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This Letter presents the fabrication and characterization of a 2D SnS memristor, proposing its integrate and fire (I&F) model as a potential hardware implementation of neuronal somatic behavior. The memristor comprises a thin layer of tin (II) sulfide (SnS) sandwiched between copper (Cu) electrodes on a silicon (Si) substrate. This structure exhibits an impressive R off : R o n ratio of 103 at a read voltage V r d of 0.25 V with exceptionally low switching V s w and set V set voltages of 0.3 and 0.35 V, respectively, with ∼ 3 order variation between the maximum R max and R min resistances offered during single voltage sweep cycle. We have explained the memristive behavior using the dual ionic conduction mechanism in the SnS active layer. We extracted the real-time band diagram of SnS using ultraviolet photoelectron spectroscopy, explaining the low V s w observed. We propose that the emulation of the I&F artificial neuron model exhibited by the fabricated device could serve as a promising application in the field of artificial neuron spiking. [ABSTRACT FROM AUTHOR]

We report the nonvolatile modulation of microwave conductivity in ferroelectric PbZr0.2Ti0.8O3-gated ultrathin LaNiO3/La0.67Sr0.33MnO3 correlated oxide channel visualized by microwave impedance microscopy. Polarization switching is obtained by applying a tip bias above the coercive voltage of the ferroelectric layer. The microwave conductivity of the correlated channel underneath the up- and down-polarized domains has been quantified by finite-element analysis of the tip-sample admittance. At room temperature, a resistance on/off ratio above 100 between the two polarization states is sustained at frequencies up to 1 GHz, which starts to drop at higher frequencies. The frequence-dependence suggests that the conductance modulation originates from ferroelectric field-effect control of carrier density. The modulation is nonvolatile, remaining stable after 6 months of domain writing. Our work is significant for potential applications of oxide-based ferroelectric field-effect transistors in high-frequency nanoelectronics and spintronics. [ABSTRACT FROM AUTHOR]

In this article, the impact of 20 MeV proton irradiation on NiOx/β-Ga2O3 p–n diodes has been investigated. After 20 MeV proton irradiation with a fluence of 2 × 1012 p/cm2, the forward current density (JF) decreased by 44.1% from 93.0 to 52.0 A/cm2, and the turn-on voltage (Von) increased from 1.55 to 1.68 V based on current–voltage (I–V) measurements. Moreover, the capacitance–voltage (C–V) measurements indicated that the net carrier concentration in the β-Ga2O3 lightly doped drift region was reduced from 1.95 × 1016 to 1.86 × 1016 cm−3 after proton irradiation. The effect of proton irradiation on NiOx/β-Ga2O3 interface trap states was also acquired utilizing the frequency-dependent conductance technique. The results indicated that the time constant increased from 0.04–0.15 to 0.13–0.23 μs after proton irradiation. Meanwhile, it was found that the density of interface trap states increases from 7.49 × 1010–1.27 × 1010 to 7.23 × 1011–1.70 × 1012 cm−2 eV−1 with an increase in trap activation energy from 0.080–0.111 to 0.088–0.121 eV after proton irradiation. This work provides an important reference for further improving the performance of NiOx/β-Ga2O3 p–n diodes through the design of subsequent anti-radiation hardening. [ABSTRACT FROM AUTHOR]

Single-cell electrorotation plays an important role in the field of single-cell imaging and electric parameter measurement. However, reported cell rotation technology often adopts a quadruple-electrode structure and is excited by an AC signal. The distribution of electric field strength in the enclosed area is not uniform, and the rotation speed of the cells is related to the location in the area, so it is difficult to achieve uniformity of electric field distribution and the stationarity of rotation. This work proposes a DC voltage switching-based octuple-electrode microdevice for cell rotation and area-specific membrane capacitance measurements. This design can switch the DC voltages on each electrode periodically to produce a uniformly distributed rotating electric field. The rotation direction of the electric field can be realized by simply controlling the switching order of the analog switches. According to the theoretical single-cell model, the area-specific membrane capacitance of cells are determined through rotation movements. Simultaneously, based on simulation results, the rotation area is normalized to enhance the accuracy of the measuring electrical parameters. This study demonstrates the potential application of the proposed octuple-electrode DC voltage-based electro-rotation device for rapid, convenient, and cost-effective manipulation and electrical parameter measurement of single cells. [ABSTRACT FROM AUTHOR]

The quantum Josephson voltage standard is well established across the metrology community for many years. It relies on the synchronization of the flux tunneling in the S/I/S Josephson junctions (JJ) with the microwave radiation (MW) of frequency f such that V = Φ 0 f m , where m = 0, 1, 2, .... The phenomenon is called the Shapiro steps. Together with the quantum Hall resistance standard, the voltage standard forms the foundation of electrostatic metrology. The current is then defined as the ratio of the voltage and resistance. Realization of the quantum current standard would close the electrostatic metrological triangle of voltage–resistance–current. The current quantization I = 2 e f m , the inverse Shapiro steps, was recently shown using the superconducting nanowires and small JJ. The effect is a synchronization of the MW with the Cooper pair tunneling. This paves the way to combine the JJ voltage and current standards on the same chip and demonstrate feasibility of the multi-standard operation. We show the voltage and current quantization on the same chip up to frequency of 10 GHz, corresponding to the amplitudes ∼ 20.67 μV and ∼ 3.2 nA, respectively. The accuracy of the voltage and current quantization, however, is relatively low, 35 and 100 ppk, respectively. We discuss measures to optimize the JJs, circuit, and environment to boost the amplitude and accuracy of the standards. [ABSTRACT FROM AUTHOR]

In this work, we report the capacitance recovery behavior in the blue quantum dot light-emitting diode (QLED) by capacitance–voltage (C–V) characterizations. A comprehensive study of the C–V, dC/dV–V, and current density–voltage characteristics of pristine and shelf-aged devices suggests that capacitance recovery is associated with space charge-induced charge accumulation. At lower temperatures, the capacitance recovery in the shelf-aged device is efficiently suppressed due to the difficulty in building up the space charge, which supports our argument. Moreover, the capacitance recovery behavior of QLED only happens at low frequencies (a few hundred hertz), which is related to the time constant for charge accumulation at the selected voltage. Our work shows the effect of space charge on device capacitance and enriches the comprehension of carrier processes in QLED under AC measurement. [ABSTRACT FROM AUTHOR]

Increasing the electric current from a single-electron source is a main challenge in an effort to establish the standard of the ampere defined by the fixed value of the elementary charge e and the operation frequency f. While the current scales with the frequency, due to an operation frequency limit for maintaining accurate single-electron transfer, parallelization of single-electron sources is expected to be a more practical solution to increase the generated electric current I = Nef , where N is the number of parallelized devices. One way to parallelize single-electron sources without increasing the complexity in device operation is to use a common gate. Such a scheme will require each device to have the same operation parameters for single-electron transfer. In order to investigate this possibility, we study the statistics for operation gate voltages using single-electron sources embedded in a multiplexer circuit. The multiplexer circuit allows us to measure 64 single-electron sources individually in a single cooldown. We also demonstrate the parallelization of three single-electron sources and observe the generated current enhanced by a factor of three. [ABSTRACT FROM AUTHOR]

Single-Event Burnout (SEB) can cause hard damage to devices, leading to permanent failure. However, previous studies have rarely explored the effects of high-energy proton irradiation-induced SEB in β-Ga2O3 Schottky Barrier Diode (SBD), and the underlying mechanisms remain largely unexplored. Experimental results indicate that the reverse bias voltage during irradiation is a critical factor influencing the failure of β-Ga2O3 SBD. Compared to 300 MeV proton irradiation without bias, the introduction of a 300 V reverse bias voltage results in a significant reduction in forward current density (JF). When the reverse bias voltage reaches 400 V or higher, the 300 MeV proton induces SEB in the device. The SEM image of the damaged region reveals that the irradiated device has "voids" formed due to the melting of the Ga2O3 material. Geant 4 and TCAD simulation results indicate that the burnout phenomenon is caused by the elevated lattice temperature inside the device, which results from the implantation of secondary particles under a high reverse bias voltage. As the reverse bias voltage increases, the maximum lattice temperature of β-Ga2O3 SBD also rises. When the reverse bias voltage is sufficiently high, the local lattice temperature inside the device reaches the melting point of Ga2O3 material, ultimately leading to SEB. [ABSTRACT FROM AUTHOR]

We investigated the photo-thermoelectric response of Landau-quantized graphene in an infrared optical cavity structure. High-quality graphene/h-BN heterostructure was fabricated on a TiO2/Au optical cavity. We observed a large enhancement of the photo-thermoelectric voltage when the energy of the inter-Landau-level optical absorption, so-called cyclotron resonance, was coincident with that of the cavity mode. This is due to cavity-enhanced cyclotron resonance absorption of mid-infrared light. A maximum photovoltage responsivity of ∼107 V/W was obtained at a wavelength of 9.27 μm under a magnetic field as low as ∼1 Tesla. The obtained responsivity was significantly higher than that of conventional graphene devices. Our results provide an efficient photo-thermoelectric conversion scheme that utilizes Landau-quantized graphene and an optical cavity. [ABSTRACT FROM AUTHOR]

In this study, AlGaN/GaN Fin-HEMTs with different nanochannel geometric parameters were fabricated and comprehensively characterized. In the arcuate Fin-HEMTs, where the sidewalls arcuate from the source to the drain side, enhancements in the drain current density and transconductance were observed. By extracting and analyzing parameters obtained from small-signal measurements and conducting an analysis of gate capacitance, it was demonstrated that the enhancement can be attributed to the modulation of gate capacitance. This enhances the control capability of the gate over channel carriers, resulting in increased transconductance of the device. Due to the enhanced transconductance, the fT and fmax of the arcuate Fin-HEMTs are both enhanced. Notably, the arcuate Fin-HEMTs achieved a power-added efficiency of 71.4% at a frequency of 3.6 GHz and a drain voltage of 20 V. Meanwhile, the linearity of the arcuate Fin-HEMTs is improved compared with the conventional Fin-HEMTs. [ABSTRACT FROM AUTHOR]

Utilizing current-induced spin–orbit torque (SOT) to control magnetization is essential for the advancement of spintronics. SOT offers high energy efficiency and rapid operation speed. The ideal SOT material should have a high charge-to-spin conversion efficiency and excellent electrical conductivity. Recently, there has been a focus on topological insulator materials with topological surface states in SOT research due to their controllability in spin–orbit coupling, conductivity, and energy band topology. While topological Dirac semimetallic materials show promise for SOT applications, research on voltage regulation of their spin Hall angle is still in its early stages. This paper investigates the multilayer structure of a Dirac semimetallic material. In an α-Sn/Ag bilayer, the voltage regulation effect can increase the spin Hall angle by five times by adjusting the strain on the Fermi level. Experiments explore the role of a silver layer as a transport layer in the electric field control of multilayer films. This material system can enhance its effects under electric field regulation and offer insight for achieving regulation in new spintronic devices. [ABSTRACT FROM AUTHOR]

This work demonstrates a high-performance monolithically integrated GaN inverters platform, which incorporates enhancement-mode (E-mode) and depletion-mode (D-mode) GaN high-electron-mobility transistors (HEMTs) simultaneously using an Al:HfOx-based charge trapping layer. The developed E-mode HEMT exhibits a positive threshold voltage of 2.6 V, a high ON–OFF current ratio of 1.9 × 108, a current density of 376 mA/mm, and an ON-resistance of 15.31 Ω·mm. Moreover, the direct-coupled field-effect-transistor logic (DCFL) GaN inverter was characterized with and without D-mode device threshold voltage (VTH) modulation, demonstrating improved output swing and switching threshold shift by proposed VTH modulation. The optimized DCFL GaN inverter manifests a switching threshold of 2.34 V, a logic voltage output swing of 4.98 V, and substantial logic-low and logic-high noise margins of 2.16 and 2.49 V, respectively, at a supply voltage of 5 V. These results present a promising approach toward realizing monolithically integrated GaN logic circuits for power IC applications. [ABSTRACT FROM AUTHOR]

In this Letter, the reliability of indium-tin-zinc-oxide thin-film transistors (TFTs) under dynamic drain voltage stress is investigated. A degradation phenomenon, associated with both pulse rising time (tr) and falling time, is observed. Through the technology computer-aided design simulation and recovery experiment, it is discovered that the tr-dependent dynamic hot carrier effect and integral voltage-dependent electron detrapping jointly affect the device's reliability. Finally, an AC degradation model in indium-tin-zinc oxide TFTs, considering the non-equilibrium junction, hot carrier injection, and recovery, was proposed. [ABSTRACT FROM AUTHOR]

The characteristic voltages in the capacitance–voltage (C–V) curve of quantum dot light-emitting diodes (QLEDs) are usually linked to the start of charge injection and recombination in a working device. However, it may lead to a misunderstanding of the carrier process in QLEDs. This is because capacitance change only reflects an electrical response of additional carriers induced by a small signal loaded on an applied DC voltage but does not directly correlate with the total free carrier response governed by the working voltage. In this work, we study the frequency-dependent C–V characteristics of a blue QLED, focusing on the characteristic voltages, characteristic times, and their relationships. First of all, we identify that the charge injection point of QLEDs should be extracted by the current density–voltage–luminance characteristics rather than the C–V curve. As for the characteristic voltages obtained from the C–V curve, they are determined by voltage-dependent characteristic times in different time domains. Furthermore, the C–V characteristic is helpful to evaluate charge accumulation or leakage in blue QLED, serving as an accessible analysis tool in the carrier transport process. Our work provides a definite physical meaning of characteristic voltages in the C–V curve and exhibits the usefulness of C–V characteristics for analyzing the charge dynamics of QLED. [ABSTRACT FROM AUTHOR]

Polarization-sensitive ultraviolet (UV) photodetectors have attracted significant interest due to the broad applications in UV polarized imaging. However, the conventional UV photodetectors to realize polarization-sensitive properties require integrated filters and polarizers, which increase the system size and cost. In this work, self-powered polarization-sensitive UV photodetectors (PDs) with high efficiency and ultrafast response speed based on the MoS2/a-GaN heterojunction have been proposed and applied to UV polarized imaging. Benefiting from the type-I band alignment formed by MoS2/a-GaN, and the reduction of interfacial trapping effect, the PDs exhibit remarkable photovoltaic and polarization sensitivity under UV light at zero bias voltage, including a high responsivity of 15 mA/W, a specific detectivity of 4.7 × 1013 Jones, an ultrafast response speed of 4/8 ms, and a high polarization ratio of 1.5. Furthermore, the as-fabricated PDs demonstrate polarization-sensitive UV imaging. This work paves an approach for the development of high-performance polarization-sensitive UV PDs and offers a feasible way for the development of UV polarized imaging based on anisotropic materials. [ABSTRACT FROM AUTHOR]

The magnetic tunnel junctions (MTJs) based on van der Waals (vdW) materials possess atomically smooth interfaces with minimal element intermixing. This characteristic ensures that spin polarization is well maintained during transport, leading to the emergence of richer magnetoresistance behaviors. Here, using all 2D vdW MTJs based on magnetic metal Fe3GeTe2 and non-magnetic semiconductor MoSe2, we demonstrate that the magnitude and even sign of the magnetoresistance can be tuned by the applied voltage. The sign inversion of the magnetoresistance is observed in a wide temperature range below the Curie temperature. This tunable magnetoresistance sign may be attributed to the spin polarizations of the tunneling carriers and the band structure of the two ferromagnetic electrodes. Such robust electrical tunability of magnetoresistance extends the functionalities of low-dimensional spintronics and makes it more appealing for next-generation spintronics with all-vdW MTJs. [ABSTRACT FROM AUTHOR]

We have investigated the magnetoelectric effect of a series of Y-type hexaferrite Ba0.8Sr1.2Co2Fe11.1−xAl0.9CrxO22 (x ≤ 0.4) at room temperature. Although the magnetoelectric voltage coefficient αE of these multiferroic hexaferrites is not high, it changes rapidly with an applied DC magnetic field, a phenomenon known as the giant magnetotranstance (GMT) effect. It is found that the GMT effect is enhanced with increasing content of Cr and reaches the maximum for x = 0.2. Specifically, the magnetotranstance ratio in the x = 0.2 sample is as high as −96% at 2000 Oe and −84% at 500 Oe. Further addition of Cr content causes a decay of the GMT effect. This kind of room-temperature GMT effect in Y-type hexaferrites opens up a route toward practical applications for the single-phase multiferroics. [ABSTRACT FROM AUTHOR]

In this study, we report on the characterization of the magnetoelectric coupling coefficient in Ba-substituted Pb(Zr, Ti)O3/Co40Fe40B20 (BPZT/CoFeB) nanoscaled waveguides with lateral dimensions of 700 nm using propagating spin-wave spectroscopy. The characterization was conducted in a Damon–Eshbach configuration to maximize the magnetoelastic coupling strength, as predicted by strain distribution calculations using finite element simulations. The spin-wave resonance frequency is controlled by applying bias voltages on the magnetoelectric waveguide. The magnitude of the frequency shift was correlated with the strength of the magnetoelastic field, which reached a maximum value of 5.71 mT in our experiments. In addition, the results demonstrated that the coupling coefficient behavior is associated with the hysteretic ferroelectric nature of BPZT, reaching a maximum value of 1.69 mT/V. [ABSTRACT FROM AUTHOR]

In this work, the gate modulation characteristics of superconducting nanowire transistors (SNTs) were investigated under different on-chip gate voltage configurations. By fabricating NbTiN-SNTs with symmetric side gate, we studied the critical current suppression of SNTs under single, opposite, and double voltage gate. We figure out that the gate voltage and leakage current can be adjusted by the gate configuration. Moreover, it revealed an approximately twofold increase in modulation voltage for the opposite gate configuration as compared to the single gate configuration, implying a possible electric field tuned superconductivity. When simultaneously apply voltage on both gates, the onset and offset voltages kept unchanged, but the leakage current is then two times higher than that of single gate. In addition, under all these three types of gate configuration, the suppression of superconductivity coincided with the onset of leakage current, suggesting a potential charge injection mechanism. Our findings demonstrate that both the electric field and charge injection play important roles on the suppression of superconductivity in SNTs, which also contributes to the further optimization and applications of SNT. [ABSTRACT FROM AUTHOR]

A ferroelectric domain-wall memory has dual functionalities, where the volatile interfacial domain nearby the electrode can function as an embedded selector in contrast to the nonvolatile domain within an inner cell for information storage. However, most of crossbar memories require independent adjustments of the onset voltage of the selector and the coercive voltage of the inner domains at the same node fabrication technology. Here, we fabricated a LiNbO3 mesa-like domain-wall device to touch two top-to-top triangular-like Cu side electrodes. The readout wall current is more than 40 μA in write time as short as 20 ns. With the reduction of the apex angle of the Cu electrode from 180° to 30°, the onset voltage increases continuously from 0.68 to 3.05 V irrespective of the coercive voltage along with the improvement of polarization retention. The underlying physics is discussed on thickening of an effective interfacial layer projected along the applied electric-field direction. This finding enables the crossbar connection of high-density ferroelectric domain-wall memory. [ABSTRACT FROM AUTHOR]

In this Letter, we present a dual-layer oxide volatile memristor characterized by an Ag/TaOx/ZnO/Pt structure. This innovative design deviates from traditional Ag/ZnO/Pt devices, chiefly through the introduction of a thin TaOx layer between the electrolyte and the active electrode. Our devices exhibit remarkable features, including an unprecedentedly low switching voltage slope, measuring a mere 0.221 mV/dec, and a threshold voltage that can be reduced to as low as 0.177 V. To further elucidate the performance enhancement of the device, we utilize first-principles calculations. The results reveal that the relatively high formation energy of oxygen vacancies in the supplementary TaOx layer facilitates meticulous control over the rupture and formation of silver conductive nanofilaments. [ABSTRACT FROM AUTHOR]

In the field of cryopreservation, recrystallization during rewarming is a significant factor leading to cryo-injury, causing ice crystal-induced mechanical injury to biological samples. Currently, methods, such as adding ice recrystallization inhibiting agents and increasing warming rates, have been adopted to reduce recrystallization injury. These methods also greatly increase the potential toxicity risk and engineering difficulty of cryopreservation. Accumulating research has progressively demonstrated that application of an electromagnetic field during cryopreservation can influence the preservation efficacy. However, the mechanism of action of the electric field has remained a subject of ongoing debate. We observed the recrystallization phenomenon of cryoprotectant solutions under a polarized light microscope and discovered promising experimental results. The electric field strength did not exhibit a discernible impact on the ice crystal size, while electric field frequency exerted a more significant impact. We found that at specific frequencies, the ice crystal size and growing rate were significantly affected during annealing. Compared to no electric field, an alternating electric field with a voltage of 10 V and a frequency of 5 × 104 Hz increased the recrystallization areas of a 15% (w/v) propylene glycol solution by 57%. And an alternating electric field with a voltage of 3 V and a frequency of 5 × 108 Hz decreased the recrystallization area of a 0.9% (w/v) NaCl aqueous solution by 9.9%. Different types of cryoprotectants exhibit varying responses to alternating electric fields frequency. These findings prompt us to reevaluate the role and mechanism of alternating electric fields in the cryopreservation of biological materials. [ABSTRACT FROM AUTHOR]

Output characteristics of top-gate amorphous InGaZnO thin-film transistors are investigated at high gate voltage. With the increasing drain voltage, an output breakdown crops up closely following a drastic uprush of drain current. Such dramatically elevated drain current derives from the self-heating (SH) effect-generated channel donors. Measured at different high gate voltages, the output breakdown occurs in either linear or saturation regime, respectively, corresponding to normally-on and normally-off transfer curve, while the SH-triggering powers are almost identical. The conductor-like channel originates from the SH-induced high donor population, while the disconnection between channel and drain is caused by a highly defective region near drain, where the hot-carrier damage is violently activated by the SH-induced high temperature and the high drain electric field in saturation regime. [ABSTRACT FROM AUTHOR]

Polarization-based synaptic transistors offer the advantages of low power consumption and non-volatility, but they face significant challenges in achieving multi-level conductance states and low operating voltage. Here, this issue was resolved by precisely controlling the alignment of polar electret molecule chains through microfluidic techniques in spin-coating. Optimized devices exhibit cycles of near-linear potentiation and depression, yielding 80 distinct conductance states under ultra-low voltage pulse stimulation (0.1 V/−0.1 V), with an ideal dynamic range of approximately 90 nA. Additionally, simulated image recognition accuracy exceeds 90%, highlighting exceptional weight updating capabilities. This work opens up an avenue for low-cost, low-power, and high-performance synaptic devices. [ABSTRACT FROM AUTHOR]

The development of high-performance optically induced voltage materials represents a significant challenge within the realm of optical detection. The constraints posed by low induced voltage and extended response times have impeded the practical applicability of optical and thermal radiation detectors. In this investigation, we propose the utilization of superconducting Bi2Sr2CuOy (Bi-2201) as a pulsed laser-induced voltage material, revealing the emergence of notable transverse voltage signals in tilted thin films. A noteworthy peak voltage of 25.12 V is attained upon exposure to ultraviolet pulsed laser (248 nm), with a rapid rise time of merely 60 ns. Furthermore, we establish an empirical equation specific to our laser detection heterostructure, serving as a benchmark for Bi-2201-based laser detection systems. These findings introduce a promising avenue for the expanded practical applications of high-temperature superconductors. [ABSTRACT FROM AUTHOR]

Neuromorphic computing that emulates brain behaviors can address the challenge of von Neumann bottleneck and is one of the crucial compositions of next-generation computing. Here, the polynary oxide of amorphous InAlZnO (a-IAZO)-based memristor is employed as electronic synapse with essential properties of biological synapse, including spiking timing-dependent plasticity, paired-pulse facilitation, long-term depression/potentiation, and Pavlov associative memory. Especially, the a-IAZO memristor properties are quite sensitive to the oxygen vacancy content, which exhibit stable switching and narrow distribution of Set/Reset voltage due to the oxygen vacancy content decrease after high-temperature annealing in air, showing promise for memristor performance enhancement. This work promotes the development of high-performance memristors with polynary oxide for neuromorphic computing and opens a path for a-IAZO film application in optoelectronics. [ABSTRACT FROM AUTHOR]

In this work, vertical gallium nitride (GaN) Schottky barrier diodes (SBDs) with an ultra-low turn-on voltage VON (0.37 V) were demonstrated. Due to the process of O2 plasma treatment, GaON was formed on the surface of GaN and further modified the surface potential of the material surface, which made the VON decrease from 0.62 to 0.37 V. Spin-on-glass was deposited on top of devices to form the floating guard ring, which was used to improve the breakdown voltage to 681 V (at J = 1 A/cm2) by reducing the electric field distribution. The vertical GaN SBDs exhibit a specific on-resistance (RON) of 2.6 mΩ cm2. Deterioration of the device under different stress time changes slightly showed great stability of the devices. [ABSTRACT FROM AUTHOR]

At present, the thermal switch for localized heating is becoming a hot research topic in MEMS packaging technology. A method of using a liquid-based thermal switch is proposed in this paper. A plate local heating device based on electric field distribution control is constructed, where a thermal liquid column can be formed under the action of the electric field. The electric field controls the formation and dissipation of the liquid column to realize the on-off and off-on function of the thermal switch. Through the control of the different conductive substrates in the plate, the localized heat transfer can be further realized, and the heat transfer position is precisely regulated. Furthermore, due to the fluidity of the liquid, the prepared thermal switch can also realize movable heating. The experimental results show that the heating time and speed can be controlled precisely by adjusting the driven voltage and the conductive area of the upper substrate. [ABSTRACT FROM AUTHOR]

The spin-to-charge conversion phenomenon is investigated in a trilayer structure consisting of Co(12 nm)/Sb(t)/Py(12 nm), where the thickness t of the antimony layer is varied. Using the spin-pumping technique, a pure spin current is injected from both FM layers into the middle layer, the DC voltage is then measured. We observe a spin-to-charge mechanism in the Sb layer that exhibits striking similarities to the inverse Rashba–Edelstein effect (IREE), driven by surface states. [ABSTRACT FROM AUTHOR]

We propose a new voltage scheme for string-select (SS) transistors to improve inhibition characteristics of unselected cells during selective 1-bit erase in vertical NAND flash memory. Different from the reported schemes, we apply different control voltages to each of the three SS transistors of unselected drain select lines and all source select lines to lower the channel potential. The change in the channel potential depending on the voltage of the SS transistors and the resulting gate-induced drain leakage is explained via TCAD simulation. The proposed pulse method can reduce the Vth of the 1-bit cell selected for erase by 168% compared to the reported method while maintaining the same inhibition characteristics. [ABSTRACT FROM AUTHOR]

The detection capability of GaN-based nano-diodes is measured up to 110 GHz in two configuration schemes: voltage and current responsivity. The ratio between both figures of merit allows one to extract the AC resistance of the diode, showing a very flat value in all the frequency spans. An optimization on the geometrical parameters is performed, finding that the narrower the channel, the higher the voltage responsivity, and the higher the number of channels in parallel, the higher the current responsivity. The expected dependence of the noise equivalent power with the width and number of channels is confirmed. The proposed configuration for best performance of these devices as RF detectors is to allocate the maximum number of channels in parallel and operate in a current responsivity mode. [ABSTRACT FROM AUTHOR]

Electron transpiration cooling has previously been predicted to be an alternative cooling mechanism for leading edges of aerospace platforms traveling at extreme velocities, where thermoelectric materials shaped as leading edges manage heat loads. Here, thermo-electron emitting LaB6 ceramics with blunt edges were placed between two conical-shaped electrodes, and a plasma glow was ignited to heat the sample. Analysis of current–voltage (I–V) curves demonstrated that insertion of LaB6 into the plasma column resulted in an increase in the electron density of the plasma, evidencing thermally stimulated electron emission. With increasing sample temperature to 1200 K, Δne increased by ∼4 × 1010 #/cm3, the electron temperature (Te) decreased from ∼8 eV (1000 K) to 2.5 eV, and the emission begins to appear to become space charge-limited. Richardson's analysis of the temperature dependence of the electron emission in the region of ion saturation, yielded an activation energy consistent with the work function of LaB6. Modulation of the LaB6 surface temperature (ΔT = 10 K) and the plasma current (ΔI = 70 μA) under electric voltage (80 V) applied between the sample and current probe was demonstrated. The results show for the first time the feasibility of electron transpiration cooling effects under plasma conditions similar to that of aerothermal environments. [ABSTRACT FROM AUTHOR]

The observed open circuit voltages in best performing solar cells are explained outside of the recombination paradigm, based on such factors as electrostatic screening, Meyer–Neldel effect, and lateral nonuniformities. The underlying concept of suppressed recombination presents a long neglected alternative pathway to efficient photovoltaic. The criteria of suppressed recombination and effective charge carrier extraction are consistent with the data for best performing solar cells. [ABSTRACT FROM AUTHOR]

Nanocrystal quantum dot (QD) films have been highlighted as unique building blocks of optoelectronic devices due to their unique properties based on electronic interactions among close-packed QDs. Although the creation and annihilation processes of trions play important roles in optical responses of isolated QDs, their contributions to photocurrent conversion processes in QD films are unclear. Here, we studied trion dynamics in QD films by transient photocurrent measurements. We observed that the transient photocurrent signal has two decay components: a fast trion component with a lifetime shorter than 1 ns and a slow exciton component with several tens of nanoseconds. Moreover, we control the signal amplitude of the fast trion decay component by tuning extra charge doping to QDs. These results demonstrate the control of optoelectronic responses of QD films via bias electric voltage and will pave the way for QD-based ultrafast optoelectronics. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate reconfigurable ferroelectric field-effect transistors (Fe-FETs) exhibiting process dependence based on poly(vinylidene fluoride-trifluoroethylene)/molybdenum telluride[P(VDF-TrFE)/MoTe2] heterostructures. By introducing a thickness gradient to a ferroelectric polymer, we constructed a gradient distribution of coercive voltage. This enables programmable configuration of the device (n–p, p–n, p–p, or n–n) depending on the input voltage sequence. Our Fe-FETs exhibit multilevel storage capacity and logic ability, including an on/off ratio of 106, an adjustable rectification ratio from 1 to 45, and a reversible rectification direction. The use of such a structure-gradient design in an Fe-FET provides a valuable strategy for realizing process-dependent reconfigurability and the creation of intelligent devices. [ABSTRACT FROM AUTHOR]

Memristive devices made of multilayer hexagonal boron nitride are attracting much attention for information storage, computation, encryption, and communication. Generating multilevel operation in these memristors would be an important added value for the field of neuromorphic computation, but the main phenomenon producing it (i.e., conductance quantization) is not well understood for this material. Here, we analyze hexagonal boron nitride memristive devices with metal electrodes operating in their quasistatic and transient regimes. Conductance quantization effects were observed both in I-V curves measured under ramped voltage stress and in the reset processes driven by voltage pulse trains. Polar and time lag plots are employed to shed light on the physics behind the device resistive switching. A model is proposed to reproduce the electrical characteristics of progressive reset processes and the discretization of the device conductance linked to quantum effects. [ABSTRACT FROM AUTHOR]

Far-ultraviolet-C (far-UVC) light-emitting diodes (LEDs) with an emission wavelength of 234 nm with different polarization-doped AlGaN hole injection layers (HILs) are compared regarding their emission power, voltage, and leakage current. The influence of the thickness of the polarization-doped layer (PDL), an additional Mg doping of the PDL, as well as a combination of a PDL with a conventionally Mg-doped AlGaN HIL will be discussed. The different PDL thicknesses show nearly no influence on the emission power or voltage. However, the leakage current of the LEDs below the turn-on voltage decreases with an increasing thickness of the PDL. In contrast, an additional Mg doping of the PDL ([Mg] ∼ 1.5 × 1019 cm−3) results in a fivefold decrease in the emission power at an unchanged voltage and leakage current. Finally, a combination of a PDL and a conventionally Mg-doped AlGaN layer ([Mg] ∼ 1.5 × 1019 cm−3) as a HIL shows also a similar emission power and voltage compared to the single PDL, but the leakage current increases. Based on these optimizations, 234 nm LEDs were realized with a maximum external quantum efficiency of 1% at 20 mA, an emission power of 4.7 mW, and a voltage of 9.0 V at 100 mA. This shows that the polarization doping concept is well suited to realize far-UVC LEDs with improved performance compared to LEDs with a conventionally Mg-doped p-side. [ABSTRACT FROM AUTHOR]

Organic memristors are considered to be the next-generation storage element due to their unique advantages of flexibility, transparency, and good solution processability. In this Letter, a Zn-porphyrin based small-molecular organic memristor is prepared by spin-coating with an ultralow resistive switching set voltage of 0.38 V. It is found that the zinc atom in the porphyrin molecule plays a very important role in improving the resistance switching characteristics of organic memristors. By tracking the change in oxygen valence in the vertical dimension, we demonstrate that Zn atom located in the core of porphyrin helps to enhance the oxygen ion migration across the active layer, clearly revealing the memory mechanism of low-cost solution-processed Zn-porphyrin based small-molecular organic memristors. This organic memristor shows excellent memristive performance resulting from rational material design and appropriate device structure engineering. [ABSTRACT FROM AUTHOR]

This work reports the enhancement of damping-like and field-like spin–orbit torque (SOT) efficiencies and interfacial spin transparency (Tin) in the Py/NiO/Pt heterostructure. The SOT efficiencies and Tin are characterized by combining the spin–torque ferromagnetic resonance (ST-FMR) and the spin-pumping (SP) techniques. The inevitable inverse spin Hall voltage contamination induced by SP in the ST-FMR spectrum is extracted and subtracted by combining additional SP measurements, which allows obtaining accurate SOT efficiencies and Tin. The damping-like and field-like SOT efficiencies vary with the NiO insertion layer thickness, which is a result of the change of Tin. The maximum Tin reaches ∼0.82 for a 0.6 nm-thick NiO layer. This work shows that NiO insertion is an effective method for enhancing Tin and, hence, the SOT efficiency. [ABSTRACT FROM AUTHOR]

This work proposes positive feedback (PF) device-based synaptic devices for reliable binary neural networks (BNNs). Due to PF operation, the fabricated PF device shows a high on/off current ratio (2.69 × 107). The PF device has a charge-trap layer by which the turn-on voltage (Von) of the device can be adjusted by program/erase operations and a long-term memory function is implemented. Also, due to the steep switching characteristics of the PF device, the conductance becomes tolerant to the retention time and the variation in turn-on voltage. Simulations show that high accuracy (88.44% for CIFAR-10 image classification) can be achieved in hardware-based BNNs using PF devices with these properties as synapses. [ABSTRACT FROM AUTHOR]

This paper demonstrates a hafnium zirconium oxide (HZO)-based ferroelectric NEMS unimorph as the fundamental building block for very low-energy capacitive readout in-memory computing. The reported device consists of a 250 × 30 μ m 2 unimorph cantilever with 20-nm-thick ferroelectric HZO on 1 μm SiO2. Partial ferroelectric switching in HZO achieves analog programmable control of the piezoelectric coefficient (d31), which serves as the computational weight for multiply accumulate (MAC) operations. The displacement of the piezoelectric unimorph was recorded by actuating the device with different input voltages Vin. The resulting displacement was measured as a function of the ferroelectric programming/poling voltage V P . The slopes of central beam displacement (δmax) vs Vin were measured to be between 182.9 nm/V (for −8 Vp) and −90.5 nm/V (for 8 Vp), which corresponds to displacement proportionality constant β of 68 nm/V2 for +ve Vp and 47 nm/V2 for −ve Vp, demonstrating linear behavior of the multiplier unit. The resultant δmax from AC actuation is in the range of −18 to 36 nm and is a scaled product of Vin and programmed d31 (governed by the Vp). The multiplication function serves as the fundamental unit for MAC operations with the ferroelectric NEMS unimorph. The displacement from many such beams can be added by summing the capacitance changes, providing a pathway to implement a multi-input and multi-weight neuron. A scaling and fabrication analysis suggests that this device can be CMOS compatible, achieving high in-memory computational throughput. [ABSTRACT FROM AUTHOR]

Due to the excellent properties, C4F7N/CO2 mixture is the most concerned eco-friendly SF6 alternative gas. For a better understanding of the surface discharge characteristics, the surface discharge pattern of C4F7N/CO2 mixture under negative impulse voltages is investigated in this work. The morphology of the surface discharge is obtained by an optical method and a dust figure method. The structure of the surface discharge is established, which from the outside to the inside consists of electron cloud, streamer, streamer stem, and leader. The propagation pattern of the surface discharge in C4F7N/CO2 mixture under negative impulse follows the stepwise expansion pattern. The structure of the surface discharge in C4F7N/CO2 mixtures with different ratios and SF6 has no obvious difference, and the propagation pattern is also the same. The results of this work can help to better understand the surface discharge phenomenon and the insulation characteristics of C4F7N/CO2 mixture. [ABSTRACT FROM AUTHOR]

For a trap-free single layer single carrier (hole-only or electron-only) organic device of thickness d, dielectric constant εr, and mobility μ, the relation of current density j with voltage V is described by the well-known Mott–Gurney equation, j = 9 ε 0 ε r μ V 2 / 8 d 3 , which can be rewritten as j = G V , where G = 9 ε 0 ε r μ / 8 d 3 can be called space-charge limited (SCL) conductance. We investigated the current–voltage characteristics of vertical organic heterojunction phototransistors based on graphene as the source and C60/copper phthalocyanine (CuPc) heterojunction as the photoactive layer. We found that the drain current vs drain voltage (Id-Vd) characteristic is composed of two distinct SCL conductions with SCL-conductance being strongly dependent on the gate voltage and illumination intensity. At low gate voltages, the Id-Vd curve can be divided into two sections of SCL current conduction with different SCL-conductance: the lower conductance in the lower drain voltage range and the higher conductance in the higher drain voltage range. Both low and high SCL-conductance increase with the gate voltage and illumination intensity. However, as the gate voltage increases to a certain threshold, the two SCL sections unify to only one with the conductance being between them. Our findings implicate that the current conduction of an ideal vertical organic phototransistor (VOPT), whose source/organic interface contact is Ohmic and organic semiconductor is trap free, can be well modeled by the SCL conduction theory with carrier density dependent mobility, which is strongly related to the gate voltage and illumination intensity, and that the mobility of VOPTs at a certain gate voltage can be extracted by the Mott–Gurney equation. [ABSTRACT FROM AUTHOR]

The output performance of triboelectric nanogenerators (TENGs) is fatally determined by the capacitive capability of triboelectric electrodes. One promising solution is embedding conductive fillers in triboelectric polymers, typically carbon nanotubes (CNTs) in polydimethylsiloxane (PDMS). Each CNT will serve as a capacitor in the PDMS matrix to store electric energy through polarization. However, the CNTs are easily cross-linked with each other, which makes the triboelectric materials conductive or semi-conductive. The output voltage will be limited due to current leaks through conducting or tunneling, and thus, suppress the energy harvesting efficiency of TENGs. Here, we propose to use an insulation layer to wrap CNTs to avoid direct-contact between CNTs and improve the overall performance of TENGs. Our results show that the leakage current has been significantly suppressed and the output performance of TENGs has been dramatically improved. This work provides a material design idea, which is expected to become a universal method to improve the output performance of TENGs. [ABSTRACT FROM AUTHOR]

Hyperspectral electroluminescence and photoluminescence imaging of photovoltaic materials and devices produces three-dimensional spatially and spectrally resolved luminescence data, which can be calibrated to an absolute scale, enabling the extraction of high resolution maps of quantities, such as the local voltage (quasi-Fermi-level splitting). This extraction requires supplemental measurements of external quantum efficiency (EQE), but these do not have the same spatial resolution. Previously, assumptions have been made to overcome this limitation. In this work, we evaluate these assumptions for InGaAs solar cells with significant spatial variation in the luminescence spectrum shape due to small regions with elevated concentrations of radiative defects. Although appropriate for small variations in the spectral shape, we find that with more significant variation, these assumptions can result in nonphysical EQEs and too-low voltages. Combining multiple methods can help to alleviate this, or a minimum voltage map can be extracted, which will be similar to the actual voltage when EQE is high. [ABSTRACT FROM AUTHOR]

We report a combined experimental and theoretical study of Gundlach resonances Un in scanning tunneling spectroscopy at constant current over an exceptional range of energy and number, typically tens of an eV and over thirty in order n. By performing (1) three-dimensional electrostatic calculations, (2) WKB quantum calculations of the current, and (3) one-dimensional solutions of the Schrödinger equation along the perpendicular line from the surface to the tip apex, we provide a theoretical understanding and prediction of the experimental U(n) curve. Unlike commonly assumed, the triangular potential well is not found to be a good approximation for the high-n states. We show that although the spectroscopy mode assures a constant electric field at the tip apex, this leads only for the intermediate resonance states (approximately 2 < n < 6) to reside in a linear potential between the tip and the surface. Whereas the low lying (n <6) states all lie approximately in the same quantum well, at higher tip-sample distances d and bias voltages V(d), the quantum well is no longer triangular but attains a curvature, which is d dependent. Each high-n state resides in its own well that can be well-approximated by a polynomial of second order. Hence, the range of Un to be analyzed in terms of spectroscopic positions needs to be chosen with great care when deducing surface work functions. [ABSTRACT FROM AUTHOR]

We report a resonant torsional micro-mirror with all-piezoelectric driving and tunable spring stiffness. Stiffness modulation finds two practical applications. First is tuning of the resonance frequency, achieved by applying DC bias voltage to the stiffness modulating structures. A tuning rate was found to be 0.95 Hz V−1 with up to 20 Hz of usable frequency range. Second, when direct excitation of the torsional mode is combined with the harmonic modulation of the spring stiffness, an optical scan angle is shown to be increased by more than 4° through 2:1 degenerate parametric amplification. By varying the phase of the parametric pump with respect to the direct excitation, the Q-factor is tuned between 617 and 898, corresponding to the minimum and maximum parametric gain factors of 0.84× and 1.21×, respectively, achieved at a nominal unpumped optical scan angle of 16.3°. Increasing the pump amplitude shows a moderate increase in the amplifier's gain with clear saturation at 1.43× in the superthreshold pumping regime, indicating a presence of the third order stiffness nonlinearity. The results show potential to apply parametric amplification to future piezo-micro-electro-mechanical-system actuators for large frequency and large-stroke mechanical response achieved at ambient pressure. [ABSTRACT FROM AUTHOR]

The ability to resolve the polarization of light with on-chip devices represents an urgent problem in optoelectronics. The detectors with polarization resolution demonstrated so far mostly require multiple oriented detectors or movable external polarizers. Here, we experimentally demonstrate the feasibility to resolve the polarization of mid-infrared light with a single chemical-vapor-deposited graphene-channel device with dissimilar metal contacts. This possibility stems from an unusual dependence of photoresponse at graphene–metal junctions on gate voltage and polarization angle. Namely, there exist certain gate voltages providing the polarization-insensitive signal; operation at these voltages can be used for power calibration of the detector. At other gate voltages, the detector features very strong polarization sensitivity, with the ratio of signals for two orthogonal polarizations reaching ∼ 10. Operation at these voltages can provide information about polarization angles, after the power calibration. We show that such unusual gate- and polarization-dependence of photosignal can appear upon competition of isotropic and anisotropic photovoltage generation pathways and discuss the possible physical candidates. [ABSTRACT FROM AUTHOR]

THz polarization control upon generation is a crucially missing functionality. THz spintronic emitters based on the inverse spin Hall effect (ISHE) allow for this by the strict implicit orthogonality between their magnetization state and the emitted polarization. This control was until now only demonstrated using cumbersome external magnetic field biasing to impose a polarization direction. We present here an efficient voltage control of the polarization state of terahertz spintronic emitters. Using a ferromagnetic spin pumping multilayer exhibiting simultaneously strong uniaxial magnetic anisotropy and magnetostriction in a crossed configuration, an emitter is achieved where, in principle, the stable magnetization direction can be fully and reversibly controlled over a 90° angle span only by an electric voltage. To achieve this, an engineered rare-earth based ferromagnetic multilayer is deposited on a piezoelectric (1 − x) [ Pb (Mg 0.33 Nb 0.66) O 3 ] − x [ PbTiO 3 ] (PMN-PT) substrate. We demonstrate experimentally a reversible 70° THz polarization rotation by sweeping the substrate voltage over 400 V. This demonstration allows for a fully THz polarization controlled ISHE spintronic terahertz emitter not needing any control of the magnetic bias. [ABSTRACT FROM AUTHOR]

In this paper, a silicon oxide based conductive bridging random access memory (CBRAM) with an ultra-low operation voltage, a high switching speed, and an ultra-low resistance at low resistance state (LRS) is reported. The CBRAM has a sandwich structure with platinum and copper as electrode layers and an ultra-thin 10-nm-thick silicon oxide film as an insulating switching layer. The CBRAMs are fabricated with CMOS compatible materials and processes. DC I–V sweep characterizations show an ultra-low SET/RESET voltage of 0.35 V/−0.05 V, and the RESET voltage is the lowest among all ultra-low voltage CBRAMs. The CBRAM is capable of withstanding endurance tests with over 106 pulses of +0.4 V/−0.1 V with 1 μs pulse width, with the resistance at LRS maintaining at an ultra-low value of only 20 Ω, which is the lowest among all CBRAMs to date, and it is reduced by at least 2.95 times compared with prior studies. Meanwhile, the switching ratio between high resistance state and LRS is more than 1.49 × 104. Moreover, the switching time characterization of the CBRAM demonstrates an ultra-short SET/RESET time of 7/9 ns. The CBRAM has potential applications in high-speed, ultra-low voltage, and ultra-low power electronics. [ABSTRACT FROM AUTHOR]