Electrical Modulation Research Articles

Optoelectronic synapses with chemical-electric behaviors in gallium nitride semiconductors for biorealistic neuromorphic functionality

Optoelectronic synapses, leveraging the integration of classic photo-electric effect with synaptic plasticity, are emerging as building blocks for artificial vision and photonic neuromorphic computing. However, the fundamental working principles of most optoelectronic synapses mainly rely on physical behaviors while missing chemical-electric synaptic processes critical for mimicking biorealistic neuromorphic functionality. Herein, we report a photoelectrochemical synaptic device based on p-AlGaN/n-GaN semiconductor nanowires to incorporate chemical-electric synaptic behaviors into optoelectronic synapses, demonstrating unparalleled dual-modal plasticity and chemically-regulated neuromorphic functions through the interplay of internal photo-electric and external electrolyte-mediated chemical-electric processes. Electrical modulation by implementing closed or open-circuit enables switching of optoelectronic synaptic operation between short-term and long-term plasticity. Furthermore, inspired by transmembrane receptors that connect extracellular and intracellular events, synaptic responses can also be effectively amplified by applying chemical modifications to nanowire surfaces, which tune external and internal charge behaviors. Notably, under varied external electrolyte environments (ion/molecule species and concentrations), our device successfully mimics chemically-regulated synaptic activities and emulates intricate oxidative stress-induced biological phenomena. Essentially, we demonstrate that through the nanowire photoelectrochemical synapse configuration, optoelectronic synapses can be incorporated with chemical-electric behaviors to bridge the gap between classic optoelectronic synapses and biological synapses, providing a promising platform for multifunctional neuromorphic applications.

Thermal Performance and Structural Optimization of Electric Heating Module Based on KAl(SO4)2·12H2O/Expanded Graphite Composite Phase‐Change Material

Under the background of vigorously promoting clean heating, the introduction of phase‐change energy storage technology into heating systems has become a new hot issue. In this study, a novel KAl(SO4)2·12H2O/expanded graphite (EG) shape‐stabilized composite phase‐change material (PCM), with a melting temperature of 91.6 °C, latent heat of 245.7 kJ kg−1, and high heat conductivity of 2.07 W m−1 K−1, is prepared to manufacture a PCM‐based module for space heating. This phase‐change electric heating module is developed, and its heat storage and release characteristics are investigated through experimental and numerical studies. The numerical model is validated by experimental results. In view of the numerical simulation, the structure of the module is optimized and its thermal performance is studied. Based on the optimized module, a peak‐valley time‐of‐use (TOU) electric heating module is finally proposed. It is revealed that the module exhibits good thermal performance and is capable of satisfying the indoor heating demand. The effective heat storage and release duration is 8.12 and 15.34 h, which can perfectly realize the operating mode under the “peak‐valley TOU electricity” mechanism. In this study, it is demonstrated that peak–valley electric energy storage heating devices have broad prospects in building space heating and provides reference for future application.

(Invited) Nitrogen Based Solid State Magneto-Ionics

Solid-state magneto-ionic (MI) effects have shown promise for energy-efficient nanoelectronics, where ionic migration may be used to achieve atomic-scale control of interfaces in magnetic nanostructures. To date, magneto-ionics have been mostly explored in oxygen-based systems [1-4], while there is a surge of interest in alternative ionic systems due to their different ionic migration mechanisms and characteristics [5-7].We have recently demonstrated effective MI control of magnetic functionalities using a variety of ionic species, particularly nitrogen. In nitride-based Ta/CoFe/MnN/Ta films, the chemically induced MI effect is combined with the electric field driving of nitrogen to electrically manipulate exchange bias [8]. Upon field-cooling the heterostructure, ionic diffusion of nitrogen from MnN into the Ta layers occurs. A significant exchange bias is observed, which can be further enhanced by ~ 20% after voltage conditioning (Figs. 1a-1e). This enhancement can be reversed by voltage conditioning with an opposite polarity. Nitrogen migration within the MnN layer and into the Ta capping layer causes the enhancement in exchange bias, which is observed in polarized neutron reflectometry studies.We have also achieved all-nitride-based magneto-ionic systems [9]. Thin films of (001)-ordered Mn4N are grown by sputtering Mn onto Mn3N2 seed layer on Si (100) substrate. Nitrogen ion migration across the Mn3N2 /Mn layers leads to a continuous evolution of the layers to Mn3N2 /Mn4N, Mn2N/Mn4N, and eventually Mn4N alone (Figs. 1f-1g). Furthermore, we have demonstrated MI control of the exchange bias effect in an all-nitride Mn4N/MnNx system, where the field-trained exchange field can be varied up to ten times by introducing or extracting nitrogen from the nitride system. This is achieved by adjusting the nitrogen gas partial pressure during deposition or varying annealing temperature after deposition.These effects demonstrate contrasts with oxygen-based MI effects in terms of operating principles, switching speed, and reversibility. Such MI systems are valuable platforms to gain quantitative understanding at buried interfaces. They also offer potentials for device applications based on electric modulation of magnetic functionalities.This work has been supported in part by the NSF (ECCS-2151809, DMR-2005108, DMR-1828420), SRC/NIST SMART Center, and KAUST.[1] U. Bauer et al., Nat. Mater. 14, 174 (2015).[2] C. Bi et al., Phys. Rev. Lett. 113, 267202 (2014).[3] D. A. Gilbert et al., Nat. Commun. 7, 11050 (2016).[4] G. Chen et al., Sci. Adv. 6, eaba4924 (2020).[5] A. J. Tan et al., Nat. Mater. 18, 35 (2019).[6] G. Chen et al., Phys. Rev. X 11, 021015 (2021).[7] J. de Rojas et al., Nat. Commun. 11, 5871 (2020).[8] C. J. Jensen et al., ACS Nano 17, 6745 (2023).[9] Z. J. Chen et al., Appl. Phys. Lett. 123, 082403 (2023). Figure 1

Self-clamped P-shield 4H-SiC trench MOSFET for low turn-off loss and suppress switching oscillation

A novel 4H-SiC trench MOSFET with self-clamped P-region (SCP-MOS) is proposed. The breakdown voltage is boosted and switching oscillation is suppressed by introducing a lightly P-type doping concentration region (LP) and additional NCSL. P+ and NCSL form a new electric field modulation region that reduces the electric field at the bottom of the gate, resulting in a higher breakdown voltage for the device. Moreover, When VDS is small, the LP region links P-shield and P+ source region, the P-shield is clamped at a low potential, which effectively reduces the gate to drain capacitance (CGD). As VDS increases, the LP region is gradually depleted, causing the P-shield to transition into floating state, the potential in the P-shield region is raised. Consequently, the described characteristics facilitate achieving low turn-off losses and Surge voltage(VSurge). SCP-MOS has 32 % lower surge voltage compared to GP-MOS and 85 % lower turn-off loss compared to FP-MOS. Overall, SCP-MOS can obtain better EOFF-VSurge trade-off.

Experimental research of electrolyte additives and battery performance of aqueous zinc-ion batteries

Abstract Aqueous zinc-ion batteries (AZBs) have received increasing attention due to their high safety, high theoretical specific capacity, and abundant resources. However, the problems of zinc anode dendrite growth, hydrogen precipitation corrosion, and irreversible side reactions in AZIBs have restricted their application process. Electrolyte additives are an effective way to solve problems. This work looked at what would happen when 4-(2-hydroxyethyl) piperazine-1-ethane sulfonic acid (HEPES) was added to the ZnSO4 solution, which is the electrolyte. It was tested on AZIBs by using coin batteries as the carriers and adding HEPES to the electrolyte. The findings demonstrated that the electrolyte exhibited robust stability following HEPES addition, effectively suppressing dendrite growth through electric field modulation at the zinc anode. Incorporating 8 mM HEPES notably enhanced battery cycle longevity to over 240 hours under conditions of 0.2 mA cm−2 and 0.2 mAh cm−2. The HEPES additive was found to be effective in improving the rate capability through the testing of Zn||Zn symmetric batteries. This work provides a feasible idea for the performance improvement of low-cost and high-efficiency AZIBs.

Ultra-high electron mobility in Sn-doped two-dimensional Ga2O3 modified by biaxial strain and electric field

2D Ga2O3 exhibits overwhelming advantages over its bulk counterpart, whereas manipulating the carriers is rare. We report strain-dependent electronic structures and transport properties of Sn-doped 2D Ga2O3 using first-principles calculations with deformation potential theory. The band gaps are tunable from 2.23 eV to 1.20 eV due to the strain-mediated σ* anti-bonding and π bonding state variations. Specifically, ultra-high electron mobility of 22579.32 cm2V−1s−1 is predicated under 8% tensile. Further electric field modulations suggest the retaining of band gap and effective mass. These results highlight its property manipulations and nanoscale electronic applications.

Successful electric field modulation to enhance DC and RF features in SOI LDMOS transistors using a β-Ga2O3 film

Successful electric field modulation to enhance DC and RF features in SOI LDMOS transistors using a β-Ga2O3 film

Design of a Real-Time Monitoring System for Electroencephalogram and Electromyography Signals in Cerebral Palsy Rehabilitation via Wearable Devices

Cerebral palsy is a disorder of central motor and postural development, resulting in limited mobility. Cerebral palsy is often accompanied by cognitive impairment and abnormal behavior, significantly impacting individuals and society. Time, energy, and economic investment in the rehabilitation process is substantial, yet the rehabilitation outcomes often remain unsatisfactory. Additionally, some patients have limited sensory perception during rehabilitation training, making it challenging to effectively regulate exercise intensity. Traditional evaluation methods are mostly based on recovery performance, lack guidance at the neurophysiological level, and have an unequal distribution of medical rehabilitation resources, which pose great challenges to the rehabilitation of patients. Based on the issues mentioned above, this paper proposes a real-time cerebral signal monitoring system based on wearable devices. This system can monitor and store blood oxygen, heart rate, myoelectric, and EEG signals during cerebral palsy rehabilitation, and it can track and monitor signals during the rehabilitation treatment process. The system includes two parts: hardware design and software design. The hardware design includes a data signal acquisition module, a main control chip (ESP32), a muscle electrical sensor module, a brain electrical sensor module, a blood/heart rate acquisition module, etc. It is primarily for real-time signal data acquisition, processing, and uploading to the cloud server. The software design includes functions such as data receiving, data processing, data storage, network configuration, and remote communication and enables the visual monitoring of data signals. The system can achieve real-time monitoring of electromyography, electroencephalography, and blood oxygen levels, as well as the heart rate of patients with cerebral palsy, and adjust rehabilitation training in real-time during the rehabilitation process. At the same time, based on the real-time storage of the original electromyography and electroencephalography data, it can provide auxiliary guidance for later rehabilitation evaluation and effective data support for the entire rehabilitation treatment process.

Electric field-induced modulation of electronic and optical properties in doped CdTe/CdS core/shell quantum dots embedded in an oxide matrix

This work presents a theoretical analysis of a CdTe/CdS core/shell quantum dots embedded in a dielectric oxide matrix under the influence of hydrogenic impurity and the applied electric field intensity. The eigenstates and their corresponding eigenfunctions are computed by solving the Schrodinger equation using the finite element method within the effective mass approximation. The first-order linear and third-order nonlinear optical absorption coefficients as well as the refractive index changes are computed based on the compact density matrix approach. The obtained result shows that the first-order linear and third-order nonlinear optical properties are more pronounced with the electric field, surrounding oxide matrix and the donor impurity effects. However, the first-order linear and third-order nonlinear optical absorption coefficients and refractive index changes can experience a red or blue shift under the influence of electric field, oxide matrix and hydrogenic impurity. In addition, under all conditions, the height peaks of these optical properties can be raised (fall). Our findings demonstrate the critical importance of considering the roles of electric field, the presence of donor impurity, and the capped dielectric oxide matrix in the design and fabrication of core–shell-based optoelectronic devices.

Half-wave voltage controllable optical voltage sensor with arbitrary electric field direction modulation*

Abstract An optical voltage sensor with an arbitrary electric field direction modulation (AEFDM) mode is proposed to increase the half-wave voltage. The mode is realized by heterogeneous electrodes arranged in a center-symmetric way, and generates an electric field with a direction at an arbitrary angle to the light propagation direction. The finite element method and coupling wave theory are used to design and optimize the electrodes and field distribution. The experimental results show that heterogeneous electrodes and AEFDM mode are able to regulate the sensor’s half-wave voltage in a range from 1 to 30 times (47–1409 kV), with 0.5 class accuracy and 99.99% linearity. This novel AEFDM method proposes a new electrode shape and position, reducing temperature drift to 50% compared to solid-state voltage divider method.

Electrically tunable third-harmonic generation using intersubband polaritonic metasurfaces

Nonlinear intersubband polaritonic metasurfaces, which integrate giant nonlinear responses derived from intersubband transitions of multiple quantum wells (MQWs) with plasmonic nanoresonators, not only facilitate efficient frequency conversion at pump intensities on the order of few tens of kW cm-2 but also enable electrical modulation of nonlinear responses at the individual meta-atom level and dynamic beam manipulation. The electrical modulation characteristics of the magnitude and phase of the nonlinear optical response are realized through Stark tuning of the resonant intersubband nonlinearity. In this study, we report, for the first time, experimental implementations of electrical modulation characteristics of mid-infrared third-harmonic generation (THG) using an intersubband polaritonic metasurface based on MQW with electrically tunable third-order nonlinear response. Experimentally, we achieved a 450% modulation depth of the THG signal, 86% suppression of zero-order THG diffraction tuning based on local phase tuning exceeding 180 degrees, and THG beam steering using phase gradients. Our work proposes a new route for electrically tunable flat nonlinear optical elements with versatile functionalities.

Unlocking guanine’s potential: Unveiling electronic transitions and nanoelectronic applications through electric field modulation

Guanines, key players in DNA and RNA, exist as dynamic keto and enol forms, influencing reactivity and potential applications. This study explores the impact of external electric fields on these forms using computational methods in gas and solvent (water) phases. Analyzing the energy gap, dipole moment, enthalpy, and Gibbs free energy revealed distinct responses. The keto form showed a significant decrease in the energy gap in the presence of an electric field, particularly in water, indicating enhanced reactivity. Conversely, the enol form exhibited a stabilizing effect with increasing electric field strength. Thermodynamic properties highlighted solvent-dependent interactions and electric field-induced changes in electron density distribution. The study further investigated guanine’s potential for nanoelectronics by calculating I-V curves, revealing promising characteristics, especially for the keto form in the aqueous phase. Additionally, the analysis of solvation and cohesive energies provided insights into solute–solvent interactions and intrinsic molecular stability. Overall, this research contributes to understanding how guanine responds to electric fields, paving the way for novel guanine-based materials with potential applications in nanoelectronics.

LiF-Rich Alloy-Doped SEI Enabling Ultra-Stable and High-Rate Li Metal Anode.

Li metal is regarded as the "Holy Grail" in the next generation of anode materials due to its high theoretical capacity and low redox potential. However, sluggish Li ions interfacial transport kinetics and uncontrollable Li dendrites growth limit practical application of the energy storage system in high-power device. Herein, separators are modified by the addition of a coating, which spontaneously grafts onto the Li anode interface for in situ lithiation. The resultant alloy possessing of strong electron-donating property promotes the decomposition of lithium bistrifluoromethane sulfonimide in the electrolyte to form a LiF-rich alloy-doped solid electrolyte interface (SEI) layer. High ionic alloy solid solution diffusivity and electric field dispersion modulation accelerate Li ions transport and uniform stripping/plating, resulting in a high-power dendrite-free Li metal anode interface. Surprisingly, the formulated SEI layer achieves an ultra-long cycle life of over 8000 h (20,000 cycles) for symmetric cells at a current density of 10 mA cm-2. It also ensures that the NCM(811)//PP@Au//Li full cell at ultra-high currents (40 C) completes the charging/discharging process in only 68 s to provide high capacity of 151 mAh g-1. The results confirm that this scalable strategy has great development potential in realizing high power dendrite-free Li metal anode.

LiF‐Rich Alloy‐Doped SEI Enabling Ultra‐Stable and High‐Rate Li Metal Anode

AbstractLi metal is regarded as the “Holy Grail” in the next generation of anode materials due to its high theoretical capacity and low redox potential. However, sluggish Li ions interfacial transport kinetics and uncontrollable Li dendrites growth limit practical application of the energy storage system in high‐power device. Herein, separators are modified by the addition of a coating, which spontaneously grafts onto the Li anode interface for in situ lithiation. The resultant alloy possessing of strong electron‐donating property promotes the decomposition of lithium bistrifluoromethane sulfonimide in the electrolyte to form a LiF‐rich alloy‐doped solid electrolyte interface (SEI) layer. High ionic alloy solid solution diffusivity and electric field dispersion modulation accelerate Li ions transport and uniform stripping/plating, resulting in a high‐power dendrite‐free Li metal anode interface. Surprisingly, the formulated SEI layer achieves an ultra‐long cycle life of over 8000 h (20,000 cycles) for symmetric cells at a current density of 10 mA cm−2. It also ensures that the NCM(811)//PP@Au//Li full cell at ultra‐high currents (40 C) completes the charging/discharging process in only 68 s to provide high capacity of 151 mAh g−1. The results confirm that this scalable strategy has great development potential in realizing high power dendrite‐free Li metal anode.

Evidence of striped electronic phases in a structurally modulated superlattice.

The electronic properties of crystals can be manipulated by superimposing spatially periodic electric, magnetic or structural modulations. Long-wavelength modulations incommensurate with the atomic lattice are particularly interesting1, exemplified by recent advances in two-dimensional (2D) moiré materials2,3. Bulk van der Waals (vdW) superlattices4-8 hosting 2D interfaces between minimally disordered layers represent scalable bulk analogues of artificial vdW heterostructures and present a complementary venue to explore incommensurately modulated 2D states. Here we report the bulk vdW superlattice SrTa2S5 realizing an incommensurate one-dimensional (1D) structural modulation of 2D transition metal dichalcogenide (TMD) H-TaS2 layers. High-quality electronic transport in the H-TaS2 layers, evidenced by quantum oscillations, is made anisotropic by the modulation and exhibits commensurability oscillations paralleling lithographically modulated 2D systems9-11. We also find unconventional, clean-limit superconductivity in SrTa2S5 with a pronounced suppression of interlayer relative to intralayer coherence. The in-plane magnetic field dependence of interlayer critical current, together with electron diffraction from the structural modulation, suggests superconductivity12-14 in SrTa2S5 is spatially modulated and mismatched between adjacent TMD layers. With phenomenology suggestive of pair-density wave superconductivity15-17, SrTa2S5 may present a pathway for microscopic evaluation of this unconventional order18-21. More broadly, SrTa2S5 establishes bulk vdW superlattices as versatile platforms to address long-standing predictions surrounding modulated electronic phases in the form of nanoscale vdW devices12,13 to macroscopic crystals22,23.

Linear Film Strain Sensors with Nanosphere‐on‐Fiber Hetero‐Modulus Microstructure for Human‐Bionic Finger Interfacing

AbstractStretchable film strain sensors show potential applications in healthcare and human‐machine interfacing, while poor signal linearity restricts their practical applications owing to inaccurate and instable strain indication. Signal sensitivity and linearity can be improved via constructing hetero‐modulus microstructure on elastomeric substrate to some extent, though it is challenging to construct hetero‐structure with distinct modulus differences for electrical signal linearity modulation over a wide strain range. Herein, a simple strategy is proposed to tune signal sensitivity, linearity, and detection range of stretchable strain sensors by adjusting the distribution of rigid polystyrene (PS) nanospheres coated on electrospun thermoplastic polyurethane (TPU) fiber mats. Heterostructure characteristics can be controlled by spray coating times of PS nanospheres, which are immobilized onto the fiber mats by weak swelling of TPU and the linking layer of reduced graphene oxide (rGO) between TPU and PS induced by hydrogen bonding and π–π stacking. Relatively, the sensors with moderate spray coating times of PS nanospheres show balanced signal sensitivity and linearity over a strain range of 0–80%, as well as fast response to tensile strain and good signal reproducibility. Such elastomeric film strain sensors can be used for monitoring physiological activities and interfacing human hand and bionic fingers.

Opto-intelligence spectrometer using diffractive neural networks

Abstract Spectral reconstruction, critical for understanding sample composition, is extensively applied in fields like remote sensing, geology, and medical imaging. However, existing spectral reconstruction methods require bulky equipment or complex electronic reconstruction algorithms, which limit the system’s performance and applications. This paper presents a novel flexible all-optical opto-intelligence spectrometer, termed OIS, using a diffractive neural network for high-precision spectral reconstruction, featuring low energy consumption and light-speed processing. Simulation experiments indicate that the OIS is able to achieve high-precision spectral reconstruction under spatially coherent and incoherent light sources without relying on any complex electronic algorithms, and integration with a simplified electrical calibration module can further improve the performance of OIS. To demonstrate the robustness of OIS, spectral reconstruction was also successfully conducted on real-world datasets. Our work provides a valuable reference for using diffractive neural networks in spectral interaction and perception, contributing to ongoing developments in photonic computing and machine learning.

Electrically Controlled High Sensitivity Strain Modulation in MoS2 Field-Effect Transistors via a Piezoelectric Thin Film on Silicon Substrates.

Strain can modulate bandgap and carrier mobilities in two-dimensional (2D) materials. Conventional strain-application methodologies relying on flexible/patterned/nanoindented substrates are limited by low thermal tolerance, poor tunability, and/or scalability. Here, we leverage the converse piezoelectric effect to electrically generate and control strain transfer from a piezoelectric thin film to electromechanically coupled 2D MoS2. Electrical bias polarity change across the piezo film tunes the nature of strain transferred to MoS2 from compressive (∼0.23%) to tensile (∼0.14%) as verified through Raman and photoluminescence spectroscopies and substantiated by density functional theory calculations. The device architecture, on silicon substrate, integrates an MoS2 field-effect transistor on a metal-piezoelectric-metal stack enabling strain modulation of transistor drain current (130×), on/off ratio (150×), and mobility (1.19×) with high precision, reversibility, and resolution. Large, tunable tensile (1056) and compressive (-1498) strain gauge factors, electrical strain modulation, and high thermal tolerance promise facile integration with silicon-based CMOS and micro-electromechanical systems.

Electrical Polarity Modulation in V-Doped Monolayer WS2 for Homogeneous CMOS Inverters.

As demand for higher integration density and smaller devices grows, silicon-based complementary metal-oxide-semiconductor (CMOS) devices will soon reach their ultimate limits. 2D transition metal dichalcogenides (TMDs) semiconductors, known for excellent electrical performance and stable atomic structure, are seen as promising materials for future integrated circuits. However, controlled and reliable doping of 2D TMDs, a key step for creating homogeneous CMOS logic components, remains a challenge. In this study, a continuous electrical polarity modulation of monolayer WS2 from intrinsic n-type to ambipolar, then to p-type, and ultimately to a quasi-metallic state is achieved simply by introducing controllable amounts of vanadium (V) atoms into the WS2 lattice as p-type dopants during chemical vapor deposition (CVD). The achievement of purely p-type field-effect transistors (FETs) is particularly noteworthy based on the 4.7 at% V-doped monolayer WS2, demonstrating a remarkable on/off current ratio of 105. Expanding on this triumph, the first initial prototype of ultrathin homogeneous CMOS inverters based on monolayer WS2 is being constructed. These outcomes validate the feasibility of constructing homogeneous CMOS devices through the atomic doping process of 2D materials, marking a significant milestone for the future development of integrated circuits.

Microwave Photonic Frequency Multiplier with Low Phase Noise Based on an Optoelectronic Oscillator

A microwave photonic frequency multiplier with low phase noise based on an optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. In this scheme, a dual-parallel Mach–Zehnder modulator (DPMZM) is employed to generate the third-harmonic frequency of the input radio frequency (RF) signal, while the oscillation frequency of the OEO is also three times the RF signal frequency. By adjusting the bias voltages of different arms in the DPMZM, a triple-frequency signal with a high side-mode suppression ratio of 64.8 dB can be obtained. The experimental results indicate that the output of the frequency-multiplier has a better single-sideband phase noise value, for instance, −126 dBc/Hz@10 kHz at 20.019 GHz. It has improvements of 34 dB and 43.5 dB compared with the input RF signal and the simulated electrical frequency tripler module, respectively.