Low Leakage Research Articles

Nitrogen-doped Ga2O3 current blocking layer using MOCVD homoepitaxy for high-voltage and low-leakage Ga2O3 vertical device fabrication

In this Letter, a high-quality and high-resistivity nitrogen (N)-doped Ga2O3 current blocking layer (CBL) is grown utilizing metal-organic chemical vapor deposition homoepitaxial technology. By using nitrous oxide (N2O) as oxygen source for Ga2O3 growth and N source for doping and controlling the growth temperature, the grown CBL can effectively achieve high (∼1019 cm−3) or low (∼1017 cm−3) N doping concentrations, as well as high crystal quality. Furthermore, the electrical properties of the developed CBL are verified at the device level, which shows that the device using the CBL can withstand bidirectional voltages exceeding 3.5 kV with very low leakage (≤1 × 10−4 A/cm2). This work can pave the way for the realization of high-voltage and low-leakage Ga2O3 vertical devices, especially metal-oxide-semiconductor field effect transistors.

Pt/β-Ga2O3 Schottky devices enabling 60 Hz half-wave rectification for power-efficient pixel display

Beta-phase gallium oxide, β-Ga2O3, in transistors and diodes has been reported due to its distinctive electrical characteristics, such as wide bandgap, low leakage current, and high breakdown electric field. However, besides such conventional basic devices, more advanced device applications using β-Ga2O3 are always necessary. Here, we report on the dynamic behavior of Pt/β-Ga2O3-based Schottky diode for power-efficient organic light emitting display (OLED). Two Schottky diodes are back-to-back connected in series to form a half-wave rectifier circuit and finally integrated with an OLED diode pixel. When AC voltage is applied to the circuit at a frequency greater than 60 Hz, blinking of the OLED light is indistinguishable to human eyes. By way of the rectifier circuit, the OLED pixel efficiently saves more than 35% of the power that should be consumed by applying DC voltage.

Elimination of dead layer in silicon particle detectors via induced electric field based charge collection

The front surface of semiconductor particle detectors typically contains undepleted recombination active regions that the impinging particles pass through before reaching the sensitive area of the device. These so-called dead layers pose a fundamental limitation for achievable energy resolutions and are unavoidable in externally doped pn-junction detectors. Here, we fabricate a silicon particle detector using an alternative method for charge collection that extends the sensitive region to the front surface of the device and minimizes the dead layer. The junction is realized by inducing an electric field at the surface of the detector using a charged thin film. Such an approach has previously been implemented in photodiodes, which have demonstrated effective collection of charge carriers from the very surface of the devices. Our detector displays low leakage currents and recombination, which allow efficient charge collection throughout the device, as demonstrated by excellent internal quantum efficiency of the device. The detector is further characterized using detection of alpha particles as a case example. We achieve 20 keV energy resolutions that are, already without extensive device optimization, on the same level with commercial externally doped silicon particle detectors. Notably, the design shows promise for detection of shallow penetrating charged particles, which is very sensitive to dead layers.

A Programmable Gate Driver Module-Based Multistage Voltage Regulation SiC MOSFET Switching Strategy

Silicon carbide (SiC) metal-oxide semiconductor field-effect transistors (MOSFETs), as a new material, have the advantages of low drain-source resistance, high thermal conductivity, low leakage current, and high switching frequency compared with silicon (Si)-based MOSFETs. Therefore, in many industrial applications, Si MOSFETs have been replaced by SiC MOSFETs. However, as the switching speed increases exponentially, some problems are amplified, the most serious of which is the overshoot of current and voltage. The increase in voltage and current slope caused by high switching speeds inevitably leads to overshoot, oscillations, and additional losses in the circuit. This paper focusses on the actual performance of the optimised switching strategy (OSS) in circuit testing and combines the existing simulation results to verify the practicability of OSS. In this paper, the optimised switching strategy is introduced first, and then, the LTspice model of SiC MOSFET is established in detail and verifies the feasibility of the OSS through half-bridge circuit simulation. Finally, the test platform is built using a programmable gate drive module (2ASC-12A1HP). Through a 400 V/30 A double-pulse test, the practicality of the OSS is verified. The experiments show that the OSS can greatly improve the switching performance of SiC MOSFETs.

Combustion-assisted low-temperature ZrO2/SnO2 films for high-performance flexible thin film transistors

We developed high-performance flexible oxide thin-film transistors (TFTs) using SnO2 semiconductor and high-k ZrO2 dielectric, both formed through combustion-assisted sol-gel processes. This method involves the exothermic reaction of fuels and oxidizers to produce high-quality oxide films without extensive external heating. The combustion ZrO2 films were revealed to have an amorphous structure with a higher proportion of oxygen corresponding to the oxide network, which contributes to the low leakage current and frequency-independent dielectric properties. The ZrO2/SnO2 TFTs fabricated on flexible substrates using combustion synthesis exhibited excellent electrical characteristics, including a field-effect mobility of 26.16 cm2/Vs, a subthreshold swing of 0.125 V/dec, and an on/off current ratio of 1.13 × 106 at a low operating voltage of 3 V. Furthermore, we demonstrated flexible ZrO2/SnO2 TFTs with robust mechanical stability, capable of withstanding 5000 cycles of bending tests at a bending radius of 2.5 mm, achieved by scaling down the device dimensions.

A Monolithically Integrated GaN-Based Light Emitting Transistor with a High On/Off Ratio and Low Gate Leakage Current

A Monolithically Integrated GaN-Based Light Emitting Transistor with a High On/Off Ratio and Low Gate Leakage Current

Barrier height modulation in Amorphous IGZO/Metal interface using Trichlorosilane-Based Self-Assembled monolayers

Amorphous InGaZnO (a-IGZO) has become a key material for thin-film transistors (TFTs) due to its high mobility, low leakage current, and optical transparency. However, the increasing demands for ultra-high-resolution displays, such as those required for virtual and augmented reality applications, pose challenges related to contact resistance and Fermi level pinning at the a-IGZO/metal interface, as TFTs are scaled down. To address these challenges, we investigated trichlorosilane-based self-assembled monolayers (SAMs) as an interfacial layer between a-IGZO and metal contacts (Al, Ag, and Ni). By employing SAMs with varying carbon chain lengths—methyl trichlorosilane (MTS), octyl trichlorosilane (OTS), and octadecyl trichlorosilane (ODTS)—we aimed to improve interface properties and reduce contact resistance. Our study comprehensively analyzed thermionic emission characteristics, including barrier height, saturation current, ideality factor, and contact resistance, across different metal electrodes. The results show that the SAM layers effectively modulate barrier height and Fermi level pinning, depending on the combination of SAM layers (MTS, OTS, and ODTS) and metal electrodes (Al, Ag, and Ni). Additionally, the study provides insights into the influence of SAM carbon chain length on direct tunneling current and interface passivation, and contributes to a deeper understanding of conduction mechanisms at a-IGZO/metal interfaces.

ENHANCING OTFS MODULATION FOR 6G THROUGH HYBRID PAPR REDUCTION TECHNIQUE FOR DIFFERENT SUB-CARRIERS

Peak-to-average power ratio (PAPR) in orthogonal time frequency space (OTFS) is vital for optimizing signal efficiency, minimizing distortion, and enhancing the performance of a beyond fifth-generation (B5G) system. The paper focuses on lowering the PAPR while retaining the bit error rate (BER) and power spectral density (PSD) for 64 and 256 sub-carriers. The PAPR is minimized by using a fractal optimization process known as selective mapping (SLM) and partial transmission sequence (PTS) at the transmitting block of the OTFS framework. The combination of SLM and PTS reduces peak power by selectively modifying the phase of transmitted symbols. SLM generates multiple versions of the signal, while PTS allocates power to these versions optimally, collectively mitigating amplitude peaks and minimizing PAPR. According to the simulation results, the suggested SLM+PTS works better than the traditional SLM and PTS, achieving low spectrum leakage and PAPR improvements of 5.5 dB and 4.9[Formula: see text]dB as well as SNR gains of 2.4[Formula: see text]dB and 2.1[Formula: see text]dB. In the future, SLM+PTS may work on lowering PAPR by making computers faster, researching adaptive algorithms, and combining machine learning methods for real-time optimization in various communication settings. Complex modeling, including fractal-based SLM and PTS approaches, provides a detailed understanding of waveform behavior and interference patterns, enabling more accurate and effective hybrid PAPR reduction techniques. This combination enhances the ability to manage to mitigate non-linear distortion across various sub-carriers, crucial for the performance and efficiency of 6G OTFS modulation.

Augmenting Rice Defenses: Exogenous Calcium Elevates GABA Levels Against WBPH Infestation

This study investigates the impact of exogenous calcium and gamma-aminobutyric acid (GABA) supplementation on rice growth and stress tolerance under white-backed planthopper (WBPH) infestation. We evaluated several phenotypic traits, including shoot/root length, leaf width, tiller number, panicle length, and relative water content, alongside physiological markers such as oxidative stress indicators, antioxidant enzymes activities, hormonal levels, and amino acids biosynthesis. Our results indicate that WBPH stress significantly reduces growth parameters but calcium and GABA supplementation markedly enhance shoot length (by 26% and 36%) and root length (by 38% and 64%), respectively, compared to WBPH-infested plants. Both supplementations also reduced oxidative stress, as evidenced by decreased H2O2 and O2•− levels and a lower electrolyte leakage. Notably, calcium and GABA treatments increased antioxidant enzyme activities, with GABA boosting catalase (CAT) activity by 800%, peroxidase (POD) by 144%, and superoxide dismutase (SOD) by 62% under WBPH stress. Additionally, calcium and GABA enhanced the accumulation of stress hormones (abscisic acid ABA) and salicylic acid (SA) and promoted stomatal closure, contributing to improved water conservation. This study reveals that calcium regulates the GABA shunt pathway, significantly increasing GABA and succinate levels in both root and shoot. Furthermore, calcium and GABA supplementation enhance the biosynthesis of key amino acids and improve ion homeostasis, particularly elevating calcium (Ca), iron (Fe), and magnesium (Mg) levels under WBPH stress. Overall, this study highlights the potential of exogenous calcium and GABA as effective strategies for enhancing rice plant tolerance to WBPH infestation by modulating various physiological and biochemical mechanisms. Further research is warranted to fully elucidate the underlying mechanisms of action.

Scalable all polymer dielectrics with self-assembled nanoscale multiboundary exhibiting superior high temperature capacitive performance

Polymers are key dielectric materials for energy storage capacitors in advanced electronics and electric power systems due to their high breakdown strengths, low loss, great reliability, lightweight, and low cost. However, their electric and dielectric performance deteriorates at elevated temperatures, making them unable to meet the rising demand for harsh-environment electronics such as electric vehicles, renewable energy, and electrified transportation. Here, we present an all-polymer nanostructured dielectric material that achieves a discharged energy density of 7.1 J/cm³ with a charge-discharge efficiency of 90% at 150°C, outperforming the existing dielectric polymers and representing more than a twofold improvement in discharged energy density compared with polyetherimide. The self-assembled nano-scale multiboundaries effectively impede the charge injection and excitation, leading to more than one order of magnitude lower leakage current density than the pristine polymer matrix PEI at high electric fields and elevated temperature. In addition, the film processing is simple, straightforward, and low cost, thus this all-polymer nanostructured dielectric material strategy is suitable for the mass production of dielectric polymer films for high-temperature capacitive energy storage.

All‐Climate Thermal Management Performance of Power Batteries Based on Double‐Layer Flexible Phase Change Materials

AbstractThermal management systems for power batteries based on phase change materials (PCM) are limited by low heat transfer efficiency, leakage issues, and high rigidity, and most of them cannot meet the needs of all‐climate thermal management. A double‐layer flexible phase change material (FPCM) sleeve structure for all‐climate thermal management is proposed in this study for the first time. Innovations in both material and design have enhanced the adaptability of the thermal management system. The outer layer FPCM achieves high thermal conductivity (4.23 W m−1 K−1) and electrical conductivity (0.95 S m−1), the inner layer FPCM achieves insulation (22.76 MΩ) and flexibility, the thermal contact resistance (TCR) between the double‐layer sleeve structure and the battery are measured to be only 0.15 °C W−1, significantly improved thermal management performance. Experimental results show that at 30 °C ambient temperature, 5 C discharge, the system reduces the maximum temperature by 14.5 °C, from 61.4 to 46.9 °C, compared to natural convection. Additionally, during heating, the system achieves heating rates of 7.0, 8.3, and 8.7 °C min−1 at −20, −10, and 0 °C, respectively, extending battery discharge duration by 32.5%, 65.9%, and 33.6%.

Stabilization of Tetragonal Phase in Hafnium Zirconium Oxide by Cation Doping for High-K Dielectric Insulators.

As electronic circuit integration intensifies, there is a rising demand for dielectric insulators that provide both superior insulation and high dielectric constants. This study focuses on developing high-k dielectric insulators by controlling the phase of the Hf0.5Zr0.5O2 (HZO) film with additional doping, utilizing yttrium (Y), tantalum (Ta), gallium (Ga), silicon (Si), and aluminum (Al) as dopants. Doping changes the ratio of tetragonal to monoclinic phases in doped HZO films, and Y-doped HZO (Y:HZO) films specifically exhibit a high tetragonal phase ratio and a dielectric constant of 40.9, indicating superior insulating properties compared to undoped HZO films. To clarify the fundamental mechanism driving the enhancement in dielectric properties, we have carried out various analyses combined with density functional theory (DFT) calculations. Through the optimization of the post-deposition annealing (PDA) process and the heterojunction structure with Al2O3, an Al2O3/Y:HZO heterojunction with a high dielectric constant and even lower leakage current compared to a single layer was developed. The thin-film transistor (TFT) with the Au/Ti/amorphous InGaZnO4 (a-IGZO)/Al2O3/YHZO/TiN heterojunction structure exhibits low subthreshold swing (SS) values within a narrow gate-source voltage (Vsg) range. This study advances knowledge on how the controlled-phase doped HZO films affect the dielectric constant and leakage current and will contribute to semiconductor technology advancements by overcoming the limitations of conventional high-k dielectric insulators.

Structural and electrical characterization of phase evolution in epitaxial Gd2O3 due to anneal temperature for silicon on insulator application

In this work, we understand the post-deposition anneal temperature effects on structural and electrical (leakage current and trap density) properties of epitaxial Gd2O3 film grown on Si (111) substrate using a cost-effective and High-Volume Manufacturing capable radio frequency sputtering method. It is found that the Rapid Thermal Annealing (RTA) at an optimum temperature of 850 °C enhances the crystallinity of the cubic phase in film. However, at higher RTA temperatures (>900 °C to 1050 °C), Si out-diffusion in Gd2O3 film is manifested as the reason for phase evolution towards the amorphous phase. The electrical characterization shows the film's low leakage current density of 100 nA/cm2. Moreover, increased breakdown voltage and field are observed with increasing RTA temperature. The frequency-dependent Capacitance-Voltage analysis shows a parallel shift accompanied by a kink at a lower frequency, indicating the presence of interface traps (Dit) with a range of time constants. After the forming gas annealing, a significant reduction in Dit is observed. The low leakage current density, low Dit and high crystallinity make Gd2O3 a promising candidate as a buried oxide in Silicon on Insulator MOSFETs.

Fast switching Ga2O3 Schottky barrier power diode with beveled-mesa and BaTiO3 field plate edge termination

Power devices rely on ideal edge termination to suppress the electric field crowding and avoid premature breakdown before the material's critical field is reached. In this work, a hybrid electric field management configuration, featuring the combination of beveled-mesa (BM) termination and high-k oxide BaTiO3 field plate (FP), was implemented in Ga2O3 Schottky barrier diodes (SBDs). This BMFP-SBD realizes a breakdown voltage (BV) of 1.7 kV with extremely low reverse leakage current, outperforming the BM terminated SBD with BV of 0.64 kV and bare SBD with BV of 0.22 kV. Based on the temperature-dependent reverse characteristics, the dominant leakage mechanism transforms from Poole–Frenkel (P–F) emission in BM-SBD to variable-range-hopping (VRH) in BMFP-SBD at high bias. In particular, under switching conditions of di/dt up to 420 A/μs, the BMFP-SBD exhibits superior dynamic switching characteristics with a short reverse recovery time of 10.1 ns, which are comparable with those in advanced commercial SiC SBDs. These findings underscore the potential of Ga2O3 SBD enabled by BM and high-k FP edge termination for high-speed and high-voltage power electronics applications.

Risk assessment of hydrogen leakage and explosion in a liquid hydrogen facility using computational analysis

In this study, the dispersion and explosion of liquid hydrogen (LH2) in leakage accidents are investigated using the Flame Accelerator Simulator (FLACS) code. The study focus was a liquid hydrogen research facility in Gimhae, South Korea. Simulations were conducted under various conditions by varying the mass flow rates (0.61 and 0.3 kg/s), directions (lateral in areas with minimal structures, lateral towards a tube trailer truck, and downward), and durations (90 and 180 s) of leakage. The results indicated that higher leakage mass flow rates produce a larger flammable cloud volume (FCV), resulting in higher maximum overpressures than that caused by lower flow rates. Downward leakage generally resulted in a larger FCV and higher overpressure than lateral leakage. The explosion characteristics were also influenced by geometry of LH2 facility, including the presence of structures in the leakage path. Contrastingly, leakage duration had a minimal effect on the maximum overpressure because an increased duration causes a greater dilution of hydrogen, only slightly expanding the FCV. According to the overpressure–impulse diagram, higher leakage flow rates cause severe health risks, approaching thresholds for lung rupture and 100% fatality. Contrary to the minor damages caused by lower leakage flow rates. High flow rates, particularly with downward leaks, can cause significant structural damage in brick buildings, potentially leading to partial demolition.

High‐Gain and Tunable Linear Photodetection in 2D Tunneling Heterostructures Through Potential Engineering

Abstract2D 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.

Design and experimental verification of a novel high-reliability variation of lateral doping (VLD) termination

Abstract A novel two-dimensional mesh-like variation of lateral doping (VLD) termination (M-VLD) is proposed, which modifies the conventional ring-shaped track VLD termination (R-VLD) mask into an interconnected mesh-like structure. The comparative simulations and experiments show that M-VLD can achieve better blocking capability and reliability than R-VLD. Vertical double diffusion MOSFET (VDMOS) with M-VLD achieves a maximum breakdown voltage ( B V max ) of 1588 V, which is 62 V higher than that of VDMOS with R-VLD. Furthermore, the devices with M-VLD exhibit lower leakage currents in 150 °C reverse-biased I − V test and successfully pass 1000 h-125 °C-1200 V high-temperature reverse bias (HTRB) test, while the devices with R-VLD fail to pass both tests.

Dual‐Phase Enabled Sinusoidal Current Anodizing for Efficient Preparation of High Specific Capacitance Anode Aluminum Foils

The anodized aluminum oxide prepared by anodizing is the core of aluminum electrolytic capacitors, and its quality determines the performance of aluminum electrolytic capacitors. The traditional direct current (t‐DC) anodizing method commonly used in industrial production today with low current density has the problems of low anodizing efficiency, poor crystallinity, and high formation constants of the oxide film. However, high current density direct current anodizing has the problems of severe defects of the oxide film and much thermal dissolution of aluminum foil. Herein, the dual‐phase enabled sinusoidal current (DESC) anodizing method is proposed for the preparation of 200 V anodized aluminum foil with much higher efficiency and performance. After testing, it is found that the alumina prepared by the DESC method has higher crystallinity and fewer defects. Consequently, the specific capacitance of the DESC sample is 23% greater than that of the t‐DC anodized sample, while the former displays a lower loss angle tangent and leakage current. Meanwhile, DESC anodizing takes 60% time less than t‐DC anodizing due to its high current density. The DESC anodizing method has been identified as a promising avenue for further investigation, exhibiting high efficiency and performance.

Enhanced Oxidation Resistance and Interface Stability of Atomic-Layer-Deposited MoNx Electrodes via TiN Passivation for DRAM Cell Capacitor Applications.

The continuous miniaturization of dynamic random-access memory (DRAM) capacitors has amplified the demand for electrode materials featuring specific characteristics, such as low resistivity, high work function, chemical stability, excellent interface quality with high-k dielectrics, and superior mechanical properties. In this study, molybdenum nitride (MoNx) films were deposited using a plasma-enhanced atomic layer deposition (PEALD) employing bis(isopropylcyclopentadienyl)molybdenum(IV) dihydride and NH3 plasma for DRAM capacitor electrode applications. Depending on the deposition temperatures of the PEALD MoNx films ranging from 200 to 400 °C, the Mo/N ratio and crystal structure varied, transitioning from the cubic NaCl-B1-type MoN phase with Mo/N ratio of 1.4 to the cubic γ-Mo2N phase with Mo/N ratio of 1.9. Notably, MoNx films grown at 400 °C exhibited low resistivity (435 μΩ·cm), a high work function (5.28 eV), and superior mechanical hardness (11.3 GPa) compared to ALD TiN films. Despite these excellent properties, the PEALD MoNx electrode demonstrated insufficient chemical stability, particularly in terms of oxidation resistance and interface quality with ALD HfxZr1-xO2 (HZO) films. This resulted in poor morphology and the formation of significant oxygen-deficient HZO layers (such as HfO2-x), leading to considerable degradation in the electrical performance of metal-insulator-metal (MIM) capacitors. To mitigate this issue, a thin (2.5-14 nm) ALD TiN layer was introduced as a passivation layer between the MoNx bottom electrode and HZO dielectric. The TiN-passivated MoNx (TiN/MoNx) electrode showed substantially enhanced oxidation resistance and reduced interfacial reactions with the HZO dielectric. Consequently, MIM capacitors with TiN/MoNx bottom electrodes demonstrated outstanding electrical performance, including excellent dielectric properties, low leakage current density, and high mechanical strength. Hence, this study proposes a promising candidates for storage nodes in the next-generation DRAM capacitors.

Chemically driven BaTiO3–CoFe2O4 nanocomposite with strong dielectric and low leakagecharacteristics for electrocatalytic water splitting reaction

The switchable electronic properties at the surface of ferroelectric nanomaterials offer possibilities for electrocatalytic hydrogen and oxygen evolution reactions, HER and OER respectively. Here, 0.5(BaTiO3)-0.5(CoFe2O4) (abbreviated as BTCF0.5) are prepared chemically. The material shows a high dielectric constant in the order of 107. Nyquist plot is consistent with non-Debye-type and negative temperature coefficient of resistance (NTCR) characteristics with low leakage current. BTCF0.5 shows superior electrocatalytic HER and OER with a low overpotential of ∼156 and ∼284 mV at current density10 mA/cm2 along with Tafel slopes of 43.37 mV/dec and 41.52 mV/dec respectively. The stability of the electrocatalyst is checked through a chronoamperometry test and up to 1000 cycles of CV both for HER and OER operations. The non-traditional behavior of the nanocomposite may make it highly desirable for usage in numerous renewable and sustainable energy-related applications in the present-day scenario.