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Terahertz (THz) quantum-cascade lasers (QCLs) are attracting an ever-increasing interest for both scientific and industrial applications in key areas, such as high-resolution spectroscopy of atomic and molecular absorption lines. Advancements in the active-region and resonator designs, hence, play a pivotal role in determining the future of this technology, especially regarding the wall-plug efficiency and the operating temperature, which are still the main factors limiting their widespread adoption. A sound characterization approach is, therefore, the foundation of the coming improvements to these semiconductor lasers. To overcome the overreliance on simulation tools for the determination of fundamental device characteristics, we report a comprehensive characterization approach to measure all relevant electrical, optical, and thermal parameters of THz QCLs in a consistent manner. Based on the lattice temperature dependence of the QCL output power, the thermal conductivity of the QCLs is extracted. We then retrieve light–current density–lattice temperature maps to decouple the influence of the bias and lattice temperature on the device performance. Applying this method to two sets of QCLs with different active-region designs allowed us to determine the internal quantum efficiency (∼12%), waveguide losses (8–20 cm−1), and transparency current density. A transparency current density greater than 60% of the threshold current density is observed for the two active regions, which demonstrates leakage currents to be the dominant factor limiting THz QCLs efficiency even at low temperatures and for optimized designs employing tall barriers of nominally pure AlAs. [ABSTRACT FROM AUTHOR]

The leakage mechanism of solar-blind AlGaN p-i-n photodetectors has been investigated. By studying the temperature-dependent I–V curves, we determined that Poole–Frenkel emission is the main source of the leakage current, and the corresponding trap energy level is 0.61 eV. Cathodoluminescence measurement demonstrates that the leakage current of the device may be related to the deep-level traps in the p-AlGaN layer. An analysis of deep-level transient spectroscopy testing results for p-AlGaN suggests that nitrogen vacancies formed during the epitaxial growth of high Al-content p-AlGaN act as electron traps. The trap potential energy decreases at high reverse bias voltage, making trapped electrons easier to escape, which increases the leakage current. [ABSTRACT FROM AUTHOR]

Both large spontaneous polarization and high breakdown strength are necessary to achieve high recoverable energy density in capacitors. Unfortunately, there is a trade-off between them within the homogeneous medium. Therefore, a sandwich structure with a high polarization layer was designed in the Aurivillius phase lead-free film to address this issue. This strategy can effectively enhance the polarization capability by introducing a highly spontaneous polarization layer and also improve the breakdown strength by reducing the leakage current caused by interfacial barriers and grain refinement. Benefiting from the synergistic effects, a high energy density of 50.4 J / cm 3 with a high efficiency of 76.6% in the sandwich-structure thin film capacitors were achieved. In addition, the energy storage performance exhibits good wide frequency range and high-temperature stability. This approach is generally applicable to the design of other ferroelectrics and dielectrics promises high-performance energy storage capacitors. [ABSTRACT FROM AUTHOR]

Due to their high similarity to biological ion channels, low power consumption, small footprint, and the fact that they do not require reset circuits, threshold switching memristors have been intensively studied for simulating neurons in neuromorphic chips. Switching speed is one of the key challenges which limit the application of threshold switching memristors in chips. In this study, Ta2O5 threshold switching memristors with high switching speeds were prepared by doping with silver. The results show that 14 wt. % Ag doped Ta2O5 threshold switching memristors exhibit excellent bi-directional threshold switching performance, featuring fast switching speeds (<20 ns, <18 ns), low leakage currents (<10 pA), and high switching ratio (>107). According to the field nucleation theory, the rapid switching speed can be attributed to the low nucleation energy (0.26 eV) of silver within the Ta2O5 matrix, which is achieved by incorporating 14 wt. % Ag during the doping process. Based on Pspice, a LIF (leaky integrate-and-fire) neuron based on the silver nanoparticles doped Ta2O5 threshold switching memristors is built, and its firing function has been simulated. The results show that the LIF neuron with a short switching time is able to excite pulse spiking with high frequencies. These results demonstrated that the silver nanoparticles doped Ta2O5-based threshold switching memristors hold significant potential for constructing high-speed artificial neural networks. [ABSTRACT FROM AUTHOR]

The S vacancy at metal/ MoS 2 interface plays a much important role than the semiconductor itself. In this work, the influence of different configurations of S vacancy concentrations on the effective work function and band structure of the Au/ MoS 2 interface has been investigated systematically using first-principles calculations. The study specifically explores the effective work function of the Au/ MoS 2 interface, the deviation of interface effects from the vacuum work function, and the dipole moment caused by interface charge transfer. The results reveal that the electronic work function of Au/ MoS 2 increases with the increase in S vacancy concentration, but the rate of increase tends to slow down with higher S concentrations. The variation in the effective work function of the Au/ MoS 2 interface may be attributed to the presence of S vacancies and the exposure of Mo atoms. S vacancies lead to a reduction in the Schottky barrier, resulting in increased leakage current. The Fermi pinning caused by S vacancy concentration and location is also observed. The results obtained in this study can serve as a theoretical foundation for applications in electronic devices that rely on metal/ MoS 2 contact. [ABSTRACT FROM AUTHOR]

Polymer dielectrics with excellent capacitive performance are urgently needed in advanced electrical and electronic systems. However, due to the dramatic increase in the conduction loss, the energy density and efficiency of polymers degrade severely at elevated temperatures, limiting their application in harsh environments up to 150 °C. Herein, an all-organic polyurea (PU)/polyetherimide (PEI) blend film is designed to prepare high-temperature polymer dielectric. It is found that carrier traps can be introduced by blending, and the hydrogen bond between PU and PEI increases the trap depth, leading to suppressed leakage current and enhanced breakdown strength, thus improving the energy storage performance. PU/30%PEI exhibits a high discharged energy density of ∼3.74 J/cm3 with an efficiency higher than 90% at 150 °C, which is 78% and 70% higher than pristine PU and PEI, respectively. This work provides a facile strategy to improve the energy storage performance of polymer dielectrics by introducing deep traps through blending. [ABSTRACT FROM AUTHOR]

This paper provides a comprehensive study of the impact of the gate recess depth (RD) on the GaN-on-Si MOS-HEMTs DC performances. IDS = f(VGS) and IDS = f(VDS) measurements are conducted at 25 and 150 °C, respectively, in forward and blocking modes. The gate recessed depth (50, 150, and 350 nm) is modulated by adjusting the plasma etching time, which is a critical step for improving the dielectric/GaN interface quality and the gate channel electron mobility. Three distinct regions can be defined separately: the bottom, the sidewall, and the corner region being the junction between the two previous regions. To assess the impact of gate recessed depth (RD) on the several mobilities around the gate cavity first, we applied our previous methodology allowing us to extract the bottom (μbot) and the entire sidewall region mobility (μT), without distinction from the corner. The mobility of the transverse region was found surprisingly to increase with deeper RD. To gain insight into the impact of the RD on this transverse section, a new extraction methodology is proposed to extract separately the gate corner (μcorner) and sidewall (μSW) mobility. These extractions show that the corner mobility is found to be reduced compared to the sidewall one (μcorner < μSW) evidencing the different weighting contributions over the transverse mobility. Moreover, these mobilities are found to be more degraded compared to the bottom one, highlighting the different contributions on the on-state resistance (RON). Indeed, the on-state resistance is lowered with the shallower RD due to the reduced sidewall resistance contribution (lower sidewall length) and despite the incremental contribution of the bottom resistance (larger effective gate length). However, the shallower RD shows an increase in the drain–source leakage current in reason of a lower gate electrostatic control. Technology Computer Aided Design (TCAD) simulations of the three RD morphologies are carried out to validate the experimental trends and the proposed methodology. [ABSTRACT FROM AUTHOR]

Amorphous composite polymers are widely used as insulators in microelectronics due to their high dielectric strength, mechanical robustness, and thermal stability. However, organic–inorganic composite systems suffer from undesirable performance and accelerated degradation due to leakage current ( J Tot ). Unfortunately, the underlying mechanism of J Tot and its components (e.g., ionic and electronic constituents) are inadequately understood, particularly in extreme use conditions (e.g., high humidity and temperature). In this study, we use numerical simulation and experimental J Tot data (in amorphous epoxy polymer with silica fillers) to (i) unify the electrostatic model for J Tot in composite polymers, (ii) illustrate that the early part of J Tot (i.e., external current) is primarily due to the image charge associated with ion transport/ localization ( J ion ) near the metallic contacts, (iii) demonstrate that the accumulated counter-ions reduce the barrier for electronic charge injection (by band bending) and facilitate electronic injection from the metals ( J elec ), and (iv) provide an algorithm for the in situ ion transport characterization of composite insulators by exploiting J ion . This work provides new insights regarding the leakage current mechanism and how it can be used as a probe into the complex transport mechanisms of the composite material. [ABSTRACT FROM AUTHOR]

In this paper, the p-GaN gate AlGaN/GaN high electron mobility transistors (HEMTs) with varying combinations of gate metal work function and gate geometry are fabricated and investigate the influence of gate leakage current (IGS) on the threshold voltage (VTH) and subthreshold swing (SS). The unique dependence of VTH and SS on gate geometry for different metals is observed, which is different from traditional field-effect transistors. A novel hybrid physics model, consisting of the traditional capacitance divider model and hole injection model, is proposed to explain this phenomenon, and the results exhibit an excellent agreement with the experimental data. The holes traverse the gate/p-GaN Schottky barrier by thermal emission or tunneling and inject into the p-GaN layer, generating the IGS. Expanding upon the traditional capacitance divider model, a portion of the injected holes accumulate at the p-GaN/AlGaN interface and induce the corresponding electrons at the AlGaN/GaN heterojunction, which promotes channel conduction. Hence, the transfer curves display the correlation between IGS and VTH as well as SS. The results show that high IGS can alleviate the instability of VTH caused by the lithographic overlay error, and simultaneously optimize SS. This work offers a novel perspective for examining the turn-on mechanism of p-GaN HEMTs, thereby contributing to device design. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate a hydrogen-terminated diamond (H-diamond) field-effect transistor (FET) with Al2O3/CeB6 gate materials. The CeB6 and Al2O3 films have been deposited by electron beam evaporation technique, sequentially. For the 4/8/12/15 μm gate length (LG) devices, the whole devices demonstrate distinct p-type normally off characteristics, and all the threshold voltage are negative; all the absolute values of leakage current density are 10−4 A/cm2 at a VGS of −11 V, exhibiting a relatively low leakage current density compared with CeB6 FETs, and this further demonstrates the feasibility of the introduction of Al2O3 to reduce the leakage current density; the maximum drain–source current density is −114.6, −96.0, −80.9, and −73.7 mA/mm, which may be benefited from the well-protected channel. For the 12 μm LG devices, the saturation carrier mobility is 593.6 cm2/V s, demonstrating a good channel transport characteristic. This work may provide a promising strategy for the application of normally off H-diamond FETs significantly. [ABSTRACT FROM AUTHOR]

In this work, bottom-Schottky-structure InGaZnOx (IGZO) Schottky barrier diodes (SBDs) with sputtered PtOx anodes were fabricated and annealed in oxygen at different temperatures. Critical parameters and negative bias stress (NBS) stability of SBDs with different annealing temperatures are investigated. With the annealing temperature increases, the barrier height and rectification ratio of the SBDs exhibited a rising-then-declining trend, while the ideality factor slightly increased until 200 °C. The SBDs show up overall reliability except for a leakage current rising trend under light, which can be attributed to free electron generation from the ionized oxygen vacancy. Among all the SBDs, the 175 °C annealed ones exhibited the best overall performance, including a high barrier height of 0.89 eV, an ideality factor of 1.14, and a large rectification ratio of over 108. Compared to the initial SBDs, the annealed ones showed up great improvement in NBS stability except for the 200 °C annealed ones, which was permanently degraded and not able to recover to original states. According to experimental result analysis and IGZO material characteristics, a stability model based on the subgap trap transition from V O 2 + to VO and new V O 2 + creation was proposed, which applies to both the short-term and long-term NBS tests. The results above demonstrate that oxygen annealing at appropriate temperature is an effective method to improve both device performance and NBS stability for PtOx–IGZO SBDs. [ABSTRACT FROM AUTHOR]

β-Ga2O3 is of great interest for power electronic devices with efficiency beyond current generation Si, 4H-SiC, and GaN devices due to its large breakdown electric field of ∼8 MV/cm. However, taking advantage of this large field strength in power diodes requires device engineering to reduce leakage current that arises at high electric fields. In this work, we elucidate the current transport mechanisms of metal/TiO2/β-Ga2O3 diodes, showing that thermionic emission is an excellent descriptor of current in forward and reverse bias. It is shown that tunneling current is greatly suppressed, and consequently, that the diodes with the TiO2 interlayer can block orders of magnitude more current than Schottky barrier diodes with the same barrier heights. Finally, a 1200 V diode structure is designed based on the derived transport models, and calculated on- and off-state current characteristics closely align with those of state-of-the-art 4H-SiC commercial devices, indicating that this diode structure is ready to enable the realization of β-Ga2O3 power diodes. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive investigation of the impact of the deposition temperature on the HfxZr1−xO2 (HZO) ferroelectric layer of ferroelectric random access memory with TaN electrodes. This investigation mainly focuses on its electrical characteristics and compares the differences. It is revealed that the deposition temperature plays a crucial role in determining the crystal structure of HZO, which can exhibit a combination of tetragonal and orthorhombic phases or exist solely in one of the two phases. Furthermore, the grain size of HZO varies with the deposition temperature. These findings correspond well to the electrical measurement results, including leakage current, polarization, capacitance, and reliability tests. The study tracks the phase transition process during the operation of switching cycles when the phase transition process can be monitored as well. To better understand the observed differences, physical models that shed light on the underlying mechanisms affected by deposition temperature are proposed at the end of the article. [ABSTRACT FROM AUTHOR]

Gallium oxide (G a 2 O 3 ) is a promising ultra-wide bandgap material offering a large bandgap (> --> 4.7 eV) and high critical electric fields. The increasing demand for electronic devices for high-power applications in electric automobiles, high-performance computing, green energy technologies, etc., requires higher voltages and currents with enhanced efficiency. Vertical transistors, such as fin-shaped field-effect transistors (FinFETs) have emerged to meet the growing need with improved current handling capabilities, reduced resistance, and enhanced thermal performance. However, to fully exploit the Ga 2 O 3 power transistors, precise and reliable physics-driven models are crucial. Therefore, a comprehensive surface potential model has been developed in this work for a vertical Ga 2 O 3 FinFET. The electric potential across the channel is explained by analyzing the two-dimensional (2D) Poisson equation employing parabolic approximation. Such a surface potential model is instrumental in determining the performance of the Ga 2 O 3 FinFET as it affects the threshold voltage, the drain current, and fringing capacitance. Exploiting the surface potentials, a fringing capacitance model is derived which is crucial in analyzing the speed of the device in compact integrated circuits. In addition, statistical analysis of the Ga 2 O 3 FinFET using the Monte Carlo simulation technique is performed to determine the leakage current fluctuation due to doping variations. The validation of the analytical model with experimental results confirms the effectiveness and prospects of the developed models in the rapid development and characterization of next-generation high-performance vertical Ga 2 O 3 power transistors. [ABSTRACT FROM AUTHOR]

We have attained low leakage current, low interfacial traps, and low border traps by effectively passivating both p- and n-In0.53Ga0.47As (InGaAs) surfaces using the same gate dielectrics of ultra-high-vacuum deposited Al2O3/Y2O3. Gate leakage currents below 2 × 10−7 A/cm2 at gate fields of ±4 MV/cm were obtained after 800 °C rapid thermal annealing, demonstrating the intactness of the interface and heterostructure. Negligibly small frequency dispersions in the capacitance–voltage (C–V) characteristics of p- and n-type metal-oxide-semiconductor capacitors (MOSCAPs) were obtained from accumulation, flatband, to depletion as measured from 300 K to 77 K, indicative of low border and interfacial trap density; the C–V frequency dispersions in the accumulation region are 1.5%/dec (300 K) and 0.19%/dec (77 K) for p-InGaAs, and 2.2%/dec (300 K) and 0.97%/dec (77 K) for n-InGaAs. Very low interfacial trap densities (Dit's) of (1.7–3.2) × 1011 eV−1cm−2 and (6.7–8.5) × 1010 eV−1cm−2, as extracted from the conductance method, were achieved on p- and n-InGaAs MOSCAPs, respectively. [ABSTRACT FROM AUTHOR]

It is a formidable challenge to find the minority carrier recombination lifetime in low-dimensional devices as low-dimensionality increases the surface recombination rate and often reduces the recombination lifetime to a scale of picoseconds. In this work, we demonstrated a simple but powerful method to quantitatively probe the minority carrier recombination lifetime in silicon nanowires or microwires by fitting the experimental photoresponses with our recently established analytical photoresponse principle of photoconductors. The nanowires were passivated with small molecules and Al2O3 to suppress surface recombination, which will increase the minority recombination lifetimes. As expected, the minority carrier recombination lifetime found by this approach increases by orders of magnitude. These wires were also made into PIN diodes, the leakage of which was reduced at least 1 order of magnitude after surface passivation by Al2O3. The minority recombination lifetime found from the leakage current of these devices is largely consistent with what we found from our analytical photoresponse principle. As a further step, we performed scanning photocurrent microscopy to find the minority diffusion length from which we found that the minority recombination lifetime is close to what we found from the analytical photoresponses. In short, this work validated that our analytical response principle is a reliable method to find the minority recombination lifetime in low-dimensional semiconductors. [ABSTRACT FROM AUTHOR]

We have analyzed and modeled the reverse-biased gate leakage current in a Schottky-gate AlGaN/GaN high electron mobility transistor. While the Poole–Frenkel emission current along conductive threading dislocations dominates at low negative gate bias, the trap-assisted tunneling of thermally energized electrons and the thermal emission of electrons from threading dislocations aided by dislocation-related states at multiple energy levels within the AlGaN bandgap are dominant at moderate to large reverse bias. Additionally, deep trap levels of high density localized near the gate/AlGaN interface cause significant leakage at 473 K at low to moderate reverse bias, which could be specific to the device we have analyzed. We extracted about 10 12 cm − 2 traps near the AlGaN/GaN interface from the difference of the barrier layer electric field profile obtained from the experimental high-frequency capacitance–gate voltage and the one needed for final matching. The thermionic- and the thermionic field-emission currents are considerably low; the latter, however, dominates in the defect-free case. Finally, the simulation framework we developed here helped us identify various conduction mechanisms contributing to the reverse-biased gate leakage and the density and electronic structure of the responsible defects. [ABSTRACT FROM AUTHOR]

Lead-free piezoelectric (K, Na)NbO3 (KNN) is considered one of the promising candidates for the replacement of Pb(ZrxTi1−x)O3. Several studies underlined the issue of K and Na volatility with increasing deposition temperatures, leading to high leakage currents in thin films, which still represents a major drawback for applications. This paper shows how epitaxial growth with concomitant preferred orientation of KNN films on niobium-doped strontium titanate (Nb:STO) depends on growth temperature and substrate strain. A preferred out-of-plane polar (001) orientation of KNN is obtained at high temperatures (>600 °C), while (100) orientation is dominant for lower ones. The (001) orientation is forced out-of-plane due to the sizeable in-plane stress derived from a negative lattice mismatch of pseudo-cubic KNN with respect to the underlying cubic (001) Nb:STO substrate. Moreover, we show that K-Na deficiency and high leakage of epitaxial KNN films deposited at high temperatures are accompanied by the appearance of a pattern of orthogonal spontaneous ferroelectric domains aligned to the [100] and [010] directions of Nb:STO. This pattern, visible in secondary electron microscopy, piezoforce response microscopy, and conductive atomic force microscopy images, is uncorrelated to the surface morphology. Supported by reciprocal space mapping by x-ray diffraction, this phenomenon is interpreted as the result of strain relaxation via ferroelectric domain formation related to K-Na deficient films displaying a sizable and increasing compressive strain when grown on Nb:SrTiO3. Our findings suggest that strain engineering strategies in thin films could be used to stabilize specific configurations of piezo- and ferroelectric domains. [ABSTRACT FROM AUTHOR]

A non-destructive method for detecting sub-micrometer-sized micropipes on an entire wafer surface is investigated. Since it is difficult to detect sub-micrometer-sized micropipes due to their small core size, a non-destructively and accurately detecting method is required. To solve the issue, we focus on a characteristic depression generated around micropipes, namely, line-shaped depressions. In this paper, the location of line-shaped depressions is identified by using optical inspection, and the line-shaped depressions are distinguished whether micropipes exhibit line-shaped depression or not by using mirror electron microscope observation as high-resolution inspection. The accuracy of the distinction results is confirmed by scanning electron microscope observation, and electrical characteristics of the P–N diode are fabricated using the inspected wafer. Furthermore, the sub-micrometer-sized micropipes are observed at the sites of leakage current identified by emission microscopy. Additionally, device simulation of the blocking-voltage characteristics of P–N diodes suggests that the increase in leakage current depends on the electric field at the sub-micrometer-sized micropipes, regardless of their core size. [ABSTRACT FROM AUTHOR]

We investigated leakage current characteristics affected by crystallinity and domain wall currents of epitaxial Bi5Ti3FeO15 (BTFO) thin films on Nb-doped SrTiO3 substrates. Highly a-oriented BTFO thin films, highly c-oriented BTFO thin films, and BTFO thin films with a mixture of a-oriented and c-oriented crystallinity were prepared by controlling the substrate temperature and the pulsed laser deposition deposition rate. Highly c-oriented BTFO thin films exhibited the best leakage current characteristics because the Bi2O2 layers were placed perpendicular to the c-axis to reduce leakage currents. The BTFO thin films with a mixture of a-oriented and c-oriented crystallinity showed larger leakage currents compared to highly c-oriented BTFO thin films. The current domains of the BTFO thin films corresponding to the ferroelectric domain structures were observed by a conducting atomic force microscope, and it was observed that leakage currents were formed around the domain walls. In particular, the largest leakage currents are formed at the boundaries of c-oriented domains and a-oriented domains, and these domain boundaries confirmed that the BTFO thin films with a mixture of a-oriented and c-oriented crystallinity were responsible for the largest leakage currents. [ABSTRACT FROM AUTHOR]

Due to the erratic switching phenomenon of the Si avalanche bipolar junction transistor (ABJT) in the Marx bank circuit (MBC), an explanation of the leakage current trigger mode in the overvoltage state with a lack of displacement current is proposed. There are random switching properties (i.e., switching or non-switching) in the ABJT with emitter–base shorted, triggered by a voltage ramp to the overvoltage state temporarily with dV/dt rate close to 0 V/ns. The experimental conditions and characteristics of erratic behaviors are summarized. The optical visualization of the current channel in an erratic switching state is obtained, and the corresponding physical model of the leakage current trigger mode is established. It shows that the switching event occurs with the change in the position of the conductive channel. The process of emitter electron injection is caused by the leakage current in the overvoltage state instead of the displacement current. Meanwhile, the intensity of this trigger mode is weak, and the instability of the leakage current may cause the failure of switching. The study of erratic switching is of great significance for the working reliability of MBCs and failure analysis of ABJTs. The proposed explanation is validated by the agreement between the simulation results and the experimental observations. [ABSTRACT FROM AUTHOR]

The ongoing trend towards downsizing silicon (Si)-based metal-oxide semiconductor (MOS) devices has led to constraints on the silicon dioxide (SiO 2) gate dielectric due to increased leakage current through the thin SiO 2. In this study, ytterbium oxide (Yb 2 O 3) as a high dielectric constant (k) gate oxide material was deposited on a Si substrate and subjected to annealing at different temperatures ranging from 400 to 1000oC in a nitrogen-oxygen-nitrogen ambient atmosphere. The successful formation of Yb 2 O 3 was verified using X-ray diffraction (XRD), Fourier transform infrared (FTIR), and ultraviolet–visible (UV–VIS) spectroscopy. The FTIR analysis indicated that Yb 2 O 3 gate dielectrics post-annealing exhibited Yb-O bonding due to oxygen diffusion, as well as N-O bonding and NO 3 -bonding, demonstrating the formation of a nitrogen barrier at the interface to hinder oxygen diffusion. The optical band gap values of Yb 2 O 3 gate dielectrics post-annealing ranged from 3.092 eV to 3.267 eV. Notably, the Yb 2 O 3 gate dielectric annealed at 800 °C showed no breakdown within the 0–3 V range across all samples. The acquisition of a high k value of 19.40 and a low effective oxide charge (Q eff) of 5.32 x 1011 cm−2, along with the superior I-V characteristics, suggest that the Yb 2 O 3 gate dielectric annealed at 800oC has the potential to be employed for next generation MOS applications. [ABSTRACT FROM AUTHOR]

Impact ionization originated by the buffer leakage current, together with high electric fields ( > 3 MV cm−1) at the anode corner of the isolating trenches, has been identified as the failure mechanism of shaped planar GaN Gunn diodes when biased above 20 V, so that no evidence of Gunn oscillations in fabricated devices has been observed yet. In order to avoid the avalanche, we propose the addition of a Schottky substrate terminal, which, by means of Monte Carlo simulations, has been confirmed to be able to suppress such not-desired leakage current when applying a negative substrate bias. When the substrate bias is positive, impact ionization is also reduced due to the lower electric field at the hotspot, but a vertical cathode-substrate current degrades the device operation. In order to avoid such current, we propose the use a MIS configuration for the substrate contact, which is the optimal solution. [ABSTRACT FROM AUTHOR]

In this study, 236 nm AlGaN-based deep ultraviolet (DUV) micro-LEDs with different sized P-contact areas are designed and fabricated, and the sidewalls are restored by a wet chemical treatment method with KOH solution. The results reveal that proper KOH treatment can effectively remove plasma damaged materials and clearly show the formation of m -plane facets. Compared with untreated micro-LEDs, the reverse leakage current of the treated micro-LEDs under −10 V decreases by up to 91.7% and the specific contact resistivity (SCR) reduces from 6.94 Ω cm2 to 0.07 Ω cm2. The underlying mechanism is that the KOH treatment removes the sidewall defects which lead to surface nonradiative recombination sites and surface leakage. Moreover, KOH treatment also removes contamination on the P+-GaN surface and leads to lower SCR. However, a much longer treatment also destructs the 20 nm P+-GaN layer, which results in higher voltage but less DUV light absorption. As a result, the peak light output power density increases from 2.12 W cm−2 to 4.01 W cm−2, representing an 89.2% increase. Efficient enhancement of micro-LEDs is anticipated to facilitate the development of DUV micro-LEDs for maskless lithography and high-capacity DUV non-line-of-sight communication. [ABSTRACT FROM AUTHOR]

Herein, the Hf0.5Zr0.5O2/nAl2O3/Hf0.5Zr0.5O2 (HZO/nAO/HZO) nanolaminates, where n represents the thickness of AO insertion layer (IL), were fabricated via atomic layer deposition with varying AO IL thicknesses. The crystal structure, ferroelectric (FE), leakage, and fatigue properties of HZO/nAO/HZO nanolaminates were systematically investigated. The results reveal that grain size of the HZO/nAO/HZO nanolaminates reduced with increasing AO IL thickness. The remanent polarization (2Pr) values first increased and then decreased with thicker AO IL. Notably, the HZO/5AO/HZO nanolaminates exhibited a maximum 2Pr value of 35.0 μC/cm2 (@ ~ 2.67 MV/cm) when the AO IL thickness is 5 Å. This value not only surpasses that of single-layer HZO film (31.8 μC/cm2) but also exceeds the previously reported value for similar HZO-based MFIFM structures (23.6 μC/cm2 @ ~ 4.0 MV/cm). This enhancement in 2Pr is a key achievement that sets this work apart. Furthermore, the incorporation of AO IL effectively disrupts the continuous growth of HZO film, resulting in a significant reduction in leakage current by approximately two orders of magnitude, and the breakdown field is increased by 66.7%. This is critical for improving the reliability and durability of HZO-based FE devices. Therefore, the monolayer HZO film showed a prolonged wake-up effect until experiencing hard breakdown after only 4.4 × 107 cycles. Whereas, the HZO film embedded with 5 Å AO IL demonstrated enhanced endurance, achieving up to 2.5 × 109 cycles. The present work confirms that the identification of an optimal thickness (5 Å) for the AO IL, which effectively balances the enhancement of FE properties and the reduction of leakage current, represents a significant contribution. This discovery offers valuable guidance for designing HZO-based devices to achieve optimal performance. [ABSTRACT FROM AUTHOR]

GaN is rapidly gaining attention for implementation in power electronics but is still impacted by its high density of threading dislocations (TDs), which have been shown to facilitate current leakage through devices limiting their performance and reliability. Here, we discuss a novel implementation of photoluminescence (PL) imaging to study TDs in regions within vertically structured p-i-n GaN (PIN) diodes consisting of metalorganic chemical vapor deposition (MOCVD) epitaxial layers grown on ammonothermal GaN (am-GaN) substrates. PL imaging with a sub-bandgap excitation energy (3.1 eV) reveals TDs with excellent clarity in three dimensions within the am-GaN substrate. Galvanometric-driven PL imaging allows the microstructure of hundreds of devices to be characterized in a single session, enhancing the screening process through the addition of device specific TD location tracking and density mapping. The visibility, structural characteristics, luminescent nature and evolution of TDs through the GaN growth process are described, potentially providing the ability to define TD structures associated with leakage current. [ABSTRACT FROM AUTHOR]

Summary: As the traditional transformerless three‐phase (TTP) inverters have the shoot‐through and common mode leakage current (CMLC) problems, as well as not being able to realize the buck‐boost conversion, topology derivation and control method of high‐reliability buck‐boost double‐grounded TTP inverters are proposed. These topologies consist of two‐port or three‐port converters with boost capability and three dual‐buck inverters. The two‐port or three‐port converters with boost capability provide the positive and negative bus voltages for the three dual‐buck inverters, realizing the boost conversion. The dual‐buck inverters address the shoot‐through problem. The double‐grounded structure is used to solve the CMLC problem. Dead time between switches is not needed, which reduces the complexity of the control system. Detailed topology derivation of the dual‐buck double grounded TTP inverters with boost capability is given. The operating principle, parameters design of the filters, and stability analysis of this inverter are analyzed in detail. Loss analysis of the inverter is given. The simulation and experimental results of a 750‐W TTP inverter are used to verify the theoretical analysis. [ABSTRACT FROM AUTHOR]

The THz photoresponse of four different structures of N‐ and Ga‐polar AlGaN/GaN plasma wave high‐electron‐mobility transistors (HEMTs) has been comparatively investigated. Based on these results, an improved N‐polar plasma wave HEMT detector is proposed: an AlGaN cap layer is introduced in the standard N‐polar HEMT, so as to obtain a lower gate leakage current, thus improving the operating characteristics of plasma wave HEMT. The results show that the responsivity of the improved N‐polar HEMT obtains a significant improvement and as the Al component of AlGaN cap layer increases, the noise equivalent power of the improved N‐polar HEMT has also been optimized. [ABSTRACT FROM AUTHOR]

The morphotropic phase boundary (MPB) is particularly crucial for high piezoelectric performance of perovskite ferroelectrics. This study focus on the shift of MPB and its impacts on the piezoelectric properties of (1- x)Bi 0.997 La 0.003 FeO 3 - x BaTiO 3 ferroelectric ceramic. Although appropriate La doping reduces leakage current, the phase boundary is moved towards tetragonal (T) phase. By adjusting BaTiO 3 component, the concentration of rhombohedral (R) and T phase is restored back to almost equality at x = 0.295, achieving optimal piezoelectric properties (d 33 = 179 pC/N, k p = 33.06 %). Furthermore, through applying quenching on 0.30 ≤ x ≤ 0.32 samples occupied mainly by T phase, a higher d 33 value of 205 pC/N and a remarkable amplification of d 33 (about 40 %) are both realized at x = 0.32, which is ascribed to the shift of R/T phase ratio close to 1:1. These results confirm the importance of phase boundary movement and provide an effective approach for performance enhancement of BiFeO 3 -BaTiO 3 system. [ABSTRACT FROM AUTHOR]

A novel dual ON/OFF logic (ONOFIC) pull-down method is presented to reduce subthreshold leakage current in FinFET domino circuit wide OR gates at the 32 nm technology node. An ONOFIC block is inserted in the pull-down network of dynamic and inverted blocks. The HSPICE simulator with the 32 nm BISM4 model is used for the simulation of the proposed work. The outcome of the CLIL (clock is low and inputs are low) state is most effective in reducing the subthreshold leakage current at low and high temperatures. The OR2, OR4, OR8, and OR16 circuits using the proposed method cut down the subthreshold leakage power dissipation up to 48.1% for low power (LP) mode when compared to the LECTOR domino gates in CHIL (clock is high and inputs are low) state, which also reduced subthreshold leakage power dissipation up to 74% for short gate (SG) mode. Due to a lower subthreshold current when all inputs are low at low and high temperatures, the proposed dual-ONOFIC pull-down technique outperforms the ONOFIC pull-up technique in LP mode. When inputs are high at low and high temperatures, the ONOFIC pull-up technique performs better than the dual-ONOFIC pull-down technique. [ABSTRACT FROM AUTHOR]

This study investigates the structural, electrical, leakage current, and magnetic characteristics of the double perovskite material Nd2NiTiO6 synthesized through the sol–gel citrate auto‐ignition method. The Rietveld refinement of the X‐ray diffraction patterns confirmed a monoclinic symmetry (space group P21/n) with an ordered arrangement of alternate NiO6 and TiO6 octahedra. Impedance spectroscopic analysis exhibited the material's non–Debye‐type relaxation mechanism and semi‐conductive nature. AC conduction analysis revealed that the conduction of charge carriers occurs via the nonoverlapping small polaron hopping mechanism, consistent with Mott's variable range hopping model. Temperature‐ and frequency‐dependent dielectric measurements were interpreted using the Maxwell–Wagner interfacial polarization model. The analysis of thermal‐ and field‐dependent leakage currents established that conduction is ohmic, which the Schottky barrier model explains. Studies on magnetization ruled out the presence of magnetic ordering connected to indirect interaction between Ni2+ ions via Ti4+ ions and the rare‐earth cation (Nd3+) moment. [ABSTRACT FROM AUTHOR]

Incorporating specific defects into complex oxides facilitates the exploration of exotic phenomena and novel functionalities based on the intricate coupling between the defects and lattice/charge. However, methods for maximizing the density of specific defects while enhancing the desired properties have been rarely explored. In this study, the effect of N+ ion bombardment‐driven specific defects on the properties of bismuth ferrite (BFO) thin films was investigated. Furthermore, atomic structure characterization and computational processing revealed the displacement and orientation of the Fe atoms, which are linearly related to the degree of polarization. The ion bombardment introduced deep‐level trap states within the lattice, leading to a significant reduction in the leakage current and improved insulation performance of the films. By precisely engineering the defect content through N+ ion bombardment, the pure BFO thin films with remarkable and stable ferroelectric properties (remnant polarization, Pr = ∼116.8 µC·cm−2; leakage current, J = ∼1.5 × 10−8 A·cm−2) were fabricated. This innovative defect engineering‐based approach enables the customization and optimization of local ferroelectric order parameters, thereby establishing a solid foundation for designing functionalities across various functional material systems. [ABSTRACT FROM AUTHOR]

High leakage current density and relatively low piezoelectric activity have become one of the main obstacles to expanding the practical application of Bi4Ti3O12 (BIT) high-temperature piezoelectric ceramics. Although ion doping can improve electrical resistivity and piezoelectric response, it often lowers the Curie temperature. In this work, by introducing CaBi2Nb2O9 (CBN) with higher Curie temperature to BIT, a composite ceramic (1−x)BIT-xCBN was designed, and the effect of CBN content on the structure and electrical properties of the ceramics was investigated. With the increase in the x value, the intensity of the highest peak (117) gradually decreased until disappearing, while the intensity of peak (115) gradually increased, and the X-ray diffraction (XRD) refinement results showed that some non-stoichiometric compounds, Bi1.74Ti2O6.624 and Ca0.5Bi2.5Ti0.5Nb1.5O9, were produced. The sheet-like grains were effectively suppressed, while the granular grains became prominent with high CBN doping content, which should contribute to improving the electrical resistivity of ceramics. The optimal electrical properties were obtained in 0.8BIT-0.2CBN composite ceramics as follows: the piezoelectric coefficient d33 = 13.8 pC/N, the Curie temperature TC = 765°C, and the electrical resistivity ρdc = 8.52 × 105 Ω·cm (@ 500°C). In addition, the d33 maintained 89.1% of the initial value after annealing at 550°C, showing good thermal stability for high-temperature sensing applications. [ABSTRACT FROM AUTHOR]

A novel AlGaN/GaN high-electron mobility transistor (HEMT) is put forward to promote its breakdown characteristics and anti-single-event transient (SET) effect. The features of the proposed device are a hybrid GaN/AlN buffer layer and a uniform-groove high-k passivation layer between the gate and drain electrodes (HGKB-HEMT). First, the uniform-groove high-k passivation layer not only reduces the peak electric field at the gate edges, but also modulates the electric field distribution between the gate and drain. Therefore, the breakdown voltage (BV) and the anti-SET effect show a great improvement. Second, the buffer leakage current was effectively reduced by the hybrid buffer layer, resulting in a further increase in the BV. The BV of the HGKB-HEMT reached 1672 V, which is 82.7% higher than the conventional GaN HEMT, and the peak drain current induced by the SET effect of the HGKB-HEMT decreased by 60.7% at VDS = 50 V. Moreover, the channel current of the HGKB-HEMT increased slightly and the on-state resistance decreased. [ABSTRACT FROM AUTHOR]

Pristine ZnO and Sm-doped ZnO nanoparticles were synthesized using a wet chemical co-precipitation technique. The morphological and structural characteristics of pristine and Sm-doped ZnO were studied by field-emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) techniques. Increases in lattice parameters, interplanar spacing, and volume was observed from the XRD patterns compared to its JCPDS card. Crystallite size, dislocation density, deformation stress, lattice strain, and energy density for both pristine and Sm-ZnO nanoparticles were calculated using Scherrer and Williamson–Hall (W–H) methods. An energy bandgap reduction was observed in the Sm-doped ZnO (Eg ~ 2.7 eV), which played a crucial role in explaining the increased leakage currents in Sm-ZnO. The Sm-doped ZnO nanoparticles exhibited a remnant polarization (Pr ~ 0.163 µC/cm2) and a coercive field (Ec ~ 25.33 kV/cm). Current–voltage (I–V) characteristics show maximum current generated on applying varying voltages (Vmax = 40 V, Imax = ~600 μA). Frequency- and temperature-dependent dielectric studies were conducted to examine the change in the values of the dielectric constant and dielectric loss with the variation in frequency and temperature. The Sm-doped ZnO-based nanogenerator generated an output voltage ~ 400 mV at tapping force of ~ 0.02 kgf, which makes it a prominent candidate for self-powered devices. [ABSTRACT FROM AUTHOR]

This study investigates the structural, electrical, leakage current, and magnetic characteristics of the double perovskite material Nd2NiTiO6 synthesized through the sol–gel citrate auto‐ignition method. The Rietveld refinement of the X‐ray diffraction patterns confirmed a monoclinic symmetry (space group P21/n) with an ordered arrangement of alternate NiO6 and TiO6 octahedra. Impedance spectroscopic analysis exhibited the material's non–Debye‐type relaxation mechanism and semi‐conductive nature. AC conduction analysis revealed that the conduction of charge carriers occurs via the nonoverlapping small polaron hopping mechanism, consistent with Mott's variable range hopping model. Temperature‐ and frequency‐dependent dielectric measurements were interpreted using the Maxwell–Wagner interfacial polarization model. The analysis of thermal‐ and field‐dependent leakage currents established that conduction is ohmic, which the Schottky barrier model explains. Studies on magnetization ruled out the presence of magnetic ordering connected to indirect interaction between Ni2+ ions via Ti4+ ions and the rare‐earth cation (Nd3+) moment. [ABSTRACT FROM AUTHOR]

2D materials are extensively employed in the fabrication of high‐performance photodetectors owing to their exceptional physical properties. However, most 2D material photodetectors fail to sustain high gain under intense illumination due to the limited intrinsic trap states. Here, an n‐n type Bi2O2Se/SnSe2 van der Waals tunneling heterojunction photodetector with a detection range from visible to near‐infrared (VIS‐NIR) is presented. Under reverse bias, the heterojunction induces a significant electron barrier and hole potential well, ensuring low leakage current and ample hole defect states. Therefore, the photodetector demonstrated a responsivity of 1636.3 AW−1 and a detectivity of 1.39 × 1014 Jones under 660 nm illumination, maintaining a tunable linear dynamic range (LDR) of ≈74.7 dB. This performance is attributed to the hole potential well‐suppressing the recombination of photogenerated carriers, thereby enhancing the device's gain. Furthermore, the tunneling of photogenerated electrons within the heterojunction's space charge region under bias enables rapid response (75.1 and 15.6 µs). In summary, the study introduces a novel strategy to overcome the limited detection capabilities of 2D devices under intense illumination, characterized by outstanding linearity for rapid detection and high‐resolution imaging. [ABSTRACT FROM AUTHOR]

Multiferroic materials, which exhibit coupled ferroelectric and magnetic properties, hold immense promise for multifunctional device applications. Here, a multistep synthesis method, involving chemical synthesis, mechanical milling, and Spark Plasma Sintering, was utilized to fabricate (1-x)BaTiO3-xCoFe2O4 (BTO-CFO) compacted ceramics composites with x = 0.1, 0.2, 0.3, and 0.4. Controlled high pressure and pulsed current facilitated rapid densification, yielding high-density fine microstructures. Structural analysis confirmed the coexistence of tetragonal BaTiO3 (BTO) and cubic spinel CoFe2O4 (CFO) phases, forming 0–3 type multiferroic composites. Microstructural analysis revealed CFO grain clustering within the BTO matrix. The temperature-dependent magnetization curve of CFO shows an increase in magnetization within the temperature range of BTO ferroelectric phase transition, suggesting a strain-mediated magnetoelectric coupling. Temperature and frequency dependence of dielectric permittivity highlighted significant CFO conductivity contribution. Ferroelectric hysteresis and magnetoelectric coupling were observed predominantly in low CFO content samples, with differences in magnetoelectric coefficient values attributed to preferential ferroelectric polarization alignment. Our findings suggest that achieving high interface coupling is very challenging due to high leakage current from the magnetic phase. [ABSTRACT FROM AUTHOR]

Metal halide perovskites are promising candidates for gamma‐ray (γ‐ray) spectrum detectors. However, achieving high‐resolution energy spectra in single‐photon pulse‐height analysis mode remains challenging, due to the inevitable leakage currents degrade the recognizable fingerprint energies which is critical for resolving γ‐ray spectroscopy. We demonstrate under high bias voltage, a deficient contact barrier can lead to excessive surface charge injection, thereby increasing leakage current from electrodes to perovskites. Hence, we conceive to employ surface ligand engineering on perovskite single crystals to manipulate energy levels to suppress leakage current. In particular, anchoring a strong dipole ligand onto the perovskite induced surface charge‐density displacement, leading to a downward band bending and heightened the corresponding contact barrier. Consequently, the strategy minimized the detectors' leakage current by an order of magnitude, to as low as 44 nA cm−2 at −100 V. The resulting detectors show a significant improvement in energy resolution, 3.9 % for 22Na 511 keV γ‐rays has been achieved at room temperature. The resulting detector further resolves each fingerprint energy for 152Eu γ‐spectrum, representing one of the best γ‐rays perovskite detectors reported to date. Moreover, the detectors exhibited stabilized energy resolution without any degradation under a continuous electric field (1,000 V cm−1) for over 300 minutes, representing the longest longevity reported to date. [ABSTRACT FROM AUTHOR]

Silicone rubber (SR) is an ideal dielectric elastomer substrate due to its excellent flexibility and fast response speed. However, the innate low dielectric permittivity (ε) of SR generally requires a rather high driving voltage that restricts its widespread application. Typical attempts to increase ε of SR usually deteriorate either its flexibility or electrical stability. Herein, conductive multi‐walled carbon nanotube (MWCNT) were first surface modified with polyphenols (PNs) (MWCNT@PNs), aiming to facilitate its well dispersion within SR matrix, which may maintain the softness and electrical stability of SR via suppressing concentrated physical crosslinking and local leakage current flow. Then, five‐layered MWCNT@PNs/SR composites were prepared with the outer two insulating layers of SR while middle three dielectric layers of MWCNT@PNs filled SR. The multilayered structure further hindered the formation of conductive pathways through the composites, promising a high breakdown strength of the composites. Therefore, the multilayered MWCNT@PNs/SR composites exhibited increased ε, maintained low Young's modulus and electrical breakdown strength compared with pure SR of the same five‐layered structure. Among them, the composite with uniformly distributed MWCNT@PNs (m‐1: 1: 1) showed a highest actuation strain of 11.9% (at 19.6 kV mm−1), which was 4.1 times higher than that of SR (2.9% at 19.1 kV mm−1). [ABSTRACT FROM AUTHOR]

BiFeO 3 (BF) based ceramics are inspiring great interest in advanced pulsed power applications owing to their giant spontaneous polarization, meanwhile limited by the significant leakage current. In this work, Sr 0.7 Bi 0.2 TiO 3 (SBT) modified 0.7BiFeO 3 -0.3BaTiO 3 (BF-BT) ternary lead-free relaxor ferroelectric ceramics are investigated to elaborate the dielectric performances, including the impedance, relaxor behavior, ferroelectric and energy storage, and strain properties. The substitution of SBT induces a phase transition from an R 3 c to an average pseudo-cubic structure and forms a secondary phase at high dopants. Simultaneously, the resistivity, electrically homogeneous, and band gaps are increased significantly, related to the inhibition of oxygen vacancy formation. Besides, the ferroelectric long-range order is disrupted, which promotes the formation of local defect fields and polar nanoregions. The structural heterogeneity for the higher doped components leads to an increased relaxation behavior with an almost hysteresis-free polarization response to external electric fields. Excellent temperature-insensitive dielectric response and promising dielectric energy storage properties in low electric fields are achieved, respectively. These results indicate that the SBT modification is an effective route in regulating the dielectric performance of bismuth ferrite based relaxors. [ABSTRACT FROM AUTHOR]

The advancement in high-performance computing technologies, including quantum and aerospace systems, necessitates components that operate efficiently at cryogenic temperatures. In this study, we demonstrate a hafnia-based ferroelectric tunnel junction (FTJ) that achieves a record-high tunneling electroresistance (TER) ratio of over 200,000 and decade-long retention characteristics. By introducing asymmetric oxygen vacancies through the strategic use of indium oxide (InOx) layer, we enhance the TER ratio without increasing off-current, addressing the longstanding issue of low on-current in hafnia-based FTJs. Unlike prior approaches that led to leakage currents, our method optimizes tunneling behavior by leveraging the differential oxygen dissociation energy between InOx and hafnium zirconium oxide (HZO). This results in asymmetric modulation of the tunnel barrier, enhancing electron tunneling in one polarization state while maintaining stability in the opposite state. Furthermore, we explore the intrinsic characteristics of the FTJ at cryogenic temperatures, where reduced thermal energy minimizes leakage currents and allows the maximization of device performance. These findings establish a new benchmark for TER in hafnia-based FTJs and provide valuable insights for the integration of these devices into advanced cryogenic memory systems. [ABSTRACT FROM AUTHOR]

This article suggests a nine‐level (9L) seven‐switch (7S) transformer‐less (TL) common‐ground (CG) switched capacitor (SC) inverter with double boosting capability. The proposed 9L7S‐CGSC‐TL inverter comprises only seven switches (7S), two diodes, three self‐balanced capacitors, and one DC source. The suggested inverter has a CG connection which eliminates ground leakage currents. Additionally, the suggested topology necessitates fewer conducting devices, thereby reducing conduction losses. The voltage across every capacitor is automatically balanced within each fundamental cycle. The proposed topology has been evaluated based on parameters such as component count, total harmonic distortion, cost, and efficiency. The proposed configuration switching sequence is governed by employing the level‐shifted pulse width modulation technique. A power loss study was conducted to determine the efficiency of the proposed switched capacitor multilevel inverter (SCMLI) under different load conditions in PLECS. The results shows that the proposed SCMLI achieves a peak efficiency of 98.17%. Further, the lifespan of the proposed SCMLI is assessed through a reliability assessment. The simulation and experimental results at different conditions are presented and elucidated. [ABSTRACT FROM AUTHOR]

This work presents a novel tape‐casting method for producing flexible, graphene‐enhanced diatomite ceramic sheets. These sheets target dielectric substrates for applications in the critical yet under‐explored, high‐frequency range. Structural and morphological analyses confirmed the incorporation of graphene nanoplatelets into the ceramics matrix, validating the efficiency of the tape‐casting process. The results show the crucial role of the composite's crystalline structure in its dielectric response, where oxygenated functional groups within the graphene nanoplatelets act as intrinsic barriers to restrict leakage current, resulting in low dielectric loss. Doping of flexible ceramic plates with graphene nanoplatelets led to significant dielectric variations of approximately 100% over a wide frequency range. The capacitance increased by 215.35%$\%$ with the addition of 10 wt.%$\%$ graphene compared to pure diatomite. Our results demonstrate the ability to adapt the framework's structural, morphological, and dielectric properties through doping with graphene in diatomite, offering promising prospects for applying flexible ceramic sheets at high frequency. [ABSTRACT FROM AUTHOR]

2D) Van der Waals ferroelectrics offer the opportunity for developing novel nanoelectronics devices. For device applications, it is necessary to generate controllable ferroelectric polarization domains and achieve non‐destructive polarization switching. However, it is very challenging to use the electric field to manipulate the domain state of ultra‐thin ferroelectric film due to the large leakage current and even electric breakdown. Here, the flexoelectric effect on the manipulation of polarization states at bending α‐In2Se3 flakes is explored via piezoresponse force microscopy (PFM). By introducing patterned Si trench substrates, the stripe micron‐scale ferroelectric domains with alternating arrangements of the out of‐plane polarization in the curved α‐In2Se3 are observed. It is found that the polarization at the bending region of α‐In2Se3 can be directly reversed by the large flexoelectric field. The controllable mechanical modulation of α‐In2Se3 ferroelectric domains opens up potential applications of ferroelectrics in strain engineering functional devices. [ABSTRACT FROM AUTHOR]

Ferroelectric transistors with a large memory window (MW) and operational stability have been of increasing interest recently. In this study, a ferroelectric thin‐film transistor (FE‐TFT) with a novel metal‐insulator‐semiconductor‐ferroelectric (MISF) structure is proposed. With the ferroelectric layer located under the semiconductor, the TFT process can be similar to a conventional coplanar structure with a SiO2 gate insulator (GI). In this work, both FE and active semiconductors are deposited by spray pyrolysis which is beneficial for large‐area and low‐cost manufacturing. The FE ZrO2 by spray pyrolysis has a nanocrystalline phase, and the semiconductor InGaO shows a polycrystalline structure. The TFT exhibits a MW of 5.6 V with an operating voltage range of −10–10 V. The device shows a low leakage current of 10−12 A, and thus the on/off ratio is >107 at VDS = 1.0 V. The device shows stable performance with increasing temperatures up to 80 °C. The endurance of the device is 5000 cycles at 0.1 Hz pulse with a negligible variation of MW less than 0.1 V, indicating excellent operational stability. [ABSTRACT FROM AUTHOR]

A new series of ladder‐type heteroarenes electro‐optic (EO) chromophores based on unique fused oligothiophene, oligofuran, and oligopyrrole bridge with a strong push–pull effect were designed, and their distinctive electric structure and nonlinear optical (NLO) properties were investigated by multiple methods, including DOS analysis, CPKS method, SOS model, TSM model, and hyperpolarizability density analysis. Interestingly, it is found that the introduction of different strengths of donor and acceptor moieties, the nature of ladder‐type heteroarenes bridge, and the medium polarity play critical roles in achieving ultra‐large hyperpolarizabilities. Encouragingly, the DN1‐6Fu‐AS1 and DN1‐6Py‐AS1 both exhibit ultra‐large βprj values (up to 12965.5 × 10−30 esu) and βtot value (up to 13238.2 × 10−30 esu), owing to their exceptionally low transitions energy and large variation of dipole moment. The DO2‐6Fu‐AO2, DO2‐6Th‐AO2, DO2‐6Fu‐AS1, and DO2‐6Th‐AS1, exhibit very deep HOMO levels, which are expected to have superior air stability and effectively prevent large leakage currents. Hirshfeld surface analysis and interaction region indicator analysis were employed to explore the noncovalent interactions in the dimer. The DO2‐6Fu‐AS1 and DO2‐6Py‐AS1 show the outstanding electro‐optical Pockels effect, and DN1‐6Fu‐AO2 exhibit large SHG responses. These unique and brand‐new push‐pull ladder‐type heteroarenes chromophores are promising candidates for chip‐scale EO modulators, and electronic and photonic devices in emerging communication, energy, analog, and digital technologies. [ABSTRACT FROM AUTHOR]

Sintering temperature is decisive for optimizing the grain boundary environment to obtain the high performance ZnO based varistor ceramic. In this work, the impacts of sintering temperature on microstructure and electrical properties of ternary Zn-Sr-Co varistor were investigated. It was found that the distribution of Sr, the critical factor to form grain boundary, was heavily sensitive to sintering temperature. The considerable Sr ions precipitated at grain boundaries and formed the clusters of SrZnO 2 while the sintering temperature increases from 1150 °C to 1190 °C. Besides, the precipitation of Sr led to the large segregation of Co at grain boundaries. The enrichment behavior of Sr and Co contributed to the optimization of grain boundaries, resulting in the enhanced barrier height. As a result, the excellent nonlinear current-voltage performances, i.e., the high nonlinear coefficient of 56.47 and the low leakage current density of 0.73 μA/cm2 were obtained in the ternary ZnO-SrCO 3 -Co 2 O 3 varistor sintered at 1190 °C. However, the grain boundary environment would be destroyed by the excessive temperature of 1210 °C, resulting in the degradation of grain boundary barrier and especially a surge in the leakage current I L from 0.73 to 92.19 μA/cm2. In addition, varying sintering temperature has the important effects on impedance and dielectric properties of the ZnO-SrCO 3 -Co 2 O 3 varistors. The findings provide new perspectives for developing the high-performance ternary ZnO-SrCO 3 -Co 2 O 3 varistor ceramics by optimizing the initial grain boundary environment at different sintering temperatures. [ABSTRACT FROM AUTHOR]

This paper studies the temperature-dependent electrical transport properties of nickel (Ni) and nickel–chromium (Ni–Cr) sputtered on n-type 4 H-SiC substrate. Barrier inhomogeneities have been found to affect the electrical parameter of the Schottky barrier diode (SBD) from 323 to 423 K temperature range, We have done current–voltage characterization of Ni and Ni–Cr Schottky junctions. The barrier height (ϕ Bo) , reverse saturation current (I r) , ideality factor (η) and series resistance (R s) were obtained from I–V characteristics of Ni and Ni–Cr and these parameters are observed to be highly dependent on temperature. It has been observed that Ni–Cr contact has exhibited better electrical characteristics as well as thermal sensitivity as compared to Ni. This may be attributed to the smaller number of barrier inhomogeneities at the Ni–Cr/4 H-SiC interface. In the temperature range from 323 to 423 K, Ni and Ni–Cr-based Schottky contacts, Following observation has been noticed (a). Schottky barrier height (SBH) increased from 1.24 to 1.37 eV and 1.15 to 1.45 eV, (b). Ideality factors reduced from 3.76 to 2.61 and 3.20 to 2.53, (c). Series resistance decreased from 10.22 to 3.37 Ω and 2.45 to 1.16 Ω , and (d). Reverse leakage current 524.88 × 10 - 12 to 79.66 × 10 - 9 A and 557.32 × 10 - 12 to 1.51 × 10 - 9 A respectively. The V–T curves for both SBDs are investigated (for the same temperature range) to calculate their thermal sensitivity (α) at 1.0 × 10 - 4 and 5 × 10 - 10 A, respectively. The V–T curves with linear behavior are used to calculate the thermal sensitivity coefficient (α) , which was found to be 7.11 to 7.93 mV/K for the Ni–Cr SBD, and 7.1 to 20.01 mV/K for the Ni/4 H-SiC contacts. The sensitivity-current (α - I) characteristics for the Ni/4 H-SiC SBD were found to be a non-linear comparison with Ni–Cr/4 H-SiC SBD, which may be attributed to the presence of a highly resistive and non-uniform coating of Ni at the interface. [ABSTRACT FROM AUTHOR]

Herein, we report electronic transport properties of transparent thin film transistors (TFTs) prepared using Sn: ZnO/ZrO2 thin films grown by dc magnetron sputtering. The fabricated devices potentially operate in low voltage mode with a high breakdown electric field. The effect of active channel length on the TFT characteristics is discussed. The high-k ZrO2 thin films were deposited at room temperature and their physical properties and their electrical characteristics such as leakage current and impedance characteristics were investigated prior to TFT fabrication. The fabricated TFTs have exhibited a current on/off ratio 105, a maximum field effect mobility of 18.30 cm2(V.s)−1 and a sub-threshold swing slope of 223 mV/dec. The average optical transmittance of the bilayers was ~ 85% in the visible region. The present results show that the chosen materials are promising for the fabrication of transparent TFTs. [ABSTRACT FROM AUTHOR]