical packet switching (OPS) and HPC applications. The equivalent planar (chained MIN) model of the DV, proposed in previous literature, is a planar diagrammatic conversion of a 3-D model of the DV network. In this paper, we will focus on exploring a new, efficient and improved generalized algorithm that enables the arrangement of routing pathways to be implemented as an equivalent planar architecture (EPA, chained MIN) of a DV to find all possible routes between each source and target node pair. The original 3-D architecture of any size can be converted to a planar structure more simply by using the new generalized equivalent planar architecture (EPA) algorithm. To verify the proposed EPA algorithm, it was tested with different input traffic loads and network sizes while keeping the active angle ‘A’ constant. Network performance parameters, including injection rate (throughput) and latency (mean hops), obtained from simulation results are also provided to confirm the validity of the proposed EPA algorithm. This new algorithm is versatile, simple and can be applied to networks of various sizes.

Dynamic Control of Asymmetric Charge Distribution for Electrocatalytic Urea Synthesis.

Constructing dual catalytic sites with charge density differences is an efficient way to promote urea electrosynthesis from parallel and CO2 reduction yet still challenging in static system. Herein, a dynamic system is constructed by precisely controlling the asymmetric charge density distribution in an Au-doped coplanar Cu7 clusters-based 3D frameworkcatalyst (Au@cpCu7CF). In Au@cpCu7CF, the redistributed charge between Au and Cu atoms changed periodically with the application of pulse potentials switching between -0.2 and -0.6 V and greatly facilitated the electrosynthesis of urea. Compared with the static condition of pristine cpCu7CF (FEurea = 5.10%), the FEurea of Au@cpCu7CF under pulsed potentials is up to 55.53%. Theoretical calculations demonstrated that the high potential of -0.6V improved the adsorption of *HNO2 and *NH2 on Au atoms and inhibited the reaction pathways of by-products. While at the low potential of -0.2V, the charge distribution between Au and Cu atomic sites facilitated the thermodynamic C-N coupling step. This work demonstrated the important role of asymmetric charge distribution under dynamic regulation for urea electrosynthesis, providing a new inspiration for precise control of electrocatalysis.

Exploring nonlinear optical properties of RbPbI3 nanorods using SSPM technique: Implications for all-optical switching applications

Nowadays, nanomaterials' nonlinear optical (NLO) properties are a fascinating topic for developing a novel all-optical switching application. Spatial self-phase modulation (SSPM) is an important technique to determine the laser-induced coherent light-matter interaction to determine the NLO properties of nanomaterials. This study successfully synthesized RbPbI3 nanorods (NRs) via a low-cost, less complicated chemical route with all the basic characterizations to confirm its structural and compositional analysis. For the first time, we conducted a comprehensive analysis of the nonlinear refractive index (n2) and third-order susceptibility (χ(3)) for RbPbI3 NRs dissolved in two different solvents, namely N-Methyl-2-pyrrolidone (NMP) and 2-propanol, utilizing the SSPM technique. Our investigation revealed significant nonlinear optical (NLO) responses with n2 = 6.19 × 10−5 cm2 W−1 and χmonolaer(3) = 2.38 × 10−8 esu for RbPbI3. We elucidated the factors contributing to this pronounced NLO behaviour, including variations in parameters such as solvent type, viscosity, wavelength, and cuvette length. Additionally, we successfully demonstrated optical information transfer through an all-optical switching application. This research sheds light on the NLO properties of Perovskite materials and holds promise for the development of advanced all-optical device applications.

Broadband nonlinear refraction transients in C-doped GaN based on absorption spectroscopy

Optical nonlinear response and its dynamics of wide-bandgap materials are key to realizing integrated nonlinear photonics and photonic circuit applications. However, those applications are severely limited by the unavailability of both dispersion and dynamics of nonlinear refraction (NLR) via conventional measurements. In this work, the broadband NLR dynamics with extremely high sensitivity (λ/1000) can be obtained from absorption spectroscopy in GaN:C using the refraction-related interference model. Both the absorption and refraction kinetics are found to be significantly modulated by the C-related defects. Especially, we demonstrate that the refractive index change Δn of GaN:C is negative and can be used to realize all-optical switching applications owing to the large NLR and ultrafast switching time. The NLR under different non-equilibrium carrier distributions originates from the capture of electrons by CN+ defect state, while the absorption modulation originates from the excitation of tri-carbon defects. We believe that this work provides a better understanding of the GaN:C nonlinear properties and an effective solution to broadband NLR dynamics of transparent thin films or heterostructure materials.

Development and Characterization of an Advanced Voltage-Controllable Capacitor Based on AlInGaN/GaN-Si (111) Epitaxy

The AlInGaN/GaN heterojunction epitaxy material with high cutoff frequency and saturated power density has become a very popular candidate for millimeter wave applications in next-generation mobile communication. In this study, an advanced voltage-controllable capacitor based on the AlInGaN/GaN-Si (111) epitaxy was proposed by employing a bi-directional series MIS capacitor structure. The capacitor was fabricated by using a pad area of 40 μm × 40 μm, with a 1 μm distance between the positive and negative electrodes. The test results show that the capacitance is turned on with a saturation capacitance density and a maximum leakage current density of 0.30 fF/μm2 of 0.37 pA/μm2, respectively, for the control voltage from −6.5 V to 6 V. In particular, in the proposed design method, the saturation capacitance required for the practical application can be obtained by simply adjusting the capacitance area. The capacitor showcases characteristics of rapid turn-on and turn-off responses coupled with low loss, underscoring its promising prospects for deployment in RF switching applications.

Multi-Period Optimal Transmission Switching with Voltage Stability and Security Constraints by the Minimum Number of Actions

Due to the ever-growing load demand and the deregulation of the electricity market, power systems often run near the stability boundaries, which deteriorates system voltage stability and raises voltage issues for the stable operations of power systems. Transmission switching (TS) has been applied to improve economic benefits and security operations for many applications. In this paper, a multi-period voltage stability-constrained problem (MP-VSTS) is established, intending to improve voltage security and the stability of a power system. Considering the online application of transmission switching, the minimum number of switching actions is taken as the objective function of the proposed MP-VSTS problem, which extends the TS application for real industries. The proposed model provides the switching lines for the upcoming period and the state of power systems for several successive periods. To overcome the solving difficulties of the proposed model, a two-stage approach is presented, which balances speed and accuracy. Numerical studies on the IEEE 118- and 662-bus power systems have demonstrated the proposed approach’s performance.

Nanophotonic structure inverse design for switching application using deep learning

Switching functionality is pivotal in advancing communication systems, serving as a paramount mechanism. Despite numerous innovations in this field, optical switch design, fabrication, and characterization have traditionally followed an iterative approach. Within this paradigm, the designer formulates an informed conjecture regarding the switch's structural configuration and subsequently resolves Maxwell's equations to ascertain its performance. Conversely, the inverse problem, which entails deriving a switch geometry to achieve a targeted electromagnetic response, continues to pose formidable challenges and necessitates substantial time and effort, particularly under the constraints of specific assumptions. In this work, we propose a deep neural network-based method to approximate the spectral transmittance of all-optical switches. The findings substantiate the efficacy of deep learning in the design of all-optical plasmonic switches, which are renowned as the fastest switches at the nanoscale. The nonlinear Kerr effect in square resonators is leveraged to demonstrate the switching performance. Juxtaposed with conventional simulations, the proposed model showcases a remarkable improvement in computational efficiency. Furthermore, deep learning can resolve nanophotonic inverse design problems without reliance on trial-and-error or empirical strategies. Compared to simulations, the mean squared error for both forward and inverse models is meager, with values of around 0.03 and 0.02, respectively. The deep learning-proposed switches exhibit excellent suitability for integration into photonic integrated circuits, substantially influencing the progression of all-optical signal processing.

Theoretical study of an electrochemically controlled polymer nanoantenna for optical switch

Conventional metallic nanoantennas allow the control of light at the nanoscale, but their untunable structural settings and material properties limit their optical modulation. Methods for dynamical control and modulation of light have become a hot topic in the development and application of nanooptics. Here, we propose a bowtie polymer poly (3,4-ethylenedioxythiophene:sulfate) (PEDOT:Sulf) nanoantenna that enables dynamical control of the optical responses by electrochemical modulation of the plasmonic (oxidated) and dielectric (reduced) states of polymers. The switch effect of the nanoantenna is related to its electric polar mode. In addition, we explore the dependence of the optical response of the nanoantenna on structural parameters in detail. The tunable response of the nanoantenna has promising applications in optical switch and encoding in information transmission.

Lateral NiO/AlN Heterojunction Rectifiers with Breakdown Voltage >11 kV

Lateral NiO/AIN heterojunction diodes (HJDs) with breakdown voltage up to 11.6 kV and Ni/Au/AlN Schottky barrier diodes (SBDs) with VB of 8.6 kV were fabricated on layers grown on sapphire substrates by metalorganic chemical vapor phase deposition. The power figure-of-merits VB 2/RON where RON is the on-resistance were 0.31 MW·cm−2 for HJD and 0.16 MW·cm−2 for SBD. The lowest turn-on voltages were ∼2.03 and 1.91 V for HJDs and SBDs, respectively, with ON/OFF ratios up to 102. The maximum field before breakdown was 0.45 MV·cm−1 in HJDs and 0.31 MV·cm−1 in SBDs. These correspond to <3% of the critical field in AlN of ∼15 MV·cm−1. This work demonstrates there is still significant optimization to be done in the overall quality of the AlN, including purity, crystal perfection, and defect density to realize the potential of this material as an ultra-wide bandgap semiconductor for efficient multi-kV power switching applications. Our results also demonstrate the promise of NiO as a p-type conducting oxide for forming heterojunctions with AlN.

Structural and ultrafast third-order nonlinearities of methyl and methoxy substituted anthracene chalcones: Z-scan, four-wave mixing, and DFT approaches

We report on the structural, thermal, linear, and ultrafast third-order nonlinear optical (NLO) properties of two novel anthracene chalcones: (2E)-1-(anthracen-9-yl)-3-(5-methylthiophen-2-yl)prop-2-en-1-one (5ML2SANC) and (2E)-1-(9-anthryl)-3-(2,4,5-trimethoxyphenyl)prop-2-en-1-one (245TMANC). The chalcones were synthesized by Claisen-Schmidt condensation reaction, and the single crystals were grown by the solvent evaporation method. The molecular structure was confirmed by FTIR and NMR spectroscopy, while the crystal structure was determined using the single crystal XRD. Both crystals belong to centrosymmetric monoclinic crystal system with space group P21/n. The Hirshfeld surface was analyzed to understand intermolecular interactions, and the band structures - including HOMO-LUMO levels, excited state energies, GCRDs and MEPs-were studied using DFT. The ultrafast third-order NLO properties were investigated by Z-scan and degenerate four-wave mixing (DFWM) techniques using Ti: Sapphire amplifier laser delivering ∼50 fs pulses at 800 nm (1 kHz, ∼4 mJ, 2 W). Two-photon absorption, positive nonlinear refraction, optical limiting and optical switching behaviors were observed by Z-scan measurements. The time-resolved DFWM show that the decay time of 5ML2SANC is ∼127 fs, while for 245TMANC it is ∼142 fs. The second hyperpolarizability (γ) measured by Z-scan, DFWM and the estimations from the DFT theory are found to be in good agreement (∼10−34 esu). The ultrafast optical response, significant NLO properties and thermal stability of the synthesized chalcones demonstrate their potential suitability in optical limiting and switching applications.

Dual-Tuned Terahertz Absorption Device Based on Vanadium Dioxide Phase Transition Properties.

In recent years, absorbers related to metamaterials have been heavily investigated. In particular, VO2 materials have received focused attention, and a large number of researchers have aimed at multilayer structures. This paper presents a new concept of a three-layer simple structure with VO2 as the base, silicon dioxide as the dielectric layer, and graphene as the top layer. When VO2 is in the insulated state, the absorber is in the closed state, Δf = 1.18 THz (absorption greater than 0.9); when VO2 is in the metallic state, the absorber is open, Δf = 4.4 THz (absorption greater than 0.9), with ultra-broadband absorption. As a result of the absorption mode conversion, a phenomenon occurs with this absorber, with total transmission and total reflection occurring at 2.4 THz (A = 99.45% or 0.29%) and 6.5 THz (A = 90% or 0.24%) for different modes. Due to this absorption property, the absorber is able to achieve full-transmission and full-absorption transitions at specific frequencies. The device has great potential for applications in terahertz absorption, terahertz switching, and terahertz modulation.

Determination of third order nonlinearity (n2 & β) of glycine zinc sulphate pentahydrate semi-organic single crystal using two laser radiations at different intensities

AbstarctThe third order nonlinear optical properties i.e. nonlinear refraction (n2), absorption coefficient (β) and third order susceptibility χ(3) of glycine zinc sulphate pentahydrate (GZS) semi-organic single crystal was investigated under the excitation of Q-switched Nd-YAG laser pulsed radiations (λ = 532 nm & 1064 nm) by familiar Z-scan method. The values of nonlinear refraction (n2), at 532 nm were 1.19 × 10−5 (cm2/GW), 2.09 × 10−5 (cm2/GW), 2.27 × 10−5 (cm2/GW), 2.48 × 10−5 (cm2/GW), and 2.55 × 10−5 (cm2/GW) at incident optical beam intensities of 0.76 (GW/cm2), 1.13 (GW/cm2), 1.17 (GW/cm2), 1.63 (GW/cm2) and 1.88 (GW/cm2) respectively while that of values at 1064 nm were 4.31 × 10−5 (cm2/GW), 4.69 × 10−5 (cm2/GW), 5.41 × 10−5 (cm2/GW) and 6.39 × 10−5 (cm2/GW) at incident optical beam intensities of 1.20 (GW/cm2), 1.25 (GW/cm2), 1.32 (GW/cm2) and 1.38 (GW/cm2) respectively. The values of nonlinear absorption coefficient (β) at 532 nm were −1.45 (cm/GW), −0.79 (cm/GW), −0.5 (cm/GW), 0.12 (cm/GW) and 0.64 (cm/GW) at incident optical beam intensities of 0.76 (GW/cm2), 1.13 (GW/cm2), 1.17 (GW/cm2), 1.63 (GW/cm2) and 1.88 (GW/cm2) respectively while that of values at 1064 nm were 0.62 (cm/GW), 0.74 (cm/GW), 0.77 (cm/GW) and 0.81 (cm/GW) at incident optical beam intensities of 1.20 (GW/cm2), 1.25 (GW/cm2), 1.32 (GW/cm2) and 1.38 (GW/cm2) respectively. The values of third order susceptibilities χ(3) at 532 nm were 0.83 × 10−12 (esu), 1.32 × 10−12 (esu), 1.42 × 10−12 (esu), 1.55 × 10−12 (esu) and 1.56 × 10−12 (esu) at intensities of 0.76 (GW/cm2), 1.13 (GW/cm2), 1.17 (GW/cm2), 1.63 (GW/cm2) and 1.88 (GW/cm2) respectively while that of values at 1064 nm were 2.71 × 10−12 (esu), 2.96 × 10−12 (esu), 3.4 × 10−12 (esu) and 4.02 × 10−12 (esu) at incident optical beam intensities of 1.20 (GW/cm2), 1.25 (GW/cm2), 1.32 (GW/cm2) and 1.38 (GW/cm2) respectively. It was seen that the sample showing saturable absorber to reverse saturable absorber at 532 nm wavelength at incident optical beam peak intensity (I0) of 1.53 GW/cm2. Thus the crystal could be a potential candidate of optical switching application. It was also seen that the material possess positive nonlinearity. It was also found that the values of nonlinear absorption coefficient (β) and nonlinear refraction (n2) increase with increase of excitation intensity irrespective of excitation wavelengths.

Speckle Pattern Analysis of PVK:rGO Composite Based Memristor Device

AbstractThe memristors are expected to be fundamental devices for neuromorphic systems and switching applications. The device made of a sandwiched layer of poly(N‐ vinylcarbazole) and reduced graphene composite between asymmetric electrodes (ITO/PVK:rGO/Al) exhibits bistable resistive switching behavior. The performance of the memristor can be optimized by controlling the doped graphene oxide. To assess the device performance when it switches between ON and OFF states, optical characterization approaches are highly promising due to their non‐destructive and remote nature. Here, speckle pattern (SP) analysis to this end is introduced. SPs include a huge amount of information about their generating mechanism, which is extracted through statistical elaboration. SPs of the PVK:rGO in different states in situ and examine the conduction mechanism is acquired. The variations in the statistical parameters are attributed to the resistance state of the PVK:rGO with regard to the physical switching mechanism. The resistance/conduction state, in turn, depends on the activity and properties of PVK:rGO memristors, as well as the additional non‐uniformities induced through the variations of density of carriers. The present optical methodology can be potentially served as a bench‐top device for characterization purposes of similar devices during their operating.

Employing the DFT engineering to tune the optoelectronic properties and mechanical performance of Europium-doped Barium Magnesium Silicate (BMS): a comparative study using HSE06 and GGA+U+SO functionals

With exceptional opto-electronic properties, BaMgSiO4 (BMS) is a valuable candidate for inorganic photochromatic materials. The host matrix BMS’s applications in high density optical memory, smart windows, photo switches, and LEDs have drawn the interest of researchers all over the world. So, the WIEN2k Package was employed to compute the optoelectronic properties of BaMgSiO4 and Ba1-xEuxMgSiO4. The electronic characteristics at the Ba/Eu sites of Ba1-xEuxMgSiO4 were investigated using the Full Potential Linearized Augmented Plane-Wave technique (FP-LAPW). Modern exchange and correlation potentials, namely the Heyd-Scuceria-Ernserhof (HSE06) and the GGA+U+SO potential, were employed to accurately describe the band structure and band gaps of the alloys. The parental material are identified as p-type semiconductors while the Eu doped materials as p-type semiconductors with gap energies of 4.147 and 3.172 (5.683 and 3.501) for BMS and BMS:Eu using GGA+U+SO (HSE06), respectively, are observed. The study included assessments of structural stabilities and mechanical optimization, with the obtained results precisely matching experimental outcomes. The BMS and Eu doped BMS material exhibit stable and ductile characteristics, as confirmed by the acquired elastic data, indicating rigid structures.